xref: /petsc/src/snes/interface/snes.c (revision c094ef4021e955ef5f85f7d8a1bbc6ed64ba7621)
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 = PetscViewerSetFormat(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 = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit",&flag,NULL);CHKERRQ(ierr);
2331     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",&flag_draw,NULL);CHKERRQ(ierr);
2332     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2333     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_operator",&flag_operator,NULL);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 = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring",&flag,NULL);CHKERRQ(ierr);
2382     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_display",&flag_display,NULL);CHKERRQ(ierr);
2383     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",&flag_draw,NULL);CHKERRQ(ierr);
2384     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2385     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",&flag_threshold,NULL);CHKERRQ(ierr);
2386     ierr = PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);CHKERRQ(ierr);
2387     ierr = PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);CHKERRQ(ierr);
2388     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2389       Mat            Bfd;
2390       PetscViewer    vdraw,vstdout;
2391       MatColoring    coloring;
2392       ISColoring     iscoloring;
2393       MatFDColoring  matfdcoloring;
2394       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2395       void           *funcctx;
2396       PetscReal      norm1,norm2,normmax;
2397 
2398       ierr = MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);CHKERRQ(ierr);
2399       ierr = MatColoringCreate(Bfd,&coloring);CHKERRQ(ierr);
2400       ierr = MatColoringSetType(coloring,MATCOLORINGSL);CHKERRQ(ierr);
2401       ierr = MatColoringSetFromOptions(coloring);CHKERRQ(ierr);
2402       ierr = MatColoringApply(coloring,&iscoloring);CHKERRQ(ierr);
2403       ierr = MatColoringDestroy(&coloring);CHKERRQ(ierr);
2404       ierr = MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);CHKERRQ(ierr);
2405       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2406       ierr = MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);CHKERRQ(ierr);
2407       ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr);
2408 
2409       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2410       ierr = SNESGetFunction(snes,NULL,&func,&funcctx);CHKERRQ(ierr);
2411       ierr = MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);CHKERRQ(ierr);
2412       ierr = PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);CHKERRQ(ierr);
2413       ierr = PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");CHKERRQ(ierr);
2414       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2415       ierr = MatFDColoringApply(Bfd,matfdcoloring,X,snes);CHKERRQ(ierr);
2416       ierr = MatFDColoringDestroy(&matfdcoloring);CHKERRQ(ierr);
2417 
2418       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2419       if (flag_draw || flag_contour) {
2420         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2421         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2422       } else vdraw = NULL;
2423       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");CHKERRQ(ierr);
2424       if (flag_display) {ierr = MatView(B,vstdout);CHKERRQ(ierr);}
2425       if (vdraw) {ierr = MatView(B,vdraw);CHKERRQ(ierr);}
2426       ierr = PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");CHKERRQ(ierr);
2427       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2428       if (vdraw) {ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);}
2429       ierr = MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2430       ierr = MatNorm(Bfd,NORM_1,&norm1);CHKERRQ(ierr);
2431       ierr = MatNorm(Bfd,NORM_FROBENIUS,&norm2);CHKERRQ(ierr);
2432       ierr = MatNorm(Bfd,NORM_MAX,&normmax);CHKERRQ(ierr);
2433       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);
2434       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2435       if (vdraw) {              /* Always use contour for the difference */
2436         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2437         ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);
2438         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2439       }
2440       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2441 
2442       if (flag_threshold) {
2443         PetscInt bs,rstart,rend,i;
2444         ierr = MatGetBlockSize(B,&bs);CHKERRQ(ierr);
2445         ierr = MatGetOwnershipRange(B,&rstart,&rend);CHKERRQ(ierr);
2446         for (i=rstart; i<rend; i++) {
2447           const PetscScalar *ba,*ca;
2448           const PetscInt    *bj,*cj;
2449           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2450           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2451           ierr = MatGetRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2452           ierr = MatGetRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2453           if (bn != cn) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2454           for (j=0; j<bn; j++) {
2455             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2456             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2457               maxentrycol = bj[j];
2458               maxentry    = PetscRealPart(ba[j]);
2459             }
2460             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2461               maxdiffcol = bj[j];
2462               maxdiff    = PetscRealPart(ca[j]);
2463             }
2464             if (rdiff > maxrdiff) {
2465               maxrdiffcol = bj[j];
2466               maxrdiff    = rdiff;
2467             }
2468           }
2469           if (maxrdiff > 1) {
2470             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);
2471             for (j=0; j<bn; j++) {
2472               PetscReal rdiff;
2473               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2474               if (rdiff > 1) {
2475                 ierr = PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));CHKERRQ(ierr);
2476               }
2477             }
2478             ierr = PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);CHKERRQ(ierr);
2479           }
2480           ierr = MatRestoreRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2481           ierr = MatRestoreRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2482         }
2483       }
2484       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2485       ierr = MatDestroy(&Bfd);CHKERRQ(ierr);
2486     }
2487   }
2488   PetscFunctionReturn(0);
2489 }
2490 
2491 /*MC
2492     SNESJacobianFunction - Function used to convey the nonlinear Jacobian of the function to be solved by SNES
2493 
2494      Synopsis:
2495      #include "petscsnes.h"
2496      PetscErrorCode SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);
2497 
2498 +  x - input vector
2499 .  Amat - the matrix that defines the (approximate) Jacobian
2500 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2501 -  ctx - [optional] user-defined Jacobian context
2502 
2503    Level: intermediate
2504 
2505 .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2506 M*/
2507 
2508 #undef __FUNCT__
2509 #define __FUNCT__ "SNESSetJacobian"
2510 /*@C
2511    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2512    location to store the matrix.
2513 
2514    Logically Collective on SNES and Mat
2515 
2516    Input Parameters:
2517 +  snes - the SNES context
2518 .  Amat - the matrix that defines the (approximate) Jacobian
2519 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2520 .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value), see SNESJacobianFunction for details
2521 -  ctx - [optional] user-defined context for private data for the
2522          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)
2523 
2524    Notes:
2525    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
2526    each matrix.
2527 
2528    If you know the operator Amat has a null space you can use MatSetNullSpace() and MatSetTransposeNullSpace() to supply the null
2529    space to Amat and the KSP solvers will automatically use that null space as needed during the solution process.
2530 
2531    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
2532    must be a MatFDColoring.
2533 
2534    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2535    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.
2536 
2537    Level: beginner
2538 
2539 .keywords: SNES, nonlinear, set, Jacobian, matrix
2540 
2541 .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J,
2542           SNESSetPicard(), SNESJacobianFunction
2543 @*/
2544 PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2545 {
2546   PetscErrorCode ierr;
2547   DM             dm;
2548 
2549   PetscFunctionBegin;
2550   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2551   if (Amat) PetscValidHeaderSpecific(Amat,MAT_CLASSID,2);
2552   if (Pmat) PetscValidHeaderSpecific(Pmat,MAT_CLASSID,3);
2553   if (Amat) PetscCheckSameComm(snes,1,Amat,2);
2554   if (Pmat) PetscCheckSameComm(snes,1,Pmat,3);
2555   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2556   ierr = DMSNESSetJacobian(dm,J,ctx);CHKERRQ(ierr);
2557   if (Amat) {
2558     ierr = PetscObjectReference((PetscObject)Amat);CHKERRQ(ierr);
2559     ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2560 
2561     snes->jacobian = Amat;
2562   }
2563   if (Pmat) {
2564     ierr = PetscObjectReference((PetscObject)Pmat);CHKERRQ(ierr);
2565     ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2566 
2567     snes->jacobian_pre = Pmat;
2568   }
2569   PetscFunctionReturn(0);
2570 }
2571 
2572 #undef __FUNCT__
2573 #define __FUNCT__ "SNESGetJacobian"
2574 /*@C
2575    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2576    provided context for evaluating the Jacobian.
2577 
2578    Not Collective, but Mat object will be parallel if SNES object is
2579 
2580    Input Parameter:
2581 .  snes - the nonlinear solver context
2582 
2583    Output Parameters:
2584 +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
2585 .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
2586 .  J - location to put Jacobian function (or NULL), see SNESJacobianFunction for details on its calling sequence
2587 -  ctx - location to stash Jacobian ctx (or NULL)
2588 
2589    Level: advanced
2590 
2591 .seealso: SNESSetJacobian(), SNESComputeJacobian(), SNESJacobianFunction, SNESGetFunction()
2592 @*/
2593 PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
2594 {
2595   PetscErrorCode ierr;
2596   DM             dm;
2597   DMSNES         sdm;
2598 
2599   PetscFunctionBegin;
2600   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2601   if (Amat) *Amat = snes->jacobian;
2602   if (Pmat) *Pmat = snes->jacobian_pre;
2603   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2604   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2605   if (J) *J = sdm->ops->computejacobian;
2606   if (ctx) *ctx = sdm->jacobianctx;
2607   PetscFunctionReturn(0);
2608 }
2609 
2610 #undef __FUNCT__
2611 #define __FUNCT__ "SNESSetUp"
2612 /*@
2613    SNESSetUp - Sets up the internal data structures for the later use
2614    of a nonlinear solver.
2615 
2616    Collective on SNES
2617 
2618    Input Parameters:
2619 .  snes - the SNES context
2620 
2621    Notes:
2622    For basic use of the SNES solvers the user need not explicitly call
2623    SNESSetUp(), since these actions will automatically occur during
2624    the call to SNESSolve().  However, if one wishes to control this
2625    phase separately, SNESSetUp() should be called after SNESCreate()
2626    and optional routines of the form SNESSetXXX(), but before SNESSolve().
2627 
2628    Level: advanced
2629 
2630 .keywords: SNES, nonlinear, setup
2631 
2632 .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
2633 @*/
2634 PetscErrorCode  SNESSetUp(SNES snes)
2635 {
2636   PetscErrorCode ierr;
2637   DM             dm;
2638   DMSNES         sdm;
2639   SNESLineSearch linesearch, pclinesearch;
2640   void           *lsprectx,*lspostctx;
2641   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
2642   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
2643   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2644   Vec            f,fpc;
2645   void           *funcctx;
2646   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
2647   void           *jacctx,*appctx;
2648   Mat            j,jpre;
2649 
2650   PetscFunctionBegin;
2651   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2652   if (snes->setupcalled) PetscFunctionReturn(0);
2653 
2654   if (!((PetscObject)snes)->type_name) {
2655     ierr = SNESSetType(snes,SNESNEWTONLS);CHKERRQ(ierr);
2656   }
2657 
2658   ierr = SNESGetFunction(snes,&snes->vec_func,NULL,NULL);CHKERRQ(ierr);
2659 
2660   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2661   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2662   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
2663   if (!sdm->ops->computejacobian) {
2664     ierr = DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);CHKERRQ(ierr);
2665   }
2666   if (!snes->vec_func) {
2667     ierr = DMCreateGlobalVector(dm,&snes->vec_func);CHKERRQ(ierr);
2668   }
2669 
2670   if (!snes->ksp) {
2671     ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);
2672   }
2673 
2674   if (!snes->linesearch) {
2675     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
2676   }
2677   ierr = SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);CHKERRQ(ierr);
2678 
2679   if (snes->pc && (snes->pcside == PC_LEFT)) {
2680     snes->mf          = PETSC_TRUE;
2681     snes->mf_operator = PETSC_FALSE;
2682   }
2683 
2684   if (snes->pc) {
2685     /* copy the DM over */
2686     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2687     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
2688 
2689     ierr = SNESGetFunction(snes,&f,&func,&funcctx);CHKERRQ(ierr);
2690     ierr = VecDuplicate(f,&fpc);CHKERRQ(ierr);
2691     ierr = SNESSetFunction(snes->pc,fpc,func,funcctx);CHKERRQ(ierr);
2692     ierr = SNESGetJacobian(snes,&j,&jpre,&jac,&jacctx);CHKERRQ(ierr);
2693     ierr = SNESSetJacobian(snes->pc,j,jpre,jac,jacctx);CHKERRQ(ierr);
2694     ierr = SNESGetApplicationContext(snes,&appctx);CHKERRQ(ierr);
2695     ierr = SNESSetApplicationContext(snes->pc,appctx);CHKERRQ(ierr);
2696     ierr = VecDestroy(&fpc);CHKERRQ(ierr);
2697 
2698     /* copy the function pointers over */
2699     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
2700 
2701     /* default to 1 iteration */
2702     ierr = SNESSetTolerances(snes->pc,0.0,0.0,0.0,1,snes->pc->max_funcs);CHKERRQ(ierr);
2703     if (snes->pcside==PC_RIGHT) {
2704       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
2705     } else {
2706       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_NONE);CHKERRQ(ierr);
2707     }
2708     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
2709 
2710     /* copy the line search context over */
2711     ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2712     ierr = SNESGetLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
2713     ierr = SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);CHKERRQ(ierr);
2714     ierr = SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);CHKERRQ(ierr);
2715     ierr = SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);CHKERRQ(ierr);
2716     ierr = SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);CHKERRQ(ierr);
2717     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);CHKERRQ(ierr);
2718   }
2719   if (snes->mf) {
2720     ierr = SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);CHKERRQ(ierr);
2721   }
2722   if (snes->ops->usercompute && !snes->user) {
2723     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2724   }
2725 
2726   snes->jac_iter = 0;
2727   snes->pre_iter = 0;
2728 
2729   if (snes->ops->setup) {
2730     ierr = (*snes->ops->setup)(snes);CHKERRQ(ierr);
2731   }
2732 
2733   if (snes->pc && (snes->pcside == PC_LEFT)) {
2734     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
2735       ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2736       ierr = SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultNPC);CHKERRQ(ierr);
2737     }
2738   }
2739 
2740   snes->setupcalled = PETSC_TRUE;
2741   PetscFunctionReturn(0);
2742 }
2743 
2744 #undef __FUNCT__
2745 #define __FUNCT__ "SNESReset"
2746 /*@
2747    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats
2748 
2749    Collective on SNES
2750 
2751    Input Parameter:
2752 .  snes - iterative context obtained from SNESCreate()
2753 
2754    Level: intermediate
2755 
2756    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()
2757 
2758 .keywords: SNES, destroy
2759 
2760 .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
2761 @*/
2762 PetscErrorCode  SNESReset(SNES snes)
2763 {
2764   PetscErrorCode ierr;
2765 
2766   PetscFunctionBegin;
2767   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2768   if (snes->ops->userdestroy && snes->user) {
2769     ierr       = (*snes->ops->userdestroy)((void**)&snes->user);CHKERRQ(ierr);
2770     snes->user = NULL;
2771   }
2772   if (snes->pc) {
2773     ierr = SNESReset(snes->pc);CHKERRQ(ierr);
2774   }
2775 
2776   if (snes->ops->reset) {
2777     ierr = (*snes->ops->reset)(snes);CHKERRQ(ierr);
2778   }
2779   if (snes->ksp) {
2780     ierr = KSPReset(snes->ksp);CHKERRQ(ierr);
2781   }
2782 
2783   if (snes->linesearch) {
2784     ierr = SNESLineSearchReset(snes->linesearch);CHKERRQ(ierr);
2785   }
2786 
2787   ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
2788   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
2789   ierr = VecDestroy(&snes->vec_sol_update);CHKERRQ(ierr);
2790   ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
2791   ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2792   ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2793   ierr = VecDestroyVecs(snes->nwork,&snes->work);CHKERRQ(ierr);
2794   ierr = VecDestroyVecs(snes->nvwork,&snes->vwork);CHKERRQ(ierr);
2795 
2796   snes->nwork       = snes->nvwork = 0;
2797   snes->setupcalled = PETSC_FALSE;
2798   PetscFunctionReturn(0);
2799 }
2800 
2801 #undef __FUNCT__
2802 #define __FUNCT__ "SNESDestroy"
2803 /*@
2804    SNESDestroy - Destroys the nonlinear solver context that was created
2805    with SNESCreate().
2806 
2807    Collective on SNES
2808 
2809    Input Parameter:
2810 .  snes - the SNES context
2811 
2812    Level: beginner
2813 
2814 .keywords: SNES, nonlinear, destroy
2815 
2816 .seealso: SNESCreate(), SNESSolve()
2817 @*/
2818 PetscErrorCode  SNESDestroy(SNES *snes)
2819 {
2820   PetscErrorCode ierr;
2821 
2822   PetscFunctionBegin;
2823   if (!*snes) PetscFunctionReturn(0);
2824   PetscValidHeaderSpecific((*snes),SNES_CLASSID,1);
2825   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; PetscFunctionReturn(0);}
2826 
2827   ierr = SNESReset((*snes));CHKERRQ(ierr);
2828   ierr = SNESDestroy(&(*snes)->pc);CHKERRQ(ierr);
2829 
2830   /* if memory was published with SAWs then destroy it */
2831   ierr = PetscObjectSAWsViewOff((PetscObject)*snes);CHKERRQ(ierr);
2832   if ((*snes)->ops->destroy) {ierr = (*((*snes))->ops->destroy)((*snes));CHKERRQ(ierr);}
2833 
2834   ierr = DMDestroy(&(*snes)->dm);CHKERRQ(ierr);
2835   ierr = KSPDestroy(&(*snes)->ksp);CHKERRQ(ierr);
2836   ierr = SNESLineSearchDestroy(&(*snes)->linesearch);CHKERRQ(ierr);
2837 
2838   ierr = PetscFree((*snes)->kspconvctx);CHKERRQ(ierr);
2839   if ((*snes)->ops->convergeddestroy) {
2840     ierr = (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);CHKERRQ(ierr);
2841   }
2842   if ((*snes)->conv_malloc) {
2843     ierr = PetscFree((*snes)->conv_hist);CHKERRQ(ierr);
2844     ierr = PetscFree((*snes)->conv_hist_its);CHKERRQ(ierr);
2845   }
2846   ierr = SNESMonitorCancel((*snes));CHKERRQ(ierr);
2847   ierr = PetscHeaderDestroy(snes);CHKERRQ(ierr);
2848   PetscFunctionReturn(0);
2849 }
2850 
2851 /* ----------- Routines to set solver parameters ---------- */
2852 
2853 #undef __FUNCT__
2854 #define __FUNCT__ "SNESSetLagPreconditioner"
2855 /*@
2856    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.
2857 
2858    Logically Collective on SNES
2859 
2860    Input Parameters:
2861 +  snes - the SNES context
2862 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2863          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2864 
2865    Options Database Keys:
2866 .    -snes_lag_preconditioner <lag>
2867 
2868    Notes:
2869    The default is 1
2870    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2871    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use
2872 
2873    Level: intermediate
2874 
2875 .keywords: SNES, nonlinear, set, convergence, tolerances
2876 
2877 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2878 
2879 @*/
2880 PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
2881 {
2882   PetscFunctionBegin;
2883   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2884   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2885   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2886   PetscValidLogicalCollectiveInt(snes,lag,2);
2887   snes->lagpreconditioner = lag;
2888   PetscFunctionReturn(0);
2889 }
2890 
2891 #undef __FUNCT__
2892 #define __FUNCT__ "SNESSetGridSequence"
2893 /*@
2894    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does
2895 
2896    Logically Collective on SNES
2897 
2898    Input Parameters:
2899 +  snes - the SNES context
2900 -  steps - the number of refinements to do, defaults to 0
2901 
2902    Options Database Keys:
2903 .    -snes_grid_sequence <steps>
2904 
2905    Level: intermediate
2906 
2907    Notes:
2908    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2909 
2910 .keywords: SNES, nonlinear, set, convergence, tolerances
2911 
2912 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetGridSequence()
2913 
2914 @*/
2915 PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
2916 {
2917   PetscFunctionBegin;
2918   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2919   PetscValidLogicalCollectiveInt(snes,steps,2);
2920   snes->gridsequence = steps;
2921   PetscFunctionReturn(0);
2922 }
2923 
2924 #undef __FUNCT__
2925 #define __FUNCT__ "SNESGetGridSequence"
2926 /*@
2927    SNESGetGridSequence - gets the number of steps of grid sequencing that SNES does
2928 
2929    Logically Collective on SNES
2930 
2931    Input Parameter:
2932 .  snes - the SNES context
2933 
2934    Output Parameter:
2935 .  steps - the number of refinements to do, defaults to 0
2936 
2937    Options Database Keys:
2938 .    -snes_grid_sequence <steps>
2939 
2940    Level: intermediate
2941 
2942    Notes:
2943    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2944 
2945 .keywords: SNES, nonlinear, set, convergence, tolerances
2946 
2947 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESSetGridSequence()
2948 
2949 @*/
2950 PetscErrorCode  SNESGetGridSequence(SNES snes,PetscInt *steps)
2951 {
2952   PetscFunctionBegin;
2953   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2954   *steps = snes->gridsequence;
2955   PetscFunctionReturn(0);
2956 }
2957 
2958 #undef __FUNCT__
2959 #define __FUNCT__ "SNESGetLagPreconditioner"
2960 /*@
2961    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt
2962 
2963    Not Collective
2964 
2965    Input Parameter:
2966 .  snes - the SNES context
2967 
2968    Output Parameter:
2969 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2970          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2971 
2972    Options Database Keys:
2973 .    -snes_lag_preconditioner <lag>
2974 
2975    Notes:
2976    The default is 1
2977    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2978 
2979    Level: intermediate
2980 
2981 .keywords: SNES, nonlinear, set, convergence, tolerances
2982 
2983 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()
2984 
2985 @*/
2986 PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
2987 {
2988   PetscFunctionBegin;
2989   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2990   *lag = snes->lagpreconditioner;
2991   PetscFunctionReturn(0);
2992 }
2993 
2994 #undef __FUNCT__
2995 #define __FUNCT__ "SNESSetLagJacobian"
2996 /*@
2997    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
2998      often the preconditioner is rebuilt.
2999 
3000    Logically Collective on SNES
3001 
3002    Input Parameters:
3003 +  snes - the SNES context
3004 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3005          the Jacobian is built etc. -2 means rebuild at next chance but then never again
3006 
3007    Options Database Keys:
3008 .    -snes_lag_jacobian <lag>
3009 
3010    Notes:
3011    The default is 1
3012    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3013    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
3014    at the next Newton step but never again (unless it is reset to another value)
3015 
3016    Level: intermediate
3017 
3018 .keywords: SNES, nonlinear, set, convergence, tolerances
3019 
3020 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()
3021 
3022 @*/
3023 PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
3024 {
3025   PetscFunctionBegin;
3026   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3027   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
3028   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
3029   PetscValidLogicalCollectiveInt(snes,lag,2);
3030   snes->lagjacobian = lag;
3031   PetscFunctionReturn(0);
3032 }
3033 
3034 #undef __FUNCT__
3035 #define __FUNCT__ "SNESGetLagJacobian"
3036 /*@
3037    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt
3038 
3039    Not Collective
3040 
3041    Input Parameter:
3042 .  snes - the SNES context
3043 
3044    Output Parameter:
3045 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3046          the Jacobian is built etc.
3047 
3048    Options Database Keys:
3049 .    -snes_lag_jacobian <lag>
3050 
3051    Notes:
3052    The default is 1
3053    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3054 
3055    Level: intermediate
3056 
3057 .keywords: SNES, nonlinear, set, convergence, tolerances
3058 
3059 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()
3060 
3061 @*/
3062 PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
3063 {
3064   PetscFunctionBegin;
3065   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3066   *lag = snes->lagjacobian;
3067   PetscFunctionReturn(0);
3068 }
3069 
3070 #undef __FUNCT__
3071 #define __FUNCT__ "SNESSetLagJacobianPersists"
3072 /*@
3073    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves
3074 
3075    Logically collective on SNES
3076 
3077    Input Parameter:
3078 +  snes - the SNES context
3079 -   flg - jacobian lagging persists if true
3080 
3081    Options Database Keys:
3082 .    -snes_lag_jacobian_persists <flg>
3083 
3084    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
3085    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
3086    timesteps may present huge efficiency gains.
3087 
3088    Level: developer
3089 
3090 .keywords: SNES, nonlinear, lag
3091 
3092 .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
3093 
3094 @*/
3095 PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
3096 {
3097   PetscFunctionBegin;
3098   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3099   PetscValidLogicalCollectiveBool(snes,flg,2);
3100   snes->lagjac_persist = flg;
3101   PetscFunctionReturn(0);
3102 }
3103 
3104 #undef __FUNCT__
3105 #define __FUNCT__ "SNESSetLagPreconditionerPersists"
3106 /*@
3107    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple solves
3108 
3109    Logically Collective on SNES
3110 
3111    Input Parameter:
3112 +  snes - the SNES context
3113 -   flg - preconditioner lagging persists if true
3114 
3115    Options Database Keys:
3116 .    -snes_lag_jacobian_persists <flg>
3117 
3118    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
3119    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
3120    several timesteps may present huge efficiency gains.
3121 
3122    Level: developer
3123 
3124 .keywords: SNES, nonlinear, lag
3125 
3126 .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
3127 
3128 @*/
3129 PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
3130 {
3131   PetscFunctionBegin;
3132   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3133   PetscValidLogicalCollectiveBool(snes,flg,2);
3134   snes->lagpre_persist = flg;
3135   PetscFunctionReturn(0);
3136 }
3137 
3138 #undef __FUNCT__
3139 #define __FUNCT__ "SNESSetTolerances"
3140 /*@
3141    SNESSetTolerances - Sets various parameters used in convergence tests.
3142 
3143    Logically Collective on SNES
3144 
3145    Input Parameters:
3146 +  snes - the SNES context
3147 .  abstol - absolute convergence tolerance
3148 .  rtol - relative convergence tolerance
3149 .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
3150 .  maxit - maximum number of iterations
3151 -  maxf - maximum number of function evaluations
3152 
3153    Options Database Keys:
3154 +    -snes_atol <abstol> - Sets abstol
3155 .    -snes_rtol <rtol> - Sets rtol
3156 .    -snes_stol <stol> - Sets stol
3157 .    -snes_max_it <maxit> - Sets maxit
3158 -    -snes_max_funcs <maxf> - Sets maxf
3159 
3160    Notes:
3161    The default maximum number of iterations is 50.
3162    The default maximum number of function evaluations is 1000.
3163 
3164    Level: intermediate
3165 
3166 .keywords: SNES, nonlinear, set, convergence, tolerances
3167 
3168 .seealso: SNESSetTrustRegionTolerance()
3169 @*/
3170 PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
3171 {
3172   PetscFunctionBegin;
3173   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3174   PetscValidLogicalCollectiveReal(snes,abstol,2);
3175   PetscValidLogicalCollectiveReal(snes,rtol,3);
3176   PetscValidLogicalCollectiveReal(snes,stol,4);
3177   PetscValidLogicalCollectiveInt(snes,maxit,5);
3178   PetscValidLogicalCollectiveInt(snes,maxf,6);
3179 
3180   if (abstol != PETSC_DEFAULT) {
3181     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %g must be non-negative",(double)abstol);
3182     snes->abstol = abstol;
3183   }
3184   if (rtol != PETSC_DEFAULT) {
3185     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);
3186     snes->rtol = rtol;
3187   }
3188   if (stol != PETSC_DEFAULT) {
3189     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %g must be non-negative",(double)stol);
3190     snes->stol = stol;
3191   }
3192   if (maxit != PETSC_DEFAULT) {
3193     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
3194     snes->max_its = maxit;
3195   }
3196   if (maxf != PETSC_DEFAULT) {
3197     if (maxf < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
3198     snes->max_funcs = maxf;
3199   }
3200   snes->tolerancesset = PETSC_TRUE;
3201   PetscFunctionReturn(0);
3202 }
3203 
3204 #undef __FUNCT__
3205 #define __FUNCT__ "SNESGetTolerances"
3206 /*@
3207    SNESGetTolerances - Gets various parameters used in convergence tests.
3208 
3209    Not Collective
3210 
3211    Input Parameters:
3212 +  snes - the SNES context
3213 .  atol - absolute convergence tolerance
3214 .  rtol - relative convergence tolerance
3215 .  stol -  convergence tolerance in terms of the norm
3216            of the change in the solution between steps
3217 .  maxit - maximum number of iterations
3218 -  maxf - maximum number of function evaluations
3219 
3220    Notes:
3221    The user can specify NULL for any parameter that is not needed.
3222 
3223    Level: intermediate
3224 
3225 .keywords: SNES, nonlinear, get, convergence, tolerances
3226 
3227 .seealso: SNESSetTolerances()
3228 @*/
3229 PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3230 {
3231   PetscFunctionBegin;
3232   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3233   if (atol)  *atol  = snes->abstol;
3234   if (rtol)  *rtol  = snes->rtol;
3235   if (stol)  *stol  = snes->stol;
3236   if (maxit) *maxit = snes->max_its;
3237   if (maxf)  *maxf  = snes->max_funcs;
3238   PetscFunctionReturn(0);
3239 }
3240 
3241 #undef __FUNCT__
3242 #define __FUNCT__ "SNESSetTrustRegionTolerance"
3243 /*@
3244    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.
3245 
3246    Logically Collective on SNES
3247 
3248    Input Parameters:
3249 +  snes - the SNES context
3250 -  tol - tolerance
3251 
3252    Options Database Key:
3253 .  -snes_trtol <tol> - Sets tol
3254 
3255    Level: intermediate
3256 
3257 .keywords: SNES, nonlinear, set, trust region, tolerance
3258 
3259 .seealso: SNESSetTolerances()
3260 @*/
3261 PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3262 {
3263   PetscFunctionBegin;
3264   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3265   PetscValidLogicalCollectiveReal(snes,tol,2);
3266   snes->deltatol = tol;
3267   PetscFunctionReturn(0);
3268 }
3269 
3270 /*
3271    Duplicate the lg monitors for SNES from KSP; for some reason with
3272    dynamic libraries things don't work under Sun4 if we just use
3273    macros instead of functions
3274 */
3275 #undef __FUNCT__
3276 #define __FUNCT__ "SNESMonitorLGResidualNorm"
3277 PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,void *ctx)
3278 {
3279   PetscErrorCode ierr;
3280 
3281   PetscFunctionBegin;
3282   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3283   ierr = KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);CHKERRQ(ierr);
3284   PetscFunctionReturn(0);
3285 }
3286 
3287 #undef __FUNCT__
3288 #define __FUNCT__ "SNESMonitorLGCreate"
3289 PetscErrorCode  SNESMonitorLGCreate(MPI_Comm comm,const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *lgctx)
3290 {
3291   PetscErrorCode ierr;
3292 
3293   PetscFunctionBegin;
3294   ierr = KSPMonitorLGResidualNormCreate(comm,host,label,x,y,m,n,lgctx);CHKERRQ(ierr);
3295   PetscFunctionReturn(0);
3296 }
3297 
3298 extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
3299 #undef __FUNCT__
3300 #define __FUNCT__ "SNESMonitorLGRange"
3301 PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3302 {
3303   PetscDrawLG      lg;
3304   PetscErrorCode   ierr;
3305   PetscReal        x,y,per;
3306   PetscViewer      v = (PetscViewer)monctx;
3307   static PetscReal prev; /* should be in the context */
3308   PetscDraw        draw;
3309 
3310   PetscFunctionBegin;
3311   PetscValidHeaderSpecific(v,PETSC_VIEWER_CLASSID,4);
3312   ierr = PetscViewerDrawGetDrawLG(v,0,&lg);CHKERRQ(ierr);
3313   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3314   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3315   ierr = PetscDrawSetTitle(draw,"Residual norm");CHKERRQ(ierr);
3316   x    = (PetscReal)n;
3317   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
3318   else y = -15.0;
3319   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3320   if (n < 20 || !(n % 5)) {
3321     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3322   }
3323 
3324   ierr = PetscViewerDrawGetDrawLG(v,1,&lg);CHKERRQ(ierr);
3325   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3326   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3327   ierr = PetscDrawSetTitle(draw,"% elemts > .2*max elemt");CHKERRQ(ierr);
3328   ierr =  SNESMonitorRange_Private(snes,n,&per);CHKERRQ(ierr);
3329   x    = (PetscReal)n;
3330   y    = 100.0*per;
3331   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3332   if (n < 20 || !(n % 5)) {
3333     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3334   }
3335 
3336   ierr = PetscViewerDrawGetDrawLG(v,2,&lg);CHKERRQ(ierr);
3337   if (!n) {prev = rnorm;ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3338   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3339   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");CHKERRQ(ierr);
3340   x    = (PetscReal)n;
3341   y    = (prev - rnorm)/prev;
3342   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3343   if (n < 20 || !(n % 5)) {
3344     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3345   }
3346 
3347   ierr = PetscViewerDrawGetDrawLG(v,3,&lg);CHKERRQ(ierr);
3348   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3349   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3350   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");CHKERRQ(ierr);
3351   x    = (PetscReal)n;
3352   y    = (prev - rnorm)/(prev*per);
3353   if (n > 2) { /*skip initial crazy value */
3354     ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3355   }
3356   if (n < 20 || !(n % 5)) {
3357     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3358   }
3359   prev = rnorm;
3360   PetscFunctionReturn(0);
3361 }
3362 
3363 #undef __FUNCT__
3364 #define __FUNCT__ "SNESMonitor"
3365 /*@
3366    SNESMonitor - runs the user provided monitor routines, if they exist
3367 
3368    Collective on SNES
3369 
3370    Input Parameters:
3371 +  snes - nonlinear solver context obtained from SNESCreate()
3372 .  iter - iteration number
3373 -  rnorm - relative norm of the residual
3374 
3375    Notes:
3376    This routine is called by the SNES implementations.
3377    It does not typically need to be called by the user.
3378 
3379    Level: developer
3380 
3381 .seealso: SNESMonitorSet()
3382 @*/
3383 PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3384 {
3385   PetscErrorCode ierr;
3386   PetscInt       i,n = snes->numbermonitors;
3387 
3388   PetscFunctionBegin;
3389   ierr = VecLockPush(snes->vec_sol);CHKERRQ(ierr);
3390   for (i=0; i<n; i++) {
3391     ierr = (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);CHKERRQ(ierr);
3392   }
3393   ierr = VecLockPop(snes->vec_sol);CHKERRQ(ierr);
3394   PetscFunctionReturn(0);
3395 }
3396 
3397 /* ------------ Routines to set performance monitoring options ----------- */
3398 
3399 /*MC
3400     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver
3401 
3402      Synopsis:
3403      #include <petscsnes.h>
3404 $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)
3405 
3406 +    snes - the SNES context
3407 .    its - iteration number
3408 .    norm - 2-norm function value (may be estimated)
3409 -    mctx - [optional] monitoring context
3410 
3411    Level: advanced
3412 
3413 .seealso:   SNESMonitorSet(), SNESMonitorGet()
3414 M*/
3415 
3416 #undef __FUNCT__
3417 #define __FUNCT__ "SNESMonitorSet"
3418 /*@C
3419    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3420    iteration of the nonlinear solver to display the iteration's
3421    progress.
3422 
3423    Logically Collective on SNES
3424 
3425    Input Parameters:
3426 +  snes - the SNES context
3427 .  f - the monitor function, see SNESMonitorFunction for the calling sequence
3428 .  mctx - [optional] user-defined context for private data for the
3429           monitor routine (use NULL if no context is desired)
3430 -  monitordestroy - [optional] routine that frees monitor context
3431           (may be NULL)
3432 
3433    Options Database Keys:
3434 +    -snes_monitor        - sets SNESMonitorDefault()
3435 .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3436                             uses SNESMonitorLGCreate()
3437 -    -snes_monitor_cancel - cancels all monitors that have
3438                             been hardwired into a code by
3439                             calls to SNESMonitorSet(), but
3440                             does not cancel those set via
3441                             the options database.
3442 
3443    Notes:
3444    Several different monitoring routines may be set by calling
3445    SNESMonitorSet() multiple times; all will be called in the
3446    order in which they were set.
3447 
3448    Fortran notes: Only a single monitor function can be set for each SNES object
3449 
3450    Level: intermediate
3451 
3452 .keywords: SNES, nonlinear, set, monitor
3453 
3454 .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
3455 @*/
3456 PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*f)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3457 {
3458   PetscInt       i;
3459   PetscErrorCode ierr;
3460 
3461   PetscFunctionBegin;
3462   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3463   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3464   for (i=0; i<snes->numbermonitors;i++) {
3465     if (f == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
3466       if (monitordestroy) {
3467         ierr = (*monitordestroy)(&mctx);CHKERRQ(ierr);
3468       }
3469       PetscFunctionReturn(0);
3470     }
3471   }
3472   snes->monitor[snes->numbermonitors]          = f;
3473   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
3474   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
3475   PetscFunctionReturn(0);
3476 }
3477 
3478 #undef __FUNCT__
3479 #define __FUNCT__ "SNESMonitorCancel"
3480 /*@
3481    SNESMonitorCancel - Clears all the monitor functions for a SNES object.
3482 
3483    Logically Collective on SNES
3484 
3485    Input Parameters:
3486 .  snes - the SNES context
3487 
3488    Options Database Key:
3489 .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3490     into a code by calls to SNESMonitorSet(), but does not cancel those
3491     set via the options database
3492 
3493    Notes:
3494    There is no way to clear one specific monitor from a SNES object.
3495 
3496    Level: intermediate
3497 
3498 .keywords: SNES, nonlinear, set, monitor
3499 
3500 .seealso: SNESMonitorDefault(), SNESMonitorSet()
3501 @*/
3502 PetscErrorCode  SNESMonitorCancel(SNES snes)
3503 {
3504   PetscErrorCode ierr;
3505   PetscInt       i;
3506 
3507   PetscFunctionBegin;
3508   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3509   for (i=0; i<snes->numbermonitors; i++) {
3510     if (snes->monitordestroy[i]) {
3511       ierr = (*snes->monitordestroy[i])(&snes->monitorcontext[i]);CHKERRQ(ierr);
3512     }
3513   }
3514   snes->numbermonitors = 0;
3515   PetscFunctionReturn(0);
3516 }
3517 
3518 /*MC
3519     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver
3520 
3521      Synopsis:
3522      #include <petscsnes.h>
3523 $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)
3524 
3525 +    snes - the SNES context
3526 .    it - current iteration (0 is the first and is before any Newton step)
3527 .    cctx - [optional] convergence context
3528 .    reason - reason for convergence/divergence
3529 .    xnorm - 2-norm of current iterate
3530 .    gnorm - 2-norm of current step
3531 -    f - 2-norm of function
3532 
3533    Level: intermediate
3534 
3535 .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
3536 M*/
3537 
3538 #undef __FUNCT__
3539 #define __FUNCT__ "SNESSetConvergenceTest"
3540 /*@C
3541    SNESSetConvergenceTest - Sets the function that is to be used
3542    to test for convergence of the nonlinear iterative solution.
3543 
3544    Logically Collective on SNES
3545 
3546    Input Parameters:
3547 +  snes - the SNES context
3548 .  SNESConvergenceTestFunction - routine to test for convergence
3549 .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
3550 -  destroy - [optional] destructor for the context (may be NULL; NULL_FUNCTION in Fortran)
3551 
3552    Level: advanced
3553 
3554 .keywords: SNES, nonlinear, set, convergence, test
3555 
3556 .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
3557 @*/
3558 PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
3559 {
3560   PetscErrorCode ierr;
3561 
3562   PetscFunctionBegin;
3563   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3564   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
3565   if (snes->ops->convergeddestroy) {
3566     ierr = (*snes->ops->convergeddestroy)(snes->cnvP);CHKERRQ(ierr);
3567   }
3568   snes->ops->converged        = SNESConvergenceTestFunction;
3569   snes->ops->convergeddestroy = destroy;
3570   snes->cnvP                  = cctx;
3571   PetscFunctionReturn(0);
3572 }
3573 
3574 #undef __FUNCT__
3575 #define __FUNCT__ "SNESGetConvergedReason"
3576 /*@
3577    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.
3578 
3579    Not Collective
3580 
3581    Input Parameter:
3582 .  snes - the SNES context
3583 
3584    Output Parameter:
3585 .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3586             manual pages for the individual convergence tests for complete lists
3587 
3588    Level: intermediate
3589 
3590    Notes: Can only be called after the call the SNESSolve() is complete.
3591 
3592 .keywords: SNES, nonlinear, set, convergence, test
3593 
3594 .seealso: SNESSetConvergenceTest(), SNESSetConvergedReason(), SNESConvergedReason
3595 @*/
3596 PetscErrorCode SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
3597 {
3598   PetscFunctionBegin;
3599   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3600   PetscValidPointer(reason,2);
3601   *reason = snes->reason;
3602   PetscFunctionReturn(0);
3603 }
3604 
3605 #undef __FUNCT__
3606 #define __FUNCT__ "SNESSetConvergedReason"
3607 /*@
3608    SNESSetConvergedReason - Sets the reason the SNES iteration was stopped.
3609 
3610    Not Collective
3611 
3612    Input Parameters:
3613 +  snes - the SNES context
3614 -  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3615             manual pages for the individual convergence tests for complete lists
3616 
3617    Level: intermediate
3618 
3619 .keywords: SNES, nonlinear, set, convergence, test
3620 .seealso: SNESGetConvergedReason(), SNESSetConvergenceTest(), SNESConvergedReason
3621 @*/
3622 PetscErrorCode SNESSetConvergedReason(SNES snes,SNESConvergedReason reason)
3623 {
3624   PetscFunctionBegin;
3625   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3626   snes->reason = reason;
3627   PetscFunctionReturn(0);
3628 }
3629 
3630 #undef __FUNCT__
3631 #define __FUNCT__ "SNESSetConvergenceHistory"
3632 /*@
3633    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.
3634 
3635    Logically Collective on SNES
3636 
3637    Input Parameters:
3638 +  snes - iterative context obtained from SNESCreate()
3639 .  a   - array to hold history, this array will contain the function norms computed at each step
3640 .  its - integer array holds the number of linear iterations for each solve.
3641 .  na  - size of a and its
3642 -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
3643            else it continues storing new values for new nonlinear solves after the old ones
3644 
3645    Notes:
3646    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
3647    default array of length 10000 is allocated.
3648 
3649    This routine is useful, e.g., when running a code for purposes
3650    of accurate performance monitoring, when no I/O should be done
3651    during the section of code that is being timed.
3652 
3653    Level: intermediate
3654 
3655 .keywords: SNES, set, convergence, history
3656 
3657 .seealso: SNESGetConvergenceHistory()
3658 
3659 @*/
3660 PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
3661 {
3662   PetscErrorCode ierr;
3663 
3664   PetscFunctionBegin;
3665   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3666   if (a) PetscValidScalarPointer(a,2);
3667   if (its) PetscValidIntPointer(its,3);
3668   if (!a) {
3669     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
3670     ierr = PetscCalloc1(na,&a);CHKERRQ(ierr);
3671     ierr = PetscCalloc1(na,&its);CHKERRQ(ierr);
3672 
3673     snes->conv_malloc = PETSC_TRUE;
3674   }
3675   snes->conv_hist       = a;
3676   snes->conv_hist_its   = its;
3677   snes->conv_hist_max   = na;
3678   snes->conv_hist_len   = 0;
3679   snes->conv_hist_reset = reset;
3680   PetscFunctionReturn(0);
3681 }
3682 
3683 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3684 #include <engine.h>   /* MATLAB include file */
3685 #include <mex.h>      /* MATLAB include file */
3686 
3687 #undef __FUNCT__
3688 #define __FUNCT__ "SNESGetConvergenceHistoryMatlab"
3689 PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
3690 {
3691   mxArray   *mat;
3692   PetscInt  i;
3693   PetscReal *ar;
3694 
3695   PetscFunctionBegin;
3696   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
3697   ar  = (PetscReal*) mxGetData(mat);
3698   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
3699   PetscFunctionReturn(mat);
3700 }
3701 #endif
3702 
3703 #undef __FUNCT__
3704 #define __FUNCT__ "SNESGetConvergenceHistory"
3705 /*@C
3706    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.
3707 
3708    Not Collective
3709 
3710    Input Parameter:
3711 .  snes - iterative context obtained from SNESCreate()
3712 
3713    Output Parameters:
3714 .  a   - array to hold history
3715 .  its - integer array holds the number of linear iterations (or
3716          negative if not converged) for each solve.
3717 -  na  - size of a and its
3718 
3719    Notes:
3720     The calling sequence for this routine in Fortran is
3721 $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
3722 
3723    This routine is useful, e.g., when running a code for purposes
3724    of accurate performance monitoring, when no I/O should be done
3725    during the section of code that is being timed.
3726 
3727    Level: intermediate
3728 
3729 .keywords: SNES, get, convergence, history
3730 
3731 .seealso: SNESSetConvergencHistory()
3732 
3733 @*/
3734 PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
3735 {
3736   PetscFunctionBegin;
3737   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3738   if (a)   *a   = snes->conv_hist;
3739   if (its) *its = snes->conv_hist_its;
3740   if (na)  *na  = snes->conv_hist_len;
3741   PetscFunctionReturn(0);
3742 }
3743 
3744 #undef __FUNCT__
3745 #define __FUNCT__ "SNESSetUpdate"
3746 /*@C
3747   SNESSetUpdate - Sets the general-purpose update function called
3748   at the beginning of every iteration of the nonlinear solve. Specifically
3749   it is called just before the Jacobian is "evaluated".
3750 
3751   Logically Collective on SNES
3752 
3753   Input Parameters:
3754 . snes - The nonlinear solver context
3755 . func - The function
3756 
3757   Calling sequence of func:
3758 . func (SNES snes, PetscInt step);
3759 
3760 . step - The current step of the iteration
3761 
3762   Level: advanced
3763 
3764   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()
3765         This is not used by most users.
3766 
3767 .keywords: SNES, update
3768 
3769 .seealso SNESSetJacobian(), SNESSolve()
3770 @*/
3771 PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
3772 {
3773   PetscFunctionBegin;
3774   PetscValidHeaderSpecific(snes, SNES_CLASSID,1);
3775   snes->ops->update = func;
3776   PetscFunctionReturn(0);
3777 }
3778 
3779 #undef __FUNCT__
3780 #define __FUNCT__ "SNESScaleStep_Private"
3781 /*
3782    SNESScaleStep_Private - Scales a step so that its length is less than the
3783    positive parameter delta.
3784 
3785     Input Parameters:
3786 +   snes - the SNES context
3787 .   y - approximate solution of linear system
3788 .   fnorm - 2-norm of current function
3789 -   delta - trust region size
3790 
3791     Output Parameters:
3792 +   gpnorm - predicted function norm at the new point, assuming local
3793     linearization.  The value is zero if the step lies within the trust
3794     region, and exceeds zero otherwise.
3795 -   ynorm - 2-norm of the step
3796 
3797     Note:
3798     For non-trust region methods such as SNESNEWTONLS, the parameter delta
3799     is set to be the maximum allowable step size.
3800 
3801 .keywords: SNES, nonlinear, scale, step
3802 */
3803 PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
3804 {
3805   PetscReal      nrm;
3806   PetscScalar    cnorm;
3807   PetscErrorCode ierr;
3808 
3809   PetscFunctionBegin;
3810   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3811   PetscValidHeaderSpecific(y,VEC_CLASSID,2);
3812   PetscCheckSameComm(snes,1,y,2);
3813 
3814   ierr = VecNorm(y,NORM_2,&nrm);CHKERRQ(ierr);
3815   if (nrm > *delta) {
3816     nrm     = *delta/nrm;
3817     *gpnorm = (1.0 - nrm)*(*fnorm);
3818     cnorm   = nrm;
3819     ierr    = VecScale(y,cnorm);CHKERRQ(ierr);
3820     *ynorm  = *delta;
3821   } else {
3822     *gpnorm = 0.0;
3823     *ynorm  = nrm;
3824   }
3825   PetscFunctionReturn(0);
3826 }
3827 
3828 #undef __FUNCT__
3829 #define __FUNCT__ "SNESReasonView"
3830 /*@
3831    SNESReasonView - Displays the reason a SNES solve converged or diverged to a viewer
3832 
3833    Collective on SNES
3834 
3835    Parameter:
3836 +  snes - iterative context obtained from SNESCreate()
3837 -  viewer - the viewer to display the reason
3838 
3839 
3840    Options Database Keys:
3841 .  -snes_converged_reason - print reason for converged or diverged, also prints number of iterations
3842 
3843    Level: beginner
3844 
3845 .keywords: SNES, solve, linear system
3846 
3847 .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault()
3848 
3849 @*/
3850 PetscErrorCode  SNESReasonView(SNES snes,PetscViewer viewer)
3851 {
3852   PetscErrorCode ierr;
3853   PetscBool      isAscii;
3854 
3855   PetscFunctionBegin;
3856   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isAscii);CHKERRQ(ierr);
3857   if (isAscii) {
3858     ierr = PetscViewerASCIIAddTab(viewer,((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3859     if (snes->reason > 0) {
3860       if (((PetscObject) snes)->prefix) {
3861         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve converged due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3862       } else {
3863         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3864       }
3865     } else {
3866       if (((PetscObject) snes)->prefix) {
3867         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);
3868       } else {
3869         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3870       }
3871     }
3872     ierr = PetscViewerASCIISubtractTab(viewer,((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3873   }
3874   PetscFunctionReturn(0);
3875 }
3876 
3877 #undef __FUNCT__
3878 #define __FUNCT__ "SNESReasonViewFromOptions"
3879 /*@C
3880   SNESReasonViewFromOptions - Processes command line options to determine if/how a SNESReason is to be viewed.
3881 
3882   Collective on SNES
3883 
3884   Input Parameters:
3885 . snes   - the SNES object
3886 
3887   Level: intermediate
3888 
3889 @*/
3890 PetscErrorCode SNESReasonViewFromOptions(SNES snes)
3891 {
3892   PetscErrorCode    ierr;
3893   PetscViewer       viewer;
3894   PetscBool         flg;
3895   static PetscBool  incall = PETSC_FALSE;
3896   PetscViewerFormat format;
3897 
3898   PetscFunctionBegin;
3899   if (incall) PetscFunctionReturn(0);
3900   incall = PETSC_TRUE;
3901   ierr   = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_converged_reason",&viewer,&format,&flg);CHKERRQ(ierr);
3902   if (flg) {
3903     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
3904     ierr = SNESReasonView(snes,viewer);CHKERRQ(ierr);
3905     ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
3906     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3907   }
3908   incall = PETSC_FALSE;
3909   PetscFunctionReturn(0);
3910 }
3911 
3912 #undef __FUNCT__
3913 #define __FUNCT__ "SNESSolve"
3914 /*@C
3915    SNESSolve - Solves a nonlinear system F(x) = b.
3916    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3917 
3918    Collective on SNES
3919 
3920    Input Parameters:
3921 +  snes - the SNES context
3922 .  b - the constant part of the equation F(x) = b, or NULL to use zero.
3923 -  x - the solution vector.
3924 
3925    Notes:
3926    The user should initialize the vector,x, with the initial guess
3927    for the nonlinear solve prior to calling SNESSolve.  In particular,
3928    to employ an initial guess of zero, the user should explicitly set
3929    this vector to zero by calling VecSet().
3930 
3931    Level: beginner
3932 
3933 .keywords: SNES, nonlinear, solve
3934 
3935 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3936 @*/
3937 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3938 {
3939   PetscErrorCode    ierr;
3940   PetscBool         flg;
3941   PetscInt          grid;
3942   Vec               xcreated = NULL;
3943   DM                dm;
3944 
3945   PetscFunctionBegin;
3946   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3947   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3948   if (x) PetscCheckSameComm(snes,1,x,3);
3949   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3950   if (b) PetscCheckSameComm(snes,1,b,2);
3951 
3952   if (!x) {
3953     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3954     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3955     x    = xcreated;
3956   }
3957   ierr = SNESViewFromOptions(snes,NULL,"-snes_view_pre");CHKERRQ(ierr);
3958 
3959   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);}
3960   for (grid=0; grid<snes->gridsequence+1; grid++) {
3961 
3962     /* set solution vector */
3963     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3964     ierr          = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3965     snes->vec_sol = x;
3966     ierr          = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3967 
3968     /* set affine vector if provided */
3969     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3970     ierr          = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3971     snes->vec_rhs = b;
3972 
3973     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
3974     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
3975     if (!snes->vec_sol_update /* && snes->vec_sol */) {
3976       ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
3977       ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);CHKERRQ(ierr);
3978     }
3979     ierr = DMShellSetGlobalVector(dm,snes->vec_sol);CHKERRQ(ierr);
3980     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3981 
3982     if (!grid) {
3983       if (snes->ops->computeinitialguess) {
3984         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3985       }
3986     }
3987 
3988     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3989     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}
3990 
3991     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3992     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3993     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3994     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3995     snes->domainerror = PETSC_FALSE; /* clear the flag if it has been set */
3996 
3997     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
3998     if (snes->lagpre_persist) snes->pre_iter += snes->iter;
3999 
4000     flg  = PETSC_FALSE;
4001     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,NULL);CHKERRQ(ierr);
4002     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
4003     ierr = SNESReasonViewFromOptions(snes);CHKERRQ(ierr);
4004 
4005     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
4006     if (snes->reason < 0) break;
4007     if (grid <  snes->gridsequence) {
4008       DM  fine;
4009       Vec xnew;
4010       Mat interp;
4011 
4012       ierr = DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);CHKERRQ(ierr);
4013       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
4014       ierr = DMCreateInterpolation(snes->dm,fine,&interp,NULL);CHKERRQ(ierr);
4015       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
4016       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
4017       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
4018       ierr = MatDestroy(&interp);CHKERRQ(ierr);
4019       x    = xnew;
4020 
4021       ierr = SNESReset(snes);CHKERRQ(ierr);
4022       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
4023       ierr = DMDestroy(&fine);CHKERRQ(ierr);
4024       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);
4025     }
4026   }
4027   ierr = SNESViewFromOptions(snes,NULL,"-snes_view");CHKERRQ(ierr);
4028   ierr = VecViewFromOptions(snes->vec_sol,(PetscObject)snes,"-snes_view_solution");CHKERRQ(ierr);
4029 
4030   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
4031   ierr = PetscObjectSAWsBlock((PetscObject)snes);CHKERRQ(ierr);
4032   PetscFunctionReturn(0);
4033 }
4034 
4035 /* --------- Internal routines for SNES Package --------- */
4036 
4037 #undef __FUNCT__
4038 #define __FUNCT__ "SNESSetType"
4039 /*@C
4040    SNESSetType - Sets the method for the nonlinear solver.
4041 
4042    Collective on SNES
4043 
4044    Input Parameters:
4045 +  snes - the SNES context
4046 -  type - a known method
4047 
4048    Options Database Key:
4049 .  -snes_type <type> - Sets the method; use -help for a list
4050    of available methods (for instance, newtonls or newtontr)
4051 
4052    Notes:
4053    See "petsc/include/petscsnes.h" for available methods (for instance)
4054 +    SNESNEWTONLS - Newton's method with line search
4055      (systems of nonlinear equations)
4056 .    SNESNEWTONTR - Newton's method with trust region
4057      (systems of nonlinear equations)
4058 
4059   Normally, it is best to use the SNESSetFromOptions() command and then
4060   set the SNES solver type from the options database rather than by using
4061   this routine.  Using the options database provides the user with
4062   maximum flexibility in evaluating the many nonlinear solvers.
4063   The SNESSetType() routine is provided for those situations where it
4064   is necessary to set the nonlinear solver independently of the command
4065   line or options database.  This might be the case, for example, when
4066   the choice of solver changes during the execution of the program,
4067   and the user's application is taking responsibility for choosing the
4068   appropriate method.
4069 
4070     Developer Notes: SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
4071     the constructor in that list and calls it to create the spexific object.
4072 
4073   Level: intermediate
4074 
4075 .keywords: SNES, set, type
4076 
4077 .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()
4078 
4079 @*/
4080 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
4081 {
4082   PetscErrorCode ierr,(*r)(SNES);
4083   PetscBool      match;
4084 
4085   PetscFunctionBegin;
4086   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4087   PetscValidCharPointer(type,2);
4088 
4089   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
4090   if (match) PetscFunctionReturn(0);
4091 
4092   ierr =  PetscFunctionListFind(SNESList,type,&r);CHKERRQ(ierr);
4093   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
4094   /* Destroy the previous private SNES context */
4095   if (snes->ops->destroy) {
4096     ierr               = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
4097     snes->ops->destroy = NULL;
4098   }
4099   /* Reinitialize function pointers in SNESOps structure */
4100   snes->ops->setup          = 0;
4101   snes->ops->solve          = 0;
4102   snes->ops->view           = 0;
4103   snes->ops->setfromoptions = 0;
4104   snes->ops->destroy        = 0;
4105   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
4106   snes->setupcalled = PETSC_FALSE;
4107 
4108   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
4109   ierr = (*r)(snes);CHKERRQ(ierr);
4110   PetscFunctionReturn(0);
4111 }
4112 
4113 #undef __FUNCT__
4114 #define __FUNCT__ "SNESGetType"
4115 /*@C
4116    SNESGetType - Gets the SNES method type and name (as a string).
4117 
4118    Not Collective
4119 
4120    Input Parameter:
4121 .  snes - nonlinear solver context
4122 
4123    Output Parameter:
4124 .  type - SNES method (a character string)
4125 
4126    Level: intermediate
4127 
4128 .keywords: SNES, nonlinear, get, type, name
4129 @*/
4130 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
4131 {
4132   PetscFunctionBegin;
4133   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4134   PetscValidPointer(type,2);
4135   *type = ((PetscObject)snes)->type_name;
4136   PetscFunctionReturn(0);
4137 }
4138 
4139 #undef __FUNCT__
4140 #define __FUNCT__ "SNESSetSolution"
4141 /*@
4142   SNESSetSolution - Sets the solution vector for use by the SNES routines.
4143 
4144   Logically Collective on SNES and Vec
4145 
4146   Input Parameters:
4147 + snes - the SNES context obtained from SNESCreate()
4148 - u    - the solution vector
4149 
4150   Level: beginner
4151 
4152 .keywords: SNES, set, solution
4153 @*/
4154 PetscErrorCode SNESSetSolution(SNES snes, Vec u)
4155 {
4156   DM             dm;
4157   PetscErrorCode ierr;
4158 
4159   PetscFunctionBegin;
4160   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4161   PetscValidHeaderSpecific(u, VEC_CLASSID, 2);
4162   ierr = PetscObjectReference((PetscObject) u);CHKERRQ(ierr);
4163   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
4164 
4165   snes->vec_sol = u;
4166 
4167   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
4168   ierr = DMShellSetGlobalVector(dm, u);CHKERRQ(ierr);
4169   PetscFunctionReturn(0);
4170 }
4171 
4172 #undef __FUNCT__
4173 #define __FUNCT__ "SNESGetSolution"
4174 /*@
4175    SNESGetSolution - Returns the vector where the approximate solution is
4176    stored. This is the fine grid solution when using SNESSetGridSequence().
4177 
4178    Not Collective, but Vec is parallel if SNES is parallel
4179 
4180    Input Parameter:
4181 .  snes - the SNES context
4182 
4183    Output Parameter:
4184 .  x - the solution
4185 
4186    Level: intermediate
4187 
4188 .keywords: SNES, nonlinear, get, solution
4189 
4190 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
4191 @*/
4192 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
4193 {
4194   PetscFunctionBegin;
4195   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4196   PetscValidPointer(x,2);
4197   *x = snes->vec_sol;
4198   PetscFunctionReturn(0);
4199 }
4200 
4201 #undef __FUNCT__
4202 #define __FUNCT__ "SNESGetSolutionUpdate"
4203 /*@
4204    SNESGetSolutionUpdate - Returns the vector where the solution update is
4205    stored.
4206 
4207    Not Collective, but Vec is parallel if SNES is parallel
4208 
4209    Input Parameter:
4210 .  snes - the SNES context
4211 
4212    Output Parameter:
4213 .  x - the solution update
4214 
4215    Level: advanced
4216 
4217 .keywords: SNES, nonlinear, get, solution, update
4218 
4219 .seealso: SNESGetSolution(), SNESGetFunction()
4220 @*/
4221 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
4222 {
4223   PetscFunctionBegin;
4224   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4225   PetscValidPointer(x,2);
4226   *x = snes->vec_sol_update;
4227   PetscFunctionReturn(0);
4228 }
4229 
4230 #undef __FUNCT__
4231 #define __FUNCT__ "SNESGetFunction"
4232 /*@C
4233    SNESGetFunction - Returns the vector where the function is stored.
4234 
4235    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
4236 
4237    Input Parameter:
4238 .  snes - the SNES context
4239 
4240    Output Parameter:
4241 +  r - the vector that is used to store residuals (or NULL if you don't want it)
4242 .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
4243 -  ctx - the function context (or NULL if you don't want it)
4244 
4245    Level: advanced
4246 
4247 .keywords: SNES, nonlinear, get, function
4248 
4249 .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
4250 @*/
4251 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
4252 {
4253   PetscErrorCode ierr;
4254   DM             dm;
4255 
4256   PetscFunctionBegin;
4257   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4258   if (r) {
4259     if (!snes->vec_func) {
4260       if (snes->vec_rhs) {
4261         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
4262       } else if (snes->vec_sol) {
4263         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
4264       } else if (snes->dm) {
4265         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
4266       }
4267     }
4268     *r = snes->vec_func;
4269   }
4270   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4271   ierr = DMSNESGetFunction(dm,f,ctx);CHKERRQ(ierr);
4272   PetscFunctionReturn(0);
4273 }
4274 
4275 /*@C
4276    SNESGetNGS - Returns the NGS function and context.
4277 
4278    Input Parameter:
4279 .  snes - the SNES context
4280 
4281    Output Parameter:
4282 +  f - the function (or NULL) see SNESNGSFunction for details
4283 -  ctx    - the function context (or NULL)
4284 
4285    Level: advanced
4286 
4287 .keywords: SNES, nonlinear, get, function
4288 
4289 .seealso: SNESSetNGS(), SNESGetFunction()
4290 @*/
4291 
4292 #undef __FUNCT__
4293 #define __FUNCT__ "SNESGetNGS"
4294 PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
4295 {
4296   PetscErrorCode ierr;
4297   DM             dm;
4298 
4299   PetscFunctionBegin;
4300   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4301   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4302   ierr = DMSNESGetNGS(dm,f,ctx);CHKERRQ(ierr);
4303   PetscFunctionReturn(0);
4304 }
4305 
4306 #undef __FUNCT__
4307 #define __FUNCT__ "SNESSetOptionsPrefix"
4308 /*@C
4309    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4310    SNES options in the database.
4311 
4312    Logically Collective on SNES
4313 
4314    Input Parameter:
4315 +  snes - the SNES context
4316 -  prefix - the prefix to prepend to all option names
4317 
4318    Notes:
4319    A hyphen (-) must NOT be given at the beginning of the prefix name.
4320    The first character of all runtime options is AUTOMATICALLY the hyphen.
4321 
4322    Level: advanced
4323 
4324 .keywords: SNES, set, options, prefix, database
4325 
4326 .seealso: SNESSetFromOptions()
4327 @*/
4328 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4329 {
4330   PetscErrorCode ierr;
4331 
4332   PetscFunctionBegin;
4333   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4334   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4335   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4336   if (snes->linesearch) {
4337     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4338     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4339   }
4340   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4341   PetscFunctionReturn(0);
4342 }
4343 
4344 #undef __FUNCT__
4345 #define __FUNCT__ "SNESAppendOptionsPrefix"
4346 /*@C
4347    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4348    SNES options in the database.
4349 
4350    Logically Collective on SNES
4351 
4352    Input Parameters:
4353 +  snes - the SNES context
4354 -  prefix - the prefix to prepend to all option names
4355 
4356    Notes:
4357    A hyphen (-) must NOT be given at the beginning of the prefix name.
4358    The first character of all runtime options is AUTOMATICALLY the hyphen.
4359 
4360    Level: advanced
4361 
4362 .keywords: SNES, append, options, prefix, database
4363 
4364 .seealso: SNESGetOptionsPrefix()
4365 @*/
4366 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4367 {
4368   PetscErrorCode ierr;
4369 
4370   PetscFunctionBegin;
4371   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4372   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4373   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4374   if (snes->linesearch) {
4375     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4376     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4377   }
4378   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4379   PetscFunctionReturn(0);
4380 }
4381 
4382 #undef __FUNCT__
4383 #define __FUNCT__ "SNESGetOptionsPrefix"
4384 /*@C
4385    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4386    SNES options in the database.
4387 
4388    Not Collective
4389 
4390    Input Parameter:
4391 .  snes - the SNES context
4392 
4393    Output Parameter:
4394 .  prefix - pointer to the prefix string used
4395 
4396    Notes: On the fortran side, the user should pass in a string 'prefix' of
4397    sufficient length to hold the prefix.
4398 
4399    Level: advanced
4400 
4401 .keywords: SNES, get, options, prefix, database
4402 
4403 .seealso: SNESAppendOptionsPrefix()
4404 @*/
4405 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4406 {
4407   PetscErrorCode ierr;
4408 
4409   PetscFunctionBegin;
4410   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4411   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4412   PetscFunctionReturn(0);
4413 }
4414 
4415 
4416 #undef __FUNCT__
4417 #define __FUNCT__ "SNESRegister"
4418 /*@C
4419   SNESRegister - Adds a method to the nonlinear solver package.
4420 
4421    Not collective
4422 
4423    Input Parameters:
4424 +  name_solver - name of a new user-defined solver
4425 -  routine_create - routine to create method context
4426 
4427    Notes:
4428    SNESRegister() may be called multiple times to add several user-defined solvers.
4429 
4430    Sample usage:
4431 .vb
4432    SNESRegister("my_solver",MySolverCreate);
4433 .ve
4434 
4435    Then, your solver can be chosen with the procedural interface via
4436 $     SNESSetType(snes,"my_solver")
4437    or at runtime via the option
4438 $     -snes_type my_solver
4439 
4440    Level: advanced
4441 
4442     Note: If your function is not being put into a shared library then use SNESRegister() instead
4443 
4444 .keywords: SNES, nonlinear, register
4445 
4446 .seealso: SNESRegisterAll(), SNESRegisterDestroy()
4447 
4448   Level: advanced
4449 @*/
4450 PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
4451 {
4452   PetscErrorCode ierr;
4453 
4454   PetscFunctionBegin;
4455   ierr = PetscFunctionListAdd(&SNESList,sname,function);CHKERRQ(ierr);
4456   PetscFunctionReturn(0);
4457 }
4458 
4459 #undef __FUNCT__
4460 #define __FUNCT__ "SNESTestLocalMin"
4461 PetscErrorCode  SNESTestLocalMin(SNES snes)
4462 {
4463   PetscErrorCode ierr;
4464   PetscInt       N,i,j;
4465   Vec            u,uh,fh;
4466   PetscScalar    value;
4467   PetscReal      norm;
4468 
4469   PetscFunctionBegin;
4470   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4471   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4472   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4473 
4474   /* currently only works for sequential */
4475   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");CHKERRQ(ierr);
4476   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4477   for (i=0; i<N; i++) {
4478     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4479     ierr = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4480     for (j=-10; j<11; j++) {
4481       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
4482       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4483       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4484       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4485       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4486       value = -value;
4487       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4488     }
4489   }
4490   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4491   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4492   PetscFunctionReturn(0);
4493 }
4494 
4495 #undef __FUNCT__
4496 #define __FUNCT__ "SNESKSPSetUseEW"
4497 /*@
4498    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4499    computing relative tolerance for linear solvers within an inexact
4500    Newton method.
4501 
4502    Logically Collective on SNES
4503 
4504    Input Parameters:
4505 +  snes - SNES context
4506 -  flag - PETSC_TRUE or PETSC_FALSE
4507 
4508     Options Database:
4509 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4510 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4511 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4512 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4513 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4514 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4515 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4516 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4517 
4518    Notes:
4519    Currently, the default is to use a constant relative tolerance for
4520    the inner linear solvers.  Alternatively, one can use the
4521    Eisenstat-Walker method, where the relative convergence tolerance
4522    is reset at each Newton iteration according progress of the nonlinear
4523    solver.
4524 
4525    Level: advanced
4526 
4527    Reference:
4528    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4529    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4530 
4531 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4532 
4533 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4534 @*/
4535 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
4536 {
4537   PetscFunctionBegin;
4538   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4539   PetscValidLogicalCollectiveBool(snes,flag,2);
4540   snes->ksp_ewconv = flag;
4541   PetscFunctionReturn(0);
4542 }
4543 
4544 #undef __FUNCT__
4545 #define __FUNCT__ "SNESKSPGetUseEW"
4546 /*@
4547    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4548    for computing relative tolerance for linear solvers within an
4549    inexact Newton method.
4550 
4551    Not Collective
4552 
4553    Input Parameter:
4554 .  snes - SNES context
4555 
4556    Output Parameter:
4557 .  flag - PETSC_TRUE or PETSC_FALSE
4558 
4559    Notes:
4560    Currently, the default is to use a constant relative tolerance for
4561    the inner linear solvers.  Alternatively, one can use the
4562    Eisenstat-Walker method, where the relative convergence tolerance
4563    is reset at each Newton iteration according progress of the nonlinear
4564    solver.
4565 
4566    Level: advanced
4567 
4568    Reference:
4569    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4570    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4571 
4572 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4573 
4574 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4575 @*/
4576 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4577 {
4578   PetscFunctionBegin;
4579   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4580   PetscValidPointer(flag,2);
4581   *flag = snes->ksp_ewconv;
4582   PetscFunctionReturn(0);
4583 }
4584 
4585 #undef __FUNCT__
4586 #define __FUNCT__ "SNESKSPSetParametersEW"
4587 /*@
4588    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4589    convergence criteria for the linear solvers within an inexact
4590    Newton method.
4591 
4592    Logically Collective on SNES
4593 
4594    Input Parameters:
4595 +    snes - SNES context
4596 .    version - version 1, 2 (default is 2) or 3
4597 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4598 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4599 .    gamma - multiplicative factor for version 2 rtol computation
4600              (0 <= gamma2 <= 1)
4601 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4602 .    alpha2 - power for safeguard
4603 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4604 
4605    Note:
4606    Version 3 was contributed by Luis Chacon, June 2006.
4607 
4608    Use PETSC_DEFAULT to retain the default for any of the parameters.
4609 
4610    Level: advanced
4611 
4612    Reference:
4613    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4614    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4615    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4616 
4617 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4618 
4619 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4620 @*/
4621 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4622 {
4623   SNESKSPEW *kctx;
4624 
4625   PetscFunctionBegin;
4626   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4627   kctx = (SNESKSPEW*)snes->kspconvctx;
4628   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4629   PetscValidLogicalCollectiveInt(snes,version,2);
4630   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4631   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4632   PetscValidLogicalCollectiveReal(snes,gamma,5);
4633   PetscValidLogicalCollectiveReal(snes,alpha,6);
4634   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4635   PetscValidLogicalCollectiveReal(snes,threshold,8);
4636 
4637   if (version != PETSC_DEFAULT)   kctx->version   = version;
4638   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4639   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4640   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4641   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4642   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4643   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4644 
4645   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);
4646   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);
4647   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);
4648   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);
4649   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);
4650   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);
4651   PetscFunctionReturn(0);
4652 }
4653 
4654 #undef __FUNCT__
4655 #define __FUNCT__ "SNESKSPGetParametersEW"
4656 /*@
4657    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4658    convergence criteria for the linear solvers within an inexact
4659    Newton method.
4660 
4661    Not Collective
4662 
4663    Input Parameters:
4664      snes - SNES context
4665 
4666    Output Parameters:
4667 +    version - version 1, 2 (default is 2) or 3
4668 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4669 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4670 .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
4671 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4672 .    alpha2 - power for safeguard
4673 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4674 
4675    Level: advanced
4676 
4677 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4678 
4679 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4680 @*/
4681 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4682 {
4683   SNESKSPEW *kctx;
4684 
4685   PetscFunctionBegin;
4686   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4687   kctx = (SNESKSPEW*)snes->kspconvctx;
4688   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4689   if (version)   *version   = kctx->version;
4690   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4691   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4692   if (gamma)     *gamma     = kctx->gamma;
4693   if (alpha)     *alpha     = kctx->alpha;
4694   if (alpha2)    *alpha2    = kctx->alpha2;
4695   if (threshold) *threshold = kctx->threshold;
4696   PetscFunctionReturn(0);
4697 }
4698 
4699 #undef __FUNCT__
4700 #define __FUNCT__ "KSPPreSolve_SNESEW"
4701  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4702 {
4703   PetscErrorCode ierr;
4704   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4705   PetscReal      rtol  = PETSC_DEFAULT,stol;
4706 
4707   PetscFunctionBegin;
4708   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4709   if (!snes->iter) {
4710     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
4711     ierr = VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);CHKERRQ(ierr);
4712   }
4713   else {
4714     if (kctx->version == 1) {
4715       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4716       if (rtol < 0.0) rtol = -rtol;
4717       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
4718       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4719     } else if (kctx->version == 2) {
4720       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4721       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
4722       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4723     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
4724       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4725       /* safeguard: avoid sharp decrease of rtol */
4726       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
4727       stol = PetscMax(rtol,stol);
4728       rtol = PetscMin(kctx->rtol_0,stol);
4729       /* safeguard: avoid oversolving */
4730       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
4731       stol = PetscMax(rtol,stol);
4732       rtol = PetscMin(kctx->rtol_0,stol);
4733     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4734   }
4735   /* safeguard: avoid rtol greater than one */
4736   rtol = PetscMin(rtol,kctx->rtol_max);
4737   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4738   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);CHKERRQ(ierr);
4739   PetscFunctionReturn(0);
4740 }
4741 
4742 #undef __FUNCT__
4743 #define __FUNCT__ "KSPPostSolve_SNESEW"
4744 PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4745 {
4746   PetscErrorCode ierr;
4747   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4748   PCSide         pcside;
4749   Vec            lres;
4750 
4751   PetscFunctionBegin;
4752   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4753   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4754   kctx->norm_last = snes->norm;
4755   if (kctx->version == 1) {
4756     PC        pc;
4757     PetscBool isNone;
4758 
4759     ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
4760     ierr = PetscObjectTypeCompare((PetscObject) pc, PCNONE, &isNone);CHKERRQ(ierr);
4761     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4762      if (pcside == PC_RIGHT || isNone) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4763       /* KSP residual is true linear residual */
4764       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4765     } else {
4766       /* KSP residual is preconditioned residual */
4767       /* compute true linear residual norm */
4768       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4769       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4770       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4771       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4772       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4773     }
4774   }
4775   PetscFunctionReturn(0);
4776 }
4777 
4778 #undef __FUNCT__
4779 #define __FUNCT__ "SNESGetKSP"
4780 /*@
4781    SNESGetKSP - Returns the KSP context for a SNES solver.
4782 
4783    Not Collective, but if SNES object is parallel, then KSP object is parallel
4784 
4785    Input Parameter:
4786 .  snes - the SNES context
4787 
4788    Output Parameter:
4789 .  ksp - the KSP context
4790 
4791    Notes:
4792    The user can then directly manipulate the KSP context to set various
4793    options, etc.  Likewise, the user can then extract and manipulate the
4794    PC contexts as well.
4795 
4796    Level: beginner
4797 
4798 .keywords: SNES, nonlinear, get, KSP, context
4799 
4800 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
4801 @*/
4802 PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
4803 {
4804   PetscErrorCode ierr;
4805 
4806   PetscFunctionBegin;
4807   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4808   PetscValidPointer(ksp,2);
4809 
4810   if (!snes->ksp) {
4811     PetscBool monitor = PETSC_FALSE;
4812 
4813     ierr = KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);CHKERRQ(ierr);
4814     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);CHKERRQ(ierr);
4815     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);CHKERRQ(ierr);
4816 
4817     ierr = KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);CHKERRQ(ierr);
4818     ierr = KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);CHKERRQ(ierr);
4819 
4820     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes",&monitor,NULL);CHKERRQ(ierr);
4821     if (monitor) {
4822       ierr = KSPMonitorSet(snes->ksp,KSPMonitorSNES,snes,NULL);CHKERRQ(ierr);
4823     }
4824     monitor = PETSC_FALSE;
4825     ierr = PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes_lg",&monitor,NULL);CHKERRQ(ierr);
4826     if (monitor) {
4827       PetscObject *objs;
4828       ierr = KSPMonitorSNESLGResidualNormCreate(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,600,600,&objs);CHKERRQ(ierr);
4829       objs[0] = (PetscObject) snes;
4830       ierr = KSPMonitorSet(snes->ksp,(PetscErrorCode (*)(KSP,PetscInt,PetscReal,void*))KSPMonitorSNESLGResidualNorm,objs,(PetscErrorCode (*)(void**))KSPMonitorSNESLGResidualNormDestroy);CHKERRQ(ierr);
4831     }
4832   }
4833   *ksp = snes->ksp;
4834   PetscFunctionReturn(0);
4835 }
4836 
4837 
4838 #include <petsc/private/dmimpl.h>
4839 #undef __FUNCT__
4840 #define __FUNCT__ "SNESSetDM"
4841 /*@
4842    SNESSetDM - Sets the DM that may be used by some preconditioners
4843 
4844    Logically Collective on SNES
4845 
4846    Input Parameters:
4847 +  snes - the preconditioner context
4848 -  dm - the dm
4849 
4850    Level: intermediate
4851 
4852 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4853 @*/
4854 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4855 {
4856   PetscErrorCode ierr;
4857   KSP            ksp;
4858   DMSNES         sdm;
4859 
4860   PetscFunctionBegin;
4861   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4862   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4863   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4864     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4865       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4866       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4867       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
4868     }
4869     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4870   }
4871   snes->dm     = dm;
4872   snes->dmAuto = PETSC_FALSE;
4873 
4874   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4875   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4876   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4877   if (snes->pc) {
4878     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4879     ierr = SNESSetNPCSide(snes,snes->pcside);CHKERRQ(ierr);
4880   }
4881   PetscFunctionReturn(0);
4882 }
4883 
4884 #undef __FUNCT__
4885 #define __FUNCT__ "SNESGetDM"
4886 /*@
4887    SNESGetDM - Gets the DM that may be used by some preconditioners
4888 
4889    Not Collective but DM obtained is parallel on SNES
4890 
4891    Input Parameter:
4892 . snes - the preconditioner context
4893 
4894    Output Parameter:
4895 .  dm - the dm
4896 
4897    Level: intermediate
4898 
4899 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4900 @*/
4901 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4902 {
4903   PetscErrorCode ierr;
4904 
4905   PetscFunctionBegin;
4906   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4907   if (!snes->dm) {
4908     ierr         = DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);CHKERRQ(ierr);
4909     snes->dmAuto = PETSC_TRUE;
4910   }
4911   *dm = snes->dm;
4912   PetscFunctionReturn(0);
4913 }
4914 
4915 #undef __FUNCT__
4916 #define __FUNCT__ "SNESSetNPC"
4917 /*@
4918   SNESSetNPC - Sets the nonlinear preconditioner to be used.
4919 
4920   Collective on SNES
4921 
4922   Input Parameters:
4923 + snes - iterative context obtained from SNESCreate()
4924 - pc   - the preconditioner object
4925 
4926   Notes:
4927   Use SNESGetNPC() to retrieve the preconditioner context (for example,
4928   to configure it using the API).
4929 
4930   Level: developer
4931 
4932 .keywords: SNES, set, precondition
4933 .seealso: SNESGetNPC(), SNESHasNPC()
4934 @*/
4935 PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
4936 {
4937   PetscErrorCode ierr;
4938 
4939   PetscFunctionBegin;
4940   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4941   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4942   PetscCheckSameComm(snes, 1, pc, 2);
4943   ierr     = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4944   ierr     = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4945   snes->pc = pc;
4946   ierr     = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->pc);CHKERRQ(ierr);
4947   PetscFunctionReturn(0);
4948 }
4949 
4950 #undef __FUNCT__
4951 #define __FUNCT__ "SNESGetNPC"
4952 /*@
4953   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.
4954 
4955   Not Collective
4956 
4957   Input Parameter:
4958 . snes - iterative context obtained from SNESCreate()
4959 
4960   Output Parameter:
4961 . pc - preconditioner context
4962 
4963   Notes: If a SNES was previously set with SNESSetNPC() then that SNES is returned.
4964 
4965   Level: developer
4966 
4967 .keywords: SNES, get, preconditioner
4968 .seealso: SNESSetNPC(), SNESHasNPC()
4969 @*/
4970 PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
4971 {
4972   PetscErrorCode ierr;
4973   const char     *optionsprefix;
4974 
4975   PetscFunctionBegin;
4976   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4977   PetscValidPointer(pc, 2);
4978   if (!snes->pc) {
4979     ierr = SNESCreate(PetscObjectComm((PetscObject)snes),&snes->pc);CHKERRQ(ierr);
4980     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4981     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
4982     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4983     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4984     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4985     ierr = SNESSetCountersReset(snes->pc,PETSC_FALSE);CHKERRQ(ierr);
4986   }
4987   *pc = snes->pc;
4988   PetscFunctionReturn(0);
4989 }
4990 
4991 #undef __FUNCT__
4992 #define __FUNCT__ "SNESHasNPC"
4993 /*@
4994   SNESHasNPC - Returns whether a nonlinear preconditioner exists
4995 
4996   Not Collective
4997 
4998   Input Parameter:
4999 . snes - iterative context obtained from SNESCreate()
5000 
5001   Output Parameter:
5002 . has_npc - whether the SNES has an NPC or not
5003 
5004   Level: developer
5005 
5006 .keywords: SNES, has, preconditioner
5007 .seealso: SNESSetNPC(), SNESGetNPC()
5008 @*/
5009 PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
5010 {
5011   PetscFunctionBegin;
5012   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
5013   *has_npc = (PetscBool) (snes->pc ? PETSC_TRUE : PETSC_FALSE);
5014   PetscFunctionReturn(0);
5015 }
5016 
5017 #undef __FUNCT__
5018 #define __FUNCT__ "SNESSetNPCSide"
5019 /*@
5020     SNESSetNPCSide - Sets the preconditioning side.
5021 
5022     Logically Collective on SNES
5023 
5024     Input Parameter:
5025 .   snes - iterative context obtained from SNESCreate()
5026 
5027     Output Parameter:
5028 .   side - the preconditioning side, where side is one of
5029 .vb
5030       PC_LEFT - left preconditioning (default)
5031       PC_RIGHT - right preconditioning
5032 .ve
5033 
5034     Options Database Keys:
5035 .   -snes_pc_side <right,left>
5036 
5037     Level: intermediate
5038 
5039 .keywords: SNES, set, right, left, side, preconditioner, flag
5040 
5041 .seealso: SNESGetNPCSide(), KSPSetPCSide()
5042 @*/
5043 PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
5044 {
5045   PetscFunctionBegin;
5046   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5047   PetscValidLogicalCollectiveEnum(snes,side,2);
5048   snes->pcside = side;
5049   PetscFunctionReturn(0);
5050 }
5051 
5052 #undef __FUNCT__
5053 #define __FUNCT__ "SNESGetNPCSide"
5054 /*@
5055     SNESGetNPCSide - Gets the preconditioning side.
5056 
5057     Not Collective
5058 
5059     Input Parameter:
5060 .   snes - iterative context obtained from SNESCreate()
5061 
5062     Output Parameter:
5063 .   side - the preconditioning side, where side is one of
5064 .vb
5065       PC_LEFT - left preconditioning (default)
5066       PC_RIGHT - right preconditioning
5067 .ve
5068 
5069     Level: intermediate
5070 
5071 .keywords: SNES, get, right, left, side, preconditioner, flag
5072 
5073 .seealso: SNESSetNPCSide(), KSPGetPCSide()
5074 @*/
5075 PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
5076 {
5077   PetscFunctionBegin;
5078   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5079   PetscValidPointer(side,2);
5080   *side = snes->pcside;
5081   PetscFunctionReturn(0);
5082 }
5083 
5084 #undef __FUNCT__
5085 #define __FUNCT__ "SNESSetLineSearch"
5086 /*@
5087   SNESSetLineSearch - Sets the linesearch on the SNES instance.
5088 
5089   Collective on SNES
5090 
5091   Input Parameters:
5092 + snes - iterative context obtained from SNESCreate()
5093 - linesearch   - the linesearch object
5094 
5095   Notes:
5096   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
5097   to configure it using the API).
5098 
5099   Level: developer
5100 
5101 .keywords: SNES, set, linesearch
5102 .seealso: SNESGetLineSearch()
5103 @*/
5104 PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
5105 {
5106   PetscErrorCode ierr;
5107 
5108   PetscFunctionBegin;
5109   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
5110   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
5111   PetscCheckSameComm(snes, 1, linesearch, 2);
5112   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
5113   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
5114 
5115   snes->linesearch = linesearch;
5116 
5117   ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
5118   PetscFunctionReturn(0);
5119 }
5120 
5121 #undef __FUNCT__
5122 #define __FUNCT__ "SNESGetLineSearch"
5123 /*@
5124   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
5125   or creates a default line search instance associated with the SNES and returns it.
5126 
5127   Not Collective
5128 
5129   Input Parameter:
5130 . snes - iterative context obtained from SNESCreate()
5131 
5132   Output Parameter:
5133 . linesearch - linesearch context
5134 
5135   Level: beginner
5136 
5137 .keywords: SNES, get, linesearch
5138 .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
5139 @*/
5140 PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
5141 {
5142   PetscErrorCode ierr;
5143   const char     *optionsprefix;
5144 
5145   PetscFunctionBegin;
5146   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
5147   PetscValidPointer(linesearch, 2);
5148   if (!snes->linesearch) {
5149     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
5150     ierr = SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);CHKERRQ(ierr);
5151     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
5152     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
5153     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
5154     ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
5155   }
5156   *linesearch = snes->linesearch;
5157   PetscFunctionReturn(0);
5158 }
5159 
5160 #if defined(PETSC_HAVE_MATLAB_ENGINE)
5161 #include <mex.h>
5162 
5163 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
5164 
5165 #undef __FUNCT__
5166 #define __FUNCT__ "SNESComputeFunction_Matlab"
5167 /*
5168    SNESComputeFunction_Matlab - Calls the function that has been set with SNESSetFunctionMatlab().
5169 
5170    Collective on SNES
5171 
5172    Input Parameters:
5173 +  snes - the SNES context
5174 -  x - input vector
5175 
5176    Output Parameter:
5177 .  y - function vector, as set by SNESSetFunction()
5178 
5179    Notes:
5180    SNESComputeFunction() is typically used within nonlinear solvers
5181    implementations, so most users would not generally call this routine
5182    themselves.
5183 
5184    Level: developer
5185 
5186 .keywords: SNES, nonlinear, compute, function
5187 
5188 .seealso: SNESSetFunction(), SNESGetFunction()
5189 */
5190 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
5191 {
5192   PetscErrorCode    ierr;
5193   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5194   int               nlhs  = 1,nrhs = 5;
5195   mxArray           *plhs[1],*prhs[5];
5196   long long int     lx = 0,ly = 0,ls = 0;
5197 
5198   PetscFunctionBegin;
5199   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5200   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
5201   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
5202   PetscCheckSameComm(snes,1,x,2);
5203   PetscCheckSameComm(snes,1,y,3);
5204 
5205   /* call Matlab function in ctx with arguments x and y */
5206 
5207   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5208   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5209   ierr    = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
5210   prhs[0] = mxCreateDoubleScalar((double)ls);
5211   prhs[1] = mxCreateDoubleScalar((double)lx);
5212   prhs[2] = mxCreateDoubleScalar((double)ly);
5213   prhs[3] = mxCreateString(sctx->funcname);
5214   prhs[4] = sctx->ctx;
5215   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
5216   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5217   mxDestroyArray(prhs[0]);
5218   mxDestroyArray(prhs[1]);
5219   mxDestroyArray(prhs[2]);
5220   mxDestroyArray(prhs[3]);
5221   mxDestroyArray(plhs[0]);
5222   PetscFunctionReturn(0);
5223 }
5224 
5225 #undef __FUNCT__
5226 #define __FUNCT__ "SNESSetFunctionMatlab"
5227 /*
5228    SNESSetFunctionMatlab - Sets the function evaluation routine and function
5229    vector for use by the SNES routines in solving systems of nonlinear
5230    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5231 
5232    Logically Collective on SNES
5233 
5234    Input Parameters:
5235 +  snes - the SNES context
5236 .  r - vector to store function value
5237 -  f - function evaluation routine
5238 
5239    Notes:
5240    The Newton-like methods typically solve linear systems of the form
5241 $      f'(x) x = -f(x),
5242    where f'(x) denotes the Jacobian matrix and f(x) is the function.
5243 
5244    Level: beginner
5245 
5246    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5247 
5248 .keywords: SNES, nonlinear, set, function
5249 
5250 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5251 */
5252 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *f,mxArray *ctx)
5253 {
5254   PetscErrorCode    ierr;
5255   SNESMatlabContext *sctx;
5256 
5257   PetscFunctionBegin;
5258   /* currently sctx is memory bleed */
5259   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5260   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5261   /*
5262      This should work, but it doesn't
5263   sctx->ctx = ctx;
5264   mexMakeArrayPersistent(sctx->ctx);
5265   */
5266   sctx->ctx = mxDuplicateArray(ctx);
5267   ierr      = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
5268   PetscFunctionReturn(0);
5269 }
5270 
5271 #undef __FUNCT__
5272 #define __FUNCT__ "SNESComputeJacobian_Matlab"
5273 /*
5274    SNESComputeJacobian_Matlab - Calls the function that has been set with SNESSetJacobianMatlab().
5275 
5276    Collective on SNES
5277 
5278    Input Parameters:
5279 +  snes - the SNES context
5280 .  x - input vector
5281 .  A, B - the matrices
5282 -  ctx - user context
5283 
5284    Level: developer
5285 
5286 .keywords: SNES, nonlinear, compute, function
5287 
5288 .seealso: SNESSetFunction(), SNESGetFunction()
5289 @*/
5290 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat A,Mat B,void *ctx)
5291 {
5292   PetscErrorCode    ierr;
5293   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5294   int               nlhs  = 2,nrhs = 6;
5295   mxArray           *plhs[2],*prhs[6];
5296   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
5297 
5298   PetscFunctionBegin;
5299   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5300   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
5301 
5302   /* call Matlab function in ctx with arguments x and y */
5303 
5304   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5305   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5306   ierr    = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
5307   ierr    = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
5308   prhs[0] = mxCreateDoubleScalar((double)ls);
5309   prhs[1] = mxCreateDoubleScalar((double)lx);
5310   prhs[2] = mxCreateDoubleScalar((double)lA);
5311   prhs[3] = mxCreateDoubleScalar((double)lB);
5312   prhs[4] = mxCreateString(sctx->funcname);
5313   prhs[5] = sctx->ctx;
5314   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
5315   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5316   mxDestroyArray(prhs[0]);
5317   mxDestroyArray(prhs[1]);
5318   mxDestroyArray(prhs[2]);
5319   mxDestroyArray(prhs[3]);
5320   mxDestroyArray(prhs[4]);
5321   mxDestroyArray(plhs[0]);
5322   mxDestroyArray(plhs[1]);
5323   PetscFunctionReturn(0);
5324 }
5325 
5326 #undef __FUNCT__
5327 #define __FUNCT__ "SNESSetJacobianMatlab"
5328 /*
5329    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
5330    vector for use by the SNES routines in solving systems of nonlinear
5331    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5332 
5333    Logically Collective on SNES
5334 
5335    Input Parameters:
5336 +  snes - the SNES context
5337 .  A,B - Jacobian matrices
5338 .  J - function evaluation routine
5339 -  ctx - user context
5340 
5341    Level: developer
5342 
5343    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5344 
5345 .keywords: SNES, nonlinear, set, function
5346 
5347 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction(), J
5348 */
5349 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *J,mxArray *ctx)
5350 {
5351   PetscErrorCode    ierr;
5352   SNESMatlabContext *sctx;
5353 
5354   PetscFunctionBegin;
5355   /* currently sctx is memory bleed */
5356   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5357   ierr = PetscStrallocpy(J,&sctx->funcname);CHKERRQ(ierr);
5358   /*
5359      This should work, but it doesn't
5360   sctx->ctx = ctx;
5361   mexMakeArrayPersistent(sctx->ctx);
5362   */
5363   sctx->ctx = mxDuplicateArray(ctx);
5364   ierr      = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
5365   PetscFunctionReturn(0);
5366 }
5367 
5368 #undef __FUNCT__
5369 #define __FUNCT__ "SNESMonitor_Matlab"
5370 /*
5371    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
5372 
5373    Collective on SNES
5374 
5375 .seealso: SNESSetFunction(), SNESGetFunction()
5376 @*/
5377 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
5378 {
5379   PetscErrorCode    ierr;
5380   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5381   int               nlhs  = 1,nrhs = 6;
5382   mxArray           *plhs[1],*prhs[6];
5383   long long int     lx = 0,ls = 0;
5384   Vec               x  = snes->vec_sol;
5385 
5386   PetscFunctionBegin;
5387   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5388 
5389   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5390   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5391   prhs[0] = mxCreateDoubleScalar((double)ls);
5392   prhs[1] = mxCreateDoubleScalar((double)it);
5393   prhs[2] = mxCreateDoubleScalar((double)fnorm);
5394   prhs[3] = mxCreateDoubleScalar((double)lx);
5395   prhs[4] = mxCreateString(sctx->funcname);
5396   prhs[5] = sctx->ctx;
5397   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
5398   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5399   mxDestroyArray(prhs[0]);
5400   mxDestroyArray(prhs[1]);
5401   mxDestroyArray(prhs[2]);
5402   mxDestroyArray(prhs[3]);
5403   mxDestroyArray(prhs[4]);
5404   mxDestroyArray(plhs[0]);
5405   PetscFunctionReturn(0);
5406 }
5407 
5408 #undef __FUNCT__
5409 #define __FUNCT__ "SNESMonitorSetMatlab"
5410 /*
5411    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
5412 
5413    Level: developer
5414 
5415    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5416 
5417 .keywords: SNES, nonlinear, set, function
5418 
5419 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5420 */
5421 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *f,mxArray *ctx)
5422 {
5423   PetscErrorCode    ierr;
5424   SNESMatlabContext *sctx;
5425 
5426   PetscFunctionBegin;
5427   /* currently sctx is memory bleed */
5428   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5429   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5430   /*
5431      This should work, but it doesn't
5432   sctx->ctx = ctx;
5433   mexMakeArrayPersistent(sctx->ctx);
5434   */
5435   sctx->ctx = mxDuplicateArray(ctx);
5436   ierr      = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,NULL);CHKERRQ(ierr);
5437   PetscFunctionReturn(0);
5438 }
5439 
5440 #endif
5441