xref: /petsc/src/snes/interface/snes.c (revision e0877f539457ad1ce8178bc0750eac5ffa490a67)
1 
2 #include <petsc/private/snesimpl.h>      /*I "petscsnes.h"  I*/
3 #include <petscdmshell.h>
4 #include <petscdraw.h>
5 
6 PetscBool         SNESRegisterAllCalled = PETSC_FALSE;
7 PetscFunctionList SNESList              = NULL;
8 
9 /* Logging support */
10 PetscClassId  SNES_CLASSID, DMSNES_CLASSID;
11 PetscLogEvent SNES_Solve, SNES_FunctionEval, SNES_JacobianEval, SNES_NGSEval, SNES_NGSFuncEval, SNES_NPCSolve, SNES_ObjectiveEval;
12 
13 #undef __FUNCT__
14 #define __FUNCT__ "SNESSetErrorIfNotConverged"
15 /*@
16    SNESSetErrorIfNotConverged - Causes SNESSolve() to generate an error if the solver has not converged.
17 
18    Logically Collective on SNES
19 
20    Input Parameters:
21 +  snes - iterative context obtained from SNESCreate()
22 -  flg - PETSC_TRUE indicates you want the error generated
23 
24    Options database keys:
25 .  -snes_error_if_not_converged : this takes an optional truth value (0/1/no/yes/true/false)
26 
27    Level: intermediate
28 
29    Notes:
30     Normally PETSc continues if a linear solver fails to converge, you can call SNESGetConvergedReason() after a SNESSolve()
31     to determine if it has converged.
32 
33 .keywords: SNES, set, initial guess, nonzero
34 
35 .seealso: SNESGetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
36 @*/
37 PetscErrorCode  SNESSetErrorIfNotConverged(SNES snes,PetscBool flg)
38 {
39   PetscFunctionBegin;
40   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
41   PetscValidLogicalCollectiveBool(snes,flg,2);
42   snes->errorifnotconverged = flg;
43   PetscFunctionReturn(0);
44 }
45 
46 #undef __FUNCT__
47 #define __FUNCT__ "SNESGetErrorIfNotConverged"
48 /*@
49    SNESGetErrorIfNotConverged - Will SNESSolve() generate an error if the solver does not converge?
50 
51    Not Collective
52 
53    Input Parameter:
54 .  snes - iterative context obtained from SNESCreate()
55 
56    Output Parameter:
57 .  flag - PETSC_TRUE if it will generate an error, else PETSC_FALSE
58 
59    Level: intermediate
60 
61 .keywords: SNES, set, initial guess, nonzero
62 
63 .seealso:  SNESSetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
64 @*/
65 PetscErrorCode  SNESGetErrorIfNotConverged(SNES snes,PetscBool  *flag)
66 {
67   PetscFunctionBegin;
68   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
69   PetscValidPointer(flag,2);
70   *flag = snes->errorifnotconverged;
71   PetscFunctionReturn(0);
72 }
73 
74 #undef __FUNCT__
75 #define __FUNCT__ "SNESSetFunctionDomainError"
76 /*@
77    SNESSetFunctionDomainError - tells SNES that the input vector to your SNESFunction is not
78      in the functions domain. For example, negative pressure.
79 
80    Logically Collective on SNES
81 
82    Input Parameters:
83 .  snes - the SNES context
84 
85    Level: advanced
86 
87 .keywords: SNES, view
88 
89 .seealso: SNESCreate(), SNESSetFunction(), SNESFunction
90 @*/
91 PetscErrorCode  SNESSetFunctionDomainError(SNES snes)
92 {
93   PetscFunctionBegin;
94   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
95   if (snes->errorifnotconverged) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"User code indicates input vector is not in the function domain");
96   snes->domainerror = PETSC_TRUE;
97   PetscFunctionReturn(0);
98 }
99 
100 #undef __FUNCT__
101 #define __FUNCT__ "SNESGetFunctionDomainError"
102 /*@
103    SNESGetFunctionDomainError - Gets the status of the domain error after a call to SNESComputeFunction;
104 
105    Logically Collective on SNES
106 
107    Input Parameters:
108 .  snes - the SNES context
109 
110    Output Parameters:
111 .  domainerror - Set to PETSC_TRUE if there's a domain error; PETSC_FALSE otherwise.
112 
113    Level: advanced
114 
115 .keywords: SNES, view
116 
117 .seealso: SNESSetFunctionDomainError(), SNESComputeFunction()
118 @*/
119 PetscErrorCode  SNESGetFunctionDomainError(SNES snes, PetscBool *domainerror)
120 {
121   PetscFunctionBegin;
122   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
123   PetscValidPointer(domainerror, 2);
124   *domainerror = snes->domainerror;
125   PetscFunctionReturn(0);
126 }
127 
128 #undef __FUNCT__
129 #define __FUNCT__ "SNESLoad"
130 /*@C
131   SNESLoad - Loads a SNES that has been stored in binary  with SNESView().
132 
133   Collective on PetscViewer
134 
135   Input Parameters:
136 + newdm - the newly loaded SNES, this needs to have been created with SNESCreate() or
137            some related function before a call to SNESLoad().
138 - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()
139 
140    Level: intermediate
141 
142   Notes:
143    The type is determined by the data in the file, any type set into the SNES before this call is ignored.
144 
145   Notes for advanced users:
146   Most users should not need to know the details of the binary storage
147   format, since SNESLoad() and TSView() completely hide these details.
148   But for anyone who's interested, the standard binary matrix storage
149   format is
150 .vb
151      has not yet been determined
152 .ve
153 
154 .seealso: PetscViewerBinaryOpen(), SNESView(), MatLoad(), VecLoad()
155 @*/
156 PetscErrorCode  SNESLoad(SNES snes, PetscViewer viewer)
157 {
158   PetscErrorCode ierr;
159   PetscBool      isbinary;
160   PetscInt       classid;
161   char           type[256];
162   KSP            ksp;
163   DM             dm;
164   DMSNES         dmsnes;
165 
166   PetscFunctionBegin;
167   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
168   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
169   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
170   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");
171 
172   ierr = PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);CHKERRQ(ierr);
173   if (classid != SNES_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONG,"Not SNES next in file");
174   ierr = PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);CHKERRQ(ierr);
175   ierr = SNESSetType(snes, type);CHKERRQ(ierr);
176   if (snes->ops->load) {
177     ierr = (*snes->ops->load)(snes,viewer);CHKERRQ(ierr);
178   }
179   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
180   ierr = DMGetDMSNES(dm,&dmsnes);CHKERRQ(ierr);
181   ierr = DMSNESLoad(dmsnes,viewer);CHKERRQ(ierr);
182   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
183   ierr = KSPLoad(ksp,viewer);CHKERRQ(ierr);
184   PetscFunctionReturn(0);
185 }
186 
187 #include <petscdraw.h>
188 #if defined(PETSC_HAVE_SAWS)
189 #include <petscviewersaws.h>
190 #endif
191 #undef __FUNCT__
192 #define __FUNCT__ "SNESView"
193 /*@C
194    SNESView - Prints the SNES data structure.
195 
196    Collective on SNES
197 
198    Input Parameters:
199 +  SNES - the SNES context
200 -  viewer - visualization context
201 
202    Options Database Key:
203 .  -snes_view - Calls SNESView() at end of SNESSolve()
204 
205    Notes:
206    The available visualization contexts include
207 +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
208 -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
209          output where only the first processor opens
210          the file.  All other processors send their
211          data to the first processor to print.
212 
213    The user can open an alternative visualization context with
214    PetscViewerASCIIOpen() - output to a specified file.
215 
216    Level: beginner
217 
218 .keywords: SNES, view
219 
220 .seealso: PetscViewerASCIIOpen()
221 @*/
222 PetscErrorCode  SNESView(SNES snes,PetscViewer viewer)
223 {
224   SNESKSPEW      *kctx;
225   PetscErrorCode ierr;
226   KSP            ksp;
227   SNESLineSearch linesearch;
228   PetscBool      iascii,isstring,isbinary,isdraw;
229   DMSNES         dmsnes;
230 #if defined(PETSC_HAVE_SAWS)
231   PetscBool      issaws;
232 #endif
233 
234   PetscFunctionBegin;
235   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
236   if (!viewer) {
237     ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&viewer);CHKERRQ(ierr);
238   }
239   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
240   PetscCheckSameComm(snes,1,viewer,2);
241 
242   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
243   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
244   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
245   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);CHKERRQ(ierr);
246 #if defined(PETSC_HAVE_SAWS)
247   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&issaws);CHKERRQ(ierr);
248 #endif
249   if (iascii) {
250     SNESNormSchedule normschedule;
251 
252     ierr = PetscObjectPrintClassNamePrefixType((PetscObject)snes,viewer);CHKERRQ(ierr);
253     if (!snes->setupcalled) {
254       ierr = PetscViewerASCIIPrintf(viewer,"  SNES has not been set up so information may be incomplete\n");CHKERRQ(ierr);
255     }
256     if (snes->ops->view) {
257       ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
258       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
259       ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
260     }
261     ierr = PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, maximum function evaluations=%D\n",snes->max_its,snes->max_funcs);CHKERRQ(ierr);
262     ierr = PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%g, absolute=%g, solution=%g\n",(double)snes->rtol,(double)snes->abstol,(double)snes->stol);CHKERRQ(ierr);
263     ierr = PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",snes->linear_its);CHKERRQ(ierr);
264     ierr = PetscViewerASCIIPrintf(viewer,"  total number of function evaluations=%D\n",snes->nfuncs);CHKERRQ(ierr);
265     ierr = SNESGetNormSchedule(snes, &normschedule);CHKERRQ(ierr);
266     if (normschedule > 0) {ierr = PetscViewerASCIIPrintf(viewer,"  norm schedule %s\n",SNESNormSchedules[normschedule]);CHKERRQ(ierr);}
267     if (snes->gridsequence) {
268       ierr = PetscViewerASCIIPrintf(viewer,"  total number of grid sequence refinements=%D\n",snes->gridsequence);CHKERRQ(ierr);
269     }
270     if (snes->ksp_ewconv) {
271       kctx = (SNESKSPEW*)snes->kspconvctx;
272       if (kctx) {
273         ierr = PetscViewerASCIIPrintf(viewer,"  Eisenstat-Walker computation of KSP relative tolerance (version %D)\n",kctx->version);CHKERRQ(ierr);
274         ierr = PetscViewerASCIIPrintf(viewer,"    rtol_0=%g, rtol_max=%g, threshold=%g\n",(double)kctx->rtol_0,(double)kctx->rtol_max,(double)kctx->threshold);CHKERRQ(ierr);
275         ierr = PetscViewerASCIIPrintf(viewer,"    gamma=%g, alpha=%g, alpha2=%g\n",(double)kctx->gamma,(double)kctx->alpha,(double)kctx->alpha2);CHKERRQ(ierr);
276       }
277     }
278     if (snes->lagpreconditioner == -1) {
279       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is never rebuilt\n");CHKERRQ(ierr);
280     } else if (snes->lagpreconditioner > 1) {
281       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is rebuilt every %D new Jacobians\n",snes->lagpreconditioner);CHKERRQ(ierr);
282     }
283     if (snes->lagjacobian == -1) {
284       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is never rebuilt\n");CHKERRQ(ierr);
285     } else if (snes->lagjacobian > 1) {
286       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is rebuilt every %D SNES iterations\n",snes->lagjacobian);CHKERRQ(ierr);
287     }
288   } else if (isstring) {
289     const char *type;
290     ierr = SNESGetType(snes,&type);CHKERRQ(ierr);
291     ierr = PetscViewerStringSPrintf(viewer," %-3.3s",type);CHKERRQ(ierr);
292   } else if (isbinary) {
293     PetscInt    classid = SNES_FILE_CLASSID;
294     MPI_Comm    comm;
295     PetscMPIInt rank;
296     char        type[256];
297 
298     ierr = PetscObjectGetComm((PetscObject)snes,&comm);CHKERRQ(ierr);
299     ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
300     if (!rank) {
301       ierr = PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);CHKERRQ(ierr);
302       ierr = PetscStrncpy(type,((PetscObject)snes)->type_name,sizeof(type));CHKERRQ(ierr);
303       ierr = PetscViewerBinaryWrite(viewer,type,sizeof(type),PETSC_CHAR,PETSC_FALSE);CHKERRQ(ierr);
304     }
305     if (snes->ops->view) {
306       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
307     }
308   } else if (isdraw) {
309     PetscDraw draw;
310     char      str[36];
311     PetscReal x,y,bottom,h;
312 
313     ierr   = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
314     ierr   = PetscDrawGetCurrentPoint(draw,&x,&y);CHKERRQ(ierr);
315     ierr   = PetscStrcpy(str,"SNES: ");CHKERRQ(ierr);
316     ierr   = PetscStrcat(str,((PetscObject)snes)->type_name);CHKERRQ(ierr);
317     ierr   = PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_BLUE,PETSC_DRAW_BLACK,str,NULL,&h);CHKERRQ(ierr);
318     bottom = y - h;
319     ierr   = PetscDrawPushCurrentPoint(draw,x,bottom);CHKERRQ(ierr);
320     if (snes->ops->view) {
321       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
322     }
323 #if defined(PETSC_HAVE_SAWS)
324   } else if (issaws) {
325     PetscMPIInt rank;
326     const char *name;
327 
328     ierr = PetscObjectGetName((PetscObject)snes,&name);CHKERRQ(ierr);
329     ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRQ(ierr);
330     if (!((PetscObject)snes)->amsmem && !rank) {
331       char       dir[1024];
332 
333       ierr = PetscObjectViewSAWs((PetscObject)snes,viewer);CHKERRQ(ierr);
334       ierr = PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);CHKERRQ(ierr);
335       PetscStackCallSAWs(SAWs_Register,(dir,&snes->iter,1,SAWs_READ,SAWs_INT));
336       if (!snes->conv_hist) {
337         ierr = SNESSetConvergenceHistory(snes,NULL,NULL,PETSC_DECIDE,PETSC_TRUE);CHKERRQ(ierr);
338       }
339       ierr = PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/conv_hist",name);CHKERRQ(ierr);
340       PetscStackCallSAWs(SAWs_Register,(dir,snes->conv_hist,10,SAWs_READ,SAWs_DOUBLE));
341     }
342 #endif
343   }
344   if (snes->linesearch) {
345     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
346     ierr = SNESGetLineSearch(snes, &linesearch);CHKERRQ(ierr);
347     ierr = SNESLineSearchView(linesearch, viewer);CHKERRQ(ierr);
348     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
349   }
350   if (snes->pc && snes->usespc) {
351     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
352     ierr = SNESView(snes->pc, viewer);CHKERRQ(ierr);
353     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
354   }
355   ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
356   ierr = DMGetDMSNES(snes->dm,&dmsnes);CHKERRQ(ierr);
357   ierr = DMSNESView(dmsnes, viewer);CHKERRQ(ierr);
358   ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
359   if (snes->usesksp) {
360     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
361     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
362     ierr = KSPView(ksp,viewer);CHKERRQ(ierr);
363     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
364   }
365   if (isdraw) {
366     PetscDraw draw;
367     ierr = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
368     ierr = PetscDrawPopCurrentPoint(draw);CHKERRQ(ierr);
369   }
370   PetscFunctionReturn(0);
371 }
372 
373 /*
374   We retain a list of functions that also take SNES command
375   line options. These are called at the end SNESSetFromOptions()
376 */
377 #define MAXSETFROMOPTIONS 5
378 static PetscInt numberofsetfromoptions;
379 static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);
380 
381 #undef __FUNCT__
382 #define __FUNCT__ "SNESAddOptionsChecker"
383 /*@C
384   SNESAddOptionsChecker - Adds an additional function to check for SNES options.
385 
386   Not Collective
387 
388   Input Parameter:
389 . snescheck - function that checks for options
390 
391   Level: developer
392 
393 .seealso: SNESSetFromOptions()
394 @*/
395 PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
396 {
397   PetscFunctionBegin;
398   if (numberofsetfromoptions >= MAXSETFROMOPTIONS) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %D allowed", MAXSETFROMOPTIONS);
399   othersetfromoptions[numberofsetfromoptions++] = snescheck;
400   PetscFunctionReturn(0);
401 }
402 
403 extern PetscErrorCode  SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);
404 
405 #undef __FUNCT__
406 #define __FUNCT__ "SNESSetUpMatrixFree_Private"
407 static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
408 {
409   Mat            J;
410   KSP            ksp;
411   PC             pc;
412   PetscBool      match;
413   PetscErrorCode ierr;
414   MatNullSpace   nullsp;
415 
416   PetscFunctionBegin;
417   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
418 
419   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
420     Mat A = snes->jacobian, B = snes->jacobian_pre;
421     ierr = MatCreateVecs(A ? A : B, NULL,&snes->vec_func);CHKERRQ(ierr);
422   }
423 
424   if (version == 1) {
425     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
426     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
427     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
428   } else if (version == 2) {
429     if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
430 #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128)
431     ierr = SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);CHKERRQ(ierr);
432 #else
433     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator rutines (version 2)");
434 #endif
435   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator rutines, only version 1 and 2");
436 
437   /* attach any user provided null space that was on Amat to the newly created matrix free matrix */
438   if (snes->jacobian) {
439     ierr = MatGetNullSpace(snes->jacobian,&nullsp);CHKERRQ(ierr);
440     if (nullsp) {
441       ierr = MatSetNullSpace(J,nullsp);CHKERRQ(ierr);
442     }
443   }
444 
445   ierr = PetscInfo1(snes,"Setting default matrix-free operator routines (version %D)\n", version);CHKERRQ(ierr);
446   if (hasOperator) {
447 
448     /* This version replaces the user provided Jacobian matrix with a
449        matrix-free version but still employs the user-provided preconditioner matrix. */
450     ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);
451   } else {
452     /* This version replaces both the user-provided Jacobian and the user-
453      provided preconditioner Jacobian with the default matrix free version. */
454     if ((snes->pcside == PC_LEFT) && snes->pc) {
455       if (!snes->jacobian){ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);}
456     } else {
457       ierr = SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,0);CHKERRQ(ierr);
458     }
459     /* Force no preconditioner */
460     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
461     ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
462     ierr = PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);CHKERRQ(ierr);
463     if (!match) {
464       ierr = PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");CHKERRQ(ierr);
465       ierr = PCSetType(pc,PCNONE);CHKERRQ(ierr);
466     }
467   }
468   ierr = MatDestroy(&J);CHKERRQ(ierr);
469   PetscFunctionReturn(0);
470 }
471 
472 #undef __FUNCT__
473 #define __FUNCT__ "DMRestrictHook_SNESVecSol"
474 static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
475 {
476   SNES           snes = (SNES)ctx;
477   PetscErrorCode ierr;
478   Vec            Xfine,Xfine_named = NULL,Xcoarse;
479 
480   PetscFunctionBegin;
481   if (PetscLogPrintInfo) {
482     PetscInt finelevel,coarselevel,fineclevel,coarseclevel;
483     ierr = DMGetRefineLevel(dmfine,&finelevel);CHKERRQ(ierr);
484     ierr = DMGetCoarsenLevel(dmfine,&fineclevel);CHKERRQ(ierr);
485     ierr = DMGetRefineLevel(dmcoarse,&coarselevel);CHKERRQ(ierr);
486     ierr = DMGetCoarsenLevel(dmcoarse,&coarseclevel);CHKERRQ(ierr);
487     ierr = PetscInfo4(dmfine,"Restricting SNES solution vector from level %D-%D to level %D-%D\n",finelevel,fineclevel,coarselevel,coarseclevel);CHKERRQ(ierr);
488   }
489   if (dmfine == snes->dm) Xfine = snes->vec_sol;
490   else {
491     ierr  = DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);
492     Xfine = Xfine_named;
493   }
494   ierr = DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
495   if (Inject) {
496     ierr = MatRestrict(Inject,Xfine,Xcoarse);CHKERRQ(ierr);
497   } else {
498     ierr = MatRestrict(Restrict,Xfine,Xcoarse);CHKERRQ(ierr);
499     ierr = VecPointwiseMult(Xcoarse,Xcoarse,Rscale);CHKERRQ(ierr);
500   }
501   ierr = DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
502   if (Xfine_named) {ierr = DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);}
503   PetscFunctionReturn(0);
504 }
505 
506 #undef __FUNCT__
507 #define __FUNCT__ "DMCoarsenHook_SNESVecSol"
508 static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm,DM dmc,void *ctx)
509 {
510   PetscErrorCode ierr;
511 
512   PetscFunctionBegin;
513   ierr = DMCoarsenHookAdd(dmc,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,ctx);CHKERRQ(ierr);
514   PetscFunctionReturn(0);
515 }
516 
517 #undef __FUNCT__
518 #define __FUNCT__ "KSPComputeOperators_SNES"
519 /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
520  * safely call SNESGetDM() in their residual evaluation routine. */
521 static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,void *ctx)
522 {
523   SNES           snes = (SNES)ctx;
524   PetscErrorCode ierr;
525   Mat            Asave = A,Bsave = B;
526   Vec            X,Xnamed = NULL;
527   DM             dmsave;
528   void           *ctxsave;
529   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
530 
531   PetscFunctionBegin;
532   dmsave = snes->dm;
533   ierr   = KSPGetDM(ksp,&snes->dm);CHKERRQ(ierr);
534   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
535   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
536     ierr = DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
537     X    = Xnamed;
538     ierr = SNESGetJacobian(snes,NULL,NULL,&jac,&ctxsave);CHKERRQ(ierr);
539     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
540     if (jac == SNESComputeJacobianDefaultColor) {
541       ierr = SNESSetJacobian(snes,NULL,NULL,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
542     }
543   }
544   /* put the previous context back */
545 
546   ierr = SNESComputeJacobian(snes,X,A,B);CHKERRQ(ierr);
547   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) {
548     ierr = SNESSetJacobian(snes,NULL,NULL,jac,ctxsave);CHKERRQ(ierr);
549   }
550 
551   if (A != Asave || B != Bsave) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_SUP,"No support for changing matrices at this time");
552   if (Xnamed) {
553     ierr = DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
554   }
555   snes->dm = dmsave;
556   PetscFunctionReturn(0);
557 }
558 
559 #undef __FUNCT__
560 #define __FUNCT__ "SNESSetUpMatrices"
561 /*@
562    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()
563 
564    Collective
565 
566    Input Arguments:
567 .  snes - snes to configure
568 
569    Level: developer
570 
571 .seealso: SNESSetUp()
572 @*/
573 PetscErrorCode SNESSetUpMatrices(SNES snes)
574 {
575   PetscErrorCode ierr;
576   DM             dm;
577   DMSNES         sdm;
578 
579   PetscFunctionBegin;
580   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
581   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
582   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_PLIB,"DMSNES not properly configured");
583   else if (!snes->jacobian && snes->mf) {
584     Mat  J;
585     void *functx;
586     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
587     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
588     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
589     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
590     ierr = SNESSetJacobian(snes,J,J,0,0);CHKERRQ(ierr);
591     ierr = MatDestroy(&J);CHKERRQ(ierr);
592   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
593     Mat J,B;
594     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
595     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
596     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
597     ierr = DMCreateMatrix(snes->dm,&B);CHKERRQ(ierr);
598     /* sdm->computejacobian was already set to reach here */
599     ierr = SNESSetJacobian(snes,J,B,NULL,NULL);CHKERRQ(ierr);
600     ierr = MatDestroy(&J);CHKERRQ(ierr);
601     ierr = MatDestroy(&B);CHKERRQ(ierr);
602   } else if (!snes->jacobian_pre) {
603     Mat J,B;
604     J    = snes->jacobian;
605     ierr = DMCreateMatrix(snes->dm,&B);CHKERRQ(ierr);
606     ierr = SNESSetJacobian(snes,J ? J : B,B,NULL,NULL);CHKERRQ(ierr);
607     ierr = MatDestroy(&B);CHKERRQ(ierr);
608   }
609   {
610     KSP ksp;
611     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
612     ierr = KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);CHKERRQ(ierr);
613     ierr = DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);CHKERRQ(ierr);
614   }
615   PetscFunctionReturn(0);
616 }
617 
618 #undef __FUNCT__
619 #define __FUNCT__ "SNESMonitorSetFromOptions"
620 /*@C
621    SNESMonitorSetFromOptions - Sets a monitor function and viewer appropriate for the type indicated by the user
622 
623    Collective on SNES
624 
625    Input Parameters:
626 +  snes - SNES object you wish to monitor
627 .  name - the monitor type one is seeking
628 .  help - message indicating what monitoring is done
629 .  manual - manual page for the monitor
630 .  monitor - the monitor function
631 -  monitorsetup - a function that is called once ONLY if the user selected this monitor that may set additional features of the SNES or PetscViewer objects
632 
633    Level: developer
634 
635 .seealso: PetscOptionsGetViewer(), PetscOptionsGetReal(), PetscOptionsHasName(), PetscOptionsGetString(),
636           PetscOptionsGetIntArray(), PetscOptionsGetRealArray(), PetscOptionsBool()
637           PetscOptionsInt(), PetscOptionsString(), PetscOptionsReal(), PetscOptionsBool(),
638           PetscOptionsName(), PetscOptionsBegin(), PetscOptionsEnd(), PetscOptionsHead(),
639           PetscOptionsStringArray(),PetscOptionsRealArray(), PetscOptionsScalar(),
640           PetscOptionsBoolGroupBegin(), PetscOptionsBoolGroup(), PetscOptionsBoolGroupEnd(),
641           PetscOptionsFList(), PetscOptionsEList()
642 @*/
643 PetscErrorCode  SNESMonitorSetFromOptions(SNES snes,const char name[],const char help[], const char manual[],PetscErrorCode (*monitor)(SNES,PetscInt,PetscReal,void*),PetscErrorCode (*monitorsetup)(SNES,PetscViewer))
644 {
645   PetscErrorCode    ierr;
646   PetscViewer       viewer;
647   PetscViewerFormat format;
648   PetscBool         flg;
649 
650   PetscFunctionBegin;
651   ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,name,&viewer,&format,&flg);CHKERRQ(ierr);
652   if (flg) {
653     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
654     if (monitorsetup) {
655       ierr = (*monitorsetup)(snes,viewer);CHKERRQ(ierr);
656     }
657     ierr = SNESMonitorSet(snes,monitor,viewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
658   }
659   PetscFunctionReturn(0);
660 }
661 
662 #undef __FUNCT__
663 #define __FUNCT__ "SNESSetFromOptions"
664 /*@
665    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.
666 
667    Collective on SNES
668 
669    Input Parameter:
670 .  snes - the SNES context
671 
672    Options Database Keys:
673 +  -snes_type <type> - newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas, SNESType for complete list
674 .  -snes_stol - convergence tolerance in terms of the norm
675                 of the change in the solution between steps
676 .  -snes_atol <abstol> - absolute tolerance of residual norm
677 .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
678 .  -snes_max_it <max_it> - maximum number of iterations
679 .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
680 .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
681 .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
682 .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
683 .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
684 .  -snes_trtol <trtol> - trust region tolerance
685 .  -snes_no_convergence_test - skip convergence test in nonlinear
686                                solver; hence iterations will continue until max_it
687                                or some other criterion is reached. Saves expense
688                                of convergence test
689 .  -snes_monitor [ascii][:filename][:viewer format] - prints residual norm at each iteration. if no filename given prints to stdout
690 .  -snes_monitor_solution [ascii binary draw][:filename][:viewer format] - plots solution at each iteration
691 .  -snes_monitor_residual [ascii binary draw][:filename][:viewer format] - plots residual (not its norm) at each iteration
692 .  -snes_monitor_solution_update [ascii binary draw][:filename][:viewer format] - plots update to solution at each iteration
693 .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
694 .  -snes_monitor_lg_range - plots residual norm at each iteration
695 .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
696 .  -snes_fd_color - use finite differences with coloring to compute Jacobian
697 .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
698 -  -snes_converged_reason - print the reason for convergence/divergence after each solve
699 
700     Options Database for Eisenstat-Walker method:
701 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
702 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
703 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
704 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
705 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
706 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
707 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
708 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
709 
710    Notes:
711    To see all options, run your program with the -help option or consult
712    Users-Manual: ch_snes
713 
714    Level: beginner
715 
716 .keywords: SNES, nonlinear, set, options, database
717 
718 .seealso: SNESSetOptionsPrefix()
719 @*/
720 PetscErrorCode  SNESSetFromOptions(SNES snes)
721 {
722   PetscBool      flg,pcset,persist,set;
723   PetscInt       i,indx,lag,grids;
724   const char     *deft        = SNESNEWTONLS;
725   const char     *convtests[] = {"default","skip"};
726   SNESKSPEW      *kctx        = NULL;
727   char           type[256], monfilename[PETSC_MAX_PATH_LEN];
728   PetscErrorCode ierr;
729   PCSide         pcside;
730   const char     *optionsprefix;
731 
732   PetscFunctionBegin;
733   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
734   ierr = SNESRegisterAll();CHKERRQ(ierr);
735   ierr = PetscObjectOptionsBegin((PetscObject)snes);CHKERRQ(ierr);
736   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
737   ierr = PetscOptionsFList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);CHKERRQ(ierr);
738   if (flg) {
739     ierr = SNESSetType(snes,type);CHKERRQ(ierr);
740   } else if (!((PetscObject)snes)->type_name) {
741     ierr = SNESSetType(snes,deft);CHKERRQ(ierr);
742   }
743   ierr = PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,NULL);CHKERRQ(ierr);
744   ierr = PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,NULL);CHKERRQ(ierr);
745 
746   ierr = PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,NULL);CHKERRQ(ierr);
747   ierr = PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,NULL);CHKERRQ(ierr);
748   ierr = PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,NULL);CHKERRQ(ierr);
749   ierr = PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,NULL);CHKERRQ(ierr);
750   ierr = PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,NULL);CHKERRQ(ierr);
751   ierr = PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,NULL);CHKERRQ(ierr);
752 
753   ierr = PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);CHKERRQ(ierr);
754   if (flg) {
755     ierr = SNESSetLagPreconditioner(snes,lag);CHKERRQ(ierr);
756   }
757   ierr = PetscOptionsBool("-snes_lag_preconditioner_persists","Preconditioner lagging through multiple solves","SNESSetLagPreconditionerPersists",snes->lagjac_persist,&persist,&flg);CHKERRQ(ierr);
758   if (flg) {
759     ierr = SNESSetLagPreconditionerPersists(snes,persist);CHKERRQ(ierr);
760   }
761   ierr = PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);CHKERRQ(ierr);
762   if (flg) {
763     ierr = SNESSetLagJacobian(snes,lag);CHKERRQ(ierr);
764   }
765   ierr = PetscOptionsBool("-snes_lag_jacobian_persists","Jacobian lagging through multiple solves","SNESSetLagJacobianPersists",snes->lagjac_persist,&persist,&flg);CHKERRQ(ierr);
766   if (flg) {
767     ierr = SNESSetLagJacobianPersists(snes,persist);CHKERRQ(ierr);
768   }
769 
770   ierr = PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);CHKERRQ(ierr);
771   if (flg) {
772     ierr = SNESSetGridSequence(snes,grids);CHKERRQ(ierr);
773   }
774 
775   ierr = PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);CHKERRQ(ierr);
776   if (flg) {
777     switch (indx) {
778     case 0: ierr = SNESSetConvergenceTest(snes,SNESConvergedDefault,NULL,NULL);CHKERRQ(ierr); break;
779     case 1: ierr = SNESSetConvergenceTest(snes,SNESConvergedSkip,NULL,NULL);CHKERRQ(ierr);    break;
780     }
781   }
782 
783   ierr = PetscOptionsEList("-snes_norm_schedule","SNES Norm schedule","SNESSetNormSchedule",SNESNormSchedules,5,"function",&indx,&flg);CHKERRQ(ierr);
784   if (flg) { ierr = SNESSetNormSchedule(snes,(SNESNormSchedule)indx);CHKERRQ(ierr); }
785 
786   ierr = PetscOptionsEList("-snes_function_type","SNES Norm schedule","SNESSetFunctionType",SNESFunctionTypes,2,"unpreconditioned",&indx,&flg);CHKERRQ(ierr);
787   if (flg) { ierr = SNESSetFunctionType(snes,(SNESFunctionType)indx);CHKERRQ(ierr); }
788 
789   kctx = (SNESKSPEW*)snes->kspconvctx;
790 
791   ierr = PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,NULL);CHKERRQ(ierr);
792 
793   ierr = PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,NULL);CHKERRQ(ierr);
794   ierr = PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,NULL);CHKERRQ(ierr);
795   ierr = PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,NULL);CHKERRQ(ierr);
796   ierr = PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,NULL);CHKERRQ(ierr);
797   ierr = PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,NULL);CHKERRQ(ierr);
798   ierr = PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,NULL);CHKERRQ(ierr);
799   ierr = PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,NULL);CHKERRQ(ierr);
800 
801   flg  = PETSC_FALSE;
802   ierr = PetscOptionsBool("-snes_check_jacobian","Check each Jacobian with a differenced one","SNESUpdateCheckJacobian",flg,&flg,&set);CHKERRQ(ierr);
803   if (set && flg) {
804     ierr = SNESSetUpdate(snes,SNESUpdateCheckJacobian);CHKERRQ(ierr);
805   }
806 
807   flg  = PETSC_FALSE;
808   ierr = PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,&set);CHKERRQ(ierr);
809   if (set && flg) {ierr = SNESMonitorCancel(snes);CHKERRQ(ierr);}
810 
811   ierr = SNESMonitorSetFromOptions(snes,"-snes_monitor","Monitor norm of function","SNESMonitorDefault",SNESMonitorDefault,NULL);CHKERRQ(ierr);
812   ierr = SNESMonitorSetFromOptions(snes,"-snes_monitor_short","Monitor norm of function with fewer digits","SNESMonitorDefaultShort",SNESMonitorDefaultShort,NULL);CHKERRQ(ierr);
813   ierr = SNESMonitorSetFromOptions(snes,"-snes_monitor_range","Monitor range of elements of function","SNESMonitorRange",SNESMonitorRange,NULL);CHKERRQ(ierr);
814 
815   ierr = SNESMonitorSetFromOptions(snes,"-snes_monitor_ratio","Monitor ratios of the norm of function for consecutive steps","SNESMonitorRatio",SNESMonitorRatio,SNESMonitorRatioSetUp);CHKERRQ(ierr);
816   ierr = SNESMonitorSetFromOptions(snes,"-snes_monitor_field","Monitor norm of function (split into fields)","SNESMonitorDefaultField",SNESMonitorDefaultField,NULL);CHKERRQ(ierr);
817   ierr = SNESMonitorSetFromOptions(snes,"-snes_monitor_solution","View solution at each iteration","SNESMonitorSolution",SNESMonitorSolution,NULL);CHKERRQ(ierr);
818   ierr = SNESMonitorSetFromOptions(snes,"-snes_monitor_solution_update","View correction at each iteration","SNESMonitorSolutionUpdate",SNESMonitorSolutionUpdate,NULL);CHKERRQ(ierr);
819   ierr = SNESMonitorSetFromOptions(snes,"-snes_monitor_residual","View residual at each iteration","SNESMonitorResidual",SNESMonitorResidual,NULL);CHKERRQ(ierr);
820   ierr = SNESMonitorSetFromOptions(snes,"-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",SNESMonitorJacUpdateSpectrum,NULL);CHKERRQ(ierr);
821   ierr = SNESMonitorSetFromOptions(snes,"-snes_monitor_fields","Monitor norm of function per field","SNESMonitorSet",SNESMonitorFields,NULL);CHKERRQ(ierr);
822 
823   ierr = PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
824   if (flg) {ierr = PetscPythonMonitorSet((PetscObject)snes,monfilename);CHKERRQ(ierr);}
825 
826 
827   flg  = PETSC_FALSE;
828   ierr = PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,NULL);CHKERRQ(ierr);
829   if (flg) {
830     PetscDrawLG ctx;
831 
832     ierr = SNESMonitorLGCreate(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
833     ierr = SNESMonitorSet(snes,SNESMonitorLGResidualNorm,ctx,(PetscErrorCode (*)(void**))PetscDrawLGDestroy);CHKERRQ(ierr);
834   }
835   flg  = PETSC_FALSE;
836   ierr = PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);CHKERRQ(ierr);
837   if (flg) {
838     PetscViewer ctx;
839 
840     ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
841     ierr = SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
842   }
843 
844 
845 
846   flg  = PETSC_FALSE;
847   ierr = PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);CHKERRQ(ierr);
848   if (flg) {
849     void *functx;
850     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
851     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);CHKERRQ(ierr);
852     ierr = PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");CHKERRQ(ierr);
853   }
854 
855   flg  = PETSC_FALSE;
856   ierr = PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);CHKERRQ(ierr);
857   if (flg) {
858     ierr = SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);CHKERRQ(ierr);
859   }
860 
861   flg  = PETSC_FALSE;
862   ierr = PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);CHKERRQ(ierr);
863   if (flg) {
864     DM             dm;
865     DMSNES         sdm;
866     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
867     ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
868     sdm->jacobianctx = NULL;
869     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
870     ierr = PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");CHKERRQ(ierr);
871   }
872 
873   flg  = PETSC_FALSE;
874   ierr = PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf_operator,&flg);CHKERRQ(ierr);
875   if (flg && snes->mf_operator) {
876     snes->mf_operator = PETSC_TRUE;
877     snes->mf          = PETSC_TRUE;
878   }
879   flg  = PETSC_FALSE;
880   ierr = PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf,&flg);CHKERRQ(ierr);
881   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
882   ierr = PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,0);CHKERRQ(ierr);
883 
884   flg  = PETSC_FALSE;
885   ierr = SNESGetNPCSide(snes,&pcside);CHKERRQ(ierr);
886   ierr = PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetNPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);CHKERRQ(ierr);
887   if (flg) {ierr = SNESSetNPCSide(snes,pcside);CHKERRQ(ierr);}
888 
889 #if defined(PETSC_HAVE_SAWS)
890   /*
891     Publish convergence information using SAWs
892   */
893   flg  = PETSC_FALSE;
894   ierr = PetscOptionsBool("-snes_monitor_saws","Publish SNES progress using SAWs","SNESMonitorSet",flg,&flg,NULL);CHKERRQ(ierr);
895   if (flg) {
896     void *ctx;
897     ierr = SNESMonitorSAWsCreate(snes,&ctx);CHKERRQ(ierr);
898     ierr = SNESMonitorSet(snes,SNESMonitorSAWs,ctx,SNESMonitorSAWsDestroy);CHKERRQ(ierr);
899   }
900 #endif
901 #if defined(PETSC_HAVE_SAWS)
902   {
903   PetscBool set;
904   flg  = PETSC_FALSE;
905   ierr = PetscOptionsBool("-snes_saws_block","Block for SAWs at end of SNESSolve","PetscObjectSAWsBlock",((PetscObject)snes)->amspublishblock,&flg,&set);CHKERRQ(ierr);
906   if (set) {
907     ierr = PetscObjectSAWsSetBlock((PetscObject)snes,flg);CHKERRQ(ierr);
908   }
909   }
910 #endif
911 
912   for (i = 0; i < numberofsetfromoptions; i++) {
913     ierr = (*othersetfromoptions[i])(snes);CHKERRQ(ierr);
914   }
915 
916   if (snes->ops->setfromoptions) {
917     ierr = (*snes->ops->setfromoptions)(PetscOptionsObject,snes);CHKERRQ(ierr);
918   }
919 
920   /* process any options handlers added with PetscObjectAddOptionsHandler() */
921   ierr = PetscObjectProcessOptionsHandlers(PetscOptionsObject,(PetscObject)snes);CHKERRQ(ierr);
922   ierr = PetscOptionsEnd();CHKERRQ(ierr);
923 
924   if (!snes->linesearch) {
925     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
926   }
927   ierr = SNESLineSearchSetFromOptions(snes->linesearch);CHKERRQ(ierr);
928 
929   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
930   ierr = KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);CHKERRQ(ierr);
931   ierr = KSPSetFromOptions(snes->ksp);CHKERRQ(ierr);
932 
933   /* if someone has set the SNES NPC type, create it. */
934   ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
935   ierr = PetscOptionsHasName(((PetscObject)snes)->options,optionsprefix, "-npc_snes_type", &pcset);CHKERRQ(ierr);
936   if (pcset && (!snes->pc)) {
937     ierr = SNESGetNPC(snes, &snes->pc);CHKERRQ(ierr);
938   }
939   PetscFunctionReturn(0);
940 }
941 
942 #undef __FUNCT__
943 #define __FUNCT__ "SNESSetComputeApplicationContext"
944 /*@C
945    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
946    the nonlinear solvers.
947 
948    Logically Collective on SNES
949 
950    Input Parameters:
951 +  snes - the SNES context
952 .  compute - function to compute the context
953 -  destroy - function to destroy the context
954 
955    Level: intermediate
956 
957    Notes:
958    This function is currently not available from Fortran.
959 
960 .keywords: SNES, nonlinear, set, application, context
961 
962 .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
963 @*/
964 PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
965 {
966   PetscFunctionBegin;
967   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
968   snes->ops->usercompute = compute;
969   snes->ops->userdestroy = destroy;
970   PetscFunctionReturn(0);
971 }
972 
973 #undef __FUNCT__
974 #define __FUNCT__ "SNESSetApplicationContext"
975 /*@
976    SNESSetApplicationContext - Sets the optional user-defined context for
977    the nonlinear solvers.
978 
979    Logically Collective on SNES
980 
981    Input Parameters:
982 +  snes - the SNES context
983 -  usrP - optional user context
984 
985    Level: intermediate
986 
987    Fortran Notes: To use this from Fortran you must write a Fortran interface definition for this
988     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.
989 
990 .keywords: SNES, nonlinear, set, application, context
991 
992 .seealso: SNESGetApplicationContext()
993 @*/
994 PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
995 {
996   PetscErrorCode ierr;
997   KSP            ksp;
998 
999   PetscFunctionBegin;
1000   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1001   ierr       = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
1002   ierr       = KSPSetApplicationContext(ksp,usrP);CHKERRQ(ierr);
1003   snes->user = usrP;
1004   PetscFunctionReturn(0);
1005 }
1006 
1007 #undef __FUNCT__
1008 #define __FUNCT__ "SNESGetApplicationContext"
1009 /*@
1010    SNESGetApplicationContext - Gets the user-defined context for the
1011    nonlinear solvers.
1012 
1013    Not Collective
1014 
1015    Input Parameter:
1016 .  snes - SNES context
1017 
1018    Output Parameter:
1019 .  usrP - user context
1020 
1021    Fortran Notes: To use this from Fortran you must write a Fortran interface definition for this
1022     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.
1023 
1024    Level: intermediate
1025 
1026 .keywords: SNES, nonlinear, get, application, context
1027 
1028 .seealso: SNESSetApplicationContext()
1029 @*/
1030 PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
1031 {
1032   PetscFunctionBegin;
1033   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1034   *(void**)usrP = snes->user;
1035   PetscFunctionReturn(0);
1036 }
1037 
1038 #undef __FUNCT__
1039 #define __FUNCT__ "SNESGetIterationNumber"
1040 /*@
1041    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
1042    at this time.
1043 
1044    Not Collective
1045 
1046    Input Parameter:
1047 .  snes - SNES context
1048 
1049    Output Parameter:
1050 .  iter - iteration number
1051 
1052    Notes:
1053    For example, during the computation of iteration 2 this would return 1.
1054 
1055    This is useful for using lagged Jacobians (where one does not recompute the
1056    Jacobian at each SNES iteration). For example, the code
1057 .vb
1058       ierr = SNESGetIterationNumber(snes,&it);
1059       if (!(it % 2)) {
1060         [compute Jacobian here]
1061       }
1062 .ve
1063    can be used in your ComputeJacobian() function to cause the Jacobian to be
1064    recomputed every second SNES iteration.
1065 
1066    Level: intermediate
1067 
1068 .keywords: SNES, nonlinear, get, iteration, number,
1069 
1070 .seealso:   SNESGetLinearSolveIterations()
1071 @*/
1072 PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
1073 {
1074   PetscFunctionBegin;
1075   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1076   PetscValidIntPointer(iter,2);
1077   *iter = snes->iter;
1078   PetscFunctionReturn(0);
1079 }
1080 
1081 #undef __FUNCT__
1082 #define __FUNCT__ "SNESSetIterationNumber"
1083 /*@
1084    SNESSetIterationNumber - Sets the current iteration number.
1085 
1086    Not Collective
1087 
1088    Input Parameter:
1089 .  snes - SNES context
1090 .  iter - iteration number
1091 
1092    Level: developer
1093 
1094 .keywords: SNES, nonlinear, set, iteration, number,
1095 
1096 .seealso:   SNESGetLinearSolveIterations()
1097 @*/
1098 PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
1099 {
1100   PetscErrorCode ierr;
1101 
1102   PetscFunctionBegin;
1103   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1104   ierr       = PetscObjectSAWsTakeAccess((PetscObject)snes);CHKERRQ(ierr);
1105   snes->iter = iter;
1106   ierr       = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr);
1107   PetscFunctionReturn(0);
1108 }
1109 
1110 #undef __FUNCT__
1111 #define __FUNCT__ "SNESGetNonlinearStepFailures"
1112 /*@
1113    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1114    attempted by the nonlinear solver.
1115 
1116    Not Collective
1117 
1118    Input Parameter:
1119 .  snes - SNES context
1120 
1121    Output Parameter:
1122 .  nfails - number of unsuccessful steps attempted
1123 
1124    Notes:
1125    This counter is reset to zero for each successive call to SNESSolve().
1126 
1127    Level: intermediate
1128 
1129 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1130 
1131 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1132           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
1133 @*/
1134 PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
1135 {
1136   PetscFunctionBegin;
1137   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1138   PetscValidIntPointer(nfails,2);
1139   *nfails = snes->numFailures;
1140   PetscFunctionReturn(0);
1141 }
1142 
1143 #undef __FUNCT__
1144 #define __FUNCT__ "SNESSetMaxNonlinearStepFailures"
1145 /*@
1146    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1147    attempted by the nonlinear solver before it gives up.
1148 
1149    Not Collective
1150 
1151    Input Parameters:
1152 +  snes     - SNES context
1153 -  maxFails - maximum of unsuccessful steps
1154 
1155    Level: intermediate
1156 
1157 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1158 
1159 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1160           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1161 @*/
1162 PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1163 {
1164   PetscFunctionBegin;
1165   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1166   snes->maxFailures = maxFails;
1167   PetscFunctionReturn(0);
1168 }
1169 
1170 #undef __FUNCT__
1171 #define __FUNCT__ "SNESGetMaxNonlinearStepFailures"
1172 /*@
1173    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1174    attempted by the nonlinear solver before it gives up.
1175 
1176    Not Collective
1177 
1178    Input Parameter:
1179 .  snes     - SNES context
1180 
1181    Output Parameter:
1182 .  maxFails - maximum of unsuccessful steps
1183 
1184    Level: intermediate
1185 
1186 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1187 
1188 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1189           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1190 
1191 @*/
1192 PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1193 {
1194   PetscFunctionBegin;
1195   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1196   PetscValidIntPointer(maxFails,2);
1197   *maxFails = snes->maxFailures;
1198   PetscFunctionReturn(0);
1199 }
1200 
1201 #undef __FUNCT__
1202 #define __FUNCT__ "SNESGetNumberFunctionEvals"
1203 /*@
1204    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1205      done by SNES.
1206 
1207    Not Collective
1208 
1209    Input Parameter:
1210 .  snes     - SNES context
1211 
1212    Output Parameter:
1213 .  nfuncs - number of evaluations
1214 
1215    Level: intermediate
1216 
1217    Notes: Reset every time SNESSolve is called unless SNESSetCountersReset() is used.
1218 
1219 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1220 
1221 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(), SNESSetCountersReset()
1222 @*/
1223 PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1224 {
1225   PetscFunctionBegin;
1226   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1227   PetscValidIntPointer(nfuncs,2);
1228   *nfuncs = snes->nfuncs;
1229   PetscFunctionReturn(0);
1230 }
1231 
1232 #undef __FUNCT__
1233 #define __FUNCT__ "SNESGetLinearSolveFailures"
1234 /*@
1235    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1236    linear solvers.
1237 
1238    Not Collective
1239 
1240    Input Parameter:
1241 .  snes - SNES context
1242 
1243    Output Parameter:
1244 .  nfails - number of failed solves
1245 
1246    Level: intermediate
1247 
1248    Options Database Keys:
1249 . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated
1250 
1251    Notes:
1252    This counter is reset to zero for each successive call to SNESSolve().
1253 
1254 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1255 
1256 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1257 @*/
1258 PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
1259 {
1260   PetscFunctionBegin;
1261   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1262   PetscValidIntPointer(nfails,2);
1263   *nfails = snes->numLinearSolveFailures;
1264   PetscFunctionReturn(0);
1265 }
1266 
1267 #undef __FUNCT__
1268 #define __FUNCT__ "SNESSetMaxLinearSolveFailures"
1269 /*@
1270    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1271    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE
1272 
1273    Logically Collective on SNES
1274 
1275    Input Parameters:
1276 +  snes     - SNES context
1277 -  maxFails - maximum allowed linear solve failures
1278 
1279    Level: intermediate
1280 
1281    Options Database Keys:
1282 . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated
1283 
1284    Notes: By default this is 0; that is SNES returns on the first failed linear solve
1285 
1286 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1287 
1288 .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1289 @*/
1290 PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1291 {
1292   PetscFunctionBegin;
1293   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1294   PetscValidLogicalCollectiveInt(snes,maxFails,2);
1295   snes->maxLinearSolveFailures = maxFails;
1296   PetscFunctionReturn(0);
1297 }
1298 
1299 #undef __FUNCT__
1300 #define __FUNCT__ "SNESGetMaxLinearSolveFailures"
1301 /*@
1302    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1303      are allowed before SNES terminates
1304 
1305    Not Collective
1306 
1307    Input Parameter:
1308 .  snes     - SNES context
1309 
1310    Output Parameter:
1311 .  maxFails - maximum of unsuccessful solves allowed
1312 
1313    Level: intermediate
1314 
1315    Notes: By default this is 1; that is SNES returns on the first failed linear solve
1316 
1317 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1318 
1319 .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1320 @*/
1321 PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1322 {
1323   PetscFunctionBegin;
1324   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1325   PetscValidIntPointer(maxFails,2);
1326   *maxFails = snes->maxLinearSolveFailures;
1327   PetscFunctionReturn(0);
1328 }
1329 
1330 #undef __FUNCT__
1331 #define __FUNCT__ "SNESGetLinearSolveIterations"
1332 /*@
1333    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1334    used by the nonlinear solver.
1335 
1336    Not Collective
1337 
1338    Input Parameter:
1339 .  snes - SNES context
1340 
1341    Output Parameter:
1342 .  lits - number of linear iterations
1343 
1344    Notes:
1345    This counter is reset to zero for each successive call to SNESSolve() unless SNESSetCountersReset() is used.
1346 
1347    If the linear solver fails inside the SNESSolve() the iterations for that call to the linear solver are not included. If you wish to count them
1348    then call KSPGetIterationNumber() after the failed solve.
1349 
1350    Level: intermediate
1351 
1352 .keywords: SNES, nonlinear, get, number, linear, iterations
1353 
1354 .seealso:  SNESGetIterationNumber(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
1355 @*/
1356 PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
1357 {
1358   PetscFunctionBegin;
1359   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1360   PetscValidIntPointer(lits,2);
1361   *lits = snes->linear_its;
1362   PetscFunctionReturn(0);
1363 }
1364 
1365 #undef __FUNCT__
1366 #define __FUNCT__ "SNESSetCountersReset"
1367 /*@
1368    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1369    are reset every time SNESSolve() is called.
1370 
1371    Logically Collective on SNES
1372 
1373    Input Parameter:
1374 +  snes - SNES context
1375 -  reset - whether to reset the counters or not
1376 
1377    Notes:
1378    This defaults to PETSC_TRUE
1379 
1380    Level: developer
1381 
1382 .keywords: SNES, nonlinear, set, reset, number, linear, iterations
1383 
1384 .seealso:  SNESGetNumberFunctionEvals(), SNESGetLinearSolveIterations(), SNESGetNPC()
1385 @*/
1386 PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
1387 {
1388   PetscFunctionBegin;
1389   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1390   PetscValidLogicalCollectiveBool(snes,reset,2);
1391   snes->counters_reset = reset;
1392   PetscFunctionReturn(0);
1393 }
1394 
1395 
1396 #undef __FUNCT__
1397 #define __FUNCT__ "SNESSetKSP"
1398 /*@
1399    SNESSetKSP - Sets a KSP context for the SNES object to use
1400 
1401    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm
1402 
1403    Input Parameters:
1404 +  snes - the SNES context
1405 -  ksp - the KSP context
1406 
1407    Notes:
1408    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1409    so this routine is rarely needed.
1410 
1411    The KSP object that is already in the SNES object has its reference count
1412    decreased by one.
1413 
1414    Level: developer
1415 
1416 .keywords: SNES, nonlinear, get, KSP, context
1417 
1418 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1419 @*/
1420 PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1421 {
1422   PetscErrorCode ierr;
1423 
1424   PetscFunctionBegin;
1425   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1426   PetscValidHeaderSpecific(ksp,KSP_CLASSID,2);
1427   PetscCheckSameComm(snes,1,ksp,2);
1428   ierr = PetscObjectReference((PetscObject)ksp);CHKERRQ(ierr);
1429   if (snes->ksp) {ierr = PetscObjectDereference((PetscObject)snes->ksp);CHKERRQ(ierr);}
1430   snes->ksp = ksp;
1431   PetscFunctionReturn(0);
1432 }
1433 
1434 /* -----------------------------------------------------------*/
1435 #undef __FUNCT__
1436 #define __FUNCT__ "SNESCreate"
1437 /*@
1438    SNESCreate - Creates a nonlinear solver context.
1439 
1440    Collective on MPI_Comm
1441 
1442    Input Parameters:
1443 .  comm - MPI communicator
1444 
1445    Output Parameter:
1446 .  outsnes - the new SNES context
1447 
1448    Options Database Keys:
1449 +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1450                and no preconditioning matrix
1451 .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1452                products, and a user-provided preconditioning matrix
1453                as set by SNESSetJacobian()
1454 -   -snes_fd - Uses (slow!) finite differences to compute Jacobian
1455 
1456    Level: beginner
1457 
1458 .keywords: SNES, nonlinear, create, context
1459 
1460 .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()
1461 
1462 @*/
1463 PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1464 {
1465   PetscErrorCode ierr;
1466   SNES           snes;
1467   SNESKSPEW      *kctx;
1468 
1469   PetscFunctionBegin;
1470   PetscValidPointer(outsnes,2);
1471   *outsnes = NULL;
1472   ierr = SNESInitializePackage();CHKERRQ(ierr);
1473 
1474   ierr = PetscHeaderCreate(snes,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);CHKERRQ(ierr);
1475 
1476   snes->ops->converged    = SNESConvergedDefault;
1477   snes->usesksp           = PETSC_TRUE;
1478   snes->tolerancesset     = PETSC_FALSE;
1479   snes->max_its           = 50;
1480   snes->max_funcs         = 10000;
1481   snes->norm              = 0.0;
1482   snes->normschedule      = SNES_NORM_ALWAYS;
1483   snes->functype          = SNES_FUNCTION_DEFAULT;
1484 #if defined(PETSC_USE_REAL_SINGLE)
1485   snes->rtol              = 1.e-5;
1486 #else
1487   snes->rtol              = 1.e-8;
1488 #endif
1489   snes->ttol              = 0.0;
1490 #if defined(PETSC_USE_REAL_SINGLE)
1491   snes->abstol            = 1.e-25;
1492 #else
1493   snes->abstol            = 1.e-50;
1494 #endif
1495   snes->stol              = 1.e-8;
1496 #if defined(PETSC_USE_REAL_SINGLE)
1497   snes->deltatol          = 1.e-6;
1498 #else
1499   snes->deltatol          = 1.e-12;
1500 #endif
1501   snes->nfuncs            = 0;
1502   snes->numFailures       = 0;
1503   snes->maxFailures       = 1;
1504   snes->linear_its        = 0;
1505   snes->lagjacobian       = 1;
1506   snes->jac_iter          = 0;
1507   snes->lagjac_persist    = PETSC_FALSE;
1508   snes->lagpreconditioner = 1;
1509   snes->pre_iter          = 0;
1510   snes->lagpre_persist    = PETSC_FALSE;
1511   snes->numbermonitors    = 0;
1512   snes->data              = 0;
1513   snes->setupcalled       = PETSC_FALSE;
1514   snes->ksp_ewconv        = PETSC_FALSE;
1515   snes->nwork             = 0;
1516   snes->work              = 0;
1517   snes->nvwork            = 0;
1518   snes->vwork             = 0;
1519   snes->conv_hist_len     = 0;
1520   snes->conv_hist_max     = 0;
1521   snes->conv_hist         = NULL;
1522   snes->conv_hist_its     = NULL;
1523   snes->conv_hist_reset   = PETSC_TRUE;
1524   snes->counters_reset    = PETSC_TRUE;
1525   snes->vec_func_init_set = PETSC_FALSE;
1526   snes->reason            = SNES_CONVERGED_ITERATING;
1527   snes->pcside            = PC_RIGHT;
1528 
1529   snes->mf          = PETSC_FALSE;
1530   snes->mf_operator = PETSC_FALSE;
1531   snes->mf_version  = 1;
1532 
1533   snes->numLinearSolveFailures = 0;
1534   snes->maxLinearSolveFailures = 1;
1535 
1536   snes->vizerotolerance = 1.e-8;
1537 
1538   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1539   ierr = PetscNewLog(snes,&kctx);CHKERRQ(ierr);
1540 
1541   snes->kspconvctx  = (void*)kctx;
1542   kctx->version     = 2;
1543   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1544                              this was too large for some test cases */
1545   kctx->rtol_last   = 0.0;
1546   kctx->rtol_max    = .9;
1547   kctx->gamma       = 1.0;
1548   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1549   kctx->alpha2      = kctx->alpha;
1550   kctx->threshold   = .1;
1551   kctx->lresid_last = 0.0;
1552   kctx->norm_last   = 0.0;
1553 
1554   *outsnes = snes;
1555   PetscFunctionReturn(0);
1556 }
1557 
1558 /*MC
1559     SNESFunction - Functional form used to convey the nonlinear function to be solved by SNES
1560 
1561      Synopsis:
1562      #include "petscsnes.h"
1563      PetscErrorCode SNESFunction(SNES snes,Vec x,Vec f,void *ctx);
1564 
1565      Input Parameters:
1566 +     snes - the SNES context
1567 .     x    - state at which to evaluate residual
1568 -     ctx     - optional user-defined function context, passed in with SNESSetFunction()
1569 
1570      Output Parameter:
1571 .     f  - vector to put residual (function value)
1572 
1573    Level: intermediate
1574 
1575 .seealso:   SNESSetFunction(), SNESGetFunction()
1576 M*/
1577 
1578 #undef __FUNCT__
1579 #define __FUNCT__ "SNESSetFunction"
1580 /*@C
1581    SNESSetFunction - Sets the function evaluation routine and function
1582    vector for use by the SNES routines in solving systems of nonlinear
1583    equations.
1584 
1585    Logically Collective on SNES
1586 
1587    Input Parameters:
1588 +  snes - the SNES context
1589 .  r - vector to store function value
1590 .  f - function evaluation routine; see SNESFunction for calling sequence details
1591 -  ctx - [optional] user-defined context for private data for the
1592          function evaluation routine (may be NULL)
1593 
1594    Notes:
1595    The Newton-like methods typically solve linear systems of the form
1596 $      f'(x) x = -f(x),
1597    where f'(x) denotes the Jacobian matrix and f(x) is the function.
1598 
1599    Level: beginner
1600 
1601 .keywords: SNES, nonlinear, set, function
1602 
1603 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
1604 @*/
1605 PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1606 {
1607   PetscErrorCode ierr;
1608   DM             dm;
1609 
1610   PetscFunctionBegin;
1611   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1612   if (r) {
1613     PetscValidHeaderSpecific(r,VEC_CLASSID,2);
1614     PetscCheckSameComm(snes,1,r,2);
1615     ierr = PetscObjectReference((PetscObject)r);CHKERRQ(ierr);
1616     ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
1617 
1618     snes->vec_func = r;
1619   }
1620   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1621   ierr = DMSNESSetFunction(dm,f,ctx);CHKERRQ(ierr);
1622   PetscFunctionReturn(0);
1623 }
1624 
1625 
1626 #undef __FUNCT__
1627 #define __FUNCT__ "SNESSetInitialFunction"
1628 /*@C
1629    SNESSetInitialFunction - Sets the function vector to be used as the
1630    function norm at the initialization of the method.  In some
1631    instances, the user has precomputed the function before calling
1632    SNESSolve.  This function allows one to avoid a redundant call
1633    to SNESComputeFunction in that case.
1634 
1635    Logically Collective on SNES
1636 
1637    Input Parameters:
1638 +  snes - the SNES context
1639 -  f - vector to store function value
1640 
1641    Notes:
1642    This should not be modified during the solution procedure.
1643 
1644    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1645 
1646    Level: developer
1647 
1648 .keywords: SNES, nonlinear, set, function
1649 
1650 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1651 @*/
1652 PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1653 {
1654   PetscErrorCode ierr;
1655   Vec            vec_func;
1656 
1657   PetscFunctionBegin;
1658   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1659   PetscValidHeaderSpecific(f,VEC_CLASSID,2);
1660   PetscCheckSameComm(snes,1,f,2);
1661   if (snes->pcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
1662     snes->vec_func_init_set = PETSC_FALSE;
1663     PetscFunctionReturn(0);
1664   }
1665   ierr = SNESGetFunction(snes,&vec_func,NULL,NULL);CHKERRQ(ierr);
1666   ierr = VecCopy(f, vec_func);CHKERRQ(ierr);
1667 
1668   snes->vec_func_init_set = PETSC_TRUE;
1669   PetscFunctionReturn(0);
1670 }
1671 
1672 #undef __FUNCT__
1673 #define __FUNCT__ "SNESSetNormSchedule"
1674 /*@
1675    SNESSetNormSchedule - Sets the SNESNormSchedule used in covergence and monitoring
1676    of the SNES method.
1677 
1678    Logically Collective on SNES
1679 
1680    Input Parameters:
1681 +  snes - the SNES context
1682 -  normschedule - the frequency of norm computation
1683 
1684    Options Database Key:
1685 .  -snes_norm_schedule <none, always, initialonly, finalonly, initalfinalonly>
1686 
1687    Notes:
1688    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1689    of the nonlinear function and the taking of its norm at every iteration to
1690    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1691    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1692    may either be monitored for convergence or not.  As these are often used as nonlinear
1693    preconditioners, monitoring the norm of their error is not a useful enterprise within
1694    their solution.
1695 
1696    Level: developer
1697 
1698 .keywords: SNES, nonlinear, set, function, norm, type
1699 
1700 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1701 @*/
1702 PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
1703 {
1704   PetscFunctionBegin;
1705   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1706   snes->normschedule = normschedule;
1707   PetscFunctionReturn(0);
1708 }
1709 
1710 
1711 #undef __FUNCT__
1712 #define __FUNCT__ "SNESGetNormSchedule"
1713 /*@
1714    SNESGetNormSchedule - Gets the SNESNormSchedule used in covergence and monitoring
1715    of the SNES method.
1716 
1717    Logically Collective on SNES
1718 
1719    Input Parameters:
1720 +  snes - the SNES context
1721 -  normschedule - the type of the norm used
1722 
1723    Level: advanced
1724 
1725 .keywords: SNES, nonlinear, set, function, norm, type
1726 
1727 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1728 @*/
1729 PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
1730 {
1731   PetscFunctionBegin;
1732   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1733   *normschedule = snes->normschedule;
1734   PetscFunctionReturn(0);
1735 }
1736 
1737 
1738 #undef __FUNCT__
1739 #define __FUNCT__ "SNESSetFunctionNorm"
1740 /*@
1741   SNESSetFunctionNorm - Sets the last computed residual norm.
1742 
1743   Logically Collective on SNES
1744 
1745   Input Parameters:
1746 + snes - the SNES context
1747 
1748 - normschedule - the frequency of norm computation
1749 
1750   Level: developer
1751 
1752 .keywords: SNES, nonlinear, set, function, norm, type
1753 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1754 @*/
1755 PetscErrorCode SNESSetFunctionNorm(SNES snes, PetscReal norm)
1756 {
1757   PetscFunctionBegin;
1758   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1759   snes->norm = norm;
1760   PetscFunctionReturn(0);
1761 }
1762 
1763 #undef __FUNCT__
1764 #define __FUNCT__ "SNESGetFunctionNorm"
1765 /*@
1766   SNESGetFunctionNorm - Gets the last computed norm of the residual
1767 
1768   Not Collective
1769 
1770   Input Parameter:
1771 . snes - the SNES context
1772 
1773   Output Parameter:
1774 . norm - the last computed residual norm
1775 
1776   Level: developer
1777 
1778 .keywords: SNES, nonlinear, set, function, norm, type
1779 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1780 @*/
1781 PetscErrorCode SNESGetFunctionNorm(SNES snes, PetscReal *norm)
1782 {
1783   PetscFunctionBegin;
1784   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1785   PetscValidPointer(norm, 2);
1786   *norm = snes->norm;
1787   PetscFunctionReturn(0);
1788 }
1789 
1790 #undef __FUNCT__
1791 #define __FUNCT__ "SNESSetFunctionType"
1792 /*@C
1793    SNESSetFunctionType - Sets the SNESNormSchedule used in covergence and monitoring
1794    of the SNES method.
1795 
1796    Logically Collective on SNES
1797 
1798    Input Parameters:
1799 +  snes - the SNES context
1800 -  normschedule - the frequency of norm computation
1801 
1802    Notes:
1803    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1804    of the nonlinear function and the taking of its norm at every iteration to
1805    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1806    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1807    may either be monitored for convergence or not.  As these are often used as nonlinear
1808    preconditioners, monitoring the norm of their error is not a useful enterprise within
1809    their solution.
1810 
1811    Level: developer
1812 
1813 .keywords: SNES, nonlinear, set, function, norm, type
1814 
1815 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1816 @*/
1817 PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
1818 {
1819   PetscFunctionBegin;
1820   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1821   snes->functype = type;
1822   PetscFunctionReturn(0);
1823 }
1824 
1825 
1826 #undef __FUNCT__
1827 #define __FUNCT__ "SNESGetFunctionType"
1828 /*@C
1829    SNESGetFunctionType - Gets the SNESNormSchedule used in covergence and monitoring
1830    of the SNES method.
1831 
1832    Logically Collective on SNES
1833 
1834    Input Parameters:
1835 +  snes - the SNES context
1836 -  normschedule - the type of the norm used
1837 
1838    Level: advanced
1839 
1840 .keywords: SNES, nonlinear, set, function, norm, type
1841 
1842 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1843 @*/
1844 PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
1845 {
1846   PetscFunctionBegin;
1847   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1848   *type = snes->functype;
1849   PetscFunctionReturn(0);
1850 }
1851 
1852 /*MC
1853     SNESNGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function
1854 
1855      Synopsis:
1856      #include <petscsnes.h>
1857 $    SNESNGSFunction(SNES snes,Vec x,Vec b,void *ctx);
1858 
1859 +  X   - solution vector
1860 .  B   - RHS vector
1861 -  ctx - optional user-defined Gauss-Seidel context
1862 
1863    Level: intermediate
1864 
1865 .seealso:   SNESSetNGS(), SNESGetNGS()
1866 M*/
1867 
1868 #undef __FUNCT__
1869 #define __FUNCT__ "SNESSetNGS"
1870 /*@C
1871    SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
1872    use with composed nonlinear solvers.
1873 
1874    Input Parameters:
1875 +  snes   - the SNES context
1876 .  f - function evaluation routine to apply Gauss-Seidel see SNESNGSFunction
1877 -  ctx    - [optional] user-defined context for private data for the
1878             smoother evaluation routine (may be NULL)
1879 
1880    Notes:
1881    The NGS routines are used by the composed nonlinear solver to generate
1882     a problem appropriate update to the solution, particularly FAS.
1883 
1884    Level: intermediate
1885 
1886 .keywords: SNES, nonlinear, set, Gauss-Seidel
1887 
1888 .seealso: SNESGetFunction(), SNESComputeNGS()
1889 @*/
1890 PetscErrorCode SNESSetNGS(SNES snes,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1891 {
1892   PetscErrorCode ierr;
1893   DM             dm;
1894 
1895   PetscFunctionBegin;
1896   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1897   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1898   ierr = DMSNESSetNGS(dm,f,ctx);CHKERRQ(ierr);
1899   PetscFunctionReturn(0);
1900 }
1901 
1902 #undef __FUNCT__
1903 #define __FUNCT__ "SNESPicardComputeFunction"
1904 PETSC_EXTERN PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
1905 {
1906   PetscErrorCode ierr;
1907   DM             dm;
1908   DMSNES         sdm;
1909 
1910   PetscFunctionBegin;
1911   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1912   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
1913   /*  A(x)*x - b(x) */
1914   if (sdm->ops->computepfunction) {
1915     ierr = (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);CHKERRQ(ierr);
1916   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");
1917 
1918   if (sdm->ops->computepjacobian) {
1919     ierr = (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);CHKERRQ(ierr);
1920   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard matrix.");
1921   ierr = VecScale(f,-1.0);CHKERRQ(ierr);
1922   ierr = MatMultAdd(snes->jacobian,x,f,f);CHKERRQ(ierr);
1923   PetscFunctionReturn(0);
1924 }
1925 
1926 #undef __FUNCT__
1927 #define __FUNCT__ "SNESPicardComputeJacobian"
1928 PETSC_EXTERN PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
1929 {
1930   PetscFunctionBegin;
1931   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
1932   PetscFunctionReturn(0);
1933 }
1934 
1935 #undef __FUNCT__
1936 #define __FUNCT__ "SNESSetPicard"
1937 /*@C
1938    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)
1939 
1940    Logically Collective on SNES
1941 
1942    Input Parameters:
1943 +  snes - the SNES context
1944 .  r - vector to store function value
1945 .  b - function evaluation routine
1946 .  Amat - matrix with which A(x) x - b(x) is to be computed
1947 .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
1948 .  J  - function to compute matrix value, see SNESJacobianFunction for details on its calling sequence
1949 -  ctx - [optional] user-defined context for private data for the
1950          function evaluation routine (may be NULL)
1951 
1952    Notes:
1953     We do not recomemend using this routine. It is far better to provide the nonlinear function F() and some approximation to the Jacobian and use
1954     an approximate Newton solver. This interface is provided to allow porting/testing a previous Picard based code in PETSc before converting it to approximate Newton.
1955 
1956     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both
1957 
1958 $     Solves the equation A(x) x = b(x) via the defect correction algorithm A(x^{n}) (x^{n+1} - x^{n}) = b(x^{n}) - A(x^{n})x^{n}
1959 $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.
1960 
1961      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.
1962 
1963    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
1964    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)
1965 
1966    There is some controversity over the definition of a Picard iteration for nonlinear systems but almost everyone agrees that it involves a linear solve and some
1967    believe it is the iteration  A(x^{n}) x^{n+1} = b(x^{n}) hence we use the name Picard. If anyone has an authoritative  reference that defines the Picard iteration
1968    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).
1969 
1970    Level: intermediate
1971 
1972 .keywords: SNES, nonlinear, set, function
1973 
1974 .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard(), SNESJacobianFunction
1975 @*/
1976 PetscErrorCode  SNESSetPicard(SNES snes,Vec r,PetscErrorCode (*b)(SNES,Vec,Vec,void*),Mat Amat, Mat Pmat, PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
1977 {
1978   PetscErrorCode ierr;
1979   DM             dm;
1980 
1981   PetscFunctionBegin;
1982   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1983   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
1984   ierr = DMSNESSetPicard(dm,b,J,ctx);CHKERRQ(ierr);
1985   ierr = SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);CHKERRQ(ierr);
1986   ierr = SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);CHKERRQ(ierr);
1987   PetscFunctionReturn(0);
1988 }
1989 
1990 #undef __FUNCT__
1991 #define __FUNCT__ "SNESGetPicard"
1992 /*@C
1993    SNESGetPicard - Returns the context for the Picard iteration
1994 
1995    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
1996 
1997    Input Parameter:
1998 .  snes - the SNES context
1999 
2000    Output Parameter:
2001 +  r - the function (or NULL)
2002 .  f - the function (or NULL); see SNESFunction for calling sequence details
2003 .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
2004 .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
2005 .  J - the function for matrix evaluation (or NULL); see SNESJacobianFunction for calling sequence details
2006 -  ctx - the function context (or NULL)
2007 
2008    Level: advanced
2009 
2010 .keywords: SNES, nonlinear, get, function
2011 
2012 .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
2013 @*/
2014 PetscErrorCode  SNESGetPicard(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),Mat *Amat, Mat *Pmat, PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
2015 {
2016   PetscErrorCode ierr;
2017   DM             dm;
2018 
2019   PetscFunctionBegin;
2020   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2021   ierr = SNESGetFunction(snes,r,NULL,NULL);CHKERRQ(ierr);
2022   ierr = SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);CHKERRQ(ierr);
2023   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2024   ierr = DMSNESGetPicard(dm,f,J,ctx);CHKERRQ(ierr);
2025   PetscFunctionReturn(0);
2026 }
2027 
2028 #undef __FUNCT__
2029 #define __FUNCT__ "SNESSetComputeInitialGuess"
2030 /*@C
2031    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem
2032 
2033    Logically Collective on SNES
2034 
2035    Input Parameters:
2036 +  snes - the SNES context
2037 .  func - function evaluation routine
2038 -  ctx - [optional] user-defined context for private data for the
2039          function evaluation routine (may be NULL)
2040 
2041    Calling sequence of func:
2042 $    func (SNES snes,Vec x,void *ctx);
2043 
2044 .  f - function vector
2045 -  ctx - optional user-defined function context
2046 
2047    Level: intermediate
2048 
2049 .keywords: SNES, nonlinear, set, function
2050 
2051 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
2052 @*/
2053 PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
2054 {
2055   PetscFunctionBegin;
2056   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2057   if (func) snes->ops->computeinitialguess = func;
2058   if (ctx)  snes->initialguessP            = ctx;
2059   PetscFunctionReturn(0);
2060 }
2061 
2062 /* --------------------------------------------------------------- */
2063 #undef __FUNCT__
2064 #define __FUNCT__ "SNESGetRhs"
2065 /*@C
2066    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
2067    it assumes a zero right hand side.
2068 
2069    Logically Collective on SNES
2070 
2071    Input Parameter:
2072 .  snes - the SNES context
2073 
2074    Output Parameter:
2075 .  rhs - the right hand side vector or NULL if the right hand side vector is null
2076 
2077    Level: intermediate
2078 
2079 .keywords: SNES, nonlinear, get, function, right hand side
2080 
2081 .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
2082 @*/
2083 PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
2084 {
2085   PetscFunctionBegin;
2086   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2087   PetscValidPointer(rhs,2);
2088   *rhs = snes->vec_rhs;
2089   PetscFunctionReturn(0);
2090 }
2091 
2092 #undef __FUNCT__
2093 #define __FUNCT__ "SNESComputeFunction"
2094 /*@
2095    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().
2096 
2097    Collective on SNES
2098 
2099    Input Parameters:
2100 +  snes - the SNES context
2101 -  x - input vector
2102 
2103    Output Parameter:
2104 .  y - function vector, as set by SNESSetFunction()
2105 
2106    Notes:
2107    SNESComputeFunction() is typically used within nonlinear solvers
2108    implementations, so most users would not generally call this routine
2109    themselves.
2110 
2111    Level: developer
2112 
2113 .keywords: SNES, nonlinear, compute, function
2114 
2115 .seealso: SNESSetFunction(), SNESGetFunction()
2116 @*/
2117 PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
2118 {
2119   PetscErrorCode ierr;
2120   DM             dm;
2121   DMSNES         sdm;
2122 
2123   PetscFunctionBegin;
2124   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2125   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2126   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
2127   PetscCheckSameComm(snes,1,x,2);
2128   PetscCheckSameComm(snes,1,y,3);
2129   ierr = VecValidValues(x,2,PETSC_TRUE);CHKERRQ(ierr);
2130 
2131   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2132   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2133   if (sdm->ops->computefunction) {
2134     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2135       ierr = PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2136     }
2137     ierr = VecLockPush(x);CHKERRQ(ierr);
2138     PetscStackPush("SNES user function");
2139     ierr = (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);CHKERRQ(ierr);
2140     PetscStackPop;
2141     ierr = VecLockPop(x);CHKERRQ(ierr);
2142     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2143       ierr = PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2144     }
2145   } else if (snes->vec_rhs) {
2146     ierr = MatMult(snes->jacobian, x, y);CHKERRQ(ierr);
2147   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2148   if (snes->vec_rhs) {
2149     ierr = VecAXPY(y,-1.0,snes->vec_rhs);CHKERRQ(ierr);
2150   }
2151   snes->nfuncs++;
2152   /*
2153      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
2154      propagate the value to all processes
2155   */
2156   if (snes->domainerror) {
2157     ierr = VecSetInf(y);CHKERRQ(ierr);
2158   }
2159   PetscFunctionReturn(0);
2160 }
2161 
2162 #undef __FUNCT__
2163 #define __FUNCT__ "SNESComputeNGS"
2164 /*@
2165    SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  SNESSetNGS().
2166 
2167    Collective on SNES
2168 
2169    Input Parameters:
2170 +  snes - the SNES context
2171 .  x - input vector
2172 -  b - rhs vector
2173 
2174    Output Parameter:
2175 .  x - new solution vector
2176 
2177    Notes:
2178    SNESComputeNGS() is typically used within composed nonlinear solver
2179    implementations, so most users would not generally call this routine
2180    themselves.
2181 
2182    Level: developer
2183 
2184 .keywords: SNES, nonlinear, compute, function
2185 
2186 .seealso: SNESSetNGS(), SNESComputeFunction()
2187 @*/
2188 PetscErrorCode  SNESComputeNGS(SNES snes,Vec b,Vec x)
2189 {
2190   PetscErrorCode ierr;
2191   DM             dm;
2192   DMSNES         sdm;
2193 
2194   PetscFunctionBegin;
2195   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2196   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2197   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,3);
2198   PetscCheckSameComm(snes,1,x,2);
2199   if (b) PetscCheckSameComm(snes,1,b,3);
2200   if (b) {ierr = VecValidValues(b,2,PETSC_TRUE);CHKERRQ(ierr);}
2201   ierr = PetscLogEventBegin(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2202   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2203   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2204   if (sdm->ops->computegs) {
2205     if (b) {ierr = VecLockPush(b);CHKERRQ(ierr);}
2206     PetscStackPush("SNES user NGS");
2207     ierr = (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);CHKERRQ(ierr);
2208     PetscStackPop;
2209     if (b) {ierr = VecLockPop(b);CHKERRQ(ierr);}
2210   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
2211   ierr = PetscLogEventEnd(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2212   PetscFunctionReturn(0);
2213 }
2214 
2215 #undef __FUNCT__
2216 #define __FUNCT__ "SNESComputeJacobian"
2217 /*@
2218    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().
2219 
2220    Collective on SNES and Mat
2221 
2222    Input Parameters:
2223 +  snes - the SNES context
2224 -  x - input vector
2225 
2226    Output Parameters:
2227 +  A - Jacobian matrix
2228 -  B - optional preconditioning matrix
2229 
2230   Options Database Keys:
2231 +    -snes_lag_preconditioner <lag>
2232 .    -snes_lag_jacobian <lag>
2233 .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2234 .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2235 .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2236 .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2237 .    -snes_compare_coloring - Compute the finite differece Jacobian using coloring and display norms of difference
2238 .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
2239 .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2240 .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2241 .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2242 .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
2243 -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences
2244 
2245 
2246    Notes:
2247    Most users should not need to explicitly call this routine, as it
2248    is used internally within the nonlinear solvers.
2249 
2250    Level: developer
2251 
2252 .keywords: SNES, compute, Jacobian, matrix
2253 
2254 .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2255 @*/
2256 PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat A,Mat B)
2257 {
2258   PetscErrorCode ierr;
2259   PetscBool      flag;
2260   DM             dm;
2261   DMSNES         sdm;
2262   KSP            ksp;
2263 
2264   PetscFunctionBegin;
2265   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2266   PetscValidHeaderSpecific(X,VEC_CLASSID,2);
2267   PetscCheckSameComm(snes,1,X,2);
2268   ierr = VecValidValues(X,2,PETSC_TRUE);CHKERRQ(ierr);
2269   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2270   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2271 
2272   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");
2273 
2274   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */
2275 
2276   if (snes->lagjacobian == -2) {
2277     snes->lagjacobian = -1;
2278 
2279     ierr = PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");CHKERRQ(ierr);
2280   } else if (snes->lagjacobian == -1) {
2281     ierr = PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");CHKERRQ(ierr);
2282     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2283     if (flag) {
2284       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2285       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2286     }
2287     PetscFunctionReturn(0);
2288   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2289     ierr = PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);CHKERRQ(ierr);
2290     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2291     if (flag) {
2292       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2293       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2294     }
2295     PetscFunctionReturn(0);
2296   }
2297   if (snes->pc && snes->pcside == PC_LEFT) {
2298       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2299       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2300       PetscFunctionReturn(0);
2301   }
2302 
2303   ierr = PetscLogEventBegin(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2304   ierr = VecLockPush(X);CHKERRQ(ierr);
2305   PetscStackPush("SNES user Jacobian function");
2306   ierr = (*sdm->ops->computejacobian)(snes,X,A,B,sdm->jacobianctx);CHKERRQ(ierr);
2307   PetscStackPop;
2308   ierr = VecLockPop(X);CHKERRQ(ierr);
2309   ierr = PetscLogEventEnd(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2310 
2311   /* the next line ensures that snes->ksp exists */
2312   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
2313   if (snes->lagpreconditioner == -2) {
2314     ierr = PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");CHKERRQ(ierr);
2315     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2316     snes->lagpreconditioner = -1;
2317   } else if (snes->lagpreconditioner == -1) {
2318     ierr = PetscInfo(snes,"Reusing preconditioner because lag is -1\n");CHKERRQ(ierr);
2319     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2320   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2321     ierr = PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);CHKERRQ(ierr);
2322     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2323   } else {
2324     ierr = PetscInfo(snes,"Rebuilding preconditioner\n");CHKERRQ(ierr);
2325     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2326   }
2327 
2328   /* make sure user returned a correct Jacobian and preconditioner */
2329   /* PetscValidHeaderSpecific(A,MAT_CLASSID,3);
2330     PetscValidHeaderSpecific(B,MAT_CLASSID,4);   */
2331   {
2332     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2333     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit",&flag,NULL);CHKERRQ(ierr);
2334     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",&flag_draw,NULL);CHKERRQ(ierr);
2335     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2336     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_operator",&flag_operator,NULL);CHKERRQ(ierr);
2337     if (flag || flag_draw || flag_contour) {
2338       Mat          Bexp_mine = NULL,Bexp,FDexp;
2339       PetscViewer  vdraw,vstdout;
2340       PetscBool    flg;
2341       if (flag_operator) {
2342         ierr = MatComputeExplicitOperator(A,&Bexp_mine);CHKERRQ(ierr);
2343         Bexp = Bexp_mine;
2344       } else {
2345         /* See if the preconditioning matrix can be viewed and added directly */
2346         ierr = PetscObjectTypeCompareAny((PetscObject)B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");CHKERRQ(ierr);
2347         if (flg) Bexp = B;
2348         else {
2349           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2350           ierr = MatComputeExplicitOperator(B,&Bexp_mine);CHKERRQ(ierr);
2351           Bexp = Bexp_mine;
2352         }
2353       }
2354       ierr = MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);CHKERRQ(ierr);
2355       ierr = SNESComputeJacobianDefault(snes,X,FDexp,FDexp,NULL);CHKERRQ(ierr);
2356       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2357       if (flag_draw || flag_contour) {
2358         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2359         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2360       } else vdraw = NULL;
2361       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");CHKERRQ(ierr);
2362       if (flag) {ierr = MatView(Bexp,vstdout);CHKERRQ(ierr);}
2363       if (vdraw) {ierr = MatView(Bexp,vdraw);CHKERRQ(ierr);}
2364       ierr = PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");CHKERRQ(ierr);
2365       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2366       if (vdraw) {ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);}
2367       ierr = MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2368       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");CHKERRQ(ierr);
2369       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2370       if (vdraw) {              /* Always use contour for the difference */
2371         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2372         ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);
2373         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2374       }
2375       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2376       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2377       ierr = MatDestroy(&Bexp_mine);CHKERRQ(ierr);
2378       ierr = MatDestroy(&FDexp);CHKERRQ(ierr);
2379     }
2380   }
2381   {
2382     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2383     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2384     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring",&flag,NULL);CHKERRQ(ierr);
2385     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_display",&flag_display,NULL);CHKERRQ(ierr);
2386     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",&flag_draw,NULL);CHKERRQ(ierr);
2387     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2388     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",&flag_threshold,NULL);CHKERRQ(ierr);
2389     ierr = PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);CHKERRQ(ierr);
2390     ierr = PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);CHKERRQ(ierr);
2391     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2392       Mat            Bfd;
2393       PetscViewer    vdraw,vstdout;
2394       MatColoring    coloring;
2395       ISColoring     iscoloring;
2396       MatFDColoring  matfdcoloring;
2397       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2398       void           *funcctx;
2399       PetscReal      norm1,norm2,normmax;
2400 
2401       ierr = MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);CHKERRQ(ierr);
2402       ierr = MatColoringCreate(Bfd,&coloring);CHKERRQ(ierr);
2403       ierr = MatColoringSetType(coloring,MATCOLORINGSL);CHKERRQ(ierr);
2404       ierr = MatColoringSetFromOptions(coloring);CHKERRQ(ierr);
2405       ierr = MatColoringApply(coloring,&iscoloring);CHKERRQ(ierr);
2406       ierr = MatColoringDestroy(&coloring);CHKERRQ(ierr);
2407       ierr = MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);CHKERRQ(ierr);
2408       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2409       ierr = MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);CHKERRQ(ierr);
2410       ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr);
2411 
2412       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2413       ierr = SNESGetFunction(snes,NULL,&func,&funcctx);CHKERRQ(ierr);
2414       ierr = MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);CHKERRQ(ierr);
2415       ierr = PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);CHKERRQ(ierr);
2416       ierr = PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");CHKERRQ(ierr);
2417       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2418       ierr = MatFDColoringApply(Bfd,matfdcoloring,X,snes);CHKERRQ(ierr);
2419       ierr = MatFDColoringDestroy(&matfdcoloring);CHKERRQ(ierr);
2420 
2421       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2422       if (flag_draw || flag_contour) {
2423         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2424         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2425       } else vdraw = NULL;
2426       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");CHKERRQ(ierr);
2427       if (flag_display) {ierr = MatView(B,vstdout);CHKERRQ(ierr);}
2428       if (vdraw) {ierr = MatView(B,vdraw);CHKERRQ(ierr);}
2429       ierr = PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");CHKERRQ(ierr);
2430       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2431       if (vdraw) {ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);}
2432       ierr = MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2433       ierr = MatNorm(Bfd,NORM_1,&norm1);CHKERRQ(ierr);
2434       ierr = MatNorm(Bfd,NORM_FROBENIUS,&norm2);CHKERRQ(ierr);
2435       ierr = MatNorm(Bfd,NORM_MAX,&normmax);CHKERRQ(ierr);
2436       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%g normFrob=%g normmax=%g\n",(double)norm1,(double)norm2,(double)normmax);CHKERRQ(ierr);
2437       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2438       if (vdraw) {              /* Always use contour for the difference */
2439         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2440         ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);
2441         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2442       }
2443       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2444 
2445       if (flag_threshold) {
2446         PetscInt bs,rstart,rend,i;
2447         ierr = MatGetBlockSize(B,&bs);CHKERRQ(ierr);
2448         ierr = MatGetOwnershipRange(B,&rstart,&rend);CHKERRQ(ierr);
2449         for (i=rstart; i<rend; i++) {
2450           const PetscScalar *ba,*ca;
2451           const PetscInt    *bj,*cj;
2452           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2453           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2454           ierr = MatGetRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2455           ierr = MatGetRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2456           if (bn != cn) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2457           for (j=0; j<bn; j++) {
2458             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2459             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2460               maxentrycol = bj[j];
2461               maxentry    = PetscRealPart(ba[j]);
2462             }
2463             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2464               maxdiffcol = bj[j];
2465               maxdiff    = PetscRealPart(ca[j]);
2466             }
2467             if (rdiff > maxrdiff) {
2468               maxrdiffcol = bj[j];
2469               maxrdiff    = rdiff;
2470             }
2471           }
2472           if (maxrdiff > 1) {
2473             ierr = PetscViewerASCIIPrintf(vstdout,"row %D (maxentry=%g at %D, maxdiff=%g at %D, maxrdiff=%g at %D):",i,(double)maxentry,maxentrycol,(double)maxdiff,maxdiffcol,(double)maxrdiff,maxrdiffcol);CHKERRQ(ierr);
2474             for (j=0; j<bn; j++) {
2475               PetscReal rdiff;
2476               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2477               if (rdiff > 1) {
2478                 ierr = PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));CHKERRQ(ierr);
2479               }
2480             }
2481             ierr = PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);CHKERRQ(ierr);
2482           }
2483           ierr = MatRestoreRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2484           ierr = MatRestoreRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2485         }
2486       }
2487       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2488       ierr = MatDestroy(&Bfd);CHKERRQ(ierr);
2489     }
2490   }
2491   PetscFunctionReturn(0);
2492 }
2493 
2494 /*MC
2495     SNESJacobianFunction - Function used to convey the nonlinear Jacobian of the function to be solved by SNES
2496 
2497      Synopsis:
2498      #include "petscsnes.h"
2499      PetscErrorCode SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);
2500 
2501 +  x - input vector
2502 .  Amat - the matrix that defines the (approximate) Jacobian
2503 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2504 -  ctx - [optional] user-defined Jacobian context
2505 
2506    Level: intermediate
2507 
2508 .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2509 M*/
2510 
2511 #undef __FUNCT__
2512 #define __FUNCT__ "SNESSetJacobian"
2513 /*@C
2514    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2515    location to store the matrix.
2516 
2517    Logically Collective on SNES and Mat
2518 
2519    Input Parameters:
2520 +  snes - the SNES context
2521 .  Amat - the matrix that defines the (approximate) Jacobian
2522 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2523 .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value), see SNESJacobianFunction for details
2524 -  ctx - [optional] user-defined context for private data for the
2525          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)
2526 
2527    Notes:
2528    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
2529    each matrix.
2530 
2531    If you know the operator Amat has a null space you can use MatSetNullSpace() and MatSetTransposeNullSpace() to supply the null
2532    space to Amat and the KSP solvers will automatically use that null space as needed during the solution process.
2533 
2534    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
2535    must be a MatFDColoring.
2536 
2537    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2538    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.
2539 
2540    Level: beginner
2541 
2542 .keywords: SNES, nonlinear, set, Jacobian, matrix
2543 
2544 .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J,
2545           SNESSetPicard(), SNESJacobianFunction
2546 @*/
2547 PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2548 {
2549   PetscErrorCode ierr;
2550   DM             dm;
2551 
2552   PetscFunctionBegin;
2553   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2554   if (Amat) PetscValidHeaderSpecific(Amat,MAT_CLASSID,2);
2555   if (Pmat) PetscValidHeaderSpecific(Pmat,MAT_CLASSID,3);
2556   if (Amat) PetscCheckSameComm(snes,1,Amat,2);
2557   if (Pmat) PetscCheckSameComm(snes,1,Pmat,3);
2558   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2559   ierr = DMSNESSetJacobian(dm,J,ctx);CHKERRQ(ierr);
2560   if (Amat) {
2561     ierr = PetscObjectReference((PetscObject)Amat);CHKERRQ(ierr);
2562     ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2563 
2564     snes->jacobian = Amat;
2565   }
2566   if (Pmat) {
2567     ierr = PetscObjectReference((PetscObject)Pmat);CHKERRQ(ierr);
2568     ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2569 
2570     snes->jacobian_pre = Pmat;
2571   }
2572   PetscFunctionReturn(0);
2573 }
2574 
2575 #undef __FUNCT__
2576 #define __FUNCT__ "SNESGetJacobian"
2577 /*@C
2578    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2579    provided context for evaluating the Jacobian.
2580 
2581    Not Collective, but Mat object will be parallel if SNES object is
2582 
2583    Input Parameter:
2584 .  snes - the nonlinear solver context
2585 
2586    Output Parameters:
2587 +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
2588 .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
2589 .  J - location to put Jacobian function (or NULL), see SNESJacobianFunction for details on its calling sequence
2590 -  ctx - location to stash Jacobian ctx (or NULL)
2591 
2592    Level: advanced
2593 
2594 .seealso: SNESSetJacobian(), SNESComputeJacobian(), SNESJacobianFunction, SNESGetFunction()
2595 @*/
2596 PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
2597 {
2598   PetscErrorCode ierr;
2599   DM             dm;
2600   DMSNES         sdm;
2601 
2602   PetscFunctionBegin;
2603   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2604   if (Amat) *Amat = snes->jacobian;
2605   if (Pmat) *Pmat = snes->jacobian_pre;
2606   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2607   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2608   if (J) *J = sdm->ops->computejacobian;
2609   if (ctx) *ctx = sdm->jacobianctx;
2610   PetscFunctionReturn(0);
2611 }
2612 
2613 #undef __FUNCT__
2614 #define __FUNCT__ "SNESSetUp"
2615 /*@
2616    SNESSetUp - Sets up the internal data structures for the later use
2617    of a nonlinear solver.
2618 
2619    Collective on SNES
2620 
2621    Input Parameters:
2622 .  snes - the SNES context
2623 
2624    Notes:
2625    For basic use of the SNES solvers the user need not explicitly call
2626    SNESSetUp(), since these actions will automatically occur during
2627    the call to SNESSolve().  However, if one wishes to control this
2628    phase separately, SNESSetUp() should be called after SNESCreate()
2629    and optional routines of the form SNESSetXXX(), but before SNESSolve().
2630 
2631    Level: advanced
2632 
2633 .keywords: SNES, nonlinear, setup
2634 
2635 .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
2636 @*/
2637 PetscErrorCode  SNESSetUp(SNES snes)
2638 {
2639   PetscErrorCode ierr;
2640   DM             dm;
2641   DMSNES         sdm;
2642   SNESLineSearch linesearch, pclinesearch;
2643   void           *lsprectx,*lspostctx;
2644   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
2645   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
2646   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2647   Vec            f,fpc;
2648   void           *funcctx;
2649   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
2650   void           *jacctx,*appctx;
2651   Mat            j,jpre;
2652 
2653   PetscFunctionBegin;
2654   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2655   if (snes->setupcalled) PetscFunctionReturn(0);
2656 
2657   if (!((PetscObject)snes)->type_name) {
2658     ierr = SNESSetType(snes,SNESNEWTONLS);CHKERRQ(ierr);
2659   }
2660 
2661   ierr = SNESGetFunction(snes,&snes->vec_func,NULL,NULL);CHKERRQ(ierr);
2662 
2663   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2664   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2665   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
2666   if (!sdm->ops->computejacobian) {
2667     ierr = DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);CHKERRQ(ierr);
2668   }
2669   if (!snes->vec_func) {
2670     ierr = DMCreateGlobalVector(dm,&snes->vec_func);CHKERRQ(ierr);
2671   }
2672 
2673   if (!snes->ksp) {
2674     ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);
2675   }
2676 
2677   if (!snes->linesearch) {
2678     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
2679   }
2680   ierr = SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);CHKERRQ(ierr);
2681 
2682   if (snes->pc && (snes->pcside == PC_LEFT)) {
2683     snes->mf          = PETSC_TRUE;
2684     snes->mf_operator = PETSC_FALSE;
2685   }
2686 
2687   if (snes->pc) {
2688     /* copy the DM over */
2689     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2690     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
2691 
2692     ierr = SNESGetFunction(snes,&f,&func,&funcctx);CHKERRQ(ierr);
2693     ierr = VecDuplicate(f,&fpc);CHKERRQ(ierr);
2694     ierr = SNESSetFunction(snes->pc,fpc,func,funcctx);CHKERRQ(ierr);
2695     ierr = SNESGetJacobian(snes,&j,&jpre,&jac,&jacctx);CHKERRQ(ierr);
2696     ierr = SNESSetJacobian(snes->pc,j,jpre,jac,jacctx);CHKERRQ(ierr);
2697     ierr = SNESGetApplicationContext(snes,&appctx);CHKERRQ(ierr);
2698     ierr = SNESSetApplicationContext(snes->pc,appctx);CHKERRQ(ierr);
2699     ierr = VecDestroy(&fpc);CHKERRQ(ierr);
2700 
2701     /* copy the function pointers over */
2702     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
2703 
2704     /* default to 1 iteration */
2705     ierr = SNESSetTolerances(snes->pc,0.0,0.0,0.0,1,snes->pc->max_funcs);CHKERRQ(ierr);
2706     if (snes->pcside==PC_RIGHT) {
2707       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
2708     } else {
2709       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_NONE);CHKERRQ(ierr);
2710     }
2711     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
2712 
2713     /* copy the line search context over */
2714     ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2715     ierr = SNESGetLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
2716     ierr = SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);CHKERRQ(ierr);
2717     ierr = SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);CHKERRQ(ierr);
2718     ierr = SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);CHKERRQ(ierr);
2719     ierr = SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);CHKERRQ(ierr);
2720     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);CHKERRQ(ierr);
2721   }
2722   if (snes->mf) {
2723     ierr = SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);CHKERRQ(ierr);
2724   }
2725   if (snes->ops->usercompute && !snes->user) {
2726     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2727   }
2728 
2729   snes->jac_iter = 0;
2730   snes->pre_iter = 0;
2731 
2732   if (snes->ops->setup) {
2733     ierr = (*snes->ops->setup)(snes);CHKERRQ(ierr);
2734   }
2735 
2736   if (snes->pc && (snes->pcside == PC_LEFT)) {
2737     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
2738       ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2739       ierr = SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultNPC);CHKERRQ(ierr);
2740     }
2741   }
2742 
2743   snes->setupcalled = PETSC_TRUE;
2744   PetscFunctionReturn(0);
2745 }
2746 
2747 #undef __FUNCT__
2748 #define __FUNCT__ "SNESReset"
2749 /*@
2750    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats
2751 
2752    Collective on SNES
2753 
2754    Input Parameter:
2755 .  snes - iterative context obtained from SNESCreate()
2756 
2757    Level: intermediate
2758 
2759    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()
2760 
2761 .keywords: SNES, destroy
2762 
2763 .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
2764 @*/
2765 PetscErrorCode  SNESReset(SNES snes)
2766 {
2767   PetscErrorCode ierr;
2768 
2769   PetscFunctionBegin;
2770   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2771   if (snes->ops->userdestroy && snes->user) {
2772     ierr       = (*snes->ops->userdestroy)((void**)&snes->user);CHKERRQ(ierr);
2773     snes->user = NULL;
2774   }
2775   if (snes->pc) {
2776     ierr = SNESReset(snes->pc);CHKERRQ(ierr);
2777   }
2778 
2779   if (snes->ops->reset) {
2780     ierr = (*snes->ops->reset)(snes);CHKERRQ(ierr);
2781   }
2782   if (snes->ksp) {
2783     ierr = KSPReset(snes->ksp);CHKERRQ(ierr);
2784   }
2785 
2786   if (snes->linesearch) {
2787     ierr = SNESLineSearchReset(snes->linesearch);CHKERRQ(ierr);
2788   }
2789 
2790   ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
2791   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
2792   ierr = VecDestroy(&snes->vec_sol_update);CHKERRQ(ierr);
2793   ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
2794   ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2795   ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2796   ierr = VecDestroyVecs(snes->nwork,&snes->work);CHKERRQ(ierr);
2797   ierr = VecDestroyVecs(snes->nvwork,&snes->vwork);CHKERRQ(ierr);
2798 
2799   snes->nwork       = snes->nvwork = 0;
2800   snes->setupcalled = PETSC_FALSE;
2801   PetscFunctionReturn(0);
2802 }
2803 
2804 #undef __FUNCT__
2805 #define __FUNCT__ "SNESDestroy"
2806 /*@
2807    SNESDestroy - Destroys the nonlinear solver context that was created
2808    with SNESCreate().
2809 
2810    Collective on SNES
2811 
2812    Input Parameter:
2813 .  snes - the SNES context
2814 
2815    Level: beginner
2816 
2817 .keywords: SNES, nonlinear, destroy
2818 
2819 .seealso: SNESCreate(), SNESSolve()
2820 @*/
2821 PetscErrorCode  SNESDestroy(SNES *snes)
2822 {
2823   PetscErrorCode ierr;
2824 
2825   PetscFunctionBegin;
2826   if (!*snes) PetscFunctionReturn(0);
2827   PetscValidHeaderSpecific((*snes),SNES_CLASSID,1);
2828   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; PetscFunctionReturn(0);}
2829 
2830   ierr = SNESReset((*snes));CHKERRQ(ierr);
2831   ierr = SNESDestroy(&(*snes)->pc);CHKERRQ(ierr);
2832 
2833   /* if memory was published with SAWs then destroy it */
2834   ierr = PetscObjectSAWsViewOff((PetscObject)*snes);CHKERRQ(ierr);
2835   if ((*snes)->ops->destroy) {ierr = (*((*snes))->ops->destroy)((*snes));CHKERRQ(ierr);}
2836 
2837   ierr = DMDestroy(&(*snes)->dm);CHKERRQ(ierr);
2838   ierr = KSPDestroy(&(*snes)->ksp);CHKERRQ(ierr);
2839   ierr = SNESLineSearchDestroy(&(*snes)->linesearch);CHKERRQ(ierr);
2840 
2841   ierr = PetscFree((*snes)->kspconvctx);CHKERRQ(ierr);
2842   if ((*snes)->ops->convergeddestroy) {
2843     ierr = (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);CHKERRQ(ierr);
2844   }
2845   if ((*snes)->conv_malloc) {
2846     ierr = PetscFree((*snes)->conv_hist);CHKERRQ(ierr);
2847     ierr = PetscFree((*snes)->conv_hist_its);CHKERRQ(ierr);
2848   }
2849   ierr = SNESMonitorCancel((*snes));CHKERRQ(ierr);
2850   ierr = PetscHeaderDestroy(snes);CHKERRQ(ierr);
2851   PetscFunctionReturn(0);
2852 }
2853 
2854 /* ----------- Routines to set solver parameters ---------- */
2855 
2856 #undef __FUNCT__
2857 #define __FUNCT__ "SNESSetLagPreconditioner"
2858 /*@
2859    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.
2860 
2861    Logically Collective on SNES
2862 
2863    Input Parameters:
2864 +  snes - the SNES context
2865 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2866          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2867 
2868    Options Database Keys:
2869 .    -snes_lag_preconditioner <lag>
2870 
2871    Notes:
2872    The default is 1
2873    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2874    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use
2875 
2876    Level: intermediate
2877 
2878 .keywords: SNES, nonlinear, set, convergence, tolerances
2879 
2880 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2881 
2882 @*/
2883 PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
2884 {
2885   PetscFunctionBegin;
2886   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2887   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2888   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2889   PetscValidLogicalCollectiveInt(snes,lag,2);
2890   snes->lagpreconditioner = lag;
2891   PetscFunctionReturn(0);
2892 }
2893 
2894 #undef __FUNCT__
2895 #define __FUNCT__ "SNESSetGridSequence"
2896 /*@
2897    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does
2898 
2899    Logically Collective on SNES
2900 
2901    Input Parameters:
2902 +  snes - the SNES context
2903 -  steps - the number of refinements to do, defaults to 0
2904 
2905    Options Database Keys:
2906 .    -snes_grid_sequence <steps>
2907 
2908    Level: intermediate
2909 
2910    Notes:
2911    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2912 
2913 .keywords: SNES, nonlinear, set, convergence, tolerances
2914 
2915 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetGridSequence()
2916 
2917 @*/
2918 PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
2919 {
2920   PetscFunctionBegin;
2921   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2922   PetscValidLogicalCollectiveInt(snes,steps,2);
2923   snes->gridsequence = steps;
2924   PetscFunctionReturn(0);
2925 }
2926 
2927 #undef __FUNCT__
2928 #define __FUNCT__ "SNESGetGridSequence"
2929 /*@
2930    SNESGetGridSequence - gets the number of steps of grid sequencing that SNES does
2931 
2932    Logically Collective on SNES
2933 
2934    Input Parameter:
2935 .  snes - the SNES context
2936 
2937    Output Parameter:
2938 .  steps - the number of refinements to do, defaults to 0
2939 
2940    Options Database Keys:
2941 .    -snes_grid_sequence <steps>
2942 
2943    Level: intermediate
2944 
2945    Notes:
2946    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2947 
2948 .keywords: SNES, nonlinear, set, convergence, tolerances
2949 
2950 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESSetGridSequence()
2951 
2952 @*/
2953 PetscErrorCode  SNESGetGridSequence(SNES snes,PetscInt *steps)
2954 {
2955   PetscFunctionBegin;
2956   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2957   *steps = snes->gridsequence;
2958   PetscFunctionReturn(0);
2959 }
2960 
2961 #undef __FUNCT__
2962 #define __FUNCT__ "SNESGetLagPreconditioner"
2963 /*@
2964    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt
2965 
2966    Not Collective
2967 
2968    Input Parameter:
2969 .  snes - the SNES context
2970 
2971    Output Parameter:
2972 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2973          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2974 
2975    Options Database Keys:
2976 .    -snes_lag_preconditioner <lag>
2977 
2978    Notes:
2979    The default is 1
2980    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2981 
2982    Level: intermediate
2983 
2984 .keywords: SNES, nonlinear, set, convergence, tolerances
2985 
2986 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()
2987 
2988 @*/
2989 PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
2990 {
2991   PetscFunctionBegin;
2992   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2993   *lag = snes->lagpreconditioner;
2994   PetscFunctionReturn(0);
2995 }
2996 
2997 #undef __FUNCT__
2998 #define __FUNCT__ "SNESSetLagJacobian"
2999 /*@
3000    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
3001      often the preconditioner is rebuilt.
3002 
3003    Logically Collective on SNES
3004 
3005    Input Parameters:
3006 +  snes - the SNES context
3007 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3008          the Jacobian is built etc. -2 means rebuild at next chance but then never again
3009 
3010    Options Database Keys:
3011 .    -snes_lag_jacobian <lag>
3012 
3013    Notes:
3014    The default is 1
3015    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3016    If  -1 is used before the very first nonlinear solve the CODE WILL FAIL! because no Jacobian is used, use -2 to indicate you want it recomputed
3017    at the next Newton step but never again (unless it is reset to another value)
3018 
3019    Level: intermediate
3020 
3021 .keywords: SNES, nonlinear, set, convergence, tolerances
3022 
3023 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()
3024 
3025 @*/
3026 PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
3027 {
3028   PetscFunctionBegin;
3029   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3030   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
3031   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
3032   PetscValidLogicalCollectiveInt(snes,lag,2);
3033   snes->lagjacobian = lag;
3034   PetscFunctionReturn(0);
3035 }
3036 
3037 #undef __FUNCT__
3038 #define __FUNCT__ "SNESGetLagJacobian"
3039 /*@
3040    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt
3041 
3042    Not Collective
3043 
3044    Input Parameter:
3045 .  snes - the SNES context
3046 
3047    Output Parameter:
3048 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3049          the Jacobian is built etc.
3050 
3051    Options Database Keys:
3052 .    -snes_lag_jacobian <lag>
3053 
3054    Notes:
3055    The default is 1
3056    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3057 
3058    Level: intermediate
3059 
3060 .keywords: SNES, nonlinear, set, convergence, tolerances
3061 
3062 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()
3063 
3064 @*/
3065 PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
3066 {
3067   PetscFunctionBegin;
3068   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3069   *lag = snes->lagjacobian;
3070   PetscFunctionReturn(0);
3071 }
3072 
3073 #undef __FUNCT__
3074 #define __FUNCT__ "SNESSetLagJacobianPersists"
3075 /*@
3076    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves
3077 
3078    Logically collective on SNES
3079 
3080    Input Parameter:
3081 +  snes - the SNES context
3082 -   flg - jacobian lagging persists if true
3083 
3084    Options Database Keys:
3085 .    -snes_lag_jacobian_persists <flg>
3086 
3087    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
3088    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
3089    timesteps may present huge efficiency gains.
3090 
3091    Level: developer
3092 
3093 .keywords: SNES, nonlinear, lag
3094 
3095 .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
3096 
3097 @*/
3098 PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
3099 {
3100   PetscFunctionBegin;
3101   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3102   PetscValidLogicalCollectiveBool(snes,flg,2);
3103   snes->lagjac_persist = flg;
3104   PetscFunctionReturn(0);
3105 }
3106 
3107 #undef __FUNCT__
3108 #define __FUNCT__ "SNESSetLagPreconditionerPersists"
3109 /*@
3110    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple solves
3111 
3112    Logically Collective on SNES
3113 
3114    Input Parameter:
3115 +  snes - the SNES context
3116 -   flg - preconditioner lagging persists if true
3117 
3118    Options Database Keys:
3119 .    -snes_lag_jacobian_persists <flg>
3120 
3121    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
3122    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
3123    several timesteps may present huge efficiency gains.
3124 
3125    Level: developer
3126 
3127 .keywords: SNES, nonlinear, lag
3128 
3129 .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
3130 
3131 @*/
3132 PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
3133 {
3134   PetscFunctionBegin;
3135   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3136   PetscValidLogicalCollectiveBool(snes,flg,2);
3137   snes->lagpre_persist = flg;
3138   PetscFunctionReturn(0);
3139 }
3140 
3141 #undef __FUNCT__
3142 #define __FUNCT__ "SNESSetTolerances"
3143 /*@
3144    SNESSetTolerances - Sets various parameters used in convergence tests.
3145 
3146    Logically Collective on SNES
3147 
3148    Input Parameters:
3149 +  snes - the SNES context
3150 .  abstol - absolute convergence tolerance
3151 .  rtol - relative convergence tolerance
3152 .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
3153 .  maxit - maximum number of iterations
3154 -  maxf - maximum number of function evaluations
3155 
3156    Options Database Keys:
3157 +    -snes_atol <abstol> - Sets abstol
3158 .    -snes_rtol <rtol> - Sets rtol
3159 .    -snes_stol <stol> - Sets stol
3160 .    -snes_max_it <maxit> - Sets maxit
3161 -    -snes_max_funcs <maxf> - Sets maxf
3162 
3163    Notes:
3164    The default maximum number of iterations is 50.
3165    The default maximum number of function evaluations is 1000.
3166 
3167    Level: intermediate
3168 
3169 .keywords: SNES, nonlinear, set, convergence, tolerances
3170 
3171 .seealso: SNESSetTrustRegionTolerance()
3172 @*/
3173 PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
3174 {
3175   PetscFunctionBegin;
3176   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3177   PetscValidLogicalCollectiveReal(snes,abstol,2);
3178   PetscValidLogicalCollectiveReal(snes,rtol,3);
3179   PetscValidLogicalCollectiveReal(snes,stol,4);
3180   PetscValidLogicalCollectiveInt(snes,maxit,5);
3181   PetscValidLogicalCollectiveInt(snes,maxf,6);
3182 
3183   if (abstol != PETSC_DEFAULT) {
3184     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %g must be non-negative",(double)abstol);
3185     snes->abstol = abstol;
3186   }
3187   if (rtol != PETSC_DEFAULT) {
3188     if (rtol < 0.0 || 1.0 <= rtol) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Relative tolerance %g must be non-negative and less than 1.0",(double)rtol);
3189     snes->rtol = rtol;
3190   }
3191   if (stol != PETSC_DEFAULT) {
3192     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %g must be non-negative",(double)stol);
3193     snes->stol = stol;
3194   }
3195   if (maxit != PETSC_DEFAULT) {
3196     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
3197     snes->max_its = maxit;
3198   }
3199   if (maxf != PETSC_DEFAULT) {
3200     if (maxf < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
3201     snes->max_funcs = maxf;
3202   }
3203   snes->tolerancesset = PETSC_TRUE;
3204   PetscFunctionReturn(0);
3205 }
3206 
3207 #undef __FUNCT__
3208 #define __FUNCT__ "SNESGetTolerances"
3209 /*@
3210    SNESGetTolerances - Gets various parameters used in convergence tests.
3211 
3212    Not Collective
3213 
3214    Input Parameters:
3215 +  snes - the SNES context
3216 .  atol - absolute convergence tolerance
3217 .  rtol - relative convergence tolerance
3218 .  stol -  convergence tolerance in terms of the norm
3219            of the change in the solution between steps
3220 .  maxit - maximum number of iterations
3221 -  maxf - maximum number of function evaluations
3222 
3223    Notes:
3224    The user can specify NULL for any parameter that is not needed.
3225 
3226    Level: intermediate
3227 
3228 .keywords: SNES, nonlinear, get, convergence, tolerances
3229 
3230 .seealso: SNESSetTolerances()
3231 @*/
3232 PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3233 {
3234   PetscFunctionBegin;
3235   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3236   if (atol)  *atol  = snes->abstol;
3237   if (rtol)  *rtol  = snes->rtol;
3238   if (stol)  *stol  = snes->stol;
3239   if (maxit) *maxit = snes->max_its;
3240   if (maxf)  *maxf  = snes->max_funcs;
3241   PetscFunctionReturn(0);
3242 }
3243 
3244 #undef __FUNCT__
3245 #define __FUNCT__ "SNESSetTrustRegionTolerance"
3246 /*@
3247    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.
3248 
3249    Logically Collective on SNES
3250 
3251    Input Parameters:
3252 +  snes - the SNES context
3253 -  tol - tolerance
3254 
3255    Options Database Key:
3256 .  -snes_trtol <tol> - Sets tol
3257 
3258    Level: intermediate
3259 
3260 .keywords: SNES, nonlinear, set, trust region, tolerance
3261 
3262 .seealso: SNESSetTolerances()
3263 @*/
3264 PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3265 {
3266   PetscFunctionBegin;
3267   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3268   PetscValidLogicalCollectiveReal(snes,tol,2);
3269   snes->deltatol = tol;
3270   PetscFunctionReturn(0);
3271 }
3272 
3273 /*
3274    Duplicate the lg monitors for SNES from KSP; for some reason with
3275    dynamic libraries things don't work under Sun4 if we just use
3276    macros instead of functions
3277 */
3278 #undef __FUNCT__
3279 #define __FUNCT__ "SNESMonitorLGResidualNorm"
3280 PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,void *ctx)
3281 {
3282   PetscErrorCode ierr;
3283 
3284   PetscFunctionBegin;
3285   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3286   ierr = KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);CHKERRQ(ierr);
3287   PetscFunctionReturn(0);
3288 }
3289 
3290 #undef __FUNCT__
3291 #define __FUNCT__ "SNESMonitorLGCreate"
3292 PetscErrorCode  SNESMonitorLGCreate(MPI_Comm comm,const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *lgctx)
3293 {
3294   PetscErrorCode ierr;
3295 
3296   PetscFunctionBegin;
3297   ierr = KSPMonitorLGResidualNormCreate(comm,host,label,x,y,m,n,lgctx);CHKERRQ(ierr);
3298   PetscFunctionReturn(0);
3299 }
3300 
3301 extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
3302 #undef __FUNCT__
3303 #define __FUNCT__ "SNESMonitorLGRange"
3304 PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3305 {
3306   PetscDrawLG      lg;
3307   PetscErrorCode   ierr;
3308   PetscReal        x,y,per;
3309   PetscViewer      v = (PetscViewer)monctx;
3310   static PetscReal prev; /* should be in the context */
3311   PetscDraw        draw;
3312 
3313   PetscFunctionBegin;
3314   PetscValidHeaderSpecific(v,PETSC_VIEWER_CLASSID,4);
3315   ierr = PetscViewerDrawGetDrawLG(v,0,&lg);CHKERRQ(ierr);
3316   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3317   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3318   ierr = PetscDrawSetTitle(draw,"Residual norm");CHKERRQ(ierr);
3319   x    = (PetscReal)n;
3320   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
3321   else y = -15.0;
3322   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3323   if (n < 20 || !(n % 5)) {
3324     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3325   }
3326 
3327   ierr = PetscViewerDrawGetDrawLG(v,1,&lg);CHKERRQ(ierr);
3328   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3329   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3330   ierr = PetscDrawSetTitle(draw,"% elemts > .2*max elemt");CHKERRQ(ierr);
3331   ierr =  SNESMonitorRange_Private(snes,n,&per);CHKERRQ(ierr);
3332   x    = (PetscReal)n;
3333   y    = 100.0*per;
3334   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3335   if (n < 20 || !(n % 5)) {
3336     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3337   }
3338 
3339   ierr = PetscViewerDrawGetDrawLG(v,2,&lg);CHKERRQ(ierr);
3340   if (!n) {prev = rnorm;ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3341   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3342   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");CHKERRQ(ierr);
3343   x    = (PetscReal)n;
3344   y    = (prev - rnorm)/prev;
3345   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3346   if (n < 20 || !(n % 5)) {
3347     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3348   }
3349 
3350   ierr = PetscViewerDrawGetDrawLG(v,3,&lg);CHKERRQ(ierr);
3351   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3352   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3353   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");CHKERRQ(ierr);
3354   x    = (PetscReal)n;
3355   y    = (prev - rnorm)/(prev*per);
3356   if (n > 2) { /*skip initial crazy value */
3357     ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3358   }
3359   if (n < 20 || !(n % 5)) {
3360     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3361   }
3362   prev = rnorm;
3363   PetscFunctionReturn(0);
3364 }
3365 
3366 #undef __FUNCT__
3367 #define __FUNCT__ "SNESMonitor"
3368 /*@
3369    SNESMonitor - runs the user provided monitor routines, if they exist
3370 
3371    Collective on SNES
3372 
3373    Input Parameters:
3374 +  snes - nonlinear solver context obtained from SNESCreate()
3375 .  iter - iteration number
3376 -  rnorm - relative norm of the residual
3377 
3378    Notes:
3379    This routine is called by the SNES implementations.
3380    It does not typically need to be called by the user.
3381 
3382    Level: developer
3383 
3384 .seealso: SNESMonitorSet()
3385 @*/
3386 PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3387 {
3388   PetscErrorCode ierr;
3389   PetscInt       i,n = snes->numbermonitors;
3390 
3391   PetscFunctionBegin;
3392   ierr = VecLockPush(snes->vec_sol);CHKERRQ(ierr);
3393   for (i=0; i<n; i++) {
3394     ierr = (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);CHKERRQ(ierr);
3395   }
3396   ierr = VecLockPop(snes->vec_sol);CHKERRQ(ierr);
3397   PetscFunctionReturn(0);
3398 }
3399 
3400 /* ------------ Routines to set performance monitoring options ----------- */
3401 
3402 /*MC
3403     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver
3404 
3405      Synopsis:
3406      #include <petscsnes.h>
3407 $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)
3408 
3409 +    snes - the SNES context
3410 .    its - iteration number
3411 .    norm - 2-norm function value (may be estimated)
3412 -    mctx - [optional] monitoring context
3413 
3414    Level: advanced
3415 
3416 .seealso:   SNESMonitorSet(), SNESMonitorGet()
3417 M*/
3418 
3419 #undef __FUNCT__
3420 #define __FUNCT__ "SNESMonitorSet"
3421 /*@C
3422    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3423    iteration of the nonlinear solver to display the iteration's
3424    progress.
3425 
3426    Logically Collective on SNES
3427 
3428    Input Parameters:
3429 +  snes - the SNES context
3430 .  f - the monitor function, see SNESMonitorFunction for the calling sequence
3431 .  mctx - [optional] user-defined context for private data for the
3432           monitor routine (use NULL if no context is desired)
3433 -  monitordestroy - [optional] routine that frees monitor context
3434           (may be NULL)
3435 
3436    Options Database Keys:
3437 +    -snes_monitor        - sets SNESMonitorDefault()
3438 .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3439                             uses SNESMonitorLGCreate()
3440 -    -snes_monitor_cancel - cancels all monitors that have
3441                             been hardwired into a code by
3442                             calls to SNESMonitorSet(), but
3443                             does not cancel those set via
3444                             the options database.
3445 
3446    Notes:
3447    Several different monitoring routines may be set by calling
3448    SNESMonitorSet() multiple times; all will be called in the
3449    order in which they were set.
3450 
3451    Fortran notes: Only a single monitor function can be set for each SNES object
3452 
3453    Level: intermediate
3454 
3455 .keywords: SNES, nonlinear, set, monitor
3456 
3457 .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
3458 @*/
3459 PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*f)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3460 {
3461   PetscInt       i;
3462   PetscErrorCode ierr;
3463 
3464   PetscFunctionBegin;
3465   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3466   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3467   for (i=0; i<snes->numbermonitors;i++) {
3468     if (f == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
3469       if (monitordestroy) {
3470         ierr = (*monitordestroy)(&mctx);CHKERRQ(ierr);
3471       }
3472       PetscFunctionReturn(0);
3473     }
3474   }
3475   snes->monitor[snes->numbermonitors]          = f;
3476   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
3477   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
3478   PetscFunctionReturn(0);
3479 }
3480 
3481 #undef __FUNCT__
3482 #define __FUNCT__ "SNESMonitorCancel"
3483 /*@
3484    SNESMonitorCancel - Clears all the monitor functions for a SNES object.
3485 
3486    Logically Collective on SNES
3487 
3488    Input Parameters:
3489 .  snes - the SNES context
3490 
3491    Options Database Key:
3492 .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3493     into a code by calls to SNESMonitorSet(), but does not cancel those
3494     set via the options database
3495 
3496    Notes:
3497    There is no way to clear one specific monitor from a SNES object.
3498 
3499    Level: intermediate
3500 
3501 .keywords: SNES, nonlinear, set, monitor
3502 
3503 .seealso: SNESMonitorDefault(), SNESMonitorSet()
3504 @*/
3505 PetscErrorCode  SNESMonitorCancel(SNES snes)
3506 {
3507   PetscErrorCode ierr;
3508   PetscInt       i;
3509 
3510   PetscFunctionBegin;
3511   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3512   for (i=0; i<snes->numbermonitors; i++) {
3513     if (snes->monitordestroy[i]) {
3514       ierr = (*snes->monitordestroy[i])(&snes->monitorcontext[i]);CHKERRQ(ierr);
3515     }
3516   }
3517   snes->numbermonitors = 0;
3518   PetscFunctionReturn(0);
3519 }
3520 
3521 /*MC
3522     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver
3523 
3524      Synopsis:
3525      #include <petscsnes.h>
3526 $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)
3527 
3528 +    snes - the SNES context
3529 .    it - current iteration (0 is the first and is before any Newton step)
3530 .    cctx - [optional] convergence context
3531 .    reason - reason for convergence/divergence
3532 .    xnorm - 2-norm of current iterate
3533 .    gnorm - 2-norm of current step
3534 -    f - 2-norm of function
3535 
3536    Level: intermediate
3537 
3538 .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
3539 M*/
3540 
3541 #undef __FUNCT__
3542 #define __FUNCT__ "SNESSetConvergenceTest"
3543 /*@C
3544    SNESSetConvergenceTest - Sets the function that is to be used
3545    to test for convergence of the nonlinear iterative solution.
3546 
3547    Logically Collective on SNES
3548 
3549    Input Parameters:
3550 +  snes - the SNES context
3551 .  SNESConvergenceTestFunction - routine to test for convergence
3552 .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
3553 -  destroy - [optional] destructor for the context (may be NULL; NULL_FUNCTION in Fortran)
3554 
3555    Level: advanced
3556 
3557 .keywords: SNES, nonlinear, set, convergence, test
3558 
3559 .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
3560 @*/
3561 PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
3562 {
3563   PetscErrorCode ierr;
3564 
3565   PetscFunctionBegin;
3566   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3567   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
3568   if (snes->ops->convergeddestroy) {
3569     ierr = (*snes->ops->convergeddestroy)(snes->cnvP);CHKERRQ(ierr);
3570   }
3571   snes->ops->converged        = SNESConvergenceTestFunction;
3572   snes->ops->convergeddestroy = destroy;
3573   snes->cnvP                  = cctx;
3574   PetscFunctionReturn(0);
3575 }
3576 
3577 #undef __FUNCT__
3578 #define __FUNCT__ "SNESGetConvergedReason"
3579 /*@
3580    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.
3581 
3582    Not Collective
3583 
3584    Input Parameter:
3585 .  snes - the SNES context
3586 
3587    Output Parameter:
3588 .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3589             manual pages for the individual convergence tests for complete lists
3590 
3591    Level: intermediate
3592 
3593    Notes: Can only be called after the call the SNESSolve() is complete.
3594 
3595 .keywords: SNES, nonlinear, set, convergence, test
3596 
3597 .seealso: SNESSetConvergenceTest(), SNESSetConvergedReason(), SNESConvergedReason
3598 @*/
3599 PetscErrorCode SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
3600 {
3601   PetscFunctionBegin;
3602   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3603   PetscValidPointer(reason,2);
3604   *reason = snes->reason;
3605   PetscFunctionReturn(0);
3606 }
3607 
3608 #undef __FUNCT__
3609 #define __FUNCT__ "SNESSetConvergedReason"
3610 /*@
3611    SNESSetConvergedReason - Sets the reason the SNES iteration was stopped.
3612 
3613    Not Collective
3614 
3615    Input Parameters:
3616 +  snes - the SNES context
3617 -  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3618             manual pages for the individual convergence tests for complete lists
3619 
3620    Level: intermediate
3621 
3622 .keywords: SNES, nonlinear, set, convergence, test
3623 .seealso: SNESGetConvergedReason(), SNESSetConvergenceTest(), SNESConvergedReason
3624 @*/
3625 PetscErrorCode SNESSetConvergedReason(SNES snes,SNESConvergedReason reason)
3626 {
3627   PetscFunctionBegin;
3628   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3629   snes->reason = reason;
3630   PetscFunctionReturn(0);
3631 }
3632 
3633 #undef __FUNCT__
3634 #define __FUNCT__ "SNESSetConvergenceHistory"
3635 /*@
3636    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.
3637 
3638    Logically Collective on SNES
3639 
3640    Input Parameters:
3641 +  snes - iterative context obtained from SNESCreate()
3642 .  a   - array to hold history, this array will contain the function norms computed at each step
3643 .  its - integer array holds the number of linear iterations for each solve.
3644 .  na  - size of a and its
3645 -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
3646            else it continues storing new values for new nonlinear solves after the old ones
3647 
3648    Notes:
3649    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
3650    default array of length 10000 is allocated.
3651 
3652    This routine is useful, e.g., when running a code for purposes
3653    of accurate performance monitoring, when no I/O should be done
3654    during the section of code that is being timed.
3655 
3656    Level: intermediate
3657 
3658 .keywords: SNES, set, convergence, history
3659 
3660 .seealso: SNESGetConvergenceHistory()
3661 
3662 @*/
3663 PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
3664 {
3665   PetscErrorCode ierr;
3666 
3667   PetscFunctionBegin;
3668   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3669   if (a) PetscValidScalarPointer(a,2);
3670   if (its) PetscValidIntPointer(its,3);
3671   if (!a) {
3672     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
3673     ierr = PetscCalloc1(na,&a);CHKERRQ(ierr);
3674     ierr = PetscCalloc1(na,&its);CHKERRQ(ierr);
3675 
3676     snes->conv_malloc = PETSC_TRUE;
3677   }
3678   snes->conv_hist       = a;
3679   snes->conv_hist_its   = its;
3680   snes->conv_hist_max   = na;
3681   snes->conv_hist_len   = 0;
3682   snes->conv_hist_reset = reset;
3683   PetscFunctionReturn(0);
3684 }
3685 
3686 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3687 #include <engine.h>   /* MATLAB include file */
3688 #include <mex.h>      /* MATLAB include file */
3689 
3690 #undef __FUNCT__
3691 #define __FUNCT__ "SNESGetConvergenceHistoryMatlab"
3692 PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
3693 {
3694   mxArray   *mat;
3695   PetscInt  i;
3696   PetscReal *ar;
3697 
3698   PetscFunctionBegin;
3699   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
3700   ar  = (PetscReal*) mxGetData(mat);
3701   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
3702   PetscFunctionReturn(mat);
3703 }
3704 #endif
3705 
3706 #undef __FUNCT__
3707 #define __FUNCT__ "SNESGetConvergenceHistory"
3708 /*@C
3709    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.
3710 
3711    Not Collective
3712 
3713    Input Parameter:
3714 .  snes - iterative context obtained from SNESCreate()
3715 
3716    Output Parameters:
3717 .  a   - array to hold history
3718 .  its - integer array holds the number of linear iterations (or
3719          negative if not converged) for each solve.
3720 -  na  - size of a and its
3721 
3722    Notes:
3723     The calling sequence for this routine in Fortran is
3724 $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
3725 
3726    This routine is useful, e.g., when running a code for purposes
3727    of accurate performance monitoring, when no I/O should be done
3728    during the section of code that is being timed.
3729 
3730    Level: intermediate
3731 
3732 .keywords: SNES, get, convergence, history
3733 
3734 .seealso: SNESSetConvergencHistory()
3735 
3736 @*/
3737 PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
3738 {
3739   PetscFunctionBegin;
3740   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3741   if (a)   *a   = snes->conv_hist;
3742   if (its) *its = snes->conv_hist_its;
3743   if (na)  *na  = snes->conv_hist_len;
3744   PetscFunctionReturn(0);
3745 }
3746 
3747 #undef __FUNCT__
3748 #define __FUNCT__ "SNESSetUpdate"
3749 /*@C
3750   SNESSetUpdate - Sets the general-purpose update function called
3751   at the beginning of every iteration of the nonlinear solve. Specifically
3752   it is called just before the Jacobian is "evaluated".
3753 
3754   Logically Collective on SNES
3755 
3756   Input Parameters:
3757 . snes - The nonlinear solver context
3758 . func - The function
3759 
3760   Calling sequence of func:
3761 . func (SNES snes, PetscInt step);
3762 
3763 . step - The current step of the iteration
3764 
3765   Level: advanced
3766 
3767   Note: This is NOT what one uses to update the ghost points before a function evaluation, that should be done at the beginning of your FormFunction()
3768         This is not used by most users.
3769 
3770 .keywords: SNES, update
3771 
3772 .seealso SNESSetJacobian(), SNESSolve()
3773 @*/
3774 PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
3775 {
3776   PetscFunctionBegin;
3777   PetscValidHeaderSpecific(snes, SNES_CLASSID,1);
3778   snes->ops->update = func;
3779   PetscFunctionReturn(0);
3780 }
3781 
3782 #undef __FUNCT__
3783 #define __FUNCT__ "SNESScaleStep_Private"
3784 /*
3785    SNESScaleStep_Private - Scales a step so that its length is less than the
3786    positive parameter delta.
3787 
3788     Input Parameters:
3789 +   snes - the SNES context
3790 .   y - approximate solution of linear system
3791 .   fnorm - 2-norm of current function
3792 -   delta - trust region size
3793 
3794     Output Parameters:
3795 +   gpnorm - predicted function norm at the new point, assuming local
3796     linearization.  The value is zero if the step lies within the trust
3797     region, and exceeds zero otherwise.
3798 -   ynorm - 2-norm of the step
3799 
3800     Note:
3801     For non-trust region methods such as SNESNEWTONLS, the parameter delta
3802     is set to be the maximum allowable step size.
3803 
3804 .keywords: SNES, nonlinear, scale, step
3805 */
3806 PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
3807 {
3808   PetscReal      nrm;
3809   PetscScalar    cnorm;
3810   PetscErrorCode ierr;
3811 
3812   PetscFunctionBegin;
3813   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3814   PetscValidHeaderSpecific(y,VEC_CLASSID,2);
3815   PetscCheckSameComm(snes,1,y,2);
3816 
3817   ierr = VecNorm(y,NORM_2,&nrm);CHKERRQ(ierr);
3818   if (nrm > *delta) {
3819     nrm     = *delta/nrm;
3820     *gpnorm = (1.0 - nrm)*(*fnorm);
3821     cnorm   = nrm;
3822     ierr    = VecScale(y,cnorm);CHKERRQ(ierr);
3823     *ynorm  = *delta;
3824   } else {
3825     *gpnorm = 0.0;
3826     *ynorm  = nrm;
3827   }
3828   PetscFunctionReturn(0);
3829 }
3830 
3831 #undef __FUNCT__
3832 #define __FUNCT__ "SNESReasonView"
3833 /*@
3834    SNESReasonView - Displays the reason a SNES solve converged or diverged to a viewer
3835 
3836    Collective on SNES
3837 
3838    Parameter:
3839 +  snes - iterative context obtained from SNESCreate()
3840 -  viewer - the viewer to display the reason
3841 
3842 
3843    Options Database Keys:
3844 .  -snes_converged_reason - print reason for converged or diverged, also prints number of iterations
3845 
3846    Level: beginner
3847 
3848 .keywords: SNES, solve, linear system
3849 
3850 .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault()
3851 
3852 @*/
3853 PetscErrorCode  SNESReasonView(SNES snes,PetscViewer viewer)
3854 {
3855   PetscErrorCode ierr;
3856   PetscBool      isAscii;
3857 
3858   PetscFunctionBegin;
3859   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isAscii);CHKERRQ(ierr);
3860   if (isAscii) {
3861     ierr = PetscViewerASCIIAddTab(viewer,((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3862     if (snes->reason > 0) {
3863       if (((PetscObject) snes)->prefix) {
3864         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve converged due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3865       } else {
3866         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3867       }
3868     } else {
3869       if (((PetscObject) snes)->prefix) {
3870         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve did not converge due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3871       } else {
3872         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3873       }
3874     }
3875     ierr = PetscViewerASCIISubtractTab(viewer,((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3876   }
3877   PetscFunctionReturn(0);
3878 }
3879 
3880 #undef __FUNCT__
3881 #define __FUNCT__ "SNESReasonViewFromOptions"
3882 /*@C
3883   SNESReasonViewFromOptions - Processes command line options to determine if/how a SNESReason is to be viewed.
3884 
3885   Collective on SNES
3886 
3887   Input Parameters:
3888 . snes   - the SNES object
3889 
3890   Level: intermediate
3891 
3892 @*/
3893 PetscErrorCode SNESReasonViewFromOptions(SNES snes)
3894 {
3895   PetscErrorCode    ierr;
3896   PetscViewer       viewer;
3897   PetscBool         flg;
3898   static PetscBool  incall = PETSC_FALSE;
3899   PetscViewerFormat format;
3900 
3901   PetscFunctionBegin;
3902   if (incall) PetscFunctionReturn(0);
3903   incall = PETSC_TRUE;
3904   ierr   = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_converged_reason",&viewer,&format,&flg);CHKERRQ(ierr);
3905   if (flg) {
3906     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
3907     ierr = SNESReasonView(snes,viewer);CHKERRQ(ierr);
3908     ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
3909     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3910   }
3911   incall = PETSC_FALSE;
3912   PetscFunctionReturn(0);
3913 }
3914 
3915 #undef __FUNCT__
3916 #define __FUNCT__ "SNESSolve"
3917 /*@C
3918    SNESSolve - Solves a nonlinear system F(x) = b.
3919    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3920 
3921    Collective on SNES
3922 
3923    Input Parameters:
3924 +  snes - the SNES context
3925 .  b - the constant part of the equation F(x) = b, or NULL to use zero.
3926 -  x - the solution vector.
3927 
3928    Notes:
3929    The user should initialize the vector,x, with the initial guess
3930    for the nonlinear solve prior to calling SNESSolve.  In particular,
3931    to employ an initial guess of zero, the user should explicitly set
3932    this vector to zero by calling VecSet().
3933 
3934    Level: beginner
3935 
3936 .keywords: SNES, nonlinear, solve
3937 
3938 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3939 @*/
3940 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3941 {
3942   PetscErrorCode    ierr;
3943   PetscBool         flg;
3944   PetscInt          grid;
3945   Vec               xcreated = NULL;
3946   DM                dm;
3947 
3948   PetscFunctionBegin;
3949   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3950   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3951   if (x) PetscCheckSameComm(snes,1,x,3);
3952   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3953   if (b) PetscCheckSameComm(snes,1,b,2);
3954 
3955   if (!x) {
3956     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3957     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3958     x    = xcreated;
3959   }
3960   ierr = SNESViewFromOptions(snes,NULL,"-snes_view_pre");CHKERRQ(ierr);
3961 
3962   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);}
3963   for (grid=0; grid<snes->gridsequence+1; grid++) {
3964 
3965     /* set solution vector */
3966     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3967     ierr          = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3968     snes->vec_sol = x;
3969     ierr          = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3970 
3971     /* set affine vector if provided */
3972     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3973     ierr          = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3974     snes->vec_rhs = b;
3975 
3976     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
3977     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
3978     if (!snes->vec_sol_update /* && snes->vec_sol */) {
3979       ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
3980       ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);CHKERRQ(ierr);
3981     }
3982     ierr = DMShellSetGlobalVector(dm,snes->vec_sol);CHKERRQ(ierr);
3983     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3984 
3985     if (!grid) {
3986       if (snes->ops->computeinitialguess) {
3987         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3988       }
3989     }
3990 
3991     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3992     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}
3993 
3994     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3995     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3996     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3997     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3998     snes->domainerror = PETSC_FALSE; /* clear the flag if it has been set */
3999 
4000     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
4001     if (snes->lagpre_persist) snes->pre_iter += snes->iter;
4002 
4003     flg  = PETSC_FALSE;
4004     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,NULL);CHKERRQ(ierr);
4005     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
4006     ierr = SNESReasonViewFromOptions(snes);CHKERRQ(ierr);
4007 
4008     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
4009     if (snes->reason < 0) break;
4010     if (grid <  snes->gridsequence) {
4011       DM  fine;
4012       Vec xnew;
4013       Mat interp;
4014 
4015       ierr = DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);CHKERRQ(ierr);
4016       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
4017       ierr = DMCreateInterpolation(snes->dm,fine,&interp,NULL);CHKERRQ(ierr);
4018       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
4019       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
4020       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
4021       ierr = MatDestroy(&interp);CHKERRQ(ierr);
4022       x    = xnew;
4023 
4024       ierr = SNESReset(snes);CHKERRQ(ierr);
4025       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
4026       ierr = DMDestroy(&fine);CHKERRQ(ierr);
4027       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);
4028     }
4029   }
4030   ierr = SNESViewFromOptions(snes,NULL,"-snes_view");CHKERRQ(ierr);
4031   ierr = VecViewFromOptions(snes->vec_sol,(PetscObject)snes,"-snes_view_solution");CHKERRQ(ierr);
4032 
4033   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
4034   ierr = PetscObjectSAWsBlock((PetscObject)snes);CHKERRQ(ierr);
4035   PetscFunctionReturn(0);
4036 }
4037 
4038 /* --------- Internal routines for SNES Package --------- */
4039 
4040 #undef __FUNCT__
4041 #define __FUNCT__ "SNESSetType"
4042 /*@C
4043    SNESSetType - Sets the method for the nonlinear solver.
4044 
4045    Collective on SNES
4046 
4047    Input Parameters:
4048 +  snes - the SNES context
4049 -  type - a known method
4050 
4051    Options Database Key:
4052 .  -snes_type <type> - Sets the method; use -help for a list
4053    of available methods (for instance, newtonls or newtontr)
4054 
4055    Notes:
4056    See "petsc/include/petscsnes.h" for available methods (for instance)
4057 +    SNESNEWTONLS - Newton's method with line search
4058      (systems of nonlinear equations)
4059 .    SNESNEWTONTR - Newton's method with trust region
4060      (systems of nonlinear equations)
4061 
4062   Normally, it is best to use the SNESSetFromOptions() command and then
4063   set the SNES solver type from the options database rather than by using
4064   this routine.  Using the options database provides the user with
4065   maximum flexibility in evaluating the many nonlinear solvers.
4066   The SNESSetType() routine is provided for those situations where it
4067   is necessary to set the nonlinear solver independently of the command
4068   line or options database.  This might be the case, for example, when
4069   the choice of solver changes during the execution of the program,
4070   and the user's application is taking responsibility for choosing the
4071   appropriate method.
4072 
4073     Developer Notes: SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
4074     the constructor in that list and calls it to create the spexific object.
4075 
4076   Level: intermediate
4077 
4078 .keywords: SNES, set, type
4079 
4080 .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()
4081 
4082 @*/
4083 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
4084 {
4085   PetscErrorCode ierr,(*r)(SNES);
4086   PetscBool      match;
4087 
4088   PetscFunctionBegin;
4089   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4090   PetscValidCharPointer(type,2);
4091 
4092   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
4093   if (match) PetscFunctionReturn(0);
4094 
4095   ierr =  PetscFunctionListFind(SNESList,type,&r);CHKERRQ(ierr);
4096   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
4097   /* Destroy the previous private SNES context */
4098   if (snes->ops->destroy) {
4099     ierr               = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
4100     snes->ops->destroy = NULL;
4101   }
4102   /* Reinitialize function pointers in SNESOps structure */
4103   snes->ops->setup          = 0;
4104   snes->ops->solve          = 0;
4105   snes->ops->view           = 0;
4106   snes->ops->setfromoptions = 0;
4107   snes->ops->destroy        = 0;
4108   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
4109   snes->setupcalled = PETSC_FALSE;
4110 
4111   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
4112   ierr = (*r)(snes);CHKERRQ(ierr);
4113   PetscFunctionReturn(0);
4114 }
4115 
4116 #undef __FUNCT__
4117 #define __FUNCT__ "SNESGetType"
4118 /*@C
4119    SNESGetType - Gets the SNES method type and name (as a string).
4120 
4121    Not Collective
4122 
4123    Input Parameter:
4124 .  snes - nonlinear solver context
4125 
4126    Output Parameter:
4127 .  type - SNES method (a character string)
4128 
4129    Level: intermediate
4130 
4131 .keywords: SNES, nonlinear, get, type, name
4132 @*/
4133 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
4134 {
4135   PetscFunctionBegin;
4136   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4137   PetscValidPointer(type,2);
4138   *type = ((PetscObject)snes)->type_name;
4139   PetscFunctionReturn(0);
4140 }
4141 
4142 #undef __FUNCT__
4143 #define __FUNCT__ "SNESSetSolution"
4144 /*@
4145   SNESSetSolution - Sets the solution vector for use by the SNES routines.
4146 
4147   Logically Collective on SNES and Vec
4148 
4149   Input Parameters:
4150 + snes - the SNES context obtained from SNESCreate()
4151 - u    - the solution vector
4152 
4153   Level: beginner
4154 
4155 .keywords: SNES, set, solution
4156 @*/
4157 PetscErrorCode SNESSetSolution(SNES snes, Vec u)
4158 {
4159   DM             dm;
4160   PetscErrorCode ierr;
4161 
4162   PetscFunctionBegin;
4163   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4164   PetscValidHeaderSpecific(u, VEC_CLASSID, 2);
4165   ierr = PetscObjectReference((PetscObject) u);CHKERRQ(ierr);
4166   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
4167 
4168   snes->vec_sol = u;
4169 
4170   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
4171   ierr = DMShellSetGlobalVector(dm, u);CHKERRQ(ierr);
4172   PetscFunctionReturn(0);
4173 }
4174 
4175 #undef __FUNCT__
4176 #define __FUNCT__ "SNESGetSolution"
4177 /*@
4178    SNESGetSolution - Returns the vector where the approximate solution is
4179    stored. This is the fine grid solution when using SNESSetGridSequence().
4180 
4181    Not Collective, but Vec is parallel if SNES is parallel
4182 
4183    Input Parameter:
4184 .  snes - the SNES context
4185 
4186    Output Parameter:
4187 .  x - the solution
4188 
4189    Level: intermediate
4190 
4191 .keywords: SNES, nonlinear, get, solution
4192 
4193 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
4194 @*/
4195 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
4196 {
4197   PetscFunctionBegin;
4198   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4199   PetscValidPointer(x,2);
4200   *x = snes->vec_sol;
4201   PetscFunctionReturn(0);
4202 }
4203 
4204 #undef __FUNCT__
4205 #define __FUNCT__ "SNESGetSolutionUpdate"
4206 /*@
4207    SNESGetSolutionUpdate - Returns the vector where the solution update is
4208    stored.
4209 
4210    Not Collective, but Vec is parallel if SNES is parallel
4211 
4212    Input Parameter:
4213 .  snes - the SNES context
4214 
4215    Output Parameter:
4216 .  x - the solution update
4217 
4218    Level: advanced
4219 
4220 .keywords: SNES, nonlinear, get, solution, update
4221 
4222 .seealso: SNESGetSolution(), SNESGetFunction()
4223 @*/
4224 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
4225 {
4226   PetscFunctionBegin;
4227   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4228   PetscValidPointer(x,2);
4229   *x = snes->vec_sol_update;
4230   PetscFunctionReturn(0);
4231 }
4232 
4233 #undef __FUNCT__
4234 #define __FUNCT__ "SNESGetFunction"
4235 /*@C
4236    SNESGetFunction - Returns the vector where the function is stored.
4237 
4238    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
4239 
4240    Input Parameter:
4241 .  snes - the SNES context
4242 
4243    Output Parameter:
4244 +  r - the vector that is used to store residuals (or NULL if you don't want it)
4245 .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
4246 -  ctx - the function context (or NULL if you don't want it)
4247 
4248    Level: advanced
4249 
4250 .keywords: SNES, nonlinear, get, function
4251 
4252 .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
4253 @*/
4254 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
4255 {
4256   PetscErrorCode ierr;
4257   DM             dm;
4258 
4259   PetscFunctionBegin;
4260   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4261   if (r) {
4262     if (!snes->vec_func) {
4263       if (snes->vec_rhs) {
4264         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
4265       } else if (snes->vec_sol) {
4266         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
4267       } else if (snes->dm) {
4268         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
4269       }
4270     }
4271     *r = snes->vec_func;
4272   }
4273   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4274   ierr = DMSNESGetFunction(dm,f,ctx);CHKERRQ(ierr);
4275   PetscFunctionReturn(0);
4276 }
4277 
4278 /*@C
4279    SNESGetNGS - Returns the NGS function and context.
4280 
4281    Input Parameter:
4282 .  snes - the SNES context
4283 
4284    Output Parameter:
4285 +  f - the function (or NULL) see SNESNGSFunction for details
4286 -  ctx    - the function context (or NULL)
4287 
4288    Level: advanced
4289 
4290 .keywords: SNES, nonlinear, get, function
4291 
4292 .seealso: SNESSetNGS(), SNESGetFunction()
4293 @*/
4294 
4295 #undef __FUNCT__
4296 #define __FUNCT__ "SNESGetNGS"
4297 PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
4298 {
4299   PetscErrorCode ierr;
4300   DM             dm;
4301 
4302   PetscFunctionBegin;
4303   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4304   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4305   ierr = DMSNESGetNGS(dm,f,ctx);CHKERRQ(ierr);
4306   PetscFunctionReturn(0);
4307 }
4308 
4309 #undef __FUNCT__
4310 #define __FUNCT__ "SNESSetOptionsPrefix"
4311 /*@C
4312    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4313    SNES options in the database.
4314 
4315    Logically Collective on SNES
4316 
4317    Input Parameter:
4318 +  snes - the SNES context
4319 -  prefix - the prefix to prepend to all option names
4320 
4321    Notes:
4322    A hyphen (-) must NOT be given at the beginning of the prefix name.
4323    The first character of all runtime options is AUTOMATICALLY the hyphen.
4324 
4325    Level: advanced
4326 
4327 .keywords: SNES, set, options, prefix, database
4328 
4329 .seealso: SNESSetFromOptions()
4330 @*/
4331 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4332 {
4333   PetscErrorCode ierr;
4334 
4335   PetscFunctionBegin;
4336   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4337   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4338   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4339   if (snes->linesearch) {
4340     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4341     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4342   }
4343   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4344   PetscFunctionReturn(0);
4345 }
4346 
4347 #undef __FUNCT__
4348 #define __FUNCT__ "SNESAppendOptionsPrefix"
4349 /*@C
4350    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4351    SNES options in the database.
4352 
4353    Logically Collective on SNES
4354 
4355    Input Parameters:
4356 +  snes - the SNES context
4357 -  prefix - the prefix to prepend to all option names
4358 
4359    Notes:
4360    A hyphen (-) must NOT be given at the beginning of the prefix name.
4361    The first character of all runtime options is AUTOMATICALLY the hyphen.
4362 
4363    Level: advanced
4364 
4365 .keywords: SNES, append, options, prefix, database
4366 
4367 .seealso: SNESGetOptionsPrefix()
4368 @*/
4369 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4370 {
4371   PetscErrorCode ierr;
4372 
4373   PetscFunctionBegin;
4374   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4375   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4376   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4377   if (snes->linesearch) {
4378     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4379     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4380   }
4381   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4382   PetscFunctionReturn(0);
4383 }
4384 
4385 #undef __FUNCT__
4386 #define __FUNCT__ "SNESGetOptionsPrefix"
4387 /*@C
4388    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4389    SNES options in the database.
4390 
4391    Not Collective
4392 
4393    Input Parameter:
4394 .  snes - the SNES context
4395 
4396    Output Parameter:
4397 .  prefix - pointer to the prefix string used
4398 
4399    Notes: On the fortran side, the user should pass in a string 'prefix' of
4400    sufficient length to hold the prefix.
4401 
4402    Level: advanced
4403 
4404 .keywords: SNES, get, options, prefix, database
4405 
4406 .seealso: SNESAppendOptionsPrefix()
4407 @*/
4408 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4409 {
4410   PetscErrorCode ierr;
4411 
4412   PetscFunctionBegin;
4413   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4414   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4415   PetscFunctionReturn(0);
4416 }
4417 
4418 
4419 #undef __FUNCT__
4420 #define __FUNCT__ "SNESRegister"
4421 /*@C
4422   SNESRegister - Adds a method to the nonlinear solver package.
4423 
4424    Not collective
4425 
4426    Input Parameters:
4427 +  name_solver - name of a new user-defined solver
4428 -  routine_create - routine to create method context
4429 
4430    Notes:
4431    SNESRegister() may be called multiple times to add several user-defined solvers.
4432 
4433    Sample usage:
4434 .vb
4435    SNESRegister("my_solver",MySolverCreate);
4436 .ve
4437 
4438    Then, your solver can be chosen with the procedural interface via
4439 $     SNESSetType(snes,"my_solver")
4440    or at runtime via the option
4441 $     -snes_type my_solver
4442 
4443    Level: advanced
4444 
4445     Note: If your function is not being put into a shared library then use SNESRegister() instead
4446 
4447 .keywords: SNES, nonlinear, register
4448 
4449 .seealso: SNESRegisterAll(), SNESRegisterDestroy()
4450 
4451   Level: advanced
4452 @*/
4453 PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
4454 {
4455   PetscErrorCode ierr;
4456 
4457   PetscFunctionBegin;
4458   ierr = PetscFunctionListAdd(&SNESList,sname,function);CHKERRQ(ierr);
4459   PetscFunctionReturn(0);
4460 }
4461 
4462 #undef __FUNCT__
4463 #define __FUNCT__ "SNESTestLocalMin"
4464 PetscErrorCode  SNESTestLocalMin(SNES snes)
4465 {
4466   PetscErrorCode ierr;
4467   PetscInt       N,i,j;
4468   Vec            u,uh,fh;
4469   PetscScalar    value;
4470   PetscReal      norm;
4471 
4472   PetscFunctionBegin;
4473   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4474   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4475   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4476 
4477   /* currently only works for sequential */
4478   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");CHKERRQ(ierr);
4479   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4480   for (i=0; i<N; i++) {
4481     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4482     ierr = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4483     for (j=-10; j<11; j++) {
4484       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
4485       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4486       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4487       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4488       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4489       value = -value;
4490       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4491     }
4492   }
4493   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4494   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4495   PetscFunctionReturn(0);
4496 }
4497 
4498 #undef __FUNCT__
4499 #define __FUNCT__ "SNESKSPSetUseEW"
4500 /*@
4501    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4502    computing relative tolerance for linear solvers within an inexact
4503    Newton method.
4504 
4505    Logically Collective on SNES
4506 
4507    Input Parameters:
4508 +  snes - SNES context
4509 -  flag - PETSC_TRUE or PETSC_FALSE
4510 
4511     Options Database:
4512 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4513 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4514 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4515 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4516 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4517 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4518 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4519 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4520 
4521    Notes:
4522    Currently, the default is to use a constant relative tolerance for
4523    the inner linear solvers.  Alternatively, one can use the
4524    Eisenstat-Walker method, where the relative convergence tolerance
4525    is reset at each Newton iteration according progress of the nonlinear
4526    solver.
4527 
4528    Level: advanced
4529 
4530    Reference:
4531    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4532    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4533 
4534 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4535 
4536 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4537 @*/
4538 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
4539 {
4540   PetscFunctionBegin;
4541   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4542   PetscValidLogicalCollectiveBool(snes,flag,2);
4543   snes->ksp_ewconv = flag;
4544   PetscFunctionReturn(0);
4545 }
4546 
4547 #undef __FUNCT__
4548 #define __FUNCT__ "SNESKSPGetUseEW"
4549 /*@
4550    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4551    for computing relative tolerance for linear solvers within an
4552    inexact Newton method.
4553 
4554    Not Collective
4555 
4556    Input Parameter:
4557 .  snes - SNES context
4558 
4559    Output Parameter:
4560 .  flag - PETSC_TRUE or PETSC_FALSE
4561 
4562    Notes:
4563    Currently, the default is to use a constant relative tolerance for
4564    the inner linear solvers.  Alternatively, one can use the
4565    Eisenstat-Walker method, where the relative convergence tolerance
4566    is reset at each Newton iteration according progress of the nonlinear
4567    solver.
4568 
4569    Level: advanced
4570 
4571    Reference:
4572    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4573    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4574 
4575 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4576 
4577 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4578 @*/
4579 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4580 {
4581   PetscFunctionBegin;
4582   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4583   PetscValidPointer(flag,2);
4584   *flag = snes->ksp_ewconv;
4585   PetscFunctionReturn(0);
4586 }
4587 
4588 #undef __FUNCT__
4589 #define __FUNCT__ "SNESKSPSetParametersEW"
4590 /*@
4591    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4592    convergence criteria for the linear solvers within an inexact
4593    Newton method.
4594 
4595    Logically Collective on SNES
4596 
4597    Input Parameters:
4598 +    snes - SNES context
4599 .    version - version 1, 2 (default is 2) or 3
4600 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4601 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4602 .    gamma - multiplicative factor for version 2 rtol computation
4603              (0 <= gamma2 <= 1)
4604 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4605 .    alpha2 - power for safeguard
4606 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4607 
4608    Note:
4609    Version 3 was contributed by Luis Chacon, June 2006.
4610 
4611    Use PETSC_DEFAULT to retain the default for any of the parameters.
4612 
4613    Level: advanced
4614 
4615    Reference:
4616    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4617    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4618    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4619 
4620 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4621 
4622 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4623 @*/
4624 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4625 {
4626   SNESKSPEW *kctx;
4627 
4628   PetscFunctionBegin;
4629   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4630   kctx = (SNESKSPEW*)snes->kspconvctx;
4631   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4632   PetscValidLogicalCollectiveInt(snes,version,2);
4633   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4634   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4635   PetscValidLogicalCollectiveReal(snes,gamma,5);
4636   PetscValidLogicalCollectiveReal(snes,alpha,6);
4637   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4638   PetscValidLogicalCollectiveReal(snes,threshold,8);
4639 
4640   if (version != PETSC_DEFAULT)   kctx->version   = version;
4641   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4642   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4643   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4644   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4645   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4646   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4647 
4648   if (kctx->version < 1 || kctx->version > 3) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 and 3 are supported: %D",kctx->version);
4649   if (kctx->rtol_0 < 0.0 || kctx->rtol_0 >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_0 < 1.0: %g",(double)kctx->rtol_0);
4650   if (kctx->rtol_max < 0.0 || kctx->rtol_max >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_max (%g) < 1.0\n",(double)kctx->rtol_max);
4651   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%g) <= 1.0\n",(double)kctx->gamma);
4652   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%g) <= 2.0\n",(double)kctx->alpha);
4653   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%g) < 1.0\n",(double)kctx->threshold);
4654   PetscFunctionReturn(0);
4655 }
4656 
4657 #undef __FUNCT__
4658 #define __FUNCT__ "SNESKSPGetParametersEW"
4659 /*@
4660    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4661    convergence criteria for the linear solvers within an inexact
4662    Newton method.
4663 
4664    Not Collective
4665 
4666    Input Parameters:
4667      snes - SNES context
4668 
4669    Output Parameters:
4670 +    version - version 1, 2 (default is 2) or 3
4671 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4672 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4673 .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
4674 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4675 .    alpha2 - power for safeguard
4676 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4677 
4678    Level: advanced
4679 
4680 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4681 
4682 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4683 @*/
4684 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4685 {
4686   SNESKSPEW *kctx;
4687 
4688   PetscFunctionBegin;
4689   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4690   kctx = (SNESKSPEW*)snes->kspconvctx;
4691   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4692   if (version)   *version   = kctx->version;
4693   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4694   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4695   if (gamma)     *gamma     = kctx->gamma;
4696   if (alpha)     *alpha     = kctx->alpha;
4697   if (alpha2)    *alpha2    = kctx->alpha2;
4698   if (threshold) *threshold = kctx->threshold;
4699   PetscFunctionReturn(0);
4700 }
4701 
4702 #undef __FUNCT__
4703 #define __FUNCT__ "KSPPreSolve_SNESEW"
4704  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4705 {
4706   PetscErrorCode ierr;
4707   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4708   PetscReal      rtol  = PETSC_DEFAULT,stol;
4709 
4710   PetscFunctionBegin;
4711   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4712   if (!snes->iter) {
4713     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
4714     ierr = VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);CHKERRQ(ierr);
4715   }
4716   else {
4717     if (kctx->version == 1) {
4718       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4719       if (rtol < 0.0) rtol = -rtol;
4720       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
4721       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4722     } else if (kctx->version == 2) {
4723       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4724       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
4725       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4726     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
4727       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4728       /* safeguard: avoid sharp decrease of rtol */
4729       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
4730       stol = PetscMax(rtol,stol);
4731       rtol = PetscMin(kctx->rtol_0,stol);
4732       /* safeguard: avoid oversolving */
4733       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
4734       stol = PetscMax(rtol,stol);
4735       rtol = PetscMin(kctx->rtol_0,stol);
4736     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4737   }
4738   /* safeguard: avoid rtol greater than one */
4739   rtol = PetscMin(rtol,kctx->rtol_max);
4740   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4741   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);CHKERRQ(ierr);
4742   PetscFunctionReturn(0);
4743 }
4744 
4745 #undef __FUNCT__
4746 #define __FUNCT__ "KSPPostSolve_SNESEW"
4747 PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4748 {
4749   PetscErrorCode ierr;
4750   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4751   PCSide         pcside;
4752   Vec            lres;
4753 
4754   PetscFunctionBegin;
4755   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4756   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4757   kctx->norm_last = snes->norm;
4758   if (kctx->version == 1) {
4759     PC        pc;
4760     PetscBool isNone;
4761 
4762     ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
4763     ierr = PetscObjectTypeCompare((PetscObject) pc, PCNONE, &isNone);CHKERRQ(ierr);
4764     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4765      if (pcside == PC_RIGHT || isNone) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4766       /* KSP residual is true linear residual */
4767       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4768     } else {
4769       /* KSP residual is preconditioned residual */
4770       /* compute true linear residual norm */
4771       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4772       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4773       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4774       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4775       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4776     }
4777   }
4778   PetscFunctionReturn(0);
4779 }
4780 
4781 #undef __FUNCT__
4782 #define __FUNCT__ "SNESGetKSP"
4783 /*@
4784    SNESGetKSP - Returns the KSP context for a SNES solver.
4785 
4786    Not Collective, but if SNES object is parallel, then KSP object is parallel
4787 
4788    Input Parameter:
4789 .  snes - the SNES context
4790 
4791    Output Parameter:
4792 .  ksp - the KSP context
4793 
4794    Notes:
4795    The user can then directly manipulate the KSP context to set various
4796    options, etc.  Likewise, the user can then extract and manipulate the
4797    PC contexts as well.
4798 
4799    Level: beginner
4800 
4801 .keywords: SNES, nonlinear, get, KSP, context
4802 
4803 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
4804 @*/
4805 PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
4806 {
4807   PetscErrorCode ierr;
4808 
4809   PetscFunctionBegin;
4810   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4811   PetscValidPointer(ksp,2);
4812 
4813   if (!snes->ksp) {
4814     PetscBool monitor = PETSC_FALSE;
4815 
4816     ierr = KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);CHKERRQ(ierr);
4817     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);CHKERRQ(ierr);
4818     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);CHKERRQ(ierr);
4819 
4820     ierr = KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);CHKERRQ(ierr);
4821     ierr = KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);CHKERRQ(ierr);
4822 
4823     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes",&monitor,NULL);CHKERRQ(ierr);
4824     if (monitor) {
4825       ierr = KSPMonitorSet(snes->ksp,KSPMonitorSNES,snes,NULL);CHKERRQ(ierr);
4826     }
4827     monitor = PETSC_FALSE;
4828     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes_lg",&monitor,NULL);CHKERRQ(ierr);
4829     if (monitor) {
4830       PetscObject *objs;
4831       ierr = KSPMonitorSNESLGResidualNormCreate(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,600,600,&objs);CHKERRQ(ierr);
4832       objs[0] = (PetscObject) snes;
4833       ierr = KSPMonitorSet(snes->ksp,(PetscErrorCode (*)(KSP,PetscInt,PetscReal,void*))KSPMonitorSNESLGResidualNorm,objs,(PetscErrorCode (*)(void**))KSPMonitorSNESLGResidualNormDestroy);CHKERRQ(ierr);
4834     }
4835   }
4836   *ksp = snes->ksp;
4837   PetscFunctionReturn(0);
4838 }
4839 
4840 
4841 #include <petsc/private/dmimpl.h>
4842 #undef __FUNCT__
4843 #define __FUNCT__ "SNESSetDM"
4844 /*@
4845    SNESSetDM - Sets the DM that may be used by some preconditioners
4846 
4847    Logically Collective on SNES
4848 
4849    Input Parameters:
4850 +  snes - the preconditioner context
4851 -  dm - the dm
4852 
4853    Level: intermediate
4854 
4855 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4856 @*/
4857 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4858 {
4859   PetscErrorCode ierr;
4860   KSP            ksp;
4861   DMSNES         sdm;
4862 
4863   PetscFunctionBegin;
4864   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4865   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4866   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4867     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4868       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4869       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4870       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
4871     }
4872     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4873   }
4874   snes->dm     = dm;
4875   snes->dmAuto = PETSC_FALSE;
4876 
4877   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4878   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4879   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4880   if (snes->pc) {
4881     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4882     ierr = SNESSetNPCSide(snes,snes->pcside);CHKERRQ(ierr);
4883   }
4884   PetscFunctionReturn(0);
4885 }
4886 
4887 #undef __FUNCT__
4888 #define __FUNCT__ "SNESGetDM"
4889 /*@
4890    SNESGetDM - Gets the DM that may be used by some preconditioners
4891 
4892    Not Collective but DM obtained is parallel on SNES
4893 
4894    Input Parameter:
4895 . snes - the preconditioner context
4896 
4897    Output Parameter:
4898 .  dm - the dm
4899 
4900    Level: intermediate
4901 
4902 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4903 @*/
4904 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4905 {
4906   PetscErrorCode ierr;
4907 
4908   PetscFunctionBegin;
4909   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4910   if (!snes->dm) {
4911     ierr         = DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);CHKERRQ(ierr);
4912     snes->dmAuto = PETSC_TRUE;
4913   }
4914   *dm = snes->dm;
4915   PetscFunctionReturn(0);
4916 }
4917 
4918 #undef __FUNCT__
4919 #define __FUNCT__ "SNESSetNPC"
4920 /*@
4921   SNESSetNPC - Sets the nonlinear preconditioner to be used.
4922 
4923   Collective on SNES
4924 
4925   Input Parameters:
4926 + snes - iterative context obtained from SNESCreate()
4927 - pc   - the preconditioner object
4928 
4929   Notes:
4930   Use SNESGetNPC() to retrieve the preconditioner context (for example,
4931   to configure it using the API).
4932 
4933   Level: developer
4934 
4935 .keywords: SNES, set, precondition
4936 .seealso: SNESGetNPC(), SNESHasNPC()
4937 @*/
4938 PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
4939 {
4940   PetscErrorCode ierr;
4941 
4942   PetscFunctionBegin;
4943   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4944   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4945   PetscCheckSameComm(snes, 1, pc, 2);
4946   ierr     = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4947   ierr     = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4948   snes->pc = pc;
4949   ierr     = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->pc);CHKERRQ(ierr);
4950   PetscFunctionReturn(0);
4951 }
4952 
4953 #undef __FUNCT__
4954 #define __FUNCT__ "SNESGetNPC"
4955 /*@
4956   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.
4957 
4958   Not Collective
4959 
4960   Input Parameter:
4961 . snes - iterative context obtained from SNESCreate()
4962 
4963   Output Parameter:
4964 . pc - preconditioner context
4965 
4966   Notes: If a SNES was previously set with SNESSetNPC() then that SNES is returned.
4967 
4968   Level: developer
4969 
4970 .keywords: SNES, get, preconditioner
4971 .seealso: SNESSetNPC(), SNESHasNPC()
4972 @*/
4973 PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
4974 {
4975   PetscErrorCode ierr;
4976   const char     *optionsprefix;
4977 
4978   PetscFunctionBegin;
4979   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4980   PetscValidPointer(pc, 2);
4981   if (!snes->pc) {
4982     ierr = SNESCreate(PetscObjectComm((PetscObject)snes),&snes->pc);CHKERRQ(ierr);
4983     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4984     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
4985     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4986     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4987     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4988     ierr = SNESSetCountersReset(snes->pc,PETSC_FALSE);CHKERRQ(ierr);
4989   }
4990   *pc = snes->pc;
4991   PetscFunctionReturn(0);
4992 }
4993 
4994 #undef __FUNCT__
4995 #define __FUNCT__ "SNESHasNPC"
4996 /*@
4997   SNESHasNPC - Returns whether a nonlinear preconditioner exists
4998 
4999   Not Collective
5000 
5001   Input Parameter:
5002 . snes - iterative context obtained from SNESCreate()
5003 
5004   Output Parameter:
5005 . has_npc - whether the SNES has an NPC or not
5006 
5007   Level: developer
5008 
5009 .keywords: SNES, has, preconditioner
5010 .seealso: SNESSetNPC(), SNESGetNPC()
5011 @*/
5012 PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
5013 {
5014   PetscFunctionBegin;
5015   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
5016   *has_npc = (PetscBool) (snes->pc ? PETSC_TRUE : PETSC_FALSE);
5017   PetscFunctionReturn(0);
5018 }
5019 
5020 #undef __FUNCT__
5021 #define __FUNCT__ "SNESSetNPCSide"
5022 /*@
5023     SNESSetNPCSide - Sets the preconditioning side.
5024 
5025     Logically Collective on SNES
5026 
5027     Input Parameter:
5028 .   snes - iterative context obtained from SNESCreate()
5029 
5030     Output Parameter:
5031 .   side - the preconditioning side, where side is one of
5032 .vb
5033       PC_LEFT - left preconditioning (default)
5034       PC_RIGHT - right preconditioning
5035 .ve
5036 
5037     Options Database Keys:
5038 .   -snes_pc_side <right,left>
5039 
5040     Level: intermediate
5041 
5042 .keywords: SNES, set, right, left, side, preconditioner, flag
5043 
5044 .seealso: SNESGetNPCSide(), KSPSetPCSide()
5045 @*/
5046 PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
5047 {
5048   PetscFunctionBegin;
5049   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5050   PetscValidLogicalCollectiveEnum(snes,side,2);
5051   snes->pcside = side;
5052   PetscFunctionReturn(0);
5053 }
5054 
5055 #undef __FUNCT__
5056 #define __FUNCT__ "SNESGetNPCSide"
5057 /*@
5058     SNESGetNPCSide - Gets the preconditioning side.
5059 
5060     Not Collective
5061 
5062     Input Parameter:
5063 .   snes - iterative context obtained from SNESCreate()
5064 
5065     Output Parameter:
5066 .   side - the preconditioning side, where side is one of
5067 .vb
5068       PC_LEFT - left preconditioning (default)
5069       PC_RIGHT - right preconditioning
5070 .ve
5071 
5072     Level: intermediate
5073 
5074 .keywords: SNES, get, right, left, side, preconditioner, flag
5075 
5076 .seealso: SNESSetNPCSide(), KSPGetPCSide()
5077 @*/
5078 PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
5079 {
5080   PetscFunctionBegin;
5081   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5082   PetscValidPointer(side,2);
5083   *side = snes->pcside;
5084   PetscFunctionReturn(0);
5085 }
5086 
5087 #undef __FUNCT__
5088 #define __FUNCT__ "SNESSetLineSearch"
5089 /*@
5090   SNESSetLineSearch - Sets the linesearch on the SNES instance.
5091 
5092   Collective on SNES
5093 
5094   Input Parameters:
5095 + snes - iterative context obtained from SNESCreate()
5096 - linesearch   - the linesearch object
5097 
5098   Notes:
5099   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
5100   to configure it using the API).
5101 
5102   Level: developer
5103 
5104 .keywords: SNES, set, linesearch
5105 .seealso: SNESGetLineSearch()
5106 @*/
5107 PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
5108 {
5109   PetscErrorCode ierr;
5110 
5111   PetscFunctionBegin;
5112   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
5113   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
5114   PetscCheckSameComm(snes, 1, linesearch, 2);
5115   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
5116   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
5117 
5118   snes->linesearch = linesearch;
5119 
5120   ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
5121   PetscFunctionReturn(0);
5122 }
5123 
5124 #undef __FUNCT__
5125 #define __FUNCT__ "SNESGetLineSearch"
5126 /*@
5127   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
5128   or creates a default line search instance associated with the SNES and returns it.
5129 
5130   Not Collective
5131 
5132   Input Parameter:
5133 . snes - iterative context obtained from SNESCreate()
5134 
5135   Output Parameter:
5136 . linesearch - linesearch context
5137 
5138   Level: beginner
5139 
5140 .keywords: SNES, get, linesearch
5141 .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
5142 @*/
5143 PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
5144 {
5145   PetscErrorCode ierr;
5146   const char     *optionsprefix;
5147 
5148   PetscFunctionBegin;
5149   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
5150   PetscValidPointer(linesearch, 2);
5151   if (!snes->linesearch) {
5152     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
5153     ierr = SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);CHKERRQ(ierr);
5154     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
5155     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
5156     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
5157     ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
5158   }
5159   *linesearch = snes->linesearch;
5160   PetscFunctionReturn(0);
5161 }
5162 
5163 #if defined(PETSC_HAVE_MATLAB_ENGINE)
5164 #include <mex.h>
5165 
5166 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
5167 
5168 #undef __FUNCT__
5169 #define __FUNCT__ "SNESComputeFunction_Matlab"
5170 /*
5171    SNESComputeFunction_Matlab - Calls the function that has been set with SNESSetFunctionMatlab().
5172 
5173    Collective on SNES
5174 
5175    Input Parameters:
5176 +  snes - the SNES context
5177 -  x - input vector
5178 
5179    Output Parameter:
5180 .  y - function vector, as set by SNESSetFunction()
5181 
5182    Notes:
5183    SNESComputeFunction() is typically used within nonlinear solvers
5184    implementations, so most users would not generally call this routine
5185    themselves.
5186 
5187    Level: developer
5188 
5189 .keywords: SNES, nonlinear, compute, function
5190 
5191 .seealso: SNESSetFunction(), SNESGetFunction()
5192 */
5193 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
5194 {
5195   PetscErrorCode    ierr;
5196   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5197   int               nlhs  = 1,nrhs = 5;
5198   mxArray           *plhs[1],*prhs[5];
5199   long long int     lx = 0,ly = 0,ls = 0;
5200 
5201   PetscFunctionBegin;
5202   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5203   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
5204   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
5205   PetscCheckSameComm(snes,1,x,2);
5206   PetscCheckSameComm(snes,1,y,3);
5207 
5208   /* call Matlab function in ctx with arguments x and y */
5209 
5210   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5211   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5212   ierr    = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
5213   prhs[0] = mxCreateDoubleScalar((double)ls);
5214   prhs[1] = mxCreateDoubleScalar((double)lx);
5215   prhs[2] = mxCreateDoubleScalar((double)ly);
5216   prhs[3] = mxCreateString(sctx->funcname);
5217   prhs[4] = sctx->ctx;
5218   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
5219   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5220   mxDestroyArray(prhs[0]);
5221   mxDestroyArray(prhs[1]);
5222   mxDestroyArray(prhs[2]);
5223   mxDestroyArray(prhs[3]);
5224   mxDestroyArray(plhs[0]);
5225   PetscFunctionReturn(0);
5226 }
5227 
5228 #undef __FUNCT__
5229 #define __FUNCT__ "SNESSetFunctionMatlab"
5230 /*
5231    SNESSetFunctionMatlab - Sets the function evaluation routine and function
5232    vector for use by the SNES routines in solving systems of nonlinear
5233    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5234 
5235    Logically Collective on SNES
5236 
5237    Input Parameters:
5238 +  snes - the SNES context
5239 .  r - vector to store function value
5240 -  f - function evaluation routine
5241 
5242    Notes:
5243    The Newton-like methods typically solve linear systems of the form
5244 $      f'(x) x = -f(x),
5245    where f'(x) denotes the Jacobian matrix and f(x) is the function.
5246 
5247    Level: beginner
5248 
5249    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5250 
5251 .keywords: SNES, nonlinear, set, function
5252 
5253 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5254 */
5255 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *f,mxArray *ctx)
5256 {
5257   PetscErrorCode    ierr;
5258   SNESMatlabContext *sctx;
5259 
5260   PetscFunctionBegin;
5261   /* currently sctx is memory bleed */
5262   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5263   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5264   /*
5265      This should work, but it doesn't
5266   sctx->ctx = ctx;
5267   mexMakeArrayPersistent(sctx->ctx);
5268   */
5269   sctx->ctx = mxDuplicateArray(ctx);
5270   ierr      = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
5271   PetscFunctionReturn(0);
5272 }
5273 
5274 #undef __FUNCT__
5275 #define __FUNCT__ "SNESComputeJacobian_Matlab"
5276 /*
5277    SNESComputeJacobian_Matlab - Calls the function that has been set with SNESSetJacobianMatlab().
5278 
5279    Collective on SNES
5280 
5281    Input Parameters:
5282 +  snes - the SNES context
5283 .  x - input vector
5284 .  A, B - the matrices
5285 -  ctx - user context
5286 
5287    Level: developer
5288 
5289 .keywords: SNES, nonlinear, compute, function
5290 
5291 .seealso: SNESSetFunction(), SNESGetFunction()
5292 @*/
5293 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat A,Mat B,void *ctx)
5294 {
5295   PetscErrorCode    ierr;
5296   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5297   int               nlhs  = 2,nrhs = 6;
5298   mxArray           *plhs[2],*prhs[6];
5299   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
5300 
5301   PetscFunctionBegin;
5302   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5303   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
5304 
5305   /* call Matlab function in ctx with arguments x and y */
5306 
5307   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5308   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5309   ierr    = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
5310   ierr    = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
5311   prhs[0] = mxCreateDoubleScalar((double)ls);
5312   prhs[1] = mxCreateDoubleScalar((double)lx);
5313   prhs[2] = mxCreateDoubleScalar((double)lA);
5314   prhs[3] = mxCreateDoubleScalar((double)lB);
5315   prhs[4] = mxCreateString(sctx->funcname);
5316   prhs[5] = sctx->ctx;
5317   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
5318   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5319   mxDestroyArray(prhs[0]);
5320   mxDestroyArray(prhs[1]);
5321   mxDestroyArray(prhs[2]);
5322   mxDestroyArray(prhs[3]);
5323   mxDestroyArray(prhs[4]);
5324   mxDestroyArray(plhs[0]);
5325   mxDestroyArray(plhs[1]);
5326   PetscFunctionReturn(0);
5327 }
5328 
5329 #undef __FUNCT__
5330 #define __FUNCT__ "SNESSetJacobianMatlab"
5331 /*
5332    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
5333    vector for use by the SNES routines in solving systems of nonlinear
5334    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5335 
5336    Logically Collective on SNES
5337 
5338    Input Parameters:
5339 +  snes - the SNES context
5340 .  A,B - Jacobian matrices
5341 .  J - function evaluation routine
5342 -  ctx - user context
5343 
5344    Level: developer
5345 
5346    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5347 
5348 .keywords: SNES, nonlinear, set, function
5349 
5350 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction(), J
5351 */
5352 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *J,mxArray *ctx)
5353 {
5354   PetscErrorCode    ierr;
5355   SNESMatlabContext *sctx;
5356 
5357   PetscFunctionBegin;
5358   /* currently sctx is memory bleed */
5359   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5360   ierr = PetscStrallocpy(J,&sctx->funcname);CHKERRQ(ierr);
5361   /*
5362      This should work, but it doesn't
5363   sctx->ctx = ctx;
5364   mexMakeArrayPersistent(sctx->ctx);
5365   */
5366   sctx->ctx = mxDuplicateArray(ctx);
5367   ierr      = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
5368   PetscFunctionReturn(0);
5369 }
5370 
5371 #undef __FUNCT__
5372 #define __FUNCT__ "SNESMonitor_Matlab"
5373 /*
5374    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
5375 
5376    Collective on SNES
5377 
5378 .seealso: SNESSetFunction(), SNESGetFunction()
5379 @*/
5380 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
5381 {
5382   PetscErrorCode    ierr;
5383   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5384   int               nlhs  = 1,nrhs = 6;
5385   mxArray           *plhs[1],*prhs[6];
5386   long long int     lx = 0,ls = 0;
5387   Vec               x  = snes->vec_sol;
5388 
5389   PetscFunctionBegin;
5390   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5391 
5392   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5393   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5394   prhs[0] = mxCreateDoubleScalar((double)ls);
5395   prhs[1] = mxCreateDoubleScalar((double)it);
5396   prhs[2] = mxCreateDoubleScalar((double)fnorm);
5397   prhs[3] = mxCreateDoubleScalar((double)lx);
5398   prhs[4] = mxCreateString(sctx->funcname);
5399   prhs[5] = sctx->ctx;
5400   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
5401   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5402   mxDestroyArray(prhs[0]);
5403   mxDestroyArray(prhs[1]);
5404   mxDestroyArray(prhs[2]);
5405   mxDestroyArray(prhs[3]);
5406   mxDestroyArray(prhs[4]);
5407   mxDestroyArray(plhs[0]);
5408   PetscFunctionReturn(0);
5409 }
5410 
5411 #undef __FUNCT__
5412 #define __FUNCT__ "SNESMonitorSetMatlab"
5413 /*
5414    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
5415 
5416    Level: developer
5417 
5418    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5419 
5420 .keywords: SNES, nonlinear, set, function
5421 
5422 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5423 */
5424 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *f,mxArray *ctx)
5425 {
5426   PetscErrorCode    ierr;
5427   SNESMatlabContext *sctx;
5428 
5429   PetscFunctionBegin;
5430   /* currently sctx is memory bleed */
5431   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5432   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5433   /*
5434      This should work, but it doesn't
5435   sctx->ctx = ctx;
5436   mexMakeArrayPersistent(sctx->ctx);
5437   */
5438   sctx->ctx = mxDuplicateArray(ctx);
5439   ierr      = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,NULL);CHKERRQ(ierr);
5440   PetscFunctionReturn(0);
5441 }
5442 
5443 #endif
5444