xref: /petsc/src/snes/interface/snes.c (revision 27b0f280e5bf9c639a7764debf82fd1b76d8a199)
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    Level: intermediate
1348 
1349 .keywords: SNES, nonlinear, get, number, linear, iterations
1350 
1351 .seealso:  SNESGetIterationNumber(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
1352 @*/
1353 PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
1354 {
1355   PetscFunctionBegin;
1356   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1357   PetscValidIntPointer(lits,2);
1358   *lits = snes->linear_its;
1359   PetscFunctionReturn(0);
1360 }
1361 
1362 #undef __FUNCT__
1363 #define __FUNCT__ "SNESSetCountersReset"
1364 /*@
1365    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1366    are reset every time SNESSolve() is called.
1367 
1368    Logically Collective on SNES
1369 
1370    Input Parameter:
1371 +  snes - SNES context
1372 -  reset - whether to reset the counters or not
1373 
1374    Notes:
1375    This defaults to PETSC_TRUE
1376 
1377    Level: developer
1378 
1379 .keywords: SNES, nonlinear, set, reset, number, linear, iterations
1380 
1381 .seealso:  SNESGetNumberFunctionEvals(), SNESGetLinearSolveIterations(), SNESGetNPC()
1382 @*/
1383 PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
1384 {
1385   PetscFunctionBegin;
1386   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1387   PetscValidLogicalCollectiveBool(snes,reset,2);
1388   snes->counters_reset = reset;
1389   PetscFunctionReturn(0);
1390 }
1391 
1392 
1393 #undef __FUNCT__
1394 #define __FUNCT__ "SNESSetKSP"
1395 /*@
1396    SNESSetKSP - Sets a KSP context for the SNES object to use
1397 
1398    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm
1399 
1400    Input Parameters:
1401 +  snes - the SNES context
1402 -  ksp - the KSP context
1403 
1404    Notes:
1405    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1406    so this routine is rarely needed.
1407 
1408    The KSP object that is already in the SNES object has its reference count
1409    decreased by one.
1410 
1411    Level: developer
1412 
1413 .keywords: SNES, nonlinear, get, KSP, context
1414 
1415 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1416 @*/
1417 PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1418 {
1419   PetscErrorCode ierr;
1420 
1421   PetscFunctionBegin;
1422   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1423   PetscValidHeaderSpecific(ksp,KSP_CLASSID,2);
1424   PetscCheckSameComm(snes,1,ksp,2);
1425   ierr = PetscObjectReference((PetscObject)ksp);CHKERRQ(ierr);
1426   if (snes->ksp) {ierr = PetscObjectDereference((PetscObject)snes->ksp);CHKERRQ(ierr);}
1427   snes->ksp = ksp;
1428   PetscFunctionReturn(0);
1429 }
1430 
1431 /* -----------------------------------------------------------*/
1432 #undef __FUNCT__
1433 #define __FUNCT__ "SNESCreate"
1434 /*@
1435    SNESCreate - Creates a nonlinear solver context.
1436 
1437    Collective on MPI_Comm
1438 
1439    Input Parameters:
1440 .  comm - MPI communicator
1441 
1442    Output Parameter:
1443 .  outsnes - the new SNES context
1444 
1445    Options Database Keys:
1446 +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1447                and no preconditioning matrix
1448 .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1449                products, and a user-provided preconditioning matrix
1450                as set by SNESSetJacobian()
1451 -   -snes_fd - Uses (slow!) finite differences to compute Jacobian
1452 
1453    Level: beginner
1454 
1455 .keywords: SNES, nonlinear, create, context
1456 
1457 .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()
1458 
1459 @*/
1460 PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1461 {
1462   PetscErrorCode ierr;
1463   SNES           snes;
1464   SNESKSPEW      *kctx;
1465 
1466   PetscFunctionBegin;
1467   PetscValidPointer(outsnes,2);
1468   *outsnes = NULL;
1469   ierr = SNESInitializePackage();CHKERRQ(ierr);
1470 
1471   ierr = PetscHeaderCreate(snes,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);CHKERRQ(ierr);
1472 
1473   snes->ops->converged    = SNESConvergedDefault;
1474   snes->usesksp           = PETSC_TRUE;
1475   snes->tolerancesset     = PETSC_FALSE;
1476   snes->max_its           = 50;
1477   snes->max_funcs         = 10000;
1478   snes->norm              = 0.0;
1479   snes->normschedule      = SNES_NORM_ALWAYS;
1480   snes->functype          = SNES_FUNCTION_DEFAULT;
1481 #if defined(PETSC_USE_REAL_SINGLE)
1482   snes->rtol              = 1.e-5;
1483 #else
1484   snes->rtol              = 1.e-8;
1485 #endif
1486   snes->ttol              = 0.0;
1487 #if defined(PETSC_USE_REAL_SINGLE)
1488   snes->abstol            = 1.e-25;
1489 #else
1490   snes->abstol            = 1.e-50;
1491 #endif
1492   snes->stol              = 1.e-8;
1493 #if defined(PETSC_USE_REAL_SINGLE)
1494   snes->deltatol          = 1.e-6;
1495 #else
1496   snes->deltatol          = 1.e-12;
1497 #endif
1498   snes->nfuncs            = 0;
1499   snes->numFailures       = 0;
1500   snes->maxFailures       = 1;
1501   snes->linear_its        = 0;
1502   snes->lagjacobian       = 1;
1503   snes->jac_iter          = 0;
1504   snes->lagjac_persist    = PETSC_FALSE;
1505   snes->lagpreconditioner = 1;
1506   snes->pre_iter          = 0;
1507   snes->lagpre_persist    = PETSC_FALSE;
1508   snes->numbermonitors    = 0;
1509   snes->data              = 0;
1510   snes->setupcalled       = PETSC_FALSE;
1511   snes->ksp_ewconv        = PETSC_FALSE;
1512   snes->nwork             = 0;
1513   snes->work              = 0;
1514   snes->nvwork            = 0;
1515   snes->vwork             = 0;
1516   snes->conv_hist_len     = 0;
1517   snes->conv_hist_max     = 0;
1518   snes->conv_hist         = NULL;
1519   snes->conv_hist_its     = NULL;
1520   snes->conv_hist_reset   = PETSC_TRUE;
1521   snes->counters_reset    = PETSC_TRUE;
1522   snes->vec_func_init_set = PETSC_FALSE;
1523   snes->reason            = SNES_CONVERGED_ITERATING;
1524   snes->pcside            = PC_RIGHT;
1525 
1526   snes->mf          = PETSC_FALSE;
1527   snes->mf_operator = PETSC_FALSE;
1528   snes->mf_version  = 1;
1529 
1530   snes->numLinearSolveFailures = 0;
1531   snes->maxLinearSolveFailures = 1;
1532 
1533   snes->vizerotolerance = 1.e-8;
1534 
1535   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1536   ierr = PetscNewLog(snes,&kctx);CHKERRQ(ierr);
1537 
1538   snes->kspconvctx  = (void*)kctx;
1539   kctx->version     = 2;
1540   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1541                              this was too large for some test cases */
1542   kctx->rtol_last   = 0.0;
1543   kctx->rtol_max    = .9;
1544   kctx->gamma       = 1.0;
1545   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1546   kctx->alpha2      = kctx->alpha;
1547   kctx->threshold   = .1;
1548   kctx->lresid_last = 0.0;
1549   kctx->norm_last   = 0.0;
1550 
1551   *outsnes = snes;
1552   PetscFunctionReturn(0);
1553 }
1554 
1555 /*MC
1556     SNESFunction - Functional form used to convey the nonlinear function to be solved by SNES
1557 
1558      Synopsis:
1559      #include "petscsnes.h"
1560      PetscErrorCode SNESFunction(SNES snes,Vec x,Vec f,void *ctx);
1561 
1562      Input Parameters:
1563 +     snes - the SNES context
1564 .     x    - state at which to evaluate residual
1565 -     ctx     - optional user-defined function context, passed in with SNESSetFunction()
1566 
1567      Output Parameter:
1568 .     f  - vector to put residual (function value)
1569 
1570    Level: intermediate
1571 
1572 .seealso:   SNESSetFunction(), SNESGetFunction()
1573 M*/
1574 
1575 #undef __FUNCT__
1576 #define __FUNCT__ "SNESSetFunction"
1577 /*@C
1578    SNESSetFunction - Sets the function evaluation routine and function
1579    vector for use by the SNES routines in solving systems of nonlinear
1580    equations.
1581 
1582    Logically Collective on SNES
1583 
1584    Input Parameters:
1585 +  snes - the SNES context
1586 .  r - vector to store function value
1587 .  f - function evaluation routine; see SNESFunction for calling sequence details
1588 -  ctx - [optional] user-defined context for private data for the
1589          function evaluation routine (may be NULL)
1590 
1591    Notes:
1592    The Newton-like methods typically solve linear systems of the form
1593 $      f'(x) x = -f(x),
1594    where f'(x) denotes the Jacobian matrix and f(x) is the function.
1595 
1596    Level: beginner
1597 
1598 .keywords: SNES, nonlinear, set, function
1599 
1600 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
1601 @*/
1602 PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1603 {
1604   PetscErrorCode ierr;
1605   DM             dm;
1606 
1607   PetscFunctionBegin;
1608   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1609   if (r) {
1610     PetscValidHeaderSpecific(r,VEC_CLASSID,2);
1611     PetscCheckSameComm(snes,1,r,2);
1612     ierr = PetscObjectReference((PetscObject)r);CHKERRQ(ierr);
1613     ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
1614 
1615     snes->vec_func = r;
1616   }
1617   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1618   ierr = DMSNESSetFunction(dm,f,ctx);CHKERRQ(ierr);
1619   PetscFunctionReturn(0);
1620 }
1621 
1622 
1623 #undef __FUNCT__
1624 #define __FUNCT__ "SNESSetInitialFunction"
1625 /*@C
1626    SNESSetInitialFunction - Sets the function vector to be used as the
1627    function norm at the initialization of the method.  In some
1628    instances, the user has precomputed the function before calling
1629    SNESSolve.  This function allows one to avoid a redundant call
1630    to SNESComputeFunction in that case.
1631 
1632    Logically Collective on SNES
1633 
1634    Input Parameters:
1635 +  snes - the SNES context
1636 -  f - vector to store function value
1637 
1638    Notes:
1639    This should not be modified during the solution procedure.
1640 
1641    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1642 
1643    Level: developer
1644 
1645 .keywords: SNES, nonlinear, set, function
1646 
1647 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1648 @*/
1649 PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1650 {
1651   PetscErrorCode ierr;
1652   Vec            vec_func;
1653 
1654   PetscFunctionBegin;
1655   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1656   PetscValidHeaderSpecific(f,VEC_CLASSID,2);
1657   PetscCheckSameComm(snes,1,f,2);
1658   if (snes->pcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
1659     snes->vec_func_init_set = PETSC_FALSE;
1660     PetscFunctionReturn(0);
1661   }
1662   ierr = SNESGetFunction(snes,&vec_func,NULL,NULL);CHKERRQ(ierr);
1663   ierr = VecCopy(f, vec_func);CHKERRQ(ierr);
1664 
1665   snes->vec_func_init_set = PETSC_TRUE;
1666   PetscFunctionReturn(0);
1667 }
1668 
1669 #undef __FUNCT__
1670 #define __FUNCT__ "SNESSetNormSchedule"
1671 /*@
1672    SNESSetNormSchedule - Sets the SNESNormSchedule used in covergence and monitoring
1673    of the SNES method.
1674 
1675    Logically Collective on SNES
1676 
1677    Input Parameters:
1678 +  snes - the SNES context
1679 -  normschedule - the frequency of norm computation
1680 
1681    Options Database Key:
1682 .  -snes_norm_schedule <none, always, initialonly, finalonly, initalfinalonly>
1683 
1684    Notes:
1685    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1686    of the nonlinear function and the taking of its norm at every iteration to
1687    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1688    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1689    may either be monitored for convergence or not.  As these are often used as nonlinear
1690    preconditioners, monitoring the norm of their error is not a useful enterprise within
1691    their solution.
1692 
1693    Level: developer
1694 
1695 .keywords: SNES, nonlinear, set, function, norm, type
1696 
1697 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1698 @*/
1699 PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
1700 {
1701   PetscFunctionBegin;
1702   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1703   snes->normschedule = normschedule;
1704   PetscFunctionReturn(0);
1705 }
1706 
1707 
1708 #undef __FUNCT__
1709 #define __FUNCT__ "SNESGetNormSchedule"
1710 /*@
1711    SNESGetNormSchedule - Gets the SNESNormSchedule used in covergence and monitoring
1712    of the SNES method.
1713 
1714    Logically Collective on SNES
1715 
1716    Input Parameters:
1717 +  snes - the SNES context
1718 -  normschedule - the type of the norm used
1719 
1720    Level: advanced
1721 
1722 .keywords: SNES, nonlinear, set, function, norm, type
1723 
1724 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1725 @*/
1726 PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
1727 {
1728   PetscFunctionBegin;
1729   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1730   *normschedule = snes->normschedule;
1731   PetscFunctionReturn(0);
1732 }
1733 
1734 
1735 #undef __FUNCT__
1736 #define __FUNCT__ "SNESSetFunctionNorm"
1737 /*@
1738   SNESSetFunctionNorm - Sets the last computed residual norm.
1739 
1740   Logically Collective on SNES
1741 
1742   Input Parameters:
1743 + snes - the SNES context
1744 
1745 - normschedule - the frequency of norm computation
1746 
1747   Level: developer
1748 
1749 .keywords: SNES, nonlinear, set, function, norm, type
1750 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1751 @*/
1752 PetscErrorCode SNESSetFunctionNorm(SNES snes, PetscReal norm)
1753 {
1754   PetscFunctionBegin;
1755   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1756   snes->norm = norm;
1757   PetscFunctionReturn(0);
1758 }
1759 
1760 #undef __FUNCT__
1761 #define __FUNCT__ "SNESGetFunctionNorm"
1762 /*@
1763   SNESGetFunctionNorm - Gets the last computed norm of the residual
1764 
1765   Not Collective
1766 
1767   Input Parameter:
1768 . snes - the SNES context
1769 
1770   Output Parameter:
1771 . norm - the last computed residual norm
1772 
1773   Level: developer
1774 
1775 .keywords: SNES, nonlinear, set, function, norm, type
1776 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1777 @*/
1778 PetscErrorCode SNESGetFunctionNorm(SNES snes, PetscReal *norm)
1779 {
1780   PetscFunctionBegin;
1781   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1782   PetscValidPointer(norm, 2);
1783   *norm = snes->norm;
1784   PetscFunctionReturn(0);
1785 }
1786 
1787 #undef __FUNCT__
1788 #define __FUNCT__ "SNESSetFunctionType"
1789 /*@C
1790    SNESSetFunctionType - Sets the SNESNormSchedule used in covergence and monitoring
1791    of the SNES method.
1792 
1793    Logically Collective on SNES
1794 
1795    Input Parameters:
1796 +  snes - the SNES context
1797 -  normschedule - the frequency of norm computation
1798 
1799    Notes:
1800    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1801    of the nonlinear function and the taking of its norm at every iteration to
1802    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1803    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1804    may either be monitored for convergence or not.  As these are often used as nonlinear
1805    preconditioners, monitoring the norm of their error is not a useful enterprise within
1806    their solution.
1807 
1808    Level: developer
1809 
1810 .keywords: SNES, nonlinear, set, function, norm, type
1811 
1812 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1813 @*/
1814 PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
1815 {
1816   PetscFunctionBegin;
1817   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1818   snes->functype = type;
1819   PetscFunctionReturn(0);
1820 }
1821 
1822 
1823 #undef __FUNCT__
1824 #define __FUNCT__ "SNESGetFunctionType"
1825 /*@C
1826    SNESGetFunctionType - Gets the SNESNormSchedule used in covergence and monitoring
1827    of the SNES method.
1828 
1829    Logically Collective on SNES
1830 
1831    Input Parameters:
1832 +  snes - the SNES context
1833 -  normschedule - the type of the norm used
1834 
1835    Level: advanced
1836 
1837 .keywords: SNES, nonlinear, set, function, norm, type
1838 
1839 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1840 @*/
1841 PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
1842 {
1843   PetscFunctionBegin;
1844   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1845   *type = snes->functype;
1846   PetscFunctionReturn(0);
1847 }
1848 
1849 /*MC
1850     SNESNGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function
1851 
1852      Synopsis:
1853      #include <petscsnes.h>
1854 $    SNESNGSFunction(SNES snes,Vec x,Vec b,void *ctx);
1855 
1856 +  X   - solution vector
1857 .  B   - RHS vector
1858 -  ctx - optional user-defined Gauss-Seidel context
1859 
1860    Level: intermediate
1861 
1862 .seealso:   SNESSetNGS(), SNESGetNGS()
1863 M*/
1864 
1865 #undef __FUNCT__
1866 #define __FUNCT__ "SNESSetNGS"
1867 /*@C
1868    SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
1869    use with composed nonlinear solvers.
1870 
1871    Input Parameters:
1872 +  snes   - the SNES context
1873 .  f - function evaluation routine to apply Gauss-Seidel see SNESNGSFunction
1874 -  ctx    - [optional] user-defined context for private data for the
1875             smoother evaluation routine (may be NULL)
1876 
1877    Notes:
1878    The NGS routines are used by the composed nonlinear solver to generate
1879     a problem appropriate update to the solution, particularly FAS.
1880 
1881    Level: intermediate
1882 
1883 .keywords: SNES, nonlinear, set, Gauss-Seidel
1884 
1885 .seealso: SNESGetFunction(), SNESComputeNGS()
1886 @*/
1887 PetscErrorCode SNESSetNGS(SNES snes,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1888 {
1889   PetscErrorCode ierr;
1890   DM             dm;
1891 
1892   PetscFunctionBegin;
1893   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1894   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1895   ierr = DMSNESSetNGS(dm,f,ctx);CHKERRQ(ierr);
1896   PetscFunctionReturn(0);
1897 }
1898 
1899 #undef __FUNCT__
1900 #define __FUNCT__ "SNESPicardComputeFunction"
1901 PETSC_EXTERN PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
1902 {
1903   PetscErrorCode ierr;
1904   DM             dm;
1905   DMSNES         sdm;
1906 
1907   PetscFunctionBegin;
1908   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1909   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
1910   /*  A(x)*x - b(x) */
1911   if (sdm->ops->computepfunction) {
1912     ierr = (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);CHKERRQ(ierr);
1913   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");
1914 
1915   if (sdm->ops->computepjacobian) {
1916     ierr = (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);CHKERRQ(ierr);
1917   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard matrix.");
1918   ierr = VecScale(f,-1.0);CHKERRQ(ierr);
1919   ierr = MatMultAdd(snes->jacobian,x,f,f);CHKERRQ(ierr);
1920   PetscFunctionReturn(0);
1921 }
1922 
1923 #undef __FUNCT__
1924 #define __FUNCT__ "SNESPicardComputeJacobian"
1925 PETSC_EXTERN PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
1926 {
1927   PetscFunctionBegin;
1928   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
1929   PetscFunctionReturn(0);
1930 }
1931 
1932 #undef __FUNCT__
1933 #define __FUNCT__ "SNESSetPicard"
1934 /*@C
1935    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)
1936 
1937    Logically Collective on SNES
1938 
1939    Input Parameters:
1940 +  snes - the SNES context
1941 .  r - vector to store function value
1942 .  b - function evaluation routine
1943 .  Amat - matrix with which A(x) x - b(x) is to be computed
1944 .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
1945 .  J  - function to compute matrix value, see SNESJacobianFunction for details on its calling sequence
1946 -  ctx - [optional] user-defined context for private data for the
1947          function evaluation routine (may be NULL)
1948 
1949    Notes:
1950     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
1951     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.
1952 
1953     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both
1954 
1955 $     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}
1956 $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.
1957 
1958      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.
1959 
1960    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
1961    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)
1962 
1963    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
1964    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
1965    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).
1966 
1967    Level: intermediate
1968 
1969 .keywords: SNES, nonlinear, set, function
1970 
1971 .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard(), SNESJacobianFunction
1972 @*/
1973 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)
1974 {
1975   PetscErrorCode ierr;
1976   DM             dm;
1977 
1978   PetscFunctionBegin;
1979   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1980   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
1981   ierr = DMSNESSetPicard(dm,b,J,ctx);CHKERRQ(ierr);
1982   ierr = SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);CHKERRQ(ierr);
1983   ierr = SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);CHKERRQ(ierr);
1984   PetscFunctionReturn(0);
1985 }
1986 
1987 #undef __FUNCT__
1988 #define __FUNCT__ "SNESGetPicard"
1989 /*@C
1990    SNESGetPicard - Returns the context for the Picard iteration
1991 
1992    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
1993 
1994    Input Parameter:
1995 .  snes - the SNES context
1996 
1997    Output Parameter:
1998 +  r - the function (or NULL)
1999 .  f - the function (or NULL); see SNESFunction for calling sequence details
2000 .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
2001 .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
2002 .  J - the function for matrix evaluation (or NULL); see SNESJacobianFunction for calling sequence details
2003 -  ctx - the function context (or NULL)
2004 
2005    Level: advanced
2006 
2007 .keywords: SNES, nonlinear, get, function
2008 
2009 .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
2010 @*/
2011 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)
2012 {
2013   PetscErrorCode ierr;
2014   DM             dm;
2015 
2016   PetscFunctionBegin;
2017   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2018   ierr = SNESGetFunction(snes,r,NULL,NULL);CHKERRQ(ierr);
2019   ierr = SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);CHKERRQ(ierr);
2020   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2021   ierr = DMSNESGetPicard(dm,f,J,ctx);CHKERRQ(ierr);
2022   PetscFunctionReturn(0);
2023 }
2024 
2025 #undef __FUNCT__
2026 #define __FUNCT__ "SNESSetComputeInitialGuess"
2027 /*@C
2028    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem
2029 
2030    Logically Collective on SNES
2031 
2032    Input Parameters:
2033 +  snes - the SNES context
2034 .  func - function evaluation routine
2035 -  ctx - [optional] user-defined context for private data for the
2036          function evaluation routine (may be NULL)
2037 
2038    Calling sequence of func:
2039 $    func (SNES snes,Vec x,void *ctx);
2040 
2041 .  f - function vector
2042 -  ctx - optional user-defined function context
2043 
2044    Level: intermediate
2045 
2046 .keywords: SNES, nonlinear, set, function
2047 
2048 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
2049 @*/
2050 PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
2051 {
2052   PetscFunctionBegin;
2053   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2054   if (func) snes->ops->computeinitialguess = func;
2055   if (ctx)  snes->initialguessP            = ctx;
2056   PetscFunctionReturn(0);
2057 }
2058 
2059 /* --------------------------------------------------------------- */
2060 #undef __FUNCT__
2061 #define __FUNCT__ "SNESGetRhs"
2062 /*@C
2063    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
2064    it assumes a zero right hand side.
2065 
2066    Logically Collective on SNES
2067 
2068    Input Parameter:
2069 .  snes - the SNES context
2070 
2071    Output Parameter:
2072 .  rhs - the right hand side vector or NULL if the right hand side vector is null
2073 
2074    Level: intermediate
2075 
2076 .keywords: SNES, nonlinear, get, function, right hand side
2077 
2078 .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
2079 @*/
2080 PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
2081 {
2082   PetscFunctionBegin;
2083   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2084   PetscValidPointer(rhs,2);
2085   *rhs = snes->vec_rhs;
2086   PetscFunctionReturn(0);
2087 }
2088 
2089 #undef __FUNCT__
2090 #define __FUNCT__ "SNESComputeFunction"
2091 /*@
2092    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().
2093 
2094    Collective on SNES
2095 
2096    Input Parameters:
2097 +  snes - the SNES context
2098 -  x - input vector
2099 
2100    Output Parameter:
2101 .  y - function vector, as set by SNESSetFunction()
2102 
2103    Notes:
2104    SNESComputeFunction() is typically used within nonlinear solvers
2105    implementations, so most users would not generally call this routine
2106    themselves.
2107 
2108    Level: developer
2109 
2110 .keywords: SNES, nonlinear, compute, function
2111 
2112 .seealso: SNESSetFunction(), SNESGetFunction()
2113 @*/
2114 PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
2115 {
2116   PetscErrorCode ierr;
2117   DM             dm;
2118   DMSNES         sdm;
2119 
2120   PetscFunctionBegin;
2121   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2122   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2123   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
2124   PetscCheckSameComm(snes,1,x,2);
2125   PetscCheckSameComm(snes,1,y,3);
2126   ierr = VecValidValues(x,2,PETSC_TRUE);CHKERRQ(ierr);
2127 
2128   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2129   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2130   if (sdm->ops->computefunction) {
2131     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2132       ierr = PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2133     }
2134     ierr = VecLockPush(x);CHKERRQ(ierr);
2135     PetscStackPush("SNES user function");
2136     ierr = (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);CHKERRQ(ierr);
2137     PetscStackPop;
2138     ierr = VecLockPop(x);CHKERRQ(ierr);
2139     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2140       ierr = PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2141     }
2142   } else if (snes->vec_rhs) {
2143     ierr = MatMult(snes->jacobian, x, y);CHKERRQ(ierr);
2144   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2145   if (snes->vec_rhs) {
2146     ierr = VecAXPY(y,-1.0,snes->vec_rhs);CHKERRQ(ierr);
2147   }
2148   snes->nfuncs++;
2149   /*
2150      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
2151      propagate the value to all processes
2152   */
2153   if (snes->domainerror) {
2154     ierr = VecSetInf(y);CHKERRQ(ierr);
2155   }
2156   PetscFunctionReturn(0);
2157 }
2158 
2159 #undef __FUNCT__
2160 #define __FUNCT__ "SNESComputeNGS"
2161 /*@
2162    SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  SNESSetNGS().
2163 
2164    Collective on SNES
2165 
2166    Input Parameters:
2167 +  snes - the SNES context
2168 .  x - input vector
2169 -  b - rhs vector
2170 
2171    Output Parameter:
2172 .  x - new solution vector
2173 
2174    Notes:
2175    SNESComputeNGS() is typically used within composed nonlinear solver
2176    implementations, so most users would not generally call this routine
2177    themselves.
2178 
2179    Level: developer
2180 
2181 .keywords: SNES, nonlinear, compute, function
2182 
2183 .seealso: SNESSetNGS(), SNESComputeFunction()
2184 @*/
2185 PetscErrorCode  SNESComputeNGS(SNES snes,Vec b,Vec x)
2186 {
2187   PetscErrorCode ierr;
2188   DM             dm;
2189   DMSNES         sdm;
2190 
2191   PetscFunctionBegin;
2192   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2193   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2194   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,3);
2195   PetscCheckSameComm(snes,1,x,2);
2196   if (b) PetscCheckSameComm(snes,1,b,3);
2197   if (b) {ierr = VecValidValues(b,2,PETSC_TRUE);CHKERRQ(ierr);}
2198   ierr = PetscLogEventBegin(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2199   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2200   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2201   if (sdm->ops->computegs) {
2202     if (b) {ierr = VecLockPush(b);CHKERRQ(ierr);}
2203     PetscStackPush("SNES user NGS");
2204     ierr = (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);CHKERRQ(ierr);
2205     PetscStackPop;
2206     if (b) {ierr = VecLockPop(b);CHKERRQ(ierr);}
2207   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
2208   ierr = PetscLogEventEnd(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2209   PetscFunctionReturn(0);
2210 }
2211 
2212 #undef __FUNCT__
2213 #define __FUNCT__ "SNESComputeJacobian"
2214 /*@
2215    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().
2216 
2217    Collective on SNES and Mat
2218 
2219    Input Parameters:
2220 +  snes - the SNES context
2221 -  x - input vector
2222 
2223    Output Parameters:
2224 +  A - Jacobian matrix
2225 -  B - optional preconditioning matrix
2226 
2227   Options Database Keys:
2228 +    -snes_lag_preconditioner <lag>
2229 .    -snes_lag_jacobian <lag>
2230 .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2231 .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2232 .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2233 .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2234 .    -snes_compare_coloring - Compute the finite differece Jacobian using coloring and display norms of difference
2235 .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
2236 .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2237 .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2238 .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2239 .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
2240 -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences
2241 
2242 
2243    Notes:
2244    Most users should not need to explicitly call this routine, as it
2245    is used internally within the nonlinear solvers.
2246 
2247    Level: developer
2248 
2249 .keywords: SNES, compute, Jacobian, matrix
2250 
2251 .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2252 @*/
2253 PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat A,Mat B)
2254 {
2255   PetscErrorCode ierr;
2256   PetscBool      flag;
2257   DM             dm;
2258   DMSNES         sdm;
2259   KSP            ksp;
2260 
2261   PetscFunctionBegin;
2262   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2263   PetscValidHeaderSpecific(X,VEC_CLASSID,2);
2264   PetscCheckSameComm(snes,1,X,2);
2265   ierr = VecValidValues(X,2,PETSC_TRUE);CHKERRQ(ierr);
2266   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2267   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2268 
2269   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");
2270 
2271   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */
2272 
2273   if (snes->lagjacobian == -2) {
2274     snes->lagjacobian = -1;
2275 
2276     ierr = PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");CHKERRQ(ierr);
2277   } else if (snes->lagjacobian == -1) {
2278     ierr = PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");CHKERRQ(ierr);
2279     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2280     if (flag) {
2281       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2282       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2283     }
2284     PetscFunctionReturn(0);
2285   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2286     ierr = PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);CHKERRQ(ierr);
2287     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2288     if (flag) {
2289       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2290       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2291     }
2292     PetscFunctionReturn(0);
2293   }
2294   if (snes->pc && snes->pcside == PC_LEFT) {
2295       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2296       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2297       PetscFunctionReturn(0);
2298   }
2299 
2300   ierr = PetscLogEventBegin(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2301   ierr = VecLockPush(X);CHKERRQ(ierr);
2302   PetscStackPush("SNES user Jacobian function");
2303   ierr = (*sdm->ops->computejacobian)(snes,X,A,B,sdm->jacobianctx);CHKERRQ(ierr);
2304   PetscStackPop;
2305   ierr = VecLockPop(X);CHKERRQ(ierr);
2306   ierr = PetscLogEventEnd(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2307 
2308   /* the next line ensures that snes->ksp exists */
2309   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
2310   if (snes->lagpreconditioner == -2) {
2311     ierr = PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");CHKERRQ(ierr);
2312     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2313     snes->lagpreconditioner = -1;
2314   } else if (snes->lagpreconditioner == -1) {
2315     ierr = PetscInfo(snes,"Reusing preconditioner because lag is -1\n");CHKERRQ(ierr);
2316     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2317   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2318     ierr = PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);CHKERRQ(ierr);
2319     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2320   } else {
2321     ierr = PetscInfo(snes,"Rebuilding preconditioner\n");CHKERRQ(ierr);
2322     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2323   }
2324 
2325   /* make sure user returned a correct Jacobian and preconditioner */
2326   /* PetscValidHeaderSpecific(A,MAT_CLASSID,3);
2327     PetscValidHeaderSpecific(B,MAT_CLASSID,4);   */
2328   {
2329     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2330     ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_explicit",NULL,NULL,&flag);CHKERRQ(ierr);
2331     ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",NULL,NULL,&flag_draw);CHKERRQ(ierr);
2332     ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",NULL,NULL,&flag_contour);CHKERRQ(ierr);
2333     ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_operator",NULL,NULL,&flag_operator);CHKERRQ(ierr);
2334     if (flag || flag_draw || flag_contour) {
2335       Mat          Bexp_mine = NULL,Bexp,FDexp;
2336       PetscViewer  vdraw,vstdout;
2337       PetscBool    flg;
2338       if (flag_operator) {
2339         ierr = MatComputeExplicitOperator(A,&Bexp_mine);CHKERRQ(ierr);
2340         Bexp = Bexp_mine;
2341       } else {
2342         /* See if the preconditioning matrix can be viewed and added directly */
2343         ierr = PetscObjectTypeCompareAny((PetscObject)B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");CHKERRQ(ierr);
2344         if (flg) Bexp = B;
2345         else {
2346           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2347           ierr = MatComputeExplicitOperator(B,&Bexp_mine);CHKERRQ(ierr);
2348           Bexp = Bexp_mine;
2349         }
2350       }
2351       ierr = MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);CHKERRQ(ierr);
2352       ierr = SNESComputeJacobianDefault(snes,X,FDexp,FDexp,NULL);CHKERRQ(ierr);
2353       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2354       if (flag_draw || flag_contour) {
2355         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2356         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2357       } else vdraw = NULL;
2358       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");CHKERRQ(ierr);
2359       if (flag) {ierr = MatView(Bexp,vstdout);CHKERRQ(ierr);}
2360       if (vdraw) {ierr = MatView(Bexp,vdraw);CHKERRQ(ierr);}
2361       ierr = PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");CHKERRQ(ierr);
2362       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2363       if (vdraw) {ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);}
2364       ierr = MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2365       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");CHKERRQ(ierr);
2366       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2367       if (vdraw) {              /* Always use contour for the difference */
2368         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2369         ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);
2370         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2371       }
2372       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2373       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2374       ierr = MatDestroy(&Bexp_mine);CHKERRQ(ierr);
2375       ierr = MatDestroy(&FDexp);CHKERRQ(ierr);
2376     }
2377   }
2378   {
2379     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2380     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2381     ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_coloring",NULL,NULL,&flag);CHKERRQ(ierr);
2382     ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_coloring_display",NULL,NULL,&flag_display);CHKERRQ(ierr);
2383     ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",NULL,NULL,&flag_draw);CHKERRQ(ierr);
2384     ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",NULL,NULL,&flag_contour);CHKERRQ(ierr);
2385     ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",NULL,NULL,&flag_threshold);CHKERRQ(ierr);
2386     if (flag_threshold) {
2387       ierr = PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);CHKERRQ(ierr);
2388       ierr = PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);CHKERRQ(ierr);
2389     }
2390     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2391       Mat            Bfd;
2392       PetscViewer    vdraw,vstdout;
2393       MatColoring    coloring;
2394       ISColoring     iscoloring;
2395       MatFDColoring  matfdcoloring;
2396       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2397       void           *funcctx;
2398       PetscReal      norm1,norm2,normmax;
2399 
2400       ierr = MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);CHKERRQ(ierr);
2401       ierr = MatColoringCreate(Bfd,&coloring);CHKERRQ(ierr);
2402       ierr = MatColoringSetType(coloring,MATCOLORINGSL);CHKERRQ(ierr);
2403       ierr = MatColoringSetFromOptions(coloring);CHKERRQ(ierr);
2404       ierr = MatColoringApply(coloring,&iscoloring);CHKERRQ(ierr);
2405       ierr = MatColoringDestroy(&coloring);CHKERRQ(ierr);
2406       ierr = MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);CHKERRQ(ierr);
2407       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2408       ierr = MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);CHKERRQ(ierr);
2409       ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr);
2410 
2411       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2412       ierr = SNESGetFunction(snes,NULL,&func,&funcctx);CHKERRQ(ierr);
2413       ierr = MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);CHKERRQ(ierr);
2414       ierr = PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);CHKERRQ(ierr);
2415       ierr = PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");CHKERRQ(ierr);
2416       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2417       ierr = MatFDColoringApply(Bfd,matfdcoloring,X,snes);CHKERRQ(ierr);
2418       ierr = MatFDColoringDestroy(&matfdcoloring);CHKERRQ(ierr);
2419 
2420       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2421       if (flag_draw || flag_contour) {
2422         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2423         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2424       } else vdraw = NULL;
2425       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");CHKERRQ(ierr);
2426       if (flag_display) {ierr = MatView(B,vstdout);CHKERRQ(ierr);}
2427       if (vdraw) {ierr = MatView(B,vdraw);CHKERRQ(ierr);}
2428       ierr = PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");CHKERRQ(ierr);
2429       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2430       if (vdraw) {ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);}
2431       ierr = MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2432       ierr = MatNorm(Bfd,NORM_1,&norm1);CHKERRQ(ierr);
2433       ierr = MatNorm(Bfd,NORM_FROBENIUS,&norm2);CHKERRQ(ierr);
2434       ierr = MatNorm(Bfd,NORM_MAX,&normmax);CHKERRQ(ierr);
2435       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);
2436       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2437       if (vdraw) {              /* Always use contour for the difference */
2438         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2439         ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);
2440         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2441       }
2442       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2443 
2444       if (flag_threshold) {
2445         PetscInt bs,rstart,rend,i;
2446         ierr = MatGetBlockSize(B,&bs);CHKERRQ(ierr);
2447         ierr = MatGetOwnershipRange(B,&rstart,&rend);CHKERRQ(ierr);
2448         for (i=rstart; i<rend; i++) {
2449           const PetscScalar *ba,*ca;
2450           const PetscInt    *bj,*cj;
2451           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2452           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2453           ierr = MatGetRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2454           ierr = MatGetRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2455           if (bn != cn) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2456           for (j=0; j<bn; j++) {
2457             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2458             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2459               maxentrycol = bj[j];
2460               maxentry    = PetscRealPart(ba[j]);
2461             }
2462             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2463               maxdiffcol = bj[j];
2464               maxdiff    = PetscRealPart(ca[j]);
2465             }
2466             if (rdiff > maxrdiff) {
2467               maxrdiffcol = bj[j];
2468               maxrdiff    = rdiff;
2469             }
2470           }
2471           if (maxrdiff > 1) {
2472             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);
2473             for (j=0; j<bn; j++) {
2474               PetscReal rdiff;
2475               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2476               if (rdiff > 1) {
2477                 ierr = PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));CHKERRQ(ierr);
2478               }
2479             }
2480             ierr = PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);CHKERRQ(ierr);
2481           }
2482           ierr = MatRestoreRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2483           ierr = MatRestoreRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2484         }
2485       }
2486       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2487       ierr = MatDestroy(&Bfd);CHKERRQ(ierr);
2488     }
2489   }
2490   PetscFunctionReturn(0);
2491 }
2492 
2493 /*MC
2494     SNESJacobianFunction - Function used to convey the nonlinear Jacobian of the function to be solved by SNES
2495 
2496      Synopsis:
2497      #include "petscsnes.h"
2498      PetscErrorCode SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);
2499 
2500 +  x - input vector
2501 .  Amat - the matrix that defines the (approximate) Jacobian
2502 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2503 -  ctx - [optional] user-defined Jacobian context
2504 
2505    Level: intermediate
2506 
2507 .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2508 M*/
2509 
2510 #undef __FUNCT__
2511 #define __FUNCT__ "SNESSetJacobian"
2512 /*@C
2513    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2514    location to store the matrix.
2515 
2516    Logically Collective on SNES and Mat
2517 
2518    Input Parameters:
2519 +  snes - the SNES context
2520 .  Amat - the matrix that defines the (approximate) Jacobian
2521 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2522 .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value), see SNESJacobianFunction for details
2523 -  ctx - [optional] user-defined context for private data for the
2524          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)
2525 
2526    Notes:
2527    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
2528    each matrix.
2529 
2530    If you know the operator Amat has a null space you can use MatSetNullSpace() and MatSetTransposeNullSpace() to supply the null
2531    space to Amat and the KSP solvers will automatically use that null space as needed during the solution process.
2532 
2533    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
2534    must be a MatFDColoring.
2535 
2536    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2537    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.
2538 
2539    Level: beginner
2540 
2541 .keywords: SNES, nonlinear, set, Jacobian, matrix
2542 
2543 .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J,
2544           SNESSetPicard(), SNESJacobianFunction
2545 @*/
2546 PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2547 {
2548   PetscErrorCode ierr;
2549   DM             dm;
2550 
2551   PetscFunctionBegin;
2552   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2553   if (Amat) PetscValidHeaderSpecific(Amat,MAT_CLASSID,2);
2554   if (Pmat) PetscValidHeaderSpecific(Pmat,MAT_CLASSID,3);
2555   if (Amat) PetscCheckSameComm(snes,1,Amat,2);
2556   if (Pmat) PetscCheckSameComm(snes,1,Pmat,3);
2557   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2558   ierr = DMSNESSetJacobian(dm,J,ctx);CHKERRQ(ierr);
2559   if (Amat) {
2560     ierr = PetscObjectReference((PetscObject)Amat);CHKERRQ(ierr);
2561     ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2562 
2563     snes->jacobian = Amat;
2564   }
2565   if (Pmat) {
2566     ierr = PetscObjectReference((PetscObject)Pmat);CHKERRQ(ierr);
2567     ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2568 
2569     snes->jacobian_pre = Pmat;
2570   }
2571   PetscFunctionReturn(0);
2572 }
2573 
2574 #undef __FUNCT__
2575 #define __FUNCT__ "SNESGetJacobian"
2576 /*@C
2577    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2578    provided context for evaluating the Jacobian.
2579 
2580    Not Collective, but Mat object will be parallel if SNES object is
2581 
2582    Input Parameter:
2583 .  snes - the nonlinear solver context
2584 
2585    Output Parameters:
2586 +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
2587 .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
2588 .  J - location to put Jacobian function (or NULL), see SNESJacobianFunction for details on its calling sequence
2589 -  ctx - location to stash Jacobian ctx (or NULL)
2590 
2591    Level: advanced
2592 
2593 .seealso: SNESSetJacobian(), SNESComputeJacobian(), SNESJacobianFunction, SNESGetFunction()
2594 @*/
2595 PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
2596 {
2597   PetscErrorCode ierr;
2598   DM             dm;
2599   DMSNES         sdm;
2600 
2601   PetscFunctionBegin;
2602   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2603   if (Amat) *Amat = snes->jacobian;
2604   if (Pmat) *Pmat = snes->jacobian_pre;
2605   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2606   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2607   if (J) *J = sdm->ops->computejacobian;
2608   if (ctx) *ctx = sdm->jacobianctx;
2609   PetscFunctionReturn(0);
2610 }
2611 
2612 #undef __FUNCT__
2613 #define __FUNCT__ "SNESSetUp"
2614 /*@
2615    SNESSetUp - Sets up the internal data structures for the later use
2616    of a nonlinear solver.
2617 
2618    Collective on SNES
2619 
2620    Input Parameters:
2621 .  snes - the SNES context
2622 
2623    Notes:
2624    For basic use of the SNES solvers the user need not explicitly call
2625    SNESSetUp(), since these actions will automatically occur during
2626    the call to SNESSolve().  However, if one wishes to control this
2627    phase separately, SNESSetUp() should be called after SNESCreate()
2628    and optional routines of the form SNESSetXXX(), but before SNESSolve().
2629 
2630    Level: advanced
2631 
2632 .keywords: SNES, nonlinear, setup
2633 
2634 .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
2635 @*/
2636 PetscErrorCode  SNESSetUp(SNES snes)
2637 {
2638   PetscErrorCode ierr;
2639   DM             dm;
2640   DMSNES         sdm;
2641   SNESLineSearch linesearch, pclinesearch;
2642   void           *lsprectx,*lspostctx;
2643   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
2644   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
2645   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2646   Vec            f,fpc;
2647   void           *funcctx;
2648   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
2649   void           *jacctx,*appctx;
2650   Mat            j,jpre;
2651 
2652   PetscFunctionBegin;
2653   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2654   if (snes->setupcalled) PetscFunctionReturn(0);
2655 
2656   if (!((PetscObject)snes)->type_name) {
2657     ierr = SNESSetType(snes,SNESNEWTONLS);CHKERRQ(ierr);
2658   }
2659 
2660   ierr = SNESGetFunction(snes,&snes->vec_func,NULL,NULL);CHKERRQ(ierr);
2661 
2662   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2663   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2664   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
2665   if (!sdm->ops->computejacobian) {
2666     ierr = DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);CHKERRQ(ierr);
2667   }
2668   if (!snes->vec_func) {
2669     ierr = DMCreateGlobalVector(dm,&snes->vec_func);CHKERRQ(ierr);
2670   }
2671 
2672   if (!snes->ksp) {
2673     ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);
2674   }
2675 
2676   if (!snes->linesearch) {
2677     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
2678   }
2679   ierr = SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);CHKERRQ(ierr);
2680 
2681   if (snes->pc && (snes->pcside == PC_LEFT)) {
2682     snes->mf          = PETSC_TRUE;
2683     snes->mf_operator = PETSC_FALSE;
2684   }
2685 
2686   if (snes->pc) {
2687     /* copy the DM over */
2688     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2689     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
2690 
2691     ierr = SNESGetFunction(snes,&f,&func,&funcctx);CHKERRQ(ierr);
2692     ierr = VecDuplicate(f,&fpc);CHKERRQ(ierr);
2693     ierr = SNESSetFunction(snes->pc,fpc,func,funcctx);CHKERRQ(ierr);
2694     ierr = SNESGetJacobian(snes,&j,&jpre,&jac,&jacctx);CHKERRQ(ierr);
2695     ierr = SNESSetJacobian(snes->pc,j,jpre,jac,jacctx);CHKERRQ(ierr);
2696     ierr = SNESGetApplicationContext(snes,&appctx);CHKERRQ(ierr);
2697     ierr = SNESSetApplicationContext(snes->pc,appctx);CHKERRQ(ierr);
2698     ierr = VecDestroy(&fpc);CHKERRQ(ierr);
2699 
2700     /* copy the function pointers over */
2701     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
2702 
2703     /* default to 1 iteration */
2704     ierr = SNESSetTolerances(snes->pc,0.0,0.0,0.0,1,snes->pc->max_funcs);CHKERRQ(ierr);
2705     if (snes->pcside==PC_RIGHT) {
2706       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
2707     } else {
2708       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_NONE);CHKERRQ(ierr);
2709     }
2710     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
2711 
2712     /* copy the line search context over */
2713     ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2714     ierr = SNESGetLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
2715     ierr = SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);CHKERRQ(ierr);
2716     ierr = SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);CHKERRQ(ierr);
2717     ierr = SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);CHKERRQ(ierr);
2718     ierr = SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);CHKERRQ(ierr);
2719     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);CHKERRQ(ierr);
2720   }
2721   if (snes->mf) {
2722     ierr = SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);CHKERRQ(ierr);
2723   }
2724   if (snes->ops->usercompute && !snes->user) {
2725     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2726   }
2727 
2728   snes->jac_iter = 0;
2729   snes->pre_iter = 0;
2730 
2731   if (snes->ops->setup) {
2732     ierr = (*snes->ops->setup)(snes);CHKERRQ(ierr);
2733   }
2734 
2735   if (snes->pc && (snes->pcside == PC_LEFT)) {
2736     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
2737       ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2738       ierr = SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultNPC);CHKERRQ(ierr);
2739     }
2740   }
2741 
2742   snes->setupcalled = PETSC_TRUE;
2743   PetscFunctionReturn(0);
2744 }
2745 
2746 #undef __FUNCT__
2747 #define __FUNCT__ "SNESReset"
2748 /*@
2749    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats
2750 
2751    Collective on SNES
2752 
2753    Input Parameter:
2754 .  snes - iterative context obtained from SNESCreate()
2755 
2756    Level: intermediate
2757 
2758    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()
2759 
2760 .keywords: SNES, destroy
2761 
2762 .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
2763 @*/
2764 PetscErrorCode  SNESReset(SNES snes)
2765 {
2766   PetscErrorCode ierr;
2767 
2768   PetscFunctionBegin;
2769   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2770   if (snes->ops->userdestroy && snes->user) {
2771     ierr       = (*snes->ops->userdestroy)((void**)&snes->user);CHKERRQ(ierr);
2772     snes->user = NULL;
2773   }
2774   if (snes->pc) {
2775     ierr = SNESReset(snes->pc);CHKERRQ(ierr);
2776   }
2777 
2778   if (snes->ops->reset) {
2779     ierr = (*snes->ops->reset)(snes);CHKERRQ(ierr);
2780   }
2781   if (snes->ksp) {
2782     ierr = KSPReset(snes->ksp);CHKERRQ(ierr);
2783   }
2784 
2785   if (snes->linesearch) {
2786     ierr = SNESLineSearchReset(snes->linesearch);CHKERRQ(ierr);
2787   }
2788 
2789   ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
2790   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
2791   ierr = VecDestroy(&snes->vec_sol_update);CHKERRQ(ierr);
2792   ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
2793   ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2794   ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2795   ierr = VecDestroyVecs(snes->nwork,&snes->work);CHKERRQ(ierr);
2796   ierr = VecDestroyVecs(snes->nvwork,&snes->vwork);CHKERRQ(ierr);
2797 
2798   snes->nwork       = snes->nvwork = 0;
2799   snes->setupcalled = PETSC_FALSE;
2800   PetscFunctionReturn(0);
2801 }
2802 
2803 #undef __FUNCT__
2804 #define __FUNCT__ "SNESDestroy"
2805 /*@
2806    SNESDestroy - Destroys the nonlinear solver context that was created
2807    with SNESCreate().
2808 
2809    Collective on SNES
2810 
2811    Input Parameter:
2812 .  snes - the SNES context
2813 
2814    Level: beginner
2815 
2816 .keywords: SNES, nonlinear, destroy
2817 
2818 .seealso: SNESCreate(), SNESSolve()
2819 @*/
2820 PetscErrorCode  SNESDestroy(SNES *snes)
2821 {
2822   PetscErrorCode ierr;
2823 
2824   PetscFunctionBegin;
2825   if (!*snes) PetscFunctionReturn(0);
2826   PetscValidHeaderSpecific((*snes),SNES_CLASSID,1);
2827   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; PetscFunctionReturn(0);}
2828 
2829   ierr = SNESReset((*snes));CHKERRQ(ierr);
2830   ierr = SNESDestroy(&(*snes)->pc);CHKERRQ(ierr);
2831 
2832   /* if memory was published with SAWs then destroy it */
2833   ierr = PetscObjectSAWsViewOff((PetscObject)*snes);CHKERRQ(ierr);
2834   if ((*snes)->ops->destroy) {ierr = (*((*snes))->ops->destroy)((*snes));CHKERRQ(ierr);}
2835 
2836   ierr = DMDestroy(&(*snes)->dm);CHKERRQ(ierr);
2837   ierr = KSPDestroy(&(*snes)->ksp);CHKERRQ(ierr);
2838   ierr = SNESLineSearchDestroy(&(*snes)->linesearch);CHKERRQ(ierr);
2839 
2840   ierr = PetscFree((*snes)->kspconvctx);CHKERRQ(ierr);
2841   if ((*snes)->ops->convergeddestroy) {
2842     ierr = (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);CHKERRQ(ierr);
2843   }
2844   if ((*snes)->conv_malloc) {
2845     ierr = PetscFree((*snes)->conv_hist);CHKERRQ(ierr);
2846     ierr = PetscFree((*snes)->conv_hist_its);CHKERRQ(ierr);
2847   }
2848   ierr = SNESMonitorCancel((*snes));CHKERRQ(ierr);
2849   ierr = PetscHeaderDestroy(snes);CHKERRQ(ierr);
2850   PetscFunctionReturn(0);
2851 }
2852 
2853 /* ----------- Routines to set solver parameters ---------- */
2854 
2855 #undef __FUNCT__
2856 #define __FUNCT__ "SNESSetLagPreconditioner"
2857 /*@
2858    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.
2859 
2860    Logically Collective on SNES
2861 
2862    Input Parameters:
2863 +  snes - the SNES context
2864 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2865          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2866 
2867    Options Database Keys:
2868 .    -snes_lag_preconditioner <lag>
2869 
2870    Notes:
2871    The default is 1
2872    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2873    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use
2874 
2875    Level: intermediate
2876 
2877 .keywords: SNES, nonlinear, set, convergence, tolerances
2878 
2879 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2880 
2881 @*/
2882 PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
2883 {
2884   PetscFunctionBegin;
2885   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2886   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2887   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2888   PetscValidLogicalCollectiveInt(snes,lag,2);
2889   snes->lagpreconditioner = lag;
2890   PetscFunctionReturn(0);
2891 }
2892 
2893 #undef __FUNCT__
2894 #define __FUNCT__ "SNESSetGridSequence"
2895 /*@
2896    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does
2897 
2898    Logically Collective on SNES
2899 
2900    Input Parameters:
2901 +  snes - the SNES context
2902 -  steps - the number of refinements to do, defaults to 0
2903 
2904    Options Database Keys:
2905 .    -snes_grid_sequence <steps>
2906 
2907    Level: intermediate
2908 
2909    Notes:
2910    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2911 
2912 .keywords: SNES, nonlinear, set, convergence, tolerances
2913 
2914 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetGridSequence()
2915 
2916 @*/
2917 PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
2918 {
2919   PetscFunctionBegin;
2920   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2921   PetscValidLogicalCollectiveInt(snes,steps,2);
2922   snes->gridsequence = steps;
2923   PetscFunctionReturn(0);
2924 }
2925 
2926 #undef __FUNCT__
2927 #define __FUNCT__ "SNESGetGridSequence"
2928 /*@
2929    SNESGetGridSequence - gets the number of steps of grid sequencing that SNES does
2930 
2931    Logically Collective on SNES
2932 
2933    Input Parameter:
2934 .  snes - the SNES context
2935 
2936    Output Parameter:
2937 .  steps - the number of refinements to do, defaults to 0
2938 
2939    Options Database Keys:
2940 .    -snes_grid_sequence <steps>
2941 
2942    Level: intermediate
2943 
2944    Notes:
2945    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2946 
2947 .keywords: SNES, nonlinear, set, convergence, tolerances
2948 
2949 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESSetGridSequence()
2950 
2951 @*/
2952 PetscErrorCode  SNESGetGridSequence(SNES snes,PetscInt *steps)
2953 {
2954   PetscFunctionBegin;
2955   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2956   *steps = snes->gridsequence;
2957   PetscFunctionReturn(0);
2958 }
2959 
2960 #undef __FUNCT__
2961 #define __FUNCT__ "SNESGetLagPreconditioner"
2962 /*@
2963    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt
2964 
2965    Not Collective
2966 
2967    Input Parameter:
2968 .  snes - the SNES context
2969 
2970    Output Parameter:
2971 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2972          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2973 
2974    Options Database Keys:
2975 .    -snes_lag_preconditioner <lag>
2976 
2977    Notes:
2978    The default is 1
2979    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2980 
2981    Level: intermediate
2982 
2983 .keywords: SNES, nonlinear, set, convergence, tolerances
2984 
2985 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()
2986 
2987 @*/
2988 PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
2989 {
2990   PetscFunctionBegin;
2991   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2992   *lag = snes->lagpreconditioner;
2993   PetscFunctionReturn(0);
2994 }
2995 
2996 #undef __FUNCT__
2997 #define __FUNCT__ "SNESSetLagJacobian"
2998 /*@
2999    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
3000      often the preconditioner is rebuilt.
3001 
3002    Logically Collective on SNES
3003 
3004    Input Parameters:
3005 +  snes - the SNES context
3006 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3007          the Jacobian is built etc. -2 means rebuild at next chance but then never again
3008 
3009    Options Database Keys:
3010 .    -snes_lag_jacobian <lag>
3011 
3012    Notes:
3013    The default is 1
3014    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3015    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
3016    at the next Newton step but never again (unless it is reset to another value)
3017 
3018    Level: intermediate
3019 
3020 .keywords: SNES, nonlinear, set, convergence, tolerances
3021 
3022 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()
3023 
3024 @*/
3025 PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
3026 {
3027   PetscFunctionBegin;
3028   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3029   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
3030   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
3031   PetscValidLogicalCollectiveInt(snes,lag,2);
3032   snes->lagjacobian = lag;
3033   PetscFunctionReturn(0);
3034 }
3035 
3036 #undef __FUNCT__
3037 #define __FUNCT__ "SNESGetLagJacobian"
3038 /*@
3039    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt
3040 
3041    Not Collective
3042 
3043    Input Parameter:
3044 .  snes - the SNES context
3045 
3046    Output Parameter:
3047 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3048          the Jacobian is built etc.
3049 
3050    Options Database Keys:
3051 .    -snes_lag_jacobian <lag>
3052 
3053    Notes:
3054    The default is 1
3055    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3056 
3057    Level: intermediate
3058 
3059 .keywords: SNES, nonlinear, set, convergence, tolerances
3060 
3061 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()
3062 
3063 @*/
3064 PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
3065 {
3066   PetscFunctionBegin;
3067   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3068   *lag = snes->lagjacobian;
3069   PetscFunctionReturn(0);
3070 }
3071 
3072 #undef __FUNCT__
3073 #define __FUNCT__ "SNESSetLagJacobianPersists"
3074 /*@
3075    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves
3076 
3077    Logically collective on SNES
3078 
3079    Input Parameter:
3080 +  snes - the SNES context
3081 -   flg - jacobian lagging persists if true
3082 
3083    Options Database Keys:
3084 .    -snes_lag_jacobian_persists <flg>
3085 
3086    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
3087    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
3088    timesteps may present huge efficiency gains.
3089 
3090    Level: developer
3091 
3092 .keywords: SNES, nonlinear, lag
3093 
3094 .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
3095 
3096 @*/
3097 PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
3098 {
3099   PetscFunctionBegin;
3100   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3101   PetscValidLogicalCollectiveBool(snes,flg,2);
3102   snes->lagjac_persist = flg;
3103   PetscFunctionReturn(0);
3104 }
3105 
3106 #undef __FUNCT__
3107 #define __FUNCT__ "SNESSetLagPreconditionerPersists"
3108 /*@
3109    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple solves
3110 
3111    Logically Collective on SNES
3112 
3113    Input Parameter:
3114 +  snes - the SNES context
3115 -   flg - preconditioner lagging persists if true
3116 
3117    Options Database Keys:
3118 .    -snes_lag_jacobian_persists <flg>
3119 
3120    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
3121    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
3122    several timesteps may present huge efficiency gains.
3123 
3124    Level: developer
3125 
3126 .keywords: SNES, nonlinear, lag
3127 
3128 .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
3129 
3130 @*/
3131 PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
3132 {
3133   PetscFunctionBegin;
3134   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3135   PetscValidLogicalCollectiveBool(snes,flg,2);
3136   snes->lagpre_persist = flg;
3137   PetscFunctionReturn(0);
3138 }
3139 
3140 #undef __FUNCT__
3141 #define __FUNCT__ "SNESSetTolerances"
3142 /*@
3143    SNESSetTolerances - Sets various parameters used in convergence tests.
3144 
3145    Logically Collective on SNES
3146 
3147    Input Parameters:
3148 +  snes - the SNES context
3149 .  abstol - absolute convergence tolerance
3150 .  rtol - relative convergence tolerance
3151 .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
3152 .  maxit - maximum number of iterations
3153 -  maxf - maximum number of function evaluations
3154 
3155    Options Database Keys:
3156 +    -snes_atol <abstol> - Sets abstol
3157 .    -snes_rtol <rtol> - Sets rtol
3158 .    -snes_stol <stol> - Sets stol
3159 .    -snes_max_it <maxit> - Sets maxit
3160 -    -snes_max_funcs <maxf> - Sets maxf
3161 
3162    Notes:
3163    The default maximum number of iterations is 50.
3164    The default maximum number of function evaluations is 1000.
3165 
3166    Level: intermediate
3167 
3168 .keywords: SNES, nonlinear, set, convergence, tolerances
3169 
3170 .seealso: SNESSetTrustRegionTolerance()
3171 @*/
3172 PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
3173 {
3174   PetscFunctionBegin;
3175   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3176   PetscValidLogicalCollectiveReal(snes,abstol,2);
3177   PetscValidLogicalCollectiveReal(snes,rtol,3);
3178   PetscValidLogicalCollectiveReal(snes,stol,4);
3179   PetscValidLogicalCollectiveInt(snes,maxit,5);
3180   PetscValidLogicalCollectiveInt(snes,maxf,6);
3181 
3182   if (abstol != PETSC_DEFAULT) {
3183     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %g must be non-negative",(double)abstol);
3184     snes->abstol = abstol;
3185   }
3186   if (rtol != PETSC_DEFAULT) {
3187     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);
3188     snes->rtol = rtol;
3189   }
3190   if (stol != PETSC_DEFAULT) {
3191     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %g must be non-negative",(double)stol);
3192     snes->stol = stol;
3193   }
3194   if (maxit != PETSC_DEFAULT) {
3195     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
3196     snes->max_its = maxit;
3197   }
3198   if (maxf != PETSC_DEFAULT) {
3199     if (maxf < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
3200     snes->max_funcs = maxf;
3201   }
3202   snes->tolerancesset = PETSC_TRUE;
3203   PetscFunctionReturn(0);
3204 }
3205 
3206 #undef __FUNCT__
3207 #define __FUNCT__ "SNESGetTolerances"
3208 /*@
3209    SNESGetTolerances - Gets various parameters used in convergence tests.
3210 
3211    Not Collective
3212 
3213    Input Parameters:
3214 +  snes - the SNES context
3215 .  atol - absolute convergence tolerance
3216 .  rtol - relative convergence tolerance
3217 .  stol -  convergence tolerance in terms of the norm
3218            of the change in the solution between steps
3219 .  maxit - maximum number of iterations
3220 -  maxf - maximum number of function evaluations
3221 
3222    Notes:
3223    The user can specify NULL for any parameter that is not needed.
3224 
3225    Level: intermediate
3226 
3227 .keywords: SNES, nonlinear, get, convergence, tolerances
3228 
3229 .seealso: SNESSetTolerances()
3230 @*/
3231 PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3232 {
3233   PetscFunctionBegin;
3234   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3235   if (atol)  *atol  = snes->abstol;
3236   if (rtol)  *rtol  = snes->rtol;
3237   if (stol)  *stol  = snes->stol;
3238   if (maxit) *maxit = snes->max_its;
3239   if (maxf)  *maxf  = snes->max_funcs;
3240   PetscFunctionReturn(0);
3241 }
3242 
3243 #undef __FUNCT__
3244 #define __FUNCT__ "SNESSetTrustRegionTolerance"
3245 /*@
3246    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.
3247 
3248    Logically Collective on SNES
3249 
3250    Input Parameters:
3251 +  snes - the SNES context
3252 -  tol - tolerance
3253 
3254    Options Database Key:
3255 .  -snes_trtol <tol> - Sets tol
3256 
3257    Level: intermediate
3258 
3259 .keywords: SNES, nonlinear, set, trust region, tolerance
3260 
3261 .seealso: SNESSetTolerances()
3262 @*/
3263 PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3264 {
3265   PetscFunctionBegin;
3266   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3267   PetscValidLogicalCollectiveReal(snes,tol,2);
3268   snes->deltatol = tol;
3269   PetscFunctionReturn(0);
3270 }
3271 
3272 /*
3273    Duplicate the lg monitors for SNES from KSP; for some reason with
3274    dynamic libraries things don't work under Sun4 if we just use
3275    macros instead of functions
3276 */
3277 #undef __FUNCT__
3278 #define __FUNCT__ "SNESMonitorLGResidualNorm"
3279 PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,void *ctx)
3280 {
3281   PetscErrorCode ierr;
3282 
3283   PetscFunctionBegin;
3284   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3285   ierr = KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);CHKERRQ(ierr);
3286   PetscFunctionReturn(0);
3287 }
3288 
3289 #undef __FUNCT__
3290 #define __FUNCT__ "SNESMonitorLGCreate"
3291 PetscErrorCode  SNESMonitorLGCreate(MPI_Comm comm,const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *lgctx)
3292 {
3293   PetscErrorCode ierr;
3294 
3295   PetscFunctionBegin;
3296   ierr = KSPMonitorLGResidualNormCreate(comm,host,label,x,y,m,n,lgctx);CHKERRQ(ierr);
3297   PetscFunctionReturn(0);
3298 }
3299 
3300 extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
3301 #undef __FUNCT__
3302 #define __FUNCT__ "SNESMonitorLGRange"
3303 PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3304 {
3305   PetscDrawLG      lg;
3306   PetscErrorCode   ierr;
3307   PetscReal        x,y,per;
3308   PetscViewer      v = (PetscViewer)monctx;
3309   static PetscReal prev; /* should be in the context */
3310   PetscDraw        draw;
3311 
3312   PetscFunctionBegin;
3313   PetscValidHeaderSpecific(v,PETSC_VIEWER_CLASSID,4);
3314   ierr = PetscViewerDrawGetDrawLG(v,0,&lg);CHKERRQ(ierr);
3315   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3316   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3317   ierr = PetscDrawSetTitle(draw,"Residual norm");CHKERRQ(ierr);
3318   x    = (PetscReal)n;
3319   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
3320   else y = -15.0;
3321   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3322   if (n < 20 || !(n % 5)) {
3323     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3324   }
3325 
3326   ierr = PetscViewerDrawGetDrawLG(v,1,&lg);CHKERRQ(ierr);
3327   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3328   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3329   ierr = PetscDrawSetTitle(draw,"% elemts > .2*max elemt");CHKERRQ(ierr);
3330   ierr =  SNESMonitorRange_Private(snes,n,&per);CHKERRQ(ierr);
3331   x    = (PetscReal)n;
3332   y    = 100.0*per;
3333   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3334   if (n < 20 || !(n % 5)) {
3335     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3336   }
3337 
3338   ierr = PetscViewerDrawGetDrawLG(v,2,&lg);CHKERRQ(ierr);
3339   if (!n) {prev = rnorm;ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3340   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3341   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");CHKERRQ(ierr);
3342   x    = (PetscReal)n;
3343   y    = (prev - rnorm)/prev;
3344   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3345   if (n < 20 || !(n % 5)) {
3346     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3347   }
3348 
3349   ierr = PetscViewerDrawGetDrawLG(v,3,&lg);CHKERRQ(ierr);
3350   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3351   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3352   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");CHKERRQ(ierr);
3353   x    = (PetscReal)n;
3354   y    = (prev - rnorm)/(prev*per);
3355   if (n > 2) { /*skip initial crazy value */
3356     ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3357   }
3358   if (n < 20 || !(n % 5)) {
3359     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3360   }
3361   prev = rnorm;
3362   PetscFunctionReturn(0);
3363 }
3364 
3365 #undef __FUNCT__
3366 #define __FUNCT__ "SNESMonitor"
3367 /*@
3368    SNESMonitor - runs the user provided monitor routines, if they exist
3369 
3370    Collective on SNES
3371 
3372    Input Parameters:
3373 +  snes - nonlinear solver context obtained from SNESCreate()
3374 .  iter - iteration number
3375 -  rnorm - relative norm of the residual
3376 
3377    Notes:
3378    This routine is called by the SNES implementations.
3379    It does not typically need to be called by the user.
3380 
3381    Level: developer
3382 
3383 .seealso: SNESMonitorSet()
3384 @*/
3385 PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3386 {
3387   PetscErrorCode ierr;
3388   PetscInt       i,n = snes->numbermonitors;
3389 
3390   PetscFunctionBegin;
3391   ierr = VecLockPush(snes->vec_sol);CHKERRQ(ierr);
3392   for (i=0; i<n; i++) {
3393     ierr = (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);CHKERRQ(ierr);
3394   }
3395   ierr = VecLockPop(snes->vec_sol);CHKERRQ(ierr);
3396   PetscFunctionReturn(0);
3397 }
3398 
3399 /* ------------ Routines to set performance monitoring options ----------- */
3400 
3401 /*MC
3402     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver
3403 
3404      Synopsis:
3405      #include <petscsnes.h>
3406 $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)
3407 
3408 +    snes - the SNES context
3409 .    its - iteration number
3410 .    norm - 2-norm function value (may be estimated)
3411 -    mctx - [optional] monitoring context
3412 
3413    Level: advanced
3414 
3415 .seealso:   SNESMonitorSet(), SNESMonitorGet()
3416 M*/
3417 
3418 #undef __FUNCT__
3419 #define __FUNCT__ "SNESMonitorSet"
3420 /*@C
3421    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3422    iteration of the nonlinear solver to display the iteration's
3423    progress.
3424 
3425    Logically Collective on SNES
3426 
3427    Input Parameters:
3428 +  snes - the SNES context
3429 .  f - the monitor function, see SNESMonitorFunction for the calling sequence
3430 .  mctx - [optional] user-defined context for private data for the
3431           monitor routine (use NULL if no context is desired)
3432 -  monitordestroy - [optional] routine that frees monitor context
3433           (may be NULL)
3434 
3435    Options Database Keys:
3436 +    -snes_monitor        - sets SNESMonitorDefault()
3437 .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3438                             uses SNESMonitorLGCreate()
3439 -    -snes_monitor_cancel - cancels all monitors that have
3440                             been hardwired into a code by
3441                             calls to SNESMonitorSet(), but
3442                             does not cancel those set via
3443                             the options database.
3444 
3445    Notes:
3446    Several different monitoring routines may be set by calling
3447    SNESMonitorSet() multiple times; all will be called in the
3448    order in which they were set.
3449 
3450    Fortran notes: Only a single monitor function can be set for each SNES object
3451 
3452    Level: intermediate
3453 
3454 .keywords: SNES, nonlinear, set, monitor
3455 
3456 .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
3457 @*/
3458 PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*f)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3459 {
3460   PetscInt       i;
3461   PetscErrorCode ierr;
3462 
3463   PetscFunctionBegin;
3464   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3465   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3466   for (i=0; i<snes->numbermonitors;i++) {
3467     if (f == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
3468       if (monitordestroy) {
3469         ierr = (*monitordestroy)(&mctx);CHKERRQ(ierr);
3470       }
3471       PetscFunctionReturn(0);
3472     }
3473   }
3474   snes->monitor[snes->numbermonitors]          = f;
3475   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
3476   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
3477   PetscFunctionReturn(0);
3478 }
3479 
3480 #undef __FUNCT__
3481 #define __FUNCT__ "SNESMonitorCancel"
3482 /*@
3483    SNESMonitorCancel - Clears all the monitor functions for a SNES object.
3484 
3485    Logically Collective on SNES
3486 
3487    Input Parameters:
3488 .  snes - the SNES context
3489 
3490    Options Database Key:
3491 .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3492     into a code by calls to SNESMonitorSet(), but does not cancel those
3493     set via the options database
3494 
3495    Notes:
3496    There is no way to clear one specific monitor from a SNES object.
3497 
3498    Level: intermediate
3499 
3500 .keywords: SNES, nonlinear, set, monitor
3501 
3502 .seealso: SNESMonitorDefault(), SNESMonitorSet()
3503 @*/
3504 PetscErrorCode  SNESMonitorCancel(SNES snes)
3505 {
3506   PetscErrorCode ierr;
3507   PetscInt       i;
3508 
3509   PetscFunctionBegin;
3510   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3511   for (i=0; i<snes->numbermonitors; i++) {
3512     if (snes->monitordestroy[i]) {
3513       ierr = (*snes->monitordestroy[i])(&snes->monitorcontext[i]);CHKERRQ(ierr);
3514     }
3515   }
3516   snes->numbermonitors = 0;
3517   PetscFunctionReturn(0);
3518 }
3519 
3520 /*MC
3521     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver
3522 
3523      Synopsis:
3524      #include <petscsnes.h>
3525 $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)
3526 
3527 +    snes - the SNES context
3528 .    it - current iteration (0 is the first and is before any Newton step)
3529 .    cctx - [optional] convergence context
3530 .    reason - reason for convergence/divergence
3531 .    xnorm - 2-norm of current iterate
3532 .    gnorm - 2-norm of current step
3533 -    f - 2-norm of function
3534 
3535    Level: intermediate
3536 
3537 .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
3538 M*/
3539 
3540 #undef __FUNCT__
3541 #define __FUNCT__ "SNESSetConvergenceTest"
3542 /*@C
3543    SNESSetConvergenceTest - Sets the function that is to be used
3544    to test for convergence of the nonlinear iterative solution.
3545 
3546    Logically Collective on SNES
3547 
3548    Input Parameters:
3549 +  snes - the SNES context
3550 .  SNESConvergenceTestFunction - routine to test for convergence
3551 .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
3552 -  destroy - [optional] destructor for the context (may be NULL; NULL_FUNCTION in Fortran)
3553 
3554    Level: advanced
3555 
3556 .keywords: SNES, nonlinear, set, convergence, test
3557 
3558 .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
3559 @*/
3560 PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
3561 {
3562   PetscErrorCode ierr;
3563 
3564   PetscFunctionBegin;
3565   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3566   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
3567   if (snes->ops->convergeddestroy) {
3568     ierr = (*snes->ops->convergeddestroy)(snes->cnvP);CHKERRQ(ierr);
3569   }
3570   snes->ops->converged        = SNESConvergenceTestFunction;
3571   snes->ops->convergeddestroy = destroy;
3572   snes->cnvP                  = cctx;
3573   PetscFunctionReturn(0);
3574 }
3575 
3576 #undef __FUNCT__
3577 #define __FUNCT__ "SNESGetConvergedReason"
3578 /*@
3579    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.
3580 
3581    Not Collective
3582 
3583    Input Parameter:
3584 .  snes - the SNES context
3585 
3586    Output Parameter:
3587 .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3588             manual pages for the individual convergence tests for complete lists
3589 
3590    Level: intermediate
3591 
3592    Notes: Can only be called after the call the SNESSolve() is complete.
3593 
3594 .keywords: SNES, nonlinear, set, convergence, test
3595 
3596 .seealso: SNESSetConvergenceTest(), SNESSetConvergedReason(), SNESConvergedReason
3597 @*/
3598 PetscErrorCode SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
3599 {
3600   PetscFunctionBegin;
3601   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3602   PetscValidPointer(reason,2);
3603   *reason = snes->reason;
3604   PetscFunctionReturn(0);
3605 }
3606 
3607 #undef __FUNCT__
3608 #define __FUNCT__ "SNESSetConvergedReason"
3609 /*@
3610    SNESSetConvergedReason - Sets the reason the SNES iteration was stopped.
3611 
3612    Not Collective
3613 
3614    Input Parameters:
3615 +  snes - the SNES context
3616 -  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3617             manual pages for the individual convergence tests for complete lists
3618 
3619    Level: intermediate
3620 
3621 .keywords: SNES, nonlinear, set, convergence, test
3622 .seealso: SNESGetConvergedReason(), SNESSetConvergenceTest(), SNESConvergedReason
3623 @*/
3624 PetscErrorCode SNESSetConvergedReason(SNES snes,SNESConvergedReason reason)
3625 {
3626   PetscFunctionBegin;
3627   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3628   snes->reason = reason;
3629   PetscFunctionReturn(0);
3630 }
3631 
3632 #undef __FUNCT__
3633 #define __FUNCT__ "SNESSetConvergenceHistory"
3634 /*@
3635    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.
3636 
3637    Logically Collective on SNES
3638 
3639    Input Parameters:
3640 +  snes - iterative context obtained from SNESCreate()
3641 .  a   - array to hold history, this array will contain the function norms computed at each step
3642 .  its - integer array holds the number of linear iterations for each solve.
3643 .  na  - size of a and its
3644 -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
3645            else it continues storing new values for new nonlinear solves after the old ones
3646 
3647    Notes:
3648    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
3649    default array of length 10000 is allocated.
3650 
3651    This routine is useful, e.g., when running a code for purposes
3652    of accurate performance monitoring, when no I/O should be done
3653    during the section of code that is being timed.
3654 
3655    Level: intermediate
3656 
3657 .keywords: SNES, set, convergence, history
3658 
3659 .seealso: SNESGetConvergenceHistory()
3660 
3661 @*/
3662 PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
3663 {
3664   PetscErrorCode ierr;
3665 
3666   PetscFunctionBegin;
3667   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3668   if (a) PetscValidScalarPointer(a,2);
3669   if (its) PetscValidIntPointer(its,3);
3670   if (!a) {
3671     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
3672     ierr = PetscCalloc1(na,&a);CHKERRQ(ierr);
3673     ierr = PetscCalloc1(na,&its);CHKERRQ(ierr);
3674 
3675     snes->conv_malloc = PETSC_TRUE;
3676   }
3677   snes->conv_hist       = a;
3678   snes->conv_hist_its   = its;
3679   snes->conv_hist_max   = na;
3680   snes->conv_hist_len   = 0;
3681   snes->conv_hist_reset = reset;
3682   PetscFunctionReturn(0);
3683 }
3684 
3685 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3686 #include <engine.h>   /* MATLAB include file */
3687 #include <mex.h>      /* MATLAB include file */
3688 
3689 #undef __FUNCT__
3690 #define __FUNCT__ "SNESGetConvergenceHistoryMatlab"
3691 PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
3692 {
3693   mxArray   *mat;
3694   PetscInt  i;
3695   PetscReal *ar;
3696 
3697   PetscFunctionBegin;
3698   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
3699   ar  = (PetscReal*) mxGetData(mat);
3700   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
3701   PetscFunctionReturn(mat);
3702 }
3703 #endif
3704 
3705 #undef __FUNCT__
3706 #define __FUNCT__ "SNESGetConvergenceHistory"
3707 /*@C
3708    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.
3709 
3710    Not Collective
3711 
3712    Input Parameter:
3713 .  snes - iterative context obtained from SNESCreate()
3714 
3715    Output Parameters:
3716 .  a   - array to hold history
3717 .  its - integer array holds the number of linear iterations (or
3718          negative if not converged) for each solve.
3719 -  na  - size of a and its
3720 
3721    Notes:
3722     The calling sequence for this routine in Fortran is
3723 $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
3724 
3725    This routine is useful, e.g., when running a code for purposes
3726    of accurate performance monitoring, when no I/O should be done
3727    during the section of code that is being timed.
3728 
3729    Level: intermediate
3730 
3731 .keywords: SNES, get, convergence, history
3732 
3733 .seealso: SNESSetConvergencHistory()
3734 
3735 @*/
3736 PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
3737 {
3738   PetscFunctionBegin;
3739   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3740   if (a)   *a   = snes->conv_hist;
3741   if (its) *its = snes->conv_hist_its;
3742   if (na)  *na  = snes->conv_hist_len;
3743   PetscFunctionReturn(0);
3744 }
3745 
3746 #undef __FUNCT__
3747 #define __FUNCT__ "SNESSetUpdate"
3748 /*@C
3749   SNESSetUpdate - Sets the general-purpose update function called
3750   at the beginning of every iteration of the nonlinear solve. Specifically
3751   it is called just before the Jacobian is "evaluated".
3752 
3753   Logically Collective on SNES
3754 
3755   Input Parameters:
3756 . snes - The nonlinear solver context
3757 . func - The function
3758 
3759   Calling sequence of func:
3760 . func (SNES snes, PetscInt step);
3761 
3762 . step - The current step of the iteration
3763 
3764   Level: advanced
3765 
3766   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()
3767         This is not used by most users.
3768 
3769 .keywords: SNES, update
3770 
3771 .seealso SNESSetJacobian(), SNESSolve()
3772 @*/
3773 PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
3774 {
3775   PetscFunctionBegin;
3776   PetscValidHeaderSpecific(snes, SNES_CLASSID,1);
3777   snes->ops->update = func;
3778   PetscFunctionReturn(0);
3779 }
3780 
3781 #undef __FUNCT__
3782 #define __FUNCT__ "SNESScaleStep_Private"
3783 /*
3784    SNESScaleStep_Private - Scales a step so that its length is less than the
3785    positive parameter delta.
3786 
3787     Input Parameters:
3788 +   snes - the SNES context
3789 .   y - approximate solution of linear system
3790 .   fnorm - 2-norm of current function
3791 -   delta - trust region size
3792 
3793     Output Parameters:
3794 +   gpnorm - predicted function norm at the new point, assuming local
3795     linearization.  The value is zero if the step lies within the trust
3796     region, and exceeds zero otherwise.
3797 -   ynorm - 2-norm of the step
3798 
3799     Note:
3800     For non-trust region methods such as SNESNEWTONLS, the parameter delta
3801     is set to be the maximum allowable step size.
3802 
3803 .keywords: SNES, nonlinear, scale, step
3804 */
3805 PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
3806 {
3807   PetscReal      nrm;
3808   PetscScalar    cnorm;
3809   PetscErrorCode ierr;
3810 
3811   PetscFunctionBegin;
3812   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3813   PetscValidHeaderSpecific(y,VEC_CLASSID,2);
3814   PetscCheckSameComm(snes,1,y,2);
3815 
3816   ierr = VecNorm(y,NORM_2,&nrm);CHKERRQ(ierr);
3817   if (nrm > *delta) {
3818     nrm     = *delta/nrm;
3819     *gpnorm = (1.0 - nrm)*(*fnorm);
3820     cnorm   = nrm;
3821     ierr    = VecScale(y,cnorm);CHKERRQ(ierr);
3822     *ynorm  = *delta;
3823   } else {
3824     *gpnorm = 0.0;
3825     *ynorm  = nrm;
3826   }
3827   PetscFunctionReturn(0);
3828 }
3829 
3830 #undef __FUNCT__
3831 #define __FUNCT__ "SNESReasonView"
3832 /*@
3833    SNESReasonView - Displays the reason a SNES solve converged or diverged to a viewer
3834 
3835    Collective on SNES
3836 
3837    Parameter:
3838 +  snes - iterative context obtained from SNESCreate()
3839 -  viewer - the viewer to display the reason
3840 
3841 
3842    Options Database Keys:
3843 .  -snes_converged_reason - print reason for converged or diverged, also prints number of iterations
3844 
3845    Level: beginner
3846 
3847 .keywords: SNES, solve, linear system
3848 
3849 .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault()
3850 
3851 @*/
3852 PetscErrorCode  SNESReasonView(SNES snes,PetscViewer viewer)
3853 {
3854   PetscErrorCode ierr;
3855   PetscBool      isAscii;
3856 
3857   PetscFunctionBegin;
3858   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isAscii);CHKERRQ(ierr);
3859   if (isAscii) {
3860     ierr = PetscViewerASCIIAddTab(viewer,((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3861     if (snes->reason > 0) {
3862       if (((PetscObject) snes)->prefix) {
3863         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve converged due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3864       } else {
3865         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3866       }
3867     } else {
3868       if (((PetscObject) snes)->prefix) {
3869         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);
3870       } else {
3871         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3872       }
3873     }
3874     ierr = PetscViewerASCIISubtractTab(viewer,((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3875   }
3876   PetscFunctionReturn(0);
3877 }
3878 
3879 #undef __FUNCT__
3880 #define __FUNCT__ "SNESReasonViewFromOptions"
3881 /*@C
3882   SNESReasonViewFromOptions - Processes command line options to determine if/how a SNESReason is to be viewed.
3883 
3884   Collective on SNES
3885 
3886   Input Parameters:
3887 . snes   - the SNES object
3888 
3889   Level: intermediate
3890 
3891 @*/
3892 PetscErrorCode SNESReasonViewFromOptions(SNES snes)
3893 {
3894   PetscErrorCode    ierr;
3895   PetscViewer       viewer;
3896   PetscBool         flg;
3897   static PetscBool  incall = PETSC_FALSE;
3898   PetscViewerFormat format;
3899 
3900   PetscFunctionBegin;
3901   if (incall) PetscFunctionReturn(0);
3902   incall = PETSC_TRUE;
3903   ierr   = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_converged_reason",&viewer,&format,&flg);CHKERRQ(ierr);
3904   if (flg) {
3905     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
3906     ierr = SNESReasonView(snes,viewer);CHKERRQ(ierr);
3907     ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
3908     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3909   }
3910   incall = PETSC_FALSE;
3911   PetscFunctionReturn(0);
3912 }
3913 
3914 #undef __FUNCT__
3915 #define __FUNCT__ "SNESSolve"
3916 /*@C
3917    SNESSolve - Solves a nonlinear system F(x) = b.
3918    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3919 
3920    Collective on SNES
3921 
3922    Input Parameters:
3923 +  snes - the SNES context
3924 .  b - the constant part of the equation F(x) = b, or NULL to use zero.
3925 -  x - the solution vector.
3926 
3927    Notes:
3928    The user should initialize the vector,x, with the initial guess
3929    for the nonlinear solve prior to calling SNESSolve.  In particular,
3930    to employ an initial guess of zero, the user should explicitly set
3931    this vector to zero by calling VecSet().
3932 
3933    Level: beginner
3934 
3935 .keywords: SNES, nonlinear, solve
3936 
3937 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3938 @*/
3939 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3940 {
3941   PetscErrorCode    ierr;
3942   PetscBool         flg;
3943   PetscInt          grid;
3944   Vec               xcreated = NULL;
3945   DM                dm;
3946 
3947   PetscFunctionBegin;
3948   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3949   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3950   if (x) PetscCheckSameComm(snes,1,x,3);
3951   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3952   if (b) PetscCheckSameComm(snes,1,b,2);
3953 
3954   if (!x) {
3955     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3956     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3957     x    = xcreated;
3958   }
3959   ierr = SNESViewFromOptions(snes,NULL,"-snes_view_pre");CHKERRQ(ierr);
3960 
3961   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);}
3962   for (grid=0; grid<snes->gridsequence+1; grid++) {
3963 
3964     /* set solution vector */
3965     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3966     ierr          = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3967     snes->vec_sol = x;
3968     ierr          = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3969 
3970     /* set affine vector if provided */
3971     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3972     ierr          = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3973     snes->vec_rhs = b;
3974 
3975     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
3976     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
3977     if (!snes->vec_sol_update /* && snes->vec_sol */) {
3978       ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
3979       ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);CHKERRQ(ierr);
3980     }
3981     ierr = DMShellSetGlobalVector(dm,snes->vec_sol);CHKERRQ(ierr);
3982     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3983 
3984     if (!grid) {
3985       if (snes->ops->computeinitialguess) {
3986         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3987       }
3988     }
3989 
3990     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3991     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}
3992 
3993     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3994     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3995     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3996     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3997     snes->domainerror = PETSC_FALSE; /* clear the flag if it has been set */
3998 
3999     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
4000     if (snes->lagpre_persist) snes->pre_iter += snes->iter;
4001 
4002     ierr   = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_test_local_min",NULL,NULL,&flg);CHKERRQ(ierr);
4003     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
4004     ierr = SNESReasonViewFromOptions(snes);CHKERRQ(ierr);
4005 
4006     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
4007     if (snes->reason < 0) break;
4008     if (grid <  snes->gridsequence) {
4009       DM  fine;
4010       Vec xnew;
4011       Mat interp;
4012 
4013       ierr = DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);CHKERRQ(ierr);
4014       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
4015       ierr = DMCreateInterpolation(snes->dm,fine,&interp,NULL);CHKERRQ(ierr);
4016       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
4017       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
4018       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
4019       ierr = MatDestroy(&interp);CHKERRQ(ierr);
4020       x    = xnew;
4021 
4022       ierr = SNESReset(snes);CHKERRQ(ierr);
4023       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
4024       ierr = DMDestroy(&fine);CHKERRQ(ierr);
4025       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);
4026     }
4027   }
4028   ierr = SNESViewFromOptions(snes,NULL,"-snes_view");CHKERRQ(ierr);
4029   ierr = VecViewFromOptions(snes->vec_sol,(PetscObject)snes,"-snes_view_solution");CHKERRQ(ierr);
4030 
4031   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
4032   ierr = PetscObjectSAWsBlock((PetscObject)snes);CHKERRQ(ierr);
4033   PetscFunctionReturn(0);
4034 }
4035 
4036 /* --------- Internal routines for SNES Package --------- */
4037 
4038 #undef __FUNCT__
4039 #define __FUNCT__ "SNESSetType"
4040 /*@C
4041    SNESSetType - Sets the method for the nonlinear solver.
4042 
4043    Collective on SNES
4044 
4045    Input Parameters:
4046 +  snes - the SNES context
4047 -  type - a known method
4048 
4049    Options Database Key:
4050 .  -snes_type <type> - Sets the method; use -help for a list
4051    of available methods (for instance, newtonls or newtontr)
4052 
4053    Notes:
4054    See "petsc/include/petscsnes.h" for available methods (for instance)
4055 +    SNESNEWTONLS - Newton's method with line search
4056      (systems of nonlinear equations)
4057 .    SNESNEWTONTR - Newton's method with trust region
4058      (systems of nonlinear equations)
4059 
4060   Normally, it is best to use the SNESSetFromOptions() command and then
4061   set the SNES solver type from the options database rather than by using
4062   this routine.  Using the options database provides the user with
4063   maximum flexibility in evaluating the many nonlinear solvers.
4064   The SNESSetType() routine is provided for those situations where it
4065   is necessary to set the nonlinear solver independently of the command
4066   line or options database.  This might be the case, for example, when
4067   the choice of solver changes during the execution of the program,
4068   and the user's application is taking responsibility for choosing the
4069   appropriate method.
4070 
4071     Developer Notes: SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
4072     the constructor in that list and calls it to create the spexific object.
4073 
4074   Level: intermediate
4075 
4076 .keywords: SNES, set, type
4077 
4078 .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()
4079 
4080 @*/
4081 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
4082 {
4083   PetscErrorCode ierr,(*r)(SNES);
4084   PetscBool      match;
4085 
4086   PetscFunctionBegin;
4087   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4088   PetscValidCharPointer(type,2);
4089 
4090   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
4091   if (match) PetscFunctionReturn(0);
4092 
4093   ierr =  PetscFunctionListFind(SNESList,type,&r);CHKERRQ(ierr);
4094   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
4095   /* Destroy the previous private SNES context */
4096   if (snes->ops->destroy) {
4097     ierr               = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
4098     snes->ops->destroy = NULL;
4099   }
4100   /* Reinitialize function pointers in SNESOps structure */
4101   snes->ops->setup          = 0;
4102   snes->ops->solve          = 0;
4103   snes->ops->view           = 0;
4104   snes->ops->setfromoptions = 0;
4105   snes->ops->destroy        = 0;
4106   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
4107   snes->setupcalled = PETSC_FALSE;
4108 
4109   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
4110   ierr = (*r)(snes);CHKERRQ(ierr);
4111   PetscFunctionReturn(0);
4112 }
4113 
4114 #undef __FUNCT__
4115 #define __FUNCT__ "SNESGetType"
4116 /*@C
4117    SNESGetType - Gets the SNES method type and name (as a string).
4118 
4119    Not Collective
4120 
4121    Input Parameter:
4122 .  snes - nonlinear solver context
4123 
4124    Output Parameter:
4125 .  type - SNES method (a character string)
4126 
4127    Level: intermediate
4128 
4129 .keywords: SNES, nonlinear, get, type, name
4130 @*/
4131 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
4132 {
4133   PetscFunctionBegin;
4134   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4135   PetscValidPointer(type,2);
4136   *type = ((PetscObject)snes)->type_name;
4137   PetscFunctionReturn(0);
4138 }
4139 
4140 #undef __FUNCT__
4141 #define __FUNCT__ "SNESSetSolution"
4142 /*@
4143   SNESSetSolution - Sets the solution vector for use by the SNES routines.
4144 
4145   Logically Collective on SNES and Vec
4146 
4147   Input Parameters:
4148 + snes - the SNES context obtained from SNESCreate()
4149 - u    - the solution vector
4150 
4151   Level: beginner
4152 
4153 .keywords: SNES, set, solution
4154 @*/
4155 PetscErrorCode SNESSetSolution(SNES snes, Vec u)
4156 {
4157   DM             dm;
4158   PetscErrorCode ierr;
4159 
4160   PetscFunctionBegin;
4161   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4162   PetscValidHeaderSpecific(u, VEC_CLASSID, 2);
4163   ierr = PetscObjectReference((PetscObject) u);CHKERRQ(ierr);
4164   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
4165 
4166   snes->vec_sol = u;
4167 
4168   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
4169   ierr = DMShellSetGlobalVector(dm, u);CHKERRQ(ierr);
4170   PetscFunctionReturn(0);
4171 }
4172 
4173 #undef __FUNCT__
4174 #define __FUNCT__ "SNESGetSolution"
4175 /*@
4176    SNESGetSolution - Returns the vector where the approximate solution is
4177    stored. This is the fine grid solution when using SNESSetGridSequence().
4178 
4179    Not Collective, but Vec is parallel if SNES is parallel
4180 
4181    Input Parameter:
4182 .  snes - the SNES context
4183 
4184    Output Parameter:
4185 .  x - the solution
4186 
4187    Level: intermediate
4188 
4189 .keywords: SNES, nonlinear, get, solution
4190 
4191 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
4192 @*/
4193 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
4194 {
4195   PetscFunctionBegin;
4196   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4197   PetscValidPointer(x,2);
4198   *x = snes->vec_sol;
4199   PetscFunctionReturn(0);
4200 }
4201 
4202 #undef __FUNCT__
4203 #define __FUNCT__ "SNESGetSolutionUpdate"
4204 /*@
4205    SNESGetSolutionUpdate - Returns the vector where the solution update is
4206    stored.
4207 
4208    Not Collective, but Vec is parallel if SNES is parallel
4209 
4210    Input Parameter:
4211 .  snes - the SNES context
4212 
4213    Output Parameter:
4214 .  x - the solution update
4215 
4216    Level: advanced
4217 
4218 .keywords: SNES, nonlinear, get, solution, update
4219 
4220 .seealso: SNESGetSolution(), SNESGetFunction()
4221 @*/
4222 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
4223 {
4224   PetscFunctionBegin;
4225   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4226   PetscValidPointer(x,2);
4227   *x = snes->vec_sol_update;
4228   PetscFunctionReturn(0);
4229 }
4230 
4231 #undef __FUNCT__
4232 #define __FUNCT__ "SNESGetFunction"
4233 /*@C
4234    SNESGetFunction - Returns the vector where the function is stored.
4235 
4236    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
4237 
4238    Input Parameter:
4239 .  snes - the SNES context
4240 
4241    Output Parameter:
4242 +  r - the vector that is used to store residuals (or NULL if you don't want it)
4243 .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
4244 -  ctx - the function context (or NULL if you don't want it)
4245 
4246    Level: advanced
4247 
4248 .keywords: SNES, nonlinear, get, function
4249 
4250 .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
4251 @*/
4252 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
4253 {
4254   PetscErrorCode ierr;
4255   DM             dm;
4256 
4257   PetscFunctionBegin;
4258   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4259   if (r) {
4260     if (!snes->vec_func) {
4261       if (snes->vec_rhs) {
4262         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
4263       } else if (snes->vec_sol) {
4264         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
4265       } else if (snes->dm) {
4266         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
4267       }
4268     }
4269     *r = snes->vec_func;
4270   }
4271   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4272   ierr = DMSNESGetFunction(dm,f,ctx);CHKERRQ(ierr);
4273   PetscFunctionReturn(0);
4274 }
4275 
4276 /*@C
4277    SNESGetNGS - Returns the NGS function and context.
4278 
4279    Input Parameter:
4280 .  snes - the SNES context
4281 
4282    Output Parameter:
4283 +  f - the function (or NULL) see SNESNGSFunction for details
4284 -  ctx    - the function context (or NULL)
4285 
4286    Level: advanced
4287 
4288 .keywords: SNES, nonlinear, get, function
4289 
4290 .seealso: SNESSetNGS(), SNESGetFunction()
4291 @*/
4292 
4293 #undef __FUNCT__
4294 #define __FUNCT__ "SNESGetNGS"
4295 PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
4296 {
4297   PetscErrorCode ierr;
4298   DM             dm;
4299 
4300   PetscFunctionBegin;
4301   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4302   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4303   ierr = DMSNESGetNGS(dm,f,ctx);CHKERRQ(ierr);
4304   PetscFunctionReturn(0);
4305 }
4306 
4307 #undef __FUNCT__
4308 #define __FUNCT__ "SNESSetOptionsPrefix"
4309 /*@C
4310    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4311    SNES options in the database.
4312 
4313    Logically Collective on SNES
4314 
4315    Input Parameter:
4316 +  snes - the SNES context
4317 -  prefix - the prefix to prepend to all option names
4318 
4319    Notes:
4320    A hyphen (-) must NOT be given at the beginning of the prefix name.
4321    The first character of all runtime options is AUTOMATICALLY the hyphen.
4322 
4323    Level: advanced
4324 
4325 .keywords: SNES, set, options, prefix, database
4326 
4327 .seealso: SNESSetFromOptions()
4328 @*/
4329 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4330 {
4331   PetscErrorCode ierr;
4332 
4333   PetscFunctionBegin;
4334   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4335   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4336   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4337   if (snes->linesearch) {
4338     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4339     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4340   }
4341   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4342   PetscFunctionReturn(0);
4343 }
4344 
4345 #undef __FUNCT__
4346 #define __FUNCT__ "SNESAppendOptionsPrefix"
4347 /*@C
4348    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4349    SNES options in the database.
4350 
4351    Logically Collective on SNES
4352 
4353    Input Parameters:
4354 +  snes - the SNES context
4355 -  prefix - the prefix to prepend to all option names
4356 
4357    Notes:
4358    A hyphen (-) must NOT be given at the beginning of the prefix name.
4359    The first character of all runtime options is AUTOMATICALLY the hyphen.
4360 
4361    Level: advanced
4362 
4363 .keywords: SNES, append, options, prefix, database
4364 
4365 .seealso: SNESGetOptionsPrefix()
4366 @*/
4367 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4368 {
4369   PetscErrorCode ierr;
4370 
4371   PetscFunctionBegin;
4372   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4373   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4374   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4375   if (snes->linesearch) {
4376     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4377     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4378   }
4379   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4380   PetscFunctionReturn(0);
4381 }
4382 
4383 #undef __FUNCT__
4384 #define __FUNCT__ "SNESGetOptionsPrefix"
4385 /*@C
4386    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4387    SNES options in the database.
4388 
4389    Not Collective
4390 
4391    Input Parameter:
4392 .  snes - the SNES context
4393 
4394    Output Parameter:
4395 .  prefix - pointer to the prefix string used
4396 
4397    Notes: On the fortran side, the user should pass in a string 'prefix' of
4398    sufficient length to hold the prefix.
4399 
4400    Level: advanced
4401 
4402 .keywords: SNES, get, options, prefix, database
4403 
4404 .seealso: SNESAppendOptionsPrefix()
4405 @*/
4406 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4407 {
4408   PetscErrorCode ierr;
4409 
4410   PetscFunctionBegin;
4411   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4412   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4413   PetscFunctionReturn(0);
4414 }
4415 
4416 
4417 #undef __FUNCT__
4418 #define __FUNCT__ "SNESRegister"
4419 /*@C
4420   SNESRegister - Adds a method to the nonlinear solver package.
4421 
4422    Not collective
4423 
4424    Input Parameters:
4425 +  name_solver - name of a new user-defined solver
4426 -  routine_create - routine to create method context
4427 
4428    Notes:
4429    SNESRegister() may be called multiple times to add several user-defined solvers.
4430 
4431    Sample usage:
4432 .vb
4433    SNESRegister("my_solver",MySolverCreate);
4434 .ve
4435 
4436    Then, your solver can be chosen with the procedural interface via
4437 $     SNESSetType(snes,"my_solver")
4438    or at runtime via the option
4439 $     -snes_type my_solver
4440 
4441    Level: advanced
4442 
4443     Note: If your function is not being put into a shared library then use SNESRegister() instead
4444 
4445 .keywords: SNES, nonlinear, register
4446 
4447 .seealso: SNESRegisterAll(), SNESRegisterDestroy()
4448 
4449   Level: advanced
4450 @*/
4451 PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
4452 {
4453   PetscErrorCode ierr;
4454 
4455   PetscFunctionBegin;
4456   ierr = PetscFunctionListAdd(&SNESList,sname,function);CHKERRQ(ierr);
4457   PetscFunctionReturn(0);
4458 }
4459 
4460 #undef __FUNCT__
4461 #define __FUNCT__ "SNESTestLocalMin"
4462 PetscErrorCode  SNESTestLocalMin(SNES snes)
4463 {
4464   PetscErrorCode ierr;
4465   PetscInt       N,i,j;
4466   Vec            u,uh,fh;
4467   PetscScalar    value;
4468   PetscReal      norm;
4469 
4470   PetscFunctionBegin;
4471   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4472   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4473   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4474 
4475   /* currently only works for sequential */
4476   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");CHKERRQ(ierr);
4477   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4478   for (i=0; i<N; i++) {
4479     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4480     ierr = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4481     for (j=-10; j<11; j++) {
4482       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
4483       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4484       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4485       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4486       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4487       value = -value;
4488       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4489     }
4490   }
4491   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4492   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4493   PetscFunctionReturn(0);
4494 }
4495 
4496 #undef __FUNCT__
4497 #define __FUNCT__ "SNESKSPSetUseEW"
4498 /*@
4499    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4500    computing relative tolerance for linear solvers within an inexact
4501    Newton method.
4502 
4503    Logically Collective on SNES
4504 
4505    Input Parameters:
4506 +  snes - SNES context
4507 -  flag - PETSC_TRUE or PETSC_FALSE
4508 
4509     Options Database:
4510 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4511 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4512 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4513 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4514 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4515 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4516 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4517 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4518 
4519    Notes:
4520    Currently, the default is to use a constant relative tolerance for
4521    the inner linear solvers.  Alternatively, one can use the
4522    Eisenstat-Walker method, where the relative convergence tolerance
4523    is reset at each Newton iteration according progress of the nonlinear
4524    solver.
4525 
4526    Level: advanced
4527 
4528    Reference:
4529    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4530    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4531 
4532 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4533 
4534 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4535 @*/
4536 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
4537 {
4538   PetscFunctionBegin;
4539   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4540   PetscValidLogicalCollectiveBool(snes,flag,2);
4541   snes->ksp_ewconv = flag;
4542   PetscFunctionReturn(0);
4543 }
4544 
4545 #undef __FUNCT__
4546 #define __FUNCT__ "SNESKSPGetUseEW"
4547 /*@
4548    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4549    for computing relative tolerance for linear solvers within an
4550    inexact Newton method.
4551 
4552    Not Collective
4553 
4554    Input Parameter:
4555 .  snes - SNES context
4556 
4557    Output Parameter:
4558 .  flag - PETSC_TRUE or PETSC_FALSE
4559 
4560    Notes:
4561    Currently, the default is to use a constant relative tolerance for
4562    the inner linear solvers.  Alternatively, one can use the
4563    Eisenstat-Walker method, where the relative convergence tolerance
4564    is reset at each Newton iteration according progress of the nonlinear
4565    solver.
4566 
4567    Level: advanced
4568 
4569    Reference:
4570    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4571    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4572 
4573 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4574 
4575 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4576 @*/
4577 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4578 {
4579   PetscFunctionBegin;
4580   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4581   PetscValidPointer(flag,2);
4582   *flag = snes->ksp_ewconv;
4583   PetscFunctionReturn(0);
4584 }
4585 
4586 #undef __FUNCT__
4587 #define __FUNCT__ "SNESKSPSetParametersEW"
4588 /*@
4589    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4590    convergence criteria for the linear solvers within an inexact
4591    Newton method.
4592 
4593    Logically Collective on SNES
4594 
4595    Input Parameters:
4596 +    snes - SNES context
4597 .    version - version 1, 2 (default is 2) or 3
4598 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4599 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4600 .    gamma - multiplicative factor for version 2 rtol computation
4601              (0 <= gamma2 <= 1)
4602 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4603 .    alpha2 - power for safeguard
4604 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4605 
4606    Note:
4607    Version 3 was contributed by Luis Chacon, June 2006.
4608 
4609    Use PETSC_DEFAULT to retain the default for any of the parameters.
4610 
4611    Level: advanced
4612 
4613    Reference:
4614    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4615    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4616    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4617 
4618 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4619 
4620 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4621 @*/
4622 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4623 {
4624   SNESKSPEW *kctx;
4625 
4626   PetscFunctionBegin;
4627   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4628   kctx = (SNESKSPEW*)snes->kspconvctx;
4629   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4630   PetscValidLogicalCollectiveInt(snes,version,2);
4631   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4632   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4633   PetscValidLogicalCollectiveReal(snes,gamma,5);
4634   PetscValidLogicalCollectiveReal(snes,alpha,6);
4635   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4636   PetscValidLogicalCollectiveReal(snes,threshold,8);
4637 
4638   if (version != PETSC_DEFAULT)   kctx->version   = version;
4639   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4640   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4641   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4642   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4643   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4644   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4645 
4646   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);
4647   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);
4648   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);
4649   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);
4650   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);
4651   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);
4652   PetscFunctionReturn(0);
4653 }
4654 
4655 #undef __FUNCT__
4656 #define __FUNCT__ "SNESKSPGetParametersEW"
4657 /*@
4658    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4659    convergence criteria for the linear solvers within an inexact
4660    Newton method.
4661 
4662    Not Collective
4663 
4664    Input Parameters:
4665      snes - SNES context
4666 
4667    Output Parameters:
4668 +    version - version 1, 2 (default is 2) or 3
4669 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4670 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4671 .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
4672 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4673 .    alpha2 - power for safeguard
4674 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4675 
4676    Level: advanced
4677 
4678 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4679 
4680 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4681 @*/
4682 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4683 {
4684   SNESKSPEW *kctx;
4685 
4686   PetscFunctionBegin;
4687   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4688   kctx = (SNESKSPEW*)snes->kspconvctx;
4689   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4690   if (version)   *version   = kctx->version;
4691   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4692   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4693   if (gamma)     *gamma     = kctx->gamma;
4694   if (alpha)     *alpha     = kctx->alpha;
4695   if (alpha2)    *alpha2    = kctx->alpha2;
4696   if (threshold) *threshold = kctx->threshold;
4697   PetscFunctionReturn(0);
4698 }
4699 
4700 #undef __FUNCT__
4701 #define __FUNCT__ "KSPPreSolve_SNESEW"
4702  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4703 {
4704   PetscErrorCode ierr;
4705   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4706   PetscReal      rtol  = PETSC_DEFAULT,stol;
4707 
4708   PetscFunctionBegin;
4709   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4710   if (!snes->iter) {
4711     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
4712     ierr = VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);CHKERRQ(ierr);
4713   }
4714   else {
4715     if (kctx->version == 1) {
4716       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4717       if (rtol < 0.0) rtol = -rtol;
4718       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
4719       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4720     } else if (kctx->version == 2) {
4721       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4722       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
4723       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4724     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
4725       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4726       /* safeguard: avoid sharp decrease of rtol */
4727       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
4728       stol = PetscMax(rtol,stol);
4729       rtol = PetscMin(kctx->rtol_0,stol);
4730       /* safeguard: avoid oversolving */
4731       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
4732       stol = PetscMax(rtol,stol);
4733       rtol = PetscMin(kctx->rtol_0,stol);
4734     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4735   }
4736   /* safeguard: avoid rtol greater than one */
4737   rtol = PetscMin(rtol,kctx->rtol_max);
4738   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4739   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);CHKERRQ(ierr);
4740   PetscFunctionReturn(0);
4741 }
4742 
4743 #undef __FUNCT__
4744 #define __FUNCT__ "KSPPostSolve_SNESEW"
4745 PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4746 {
4747   PetscErrorCode ierr;
4748   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4749   PCSide         pcside;
4750   Vec            lres;
4751 
4752   PetscFunctionBegin;
4753   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4754   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4755   kctx->norm_last = snes->norm;
4756   if (kctx->version == 1) {
4757     PC        pc;
4758     PetscBool isNone;
4759 
4760     ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
4761     ierr = PetscObjectTypeCompare((PetscObject) pc, PCNONE, &isNone);CHKERRQ(ierr);
4762     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4763      if (pcside == PC_RIGHT || isNone) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4764       /* KSP residual is true linear residual */
4765       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4766     } else {
4767       /* KSP residual is preconditioned residual */
4768       /* compute true linear residual norm */
4769       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4770       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4771       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4772       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4773       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4774     }
4775   }
4776   PetscFunctionReturn(0);
4777 }
4778 
4779 #undef __FUNCT__
4780 #define __FUNCT__ "SNESGetKSP"
4781 /*@
4782    SNESGetKSP - Returns the KSP context for a SNES solver.
4783 
4784    Not Collective, but if SNES object is parallel, then KSP object is parallel
4785 
4786    Input Parameter:
4787 .  snes - the SNES context
4788 
4789    Output Parameter:
4790 .  ksp - the KSP context
4791 
4792    Notes:
4793    The user can then directly manipulate the KSP context to set various
4794    options, etc.  Likewise, the user can then extract and manipulate the
4795    PC contexts as well.
4796 
4797    Level: beginner
4798 
4799 .keywords: SNES, nonlinear, get, KSP, context
4800 
4801 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
4802 @*/
4803 PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
4804 {
4805   PetscErrorCode ierr;
4806 
4807   PetscFunctionBegin;
4808   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4809   PetscValidPointer(ksp,2);
4810 
4811   if (!snes->ksp) {
4812     PetscBool monitor = PETSC_FALSE;
4813 
4814     ierr = KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);CHKERRQ(ierr);
4815     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);CHKERRQ(ierr);
4816     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);CHKERRQ(ierr);
4817 
4818     ierr = KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);CHKERRQ(ierr);
4819     ierr = KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);CHKERRQ(ierr);
4820 
4821     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes",&monitor,NULL);CHKERRQ(ierr);
4822     if (monitor) {
4823       ierr = KSPMonitorSet(snes->ksp,KSPMonitorSNES,snes,NULL);CHKERRQ(ierr);
4824     }
4825     monitor = PETSC_FALSE;
4826     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes_lg",&monitor,NULL);CHKERRQ(ierr);
4827     if (monitor) {
4828       PetscObject *objs;
4829       ierr = KSPMonitorSNESLGResidualNormCreate(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,600,600,&objs);CHKERRQ(ierr);
4830       objs[0] = (PetscObject) snes;
4831       ierr = KSPMonitorSet(snes->ksp,(PetscErrorCode (*)(KSP,PetscInt,PetscReal,void*))KSPMonitorSNESLGResidualNorm,objs,(PetscErrorCode (*)(void**))KSPMonitorSNESLGResidualNormDestroy);CHKERRQ(ierr);
4832     }
4833   }
4834   *ksp = snes->ksp;
4835   PetscFunctionReturn(0);
4836 }
4837 
4838 
4839 #include <petsc/private/dmimpl.h>
4840 #undef __FUNCT__
4841 #define __FUNCT__ "SNESSetDM"
4842 /*@
4843    SNESSetDM - Sets the DM that may be used by some preconditioners
4844 
4845    Logically Collective on SNES
4846 
4847    Input Parameters:
4848 +  snes - the preconditioner context
4849 -  dm - the dm
4850 
4851    Level: intermediate
4852 
4853 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4854 @*/
4855 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4856 {
4857   PetscErrorCode ierr;
4858   KSP            ksp;
4859   DMSNES         sdm;
4860 
4861   PetscFunctionBegin;
4862   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4863   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4864   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4865     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4866       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4867       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4868       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
4869     }
4870     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4871   }
4872   snes->dm     = dm;
4873   snes->dmAuto = PETSC_FALSE;
4874 
4875   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4876   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4877   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4878   if (snes->pc) {
4879     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4880     ierr = SNESSetNPCSide(snes,snes->pcside);CHKERRQ(ierr);
4881   }
4882   PetscFunctionReturn(0);
4883 }
4884 
4885 #undef __FUNCT__
4886 #define __FUNCT__ "SNESGetDM"
4887 /*@
4888    SNESGetDM - Gets the DM that may be used by some preconditioners
4889 
4890    Not Collective but DM obtained is parallel on SNES
4891 
4892    Input Parameter:
4893 . snes - the preconditioner context
4894 
4895    Output Parameter:
4896 .  dm - the dm
4897 
4898    Level: intermediate
4899 
4900 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4901 @*/
4902 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4903 {
4904   PetscErrorCode ierr;
4905 
4906   PetscFunctionBegin;
4907   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4908   if (!snes->dm) {
4909     ierr         = DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);CHKERRQ(ierr);
4910     snes->dmAuto = PETSC_TRUE;
4911   }
4912   *dm = snes->dm;
4913   PetscFunctionReturn(0);
4914 }
4915 
4916 #undef __FUNCT__
4917 #define __FUNCT__ "SNESSetNPC"
4918 /*@
4919   SNESSetNPC - Sets the nonlinear preconditioner to be used.
4920 
4921   Collective on SNES
4922 
4923   Input Parameters:
4924 + snes - iterative context obtained from SNESCreate()
4925 - pc   - the preconditioner object
4926 
4927   Notes:
4928   Use SNESGetNPC() to retrieve the preconditioner context (for example,
4929   to configure it using the API).
4930 
4931   Level: developer
4932 
4933 .keywords: SNES, set, precondition
4934 .seealso: SNESGetNPC(), SNESHasNPC()
4935 @*/
4936 PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
4937 {
4938   PetscErrorCode ierr;
4939 
4940   PetscFunctionBegin;
4941   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4942   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4943   PetscCheckSameComm(snes, 1, pc, 2);
4944   ierr     = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4945   ierr     = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4946   snes->pc = pc;
4947   ierr     = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->pc);CHKERRQ(ierr);
4948   PetscFunctionReturn(0);
4949 }
4950 
4951 #undef __FUNCT__
4952 #define __FUNCT__ "SNESGetNPC"
4953 /*@
4954   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.
4955 
4956   Not Collective
4957 
4958   Input Parameter:
4959 . snes - iterative context obtained from SNESCreate()
4960 
4961   Output Parameter:
4962 . pc - preconditioner context
4963 
4964   Notes: If a SNES was previously set with SNESSetNPC() then that SNES is returned.
4965 
4966   Level: developer
4967 
4968 .keywords: SNES, get, preconditioner
4969 .seealso: SNESSetNPC(), SNESHasNPC()
4970 @*/
4971 PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
4972 {
4973   PetscErrorCode ierr;
4974   const char     *optionsprefix;
4975 
4976   PetscFunctionBegin;
4977   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4978   PetscValidPointer(pc, 2);
4979   if (!snes->pc) {
4980     ierr = SNESCreate(PetscObjectComm((PetscObject)snes),&snes->pc);CHKERRQ(ierr);
4981     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4982     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
4983     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4984     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4985     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4986     ierr = SNESSetCountersReset(snes->pc,PETSC_FALSE);CHKERRQ(ierr);
4987   }
4988   *pc = snes->pc;
4989   PetscFunctionReturn(0);
4990 }
4991 
4992 #undef __FUNCT__
4993 #define __FUNCT__ "SNESHasNPC"
4994 /*@
4995   SNESHasNPC - Returns whether a nonlinear preconditioner exists
4996 
4997   Not Collective
4998 
4999   Input Parameter:
5000 . snes - iterative context obtained from SNESCreate()
5001 
5002   Output Parameter:
5003 . has_npc - whether the SNES has an NPC or not
5004 
5005   Level: developer
5006 
5007 .keywords: SNES, has, preconditioner
5008 .seealso: SNESSetNPC(), SNESGetNPC()
5009 @*/
5010 PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
5011 {
5012   PetscFunctionBegin;
5013   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
5014   *has_npc = (PetscBool) (snes->pc ? PETSC_TRUE : PETSC_FALSE);
5015   PetscFunctionReturn(0);
5016 }
5017 
5018 #undef __FUNCT__
5019 #define __FUNCT__ "SNESSetNPCSide"
5020 /*@
5021     SNESSetNPCSide - Sets the preconditioning side.
5022 
5023     Logically Collective on SNES
5024 
5025     Input Parameter:
5026 .   snes - iterative context obtained from SNESCreate()
5027 
5028     Output Parameter:
5029 .   side - the preconditioning side, where side is one of
5030 .vb
5031       PC_LEFT - left preconditioning (default)
5032       PC_RIGHT - right preconditioning
5033 .ve
5034 
5035     Options Database Keys:
5036 .   -snes_pc_side <right,left>
5037 
5038     Level: intermediate
5039 
5040 .keywords: SNES, set, right, left, side, preconditioner, flag
5041 
5042 .seealso: SNESGetNPCSide(), KSPSetPCSide()
5043 @*/
5044 PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
5045 {
5046   PetscFunctionBegin;
5047   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5048   PetscValidLogicalCollectiveEnum(snes,side,2);
5049   snes->pcside = side;
5050   PetscFunctionReturn(0);
5051 }
5052 
5053 #undef __FUNCT__
5054 #define __FUNCT__ "SNESGetNPCSide"
5055 /*@
5056     SNESGetNPCSide - Gets the preconditioning side.
5057 
5058     Not Collective
5059 
5060     Input Parameter:
5061 .   snes - iterative context obtained from SNESCreate()
5062 
5063     Output Parameter:
5064 .   side - the preconditioning side, where side is one of
5065 .vb
5066       PC_LEFT - left preconditioning (default)
5067       PC_RIGHT - right preconditioning
5068 .ve
5069 
5070     Level: intermediate
5071 
5072 .keywords: SNES, get, right, left, side, preconditioner, flag
5073 
5074 .seealso: SNESSetNPCSide(), KSPGetPCSide()
5075 @*/
5076 PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
5077 {
5078   PetscFunctionBegin;
5079   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5080   PetscValidPointer(side,2);
5081   *side = snes->pcside;
5082   PetscFunctionReturn(0);
5083 }
5084 
5085 #undef __FUNCT__
5086 #define __FUNCT__ "SNESSetLineSearch"
5087 /*@
5088   SNESSetLineSearch - Sets the linesearch on the SNES instance.
5089 
5090   Collective on SNES
5091 
5092   Input Parameters:
5093 + snes - iterative context obtained from SNESCreate()
5094 - linesearch   - the linesearch object
5095 
5096   Notes:
5097   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
5098   to configure it using the API).
5099 
5100   Level: developer
5101 
5102 .keywords: SNES, set, linesearch
5103 .seealso: SNESGetLineSearch()
5104 @*/
5105 PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
5106 {
5107   PetscErrorCode ierr;
5108 
5109   PetscFunctionBegin;
5110   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
5111   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
5112   PetscCheckSameComm(snes, 1, linesearch, 2);
5113   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
5114   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
5115 
5116   snes->linesearch = linesearch;
5117 
5118   ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
5119   PetscFunctionReturn(0);
5120 }
5121 
5122 #undef __FUNCT__
5123 #define __FUNCT__ "SNESGetLineSearch"
5124 /*@
5125   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
5126   or creates a default line search instance associated with the SNES and returns it.
5127 
5128   Not Collective
5129 
5130   Input Parameter:
5131 . snes - iterative context obtained from SNESCreate()
5132 
5133   Output Parameter:
5134 . linesearch - linesearch context
5135 
5136   Level: beginner
5137 
5138 .keywords: SNES, get, linesearch
5139 .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
5140 @*/
5141 PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
5142 {
5143   PetscErrorCode ierr;
5144   const char     *optionsprefix;
5145 
5146   PetscFunctionBegin;
5147   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
5148   PetscValidPointer(linesearch, 2);
5149   if (!snes->linesearch) {
5150     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
5151     ierr = SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);CHKERRQ(ierr);
5152     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
5153     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
5154     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
5155     ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
5156   }
5157   *linesearch = snes->linesearch;
5158   PetscFunctionReturn(0);
5159 }
5160 
5161 #if defined(PETSC_HAVE_MATLAB_ENGINE)
5162 #include <mex.h>
5163 
5164 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
5165 
5166 #undef __FUNCT__
5167 #define __FUNCT__ "SNESComputeFunction_Matlab"
5168 /*
5169    SNESComputeFunction_Matlab - Calls the function that has been set with SNESSetFunctionMatlab().
5170 
5171    Collective on SNES
5172 
5173    Input Parameters:
5174 +  snes - the SNES context
5175 -  x - input vector
5176 
5177    Output Parameter:
5178 .  y - function vector, as set by SNESSetFunction()
5179 
5180    Notes:
5181    SNESComputeFunction() is typically used within nonlinear solvers
5182    implementations, so most users would not generally call this routine
5183    themselves.
5184 
5185    Level: developer
5186 
5187 .keywords: SNES, nonlinear, compute, function
5188 
5189 .seealso: SNESSetFunction(), SNESGetFunction()
5190 */
5191 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
5192 {
5193   PetscErrorCode    ierr;
5194   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5195   int               nlhs  = 1,nrhs = 5;
5196   mxArray           *plhs[1],*prhs[5];
5197   long long int     lx = 0,ly = 0,ls = 0;
5198 
5199   PetscFunctionBegin;
5200   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5201   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
5202   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
5203   PetscCheckSameComm(snes,1,x,2);
5204   PetscCheckSameComm(snes,1,y,3);
5205 
5206   /* call Matlab function in ctx with arguments x and y */
5207 
5208   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5209   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5210   ierr    = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
5211   prhs[0] = mxCreateDoubleScalar((double)ls);
5212   prhs[1] = mxCreateDoubleScalar((double)lx);
5213   prhs[2] = mxCreateDoubleScalar((double)ly);
5214   prhs[3] = mxCreateString(sctx->funcname);
5215   prhs[4] = sctx->ctx;
5216   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
5217   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5218   mxDestroyArray(prhs[0]);
5219   mxDestroyArray(prhs[1]);
5220   mxDestroyArray(prhs[2]);
5221   mxDestroyArray(prhs[3]);
5222   mxDestroyArray(plhs[0]);
5223   PetscFunctionReturn(0);
5224 }
5225 
5226 #undef __FUNCT__
5227 #define __FUNCT__ "SNESSetFunctionMatlab"
5228 /*
5229    SNESSetFunctionMatlab - Sets the function evaluation routine and function
5230    vector for use by the SNES routines in solving systems of nonlinear
5231    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5232 
5233    Logically Collective on SNES
5234 
5235    Input Parameters:
5236 +  snes - the SNES context
5237 .  r - vector to store function value
5238 -  f - function evaluation routine
5239 
5240    Notes:
5241    The Newton-like methods typically solve linear systems of the form
5242 $      f'(x) x = -f(x),
5243    where f'(x) denotes the Jacobian matrix and f(x) is the function.
5244 
5245    Level: beginner
5246 
5247    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5248 
5249 .keywords: SNES, nonlinear, set, function
5250 
5251 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5252 */
5253 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *f,mxArray *ctx)
5254 {
5255   PetscErrorCode    ierr;
5256   SNESMatlabContext *sctx;
5257 
5258   PetscFunctionBegin;
5259   /* currently sctx is memory bleed */
5260   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5261   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5262   /*
5263      This should work, but it doesn't
5264   sctx->ctx = ctx;
5265   mexMakeArrayPersistent(sctx->ctx);
5266   */
5267   sctx->ctx = mxDuplicateArray(ctx);
5268   ierr      = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
5269   PetscFunctionReturn(0);
5270 }
5271 
5272 #undef __FUNCT__
5273 #define __FUNCT__ "SNESComputeJacobian_Matlab"
5274 /*
5275    SNESComputeJacobian_Matlab - Calls the function that has been set with SNESSetJacobianMatlab().
5276 
5277    Collective on SNES
5278 
5279    Input Parameters:
5280 +  snes - the SNES context
5281 .  x - input vector
5282 .  A, B - the matrices
5283 -  ctx - user context
5284 
5285    Level: developer
5286 
5287 .keywords: SNES, nonlinear, compute, function
5288 
5289 .seealso: SNESSetFunction(), SNESGetFunction()
5290 @*/
5291 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat A,Mat B,void *ctx)
5292 {
5293   PetscErrorCode    ierr;
5294   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5295   int               nlhs  = 2,nrhs = 6;
5296   mxArray           *plhs[2],*prhs[6];
5297   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
5298 
5299   PetscFunctionBegin;
5300   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5301   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
5302 
5303   /* call Matlab function in ctx with arguments x and y */
5304 
5305   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5306   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5307   ierr    = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
5308   ierr    = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
5309   prhs[0] = mxCreateDoubleScalar((double)ls);
5310   prhs[1] = mxCreateDoubleScalar((double)lx);
5311   prhs[2] = mxCreateDoubleScalar((double)lA);
5312   prhs[3] = mxCreateDoubleScalar((double)lB);
5313   prhs[4] = mxCreateString(sctx->funcname);
5314   prhs[5] = sctx->ctx;
5315   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
5316   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5317   mxDestroyArray(prhs[0]);
5318   mxDestroyArray(prhs[1]);
5319   mxDestroyArray(prhs[2]);
5320   mxDestroyArray(prhs[3]);
5321   mxDestroyArray(prhs[4]);
5322   mxDestroyArray(plhs[0]);
5323   mxDestroyArray(plhs[1]);
5324   PetscFunctionReturn(0);
5325 }
5326 
5327 #undef __FUNCT__
5328 #define __FUNCT__ "SNESSetJacobianMatlab"
5329 /*
5330    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
5331    vector for use by the SNES routines in solving systems of nonlinear
5332    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5333 
5334    Logically Collective on SNES
5335 
5336    Input Parameters:
5337 +  snes - the SNES context
5338 .  A,B - Jacobian matrices
5339 .  J - function evaluation routine
5340 -  ctx - user context
5341 
5342    Level: developer
5343 
5344    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5345 
5346 .keywords: SNES, nonlinear, set, function
5347 
5348 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction(), J
5349 */
5350 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *J,mxArray *ctx)
5351 {
5352   PetscErrorCode    ierr;
5353   SNESMatlabContext *sctx;
5354 
5355   PetscFunctionBegin;
5356   /* currently sctx is memory bleed */
5357   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5358   ierr = PetscStrallocpy(J,&sctx->funcname);CHKERRQ(ierr);
5359   /*
5360      This should work, but it doesn't
5361   sctx->ctx = ctx;
5362   mexMakeArrayPersistent(sctx->ctx);
5363   */
5364   sctx->ctx = mxDuplicateArray(ctx);
5365   ierr      = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
5366   PetscFunctionReturn(0);
5367 }
5368 
5369 #undef __FUNCT__
5370 #define __FUNCT__ "SNESMonitor_Matlab"
5371 /*
5372    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
5373 
5374    Collective on SNES
5375 
5376 .seealso: SNESSetFunction(), SNESGetFunction()
5377 @*/
5378 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
5379 {
5380   PetscErrorCode    ierr;
5381   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5382   int               nlhs  = 1,nrhs = 6;
5383   mxArray           *plhs[1],*prhs[6];
5384   long long int     lx = 0,ls = 0;
5385   Vec               x  = snes->vec_sol;
5386 
5387   PetscFunctionBegin;
5388   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5389 
5390   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5391   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5392   prhs[0] = mxCreateDoubleScalar((double)ls);
5393   prhs[1] = mxCreateDoubleScalar((double)it);
5394   prhs[2] = mxCreateDoubleScalar((double)fnorm);
5395   prhs[3] = mxCreateDoubleScalar((double)lx);
5396   prhs[4] = mxCreateString(sctx->funcname);
5397   prhs[5] = sctx->ctx;
5398   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
5399   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5400   mxDestroyArray(prhs[0]);
5401   mxDestroyArray(prhs[1]);
5402   mxDestroyArray(prhs[2]);
5403   mxDestroyArray(prhs[3]);
5404   mxDestroyArray(prhs[4]);
5405   mxDestroyArray(plhs[0]);
5406   PetscFunctionReturn(0);
5407 }
5408 
5409 #undef __FUNCT__
5410 #define __FUNCT__ "SNESMonitorSetMatlab"
5411 /*
5412    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
5413 
5414    Level: developer
5415 
5416    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5417 
5418 .keywords: SNES, nonlinear, set, function
5419 
5420 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5421 */
5422 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *f,mxArray *ctx)
5423 {
5424   PetscErrorCode    ierr;
5425   SNESMatlabContext *sctx;
5426 
5427   PetscFunctionBegin;
5428   /* currently sctx is memory bleed */
5429   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5430   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5431   /*
5432      This should work, but it doesn't
5433   sctx->ctx = ctx;
5434   mexMakeArrayPersistent(sctx->ctx);
5435   */
5436   sctx->ctx = mxDuplicateArray(ctx);
5437   ierr      = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,NULL);CHKERRQ(ierr);
5438   PetscFunctionReturn(0);
5439 }
5440 
5441 #endif
5442