xref: /petsc/src/snes/interface/snes.c (revision 94db00eb74dc6785a2cc384ad72a48c28b49492e)
1 
2 #include <petsc/private/snesimpl.h>      /*I "petscsnes.h"  I*/
3 #include <petscdmshell.h>
4 
5 PetscBool         SNESRegisterAllCalled = PETSC_FALSE;
6 PetscFunctionList SNESList              = NULL;
7 
8 /* Logging support */
9 PetscClassId  SNES_CLASSID, DMSNES_CLASSID;
10 PetscLogEvent SNES_Solve, SNES_FunctionEval, SNES_JacobianEval, SNES_NGSEval, SNES_NGSFuncEval, SNES_NPCSolve, SNES_ObjectiveEval;
11 
12 #undef __FUNCT__
13 #define __FUNCT__ "SNESSetErrorIfNotConverged"
14 /*@
15    SNESSetErrorIfNotConverged - Causes SNESSolve() to generate an error if the solver has not converged.
16 
17    Logically Collective on SNES
18 
19    Input Parameters:
20 +  snes - iterative context obtained from SNESCreate()
21 -  flg - PETSC_TRUE indicates you want the error generated
22 
23    Options database keys:
24 .  -snes_error_if_not_converged : this takes an optional truth value (0/1/no/yes/true/false)
25 
26    Level: intermediate
27 
28    Notes:
29     Normally PETSc continues if a linear solver fails to converge, you can call SNESGetConvergedReason() after a SNESSolve()
30     to determine if it has converged.
31 
32 .keywords: SNES, set, initial guess, nonzero
33 
34 .seealso: SNESGetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
35 @*/
36 PetscErrorCode  SNESSetErrorIfNotConverged(SNES snes,PetscBool flg)
37 {
38   PetscFunctionBegin;
39   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
40   PetscValidLogicalCollectiveBool(snes,flg,2);
41   snes->errorifnotconverged = flg;
42   PetscFunctionReturn(0);
43 }
44 
45 #undef __FUNCT__
46 #define __FUNCT__ "SNESGetErrorIfNotConverged"
47 /*@
48    SNESGetErrorIfNotConverged - Will SNESSolve() generate an error if the solver does not converge?
49 
50    Not Collective
51 
52    Input Parameter:
53 .  snes - iterative context obtained from SNESCreate()
54 
55    Output Parameter:
56 .  flag - PETSC_TRUE if it will generate an error, else PETSC_FALSE
57 
58    Level: intermediate
59 
60 .keywords: SNES, set, initial guess, nonzero
61 
62 .seealso:  SNESSetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
63 @*/
64 PetscErrorCode  SNESGetErrorIfNotConverged(SNES snes,PetscBool  *flag)
65 {
66   PetscFunctionBegin;
67   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
68   PetscValidPointer(flag,2);
69   *flag = snes->errorifnotconverged;
70   PetscFunctionReturn(0);
71 }
72 
73 #undef __FUNCT__
74 #define __FUNCT__ "SNESSetFunctionDomainError"
75 /*@
76    SNESSetFunctionDomainError - tells SNES that the input vector to your SNESFunction is not
77      in the functions domain. For example, negative pressure.
78 
79    Logically Collective on SNES
80 
81    Input Parameters:
82 .  snes - the SNES context
83 
84    Level: advanced
85 
86 .keywords: SNES, view
87 
88 .seealso: SNESCreate(), SNESSetFunction(), SNESFunction
89 @*/
90 PetscErrorCode  SNESSetFunctionDomainError(SNES snes)
91 {
92   PetscFunctionBegin;
93   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
94   if (snes->errorifnotconverged) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"User code indicates input vector is not in the function domain");
95   snes->domainerror = PETSC_TRUE;
96   PetscFunctionReturn(0);
97 }
98 
99 #undef __FUNCT__
100 #define __FUNCT__ "SNESGetFunctionDomainError"
101 /*@
102    SNESGetFunctionDomainError - Gets the status of the domain error after a call to SNESComputeFunction;
103 
104    Logically Collective on SNES
105 
106    Input Parameters:
107 .  snes - the SNES context
108 
109    Output Parameters:
110 .  domainerror - Set to PETSC_TRUE if there's a domain error; PETSC_FALSE otherwise.
111 
112    Level: advanced
113 
114 .keywords: SNES, view
115 
116 .seealso: SNESSetFunctionDomainError(), SNESComputeFunction()
117 @*/
118 PetscErrorCode  SNESGetFunctionDomainError(SNES snes, PetscBool *domainerror)
119 {
120   PetscFunctionBegin;
121   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
122   PetscValidPointer(domainerror, 2);
123   *domainerror = snes->domainerror;
124   PetscFunctionReturn(0);
125 }
126 
127 #undef __FUNCT__
128 #define __FUNCT__ "SNESLoad"
129 /*@C
130   SNESLoad - Loads a SNES that has been stored in binary  with SNESView().
131 
132   Collective on PetscViewer
133 
134   Input Parameters:
135 + newdm - the newly loaded SNES, this needs to have been created with SNESCreate() or
136            some related function before a call to SNESLoad().
137 - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()
138 
139    Level: intermediate
140 
141   Notes:
142    The type is determined by the data in the file, any type set into the SNES before this call is ignored.
143 
144   Notes for advanced users:
145   Most users should not need to know the details of the binary storage
146   format, since SNESLoad() and TSView() completely hide these details.
147   But for anyone who's interested, the standard binary matrix storage
148   format is
149 .vb
150      has not yet been determined
151 .ve
152 
153 .seealso: PetscViewerBinaryOpen(), SNESView(), MatLoad(), VecLoad()
154 @*/
155 PetscErrorCode  SNESLoad(SNES snes, PetscViewer viewer)
156 {
157   PetscErrorCode ierr;
158   PetscBool      isbinary;
159   PetscInt       classid;
160   char           type[256];
161   KSP            ksp;
162   DM             dm;
163   DMSNES         dmsnes;
164 
165   PetscFunctionBegin;
166   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
167   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
168   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
169   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");
170 
171   ierr = PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);CHKERRQ(ierr);
172   if (classid != SNES_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONG,"Not SNES next in file");
173   ierr = PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);CHKERRQ(ierr);
174   ierr = SNESSetType(snes, type);CHKERRQ(ierr);
175   if (snes->ops->load) {
176     ierr = (*snes->ops->load)(snes,viewer);CHKERRQ(ierr);
177   }
178   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
179   ierr = DMGetDMSNES(dm,&dmsnes);CHKERRQ(ierr);
180   ierr = DMSNESLoad(dmsnes,viewer);CHKERRQ(ierr);
181   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
182   ierr = KSPLoad(ksp,viewer);CHKERRQ(ierr);
183   PetscFunctionReturn(0);
184 }
185 
186 #include <petscdraw.h>
187 #if defined(PETSC_HAVE_SAWS)
188 #include <petscviewersaws.h>
189 #endif
190 #undef __FUNCT__
191 #define __FUNCT__ "SNESView"
192 /*@C
193    SNESView - Prints the SNES data structure.
194 
195    Collective on SNES
196 
197    Input Parameters:
198 +  SNES - the SNES context
199 -  viewer - visualization context
200 
201    Options Database Key:
202 .  -snes_view - Calls SNESView() at end of SNESSolve()
203 
204    Notes:
205    The available visualization contexts include
206 +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
207 -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
208          output where only the first processor opens
209          the file.  All other processors send their
210          data to the first processor to print.
211 
212    The user can open an alternative visualization context with
213    PetscViewerASCIIOpen() - output to a specified file.
214 
215    Level: beginner
216 
217 .keywords: SNES, view
218 
219 .seealso: PetscViewerASCIIOpen()
220 @*/
221 PetscErrorCode  SNESView(SNES snes,PetscViewer viewer)
222 {
223   SNESKSPEW      *kctx;
224   PetscErrorCode ierr;
225   KSP            ksp;
226   SNESLineSearch linesearch;
227   PetscBool      iascii,isstring,isbinary,isdraw;
228   DMSNES         dmsnes;
229 #if defined(PETSC_HAVE_SAWS)
230   PetscBool      issaws;
231 #endif
232 
233   PetscFunctionBegin;
234   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
235   if (!viewer) {
236     ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&viewer);CHKERRQ(ierr);
237   }
238   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
239   PetscCheckSameComm(snes,1,viewer,2);
240 
241   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
242   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
243   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
244   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);CHKERRQ(ierr);
245 #if defined(PETSC_HAVE_SAWS)
246   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&issaws);CHKERRQ(ierr);
247 #endif
248   if (iascii) {
249     SNESNormSchedule normschedule;
250 
251     ierr = PetscObjectPrintClassNamePrefixType((PetscObject)snes,viewer);CHKERRQ(ierr);
252     if (!snes->setupcalled) {
253       ierr = PetscViewerASCIIPrintf(viewer,"  SNES has not been set up so information may be incomplete\n");CHKERRQ(ierr);
254     }
255     if (snes->ops->view) {
256       ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
257       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
258       ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
259     }
260     ierr = PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, maximum function evaluations=%D\n",snes->max_its,snes->max_funcs);CHKERRQ(ierr);
261     ierr = PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%g, absolute=%g, solution=%g\n",(double)snes->rtol,(double)snes->abstol,(double)snes->stol);CHKERRQ(ierr);
262     ierr = PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",snes->linear_its);CHKERRQ(ierr);
263     ierr = PetscViewerASCIIPrintf(viewer,"  total number of function evaluations=%D\n",snes->nfuncs);CHKERRQ(ierr);
264     ierr = SNESGetNormSchedule(snes, &normschedule);CHKERRQ(ierr);
265     if (normschedule > 0) {ierr = PetscViewerASCIIPrintf(viewer,"  norm schedule %s\n",SNESNormSchedules[normschedule]);CHKERRQ(ierr);}
266     if (snes->gridsequence) {
267       ierr = PetscViewerASCIIPrintf(viewer,"  total number of grid sequence refinements=%D\n",snes->gridsequence);CHKERRQ(ierr);
268     }
269     if (snes->ksp_ewconv) {
270       kctx = (SNESKSPEW*)snes->kspconvctx;
271       if (kctx) {
272         ierr = PetscViewerASCIIPrintf(viewer,"  Eisenstat-Walker computation of KSP relative tolerance (version %D)\n",kctx->version);CHKERRQ(ierr);
273         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);
274         ierr = PetscViewerASCIIPrintf(viewer,"    gamma=%g, alpha=%g, alpha2=%g\n",(double)kctx->gamma,(double)kctx->alpha,(double)kctx->alpha2);CHKERRQ(ierr);
275       }
276     }
277     if (snes->lagpreconditioner == -1) {
278       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is never rebuilt\n");CHKERRQ(ierr);
279     } else if (snes->lagpreconditioner > 1) {
280       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is rebuilt every %D new Jacobians\n",snes->lagpreconditioner);CHKERRQ(ierr);
281     }
282     if (snes->lagjacobian == -1) {
283       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is never rebuilt\n");CHKERRQ(ierr);
284     } else if (snes->lagjacobian > 1) {
285       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is rebuilt every %D SNES iterations\n",snes->lagjacobian);CHKERRQ(ierr);
286     }
287   } else if (isstring) {
288     const char *type;
289     ierr = SNESGetType(snes,&type);CHKERRQ(ierr);
290     ierr = PetscViewerStringSPrintf(viewer," %-3.3s",type);CHKERRQ(ierr);
291   } else if (isbinary) {
292     PetscInt    classid = SNES_FILE_CLASSID;
293     MPI_Comm    comm;
294     PetscMPIInt rank;
295     char        type[256];
296 
297     ierr = PetscObjectGetComm((PetscObject)snes,&comm);CHKERRQ(ierr);
298     ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
299     if (!rank) {
300       ierr = PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);CHKERRQ(ierr);
301       ierr = PetscStrncpy(type,((PetscObject)snes)->type_name,sizeof(type));CHKERRQ(ierr);
302       ierr = PetscViewerBinaryWrite(viewer,type,sizeof(type),PETSC_CHAR,PETSC_FALSE);CHKERRQ(ierr);
303     }
304     if (snes->ops->view) {
305       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
306     }
307   } else if (isdraw) {
308     PetscDraw draw;
309     char      str[36];
310     PetscReal x,y,bottom,h;
311 
312     ierr   = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
313     ierr   = PetscDrawGetCurrentPoint(draw,&x,&y);CHKERRQ(ierr);
314     ierr   = PetscStrcpy(str,"SNES: ");CHKERRQ(ierr);
315     ierr   = PetscStrcat(str,((PetscObject)snes)->type_name);CHKERRQ(ierr);
316     ierr   = PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_BLUE,PETSC_DRAW_BLACK,str,NULL,&h);CHKERRQ(ierr);
317     bottom = y - h;
318     ierr   = PetscDrawPushCurrentPoint(draw,x,bottom);CHKERRQ(ierr);
319     if (snes->ops->view) {
320       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
321     }
322 #if defined(PETSC_HAVE_SAWS)
323   } else if (issaws) {
324     PetscMPIInt rank;
325     const char *name;
326 
327     ierr = PetscObjectGetName((PetscObject)snes,&name);CHKERRQ(ierr);
328     ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRQ(ierr);
329     if (!((PetscObject)snes)->amsmem && !rank) {
330       char       dir[1024];
331 
332       ierr = PetscObjectViewSAWs((PetscObject)snes,viewer);CHKERRQ(ierr);
333       ierr = PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);CHKERRQ(ierr);
334       PetscStackCallSAWs(SAWs_Register,(dir,&snes->iter,1,SAWs_READ,SAWs_INT));
335       if (!snes->conv_hist) {
336         ierr = SNESSetConvergenceHistory(snes,NULL,NULL,PETSC_DECIDE,PETSC_TRUE);CHKERRQ(ierr);
337       }
338       ierr = PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/conv_hist",name);CHKERRQ(ierr);
339       PetscStackCallSAWs(SAWs_Register,(dir,snes->conv_hist,10,SAWs_READ,SAWs_DOUBLE));
340     }
341 #endif
342   }
343   if (snes->linesearch) {
344     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
345     ierr = SNESGetLineSearch(snes, &linesearch);CHKERRQ(ierr);
346     ierr = SNESLineSearchView(linesearch, viewer);CHKERRQ(ierr);
347     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
348   }
349   if (snes->pc && snes->usespc) {
350     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
351     ierr = SNESView(snes->pc, viewer);CHKERRQ(ierr);
352     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
353   }
354   ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
355   ierr = DMGetDMSNES(snes->dm,&dmsnes);CHKERRQ(ierr);
356   ierr = DMSNESView(dmsnes, viewer);CHKERRQ(ierr);
357   ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
358   if (snes->usesksp) {
359     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
360     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
361     ierr = KSPView(ksp,viewer);CHKERRQ(ierr);
362     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
363   }
364   if (isdraw) {
365     PetscDraw draw;
366     ierr = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
367     ierr = PetscDrawPopCurrentPoint(draw);CHKERRQ(ierr);
368   }
369   PetscFunctionReturn(0);
370 }
371 
372 /*
373   We retain a list of functions that also take SNES command
374   line options. These are called at the end SNESSetFromOptions()
375 */
376 #define MAXSETFROMOPTIONS 5
377 static PetscInt numberofsetfromoptions;
378 static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);
379 
380 #undef __FUNCT__
381 #define __FUNCT__ "SNESAddOptionsChecker"
382 /*@C
383   SNESAddOptionsChecker - Adds an additional function to check for SNES options.
384 
385   Not Collective
386 
387   Input Parameter:
388 . snescheck - function that checks for options
389 
390   Level: developer
391 
392 .seealso: SNESSetFromOptions()
393 @*/
394 PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
395 {
396   PetscFunctionBegin;
397   if (numberofsetfromoptions >= MAXSETFROMOPTIONS) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %D allowed", MAXSETFROMOPTIONS);
398   othersetfromoptions[numberofsetfromoptions++] = snescheck;
399   PetscFunctionReturn(0);
400 }
401 
402 extern PetscErrorCode  SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);
403 
404 #undef __FUNCT__
405 #define __FUNCT__ "SNESSetUpMatrixFree_Private"
406 static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
407 {
408   Mat            J;
409   KSP            ksp;
410   PC             pc;
411   PetscBool      match;
412   PetscErrorCode ierr;
413   MatNullSpace   nullsp;
414 
415   PetscFunctionBegin;
416   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
417 
418   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
419     Mat A = snes->jacobian, B = snes->jacobian_pre;
420     ierr = MatCreateVecs(A ? A : B, NULL,&snes->vec_func);CHKERRQ(ierr);
421   }
422 
423   if (version == 1) {
424     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
425     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
426     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
427   } else if (version == 2) {
428     if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
429 #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128)
430     ierr = SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);CHKERRQ(ierr);
431 #else
432     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator rutines (version 2)");
433 #endif
434   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator rutines, only version 1 and 2");
435 
436   /* attach any user provided null space that was on Amat to the newly created matrix free matrix */
437   if (snes->jacobian) {
438     ierr = MatGetNullSpace(snes->jacobian,&nullsp);CHKERRQ(ierr);
439     if (nullsp) {
440       ierr = MatSetNullSpace(J,nullsp);CHKERRQ(ierr);
441     }
442   }
443 
444   ierr = PetscInfo1(snes,"Setting default matrix-free operator routines (version %D)\n", version);CHKERRQ(ierr);
445   if (hasOperator) {
446 
447     /* This version replaces the user provided Jacobian matrix with a
448        matrix-free version but still employs the user-provided preconditioner matrix. */
449     ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);
450   } else {
451     /* This version replaces both the user-provided Jacobian and the user-
452      provided preconditioner Jacobian with the default matrix free version. */
453     if ((snes->pcside == PC_LEFT) && snes->pc) {
454       if (!snes->jacobian){ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);}
455     } else {
456       ierr = SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,0);CHKERRQ(ierr);
457     }
458     /* Force no preconditioner */
459     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
460     ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
461     ierr = PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);CHKERRQ(ierr);
462     if (!match) {
463       ierr = PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");CHKERRQ(ierr);
464       ierr = PCSetType(pc,PCNONE);CHKERRQ(ierr);
465     }
466   }
467   ierr = MatDestroy(&J);CHKERRQ(ierr);
468   PetscFunctionReturn(0);
469 }
470 
471 #undef __FUNCT__
472 #define __FUNCT__ "DMRestrictHook_SNESVecSol"
473 static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
474 {
475   SNES           snes = (SNES)ctx;
476   PetscErrorCode ierr;
477   Vec            Xfine,Xfine_named = NULL,Xcoarse;
478 
479   PetscFunctionBegin;
480   if (PetscLogPrintInfo) {
481     PetscInt finelevel,coarselevel,fineclevel,coarseclevel;
482     ierr = DMGetRefineLevel(dmfine,&finelevel);CHKERRQ(ierr);
483     ierr = DMGetCoarsenLevel(dmfine,&fineclevel);CHKERRQ(ierr);
484     ierr = DMGetRefineLevel(dmcoarse,&coarselevel);CHKERRQ(ierr);
485     ierr = DMGetCoarsenLevel(dmcoarse,&coarseclevel);CHKERRQ(ierr);
486     ierr = PetscInfo4(dmfine,"Restricting SNES solution vector from level %D-%D to level %D-%D\n",finelevel,fineclevel,coarselevel,coarseclevel);CHKERRQ(ierr);
487   }
488   if (dmfine == snes->dm) Xfine = snes->vec_sol;
489   else {
490     ierr  = DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);
491     Xfine = Xfine_named;
492   }
493   ierr = DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
494   if (Inject) {
495     ierr = MatRestrict(Inject,Xfine,Xcoarse);CHKERRQ(ierr);
496   } else {
497     ierr = MatRestrict(Restrict,Xfine,Xcoarse);CHKERRQ(ierr);
498     ierr = VecPointwiseMult(Xcoarse,Xcoarse,Rscale);CHKERRQ(ierr);
499   }
500   ierr = DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
501   if (Xfine_named) {ierr = DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);}
502   PetscFunctionReturn(0);
503 }
504 
505 #undef __FUNCT__
506 #define __FUNCT__ "DMCoarsenHook_SNESVecSol"
507 static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm,DM dmc,void *ctx)
508 {
509   PetscErrorCode ierr;
510 
511   PetscFunctionBegin;
512   ierr = DMCoarsenHookAdd(dmc,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,ctx);CHKERRQ(ierr);
513   PetscFunctionReturn(0);
514 }
515 
516 #undef __FUNCT__
517 #define __FUNCT__ "KSPComputeOperators_SNES"
518 /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
519  * safely call SNESGetDM() in their residual evaluation routine. */
520 static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,void *ctx)
521 {
522   SNES           snes = (SNES)ctx;
523   PetscErrorCode ierr;
524   Mat            Asave = A,Bsave = B;
525   Vec            X,Xnamed = NULL;
526   DM             dmsave;
527   void           *ctxsave;
528   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
529 
530   PetscFunctionBegin;
531   dmsave = snes->dm;
532   ierr   = KSPGetDM(ksp,&snes->dm);CHKERRQ(ierr);
533   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
534   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
535     ierr = DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
536     X    = Xnamed;
537     ierr = SNESGetJacobian(snes,NULL,NULL,&jac,&ctxsave);CHKERRQ(ierr);
538     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
539     if (jac == SNESComputeJacobianDefaultColor) {
540       ierr = SNESSetJacobian(snes,NULL,NULL,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
541     }
542   }
543   /* put the previous context back */
544 
545   ierr = SNESComputeJacobian(snes,X,A,B);CHKERRQ(ierr);
546   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) {
547     ierr = SNESSetJacobian(snes,NULL,NULL,jac,ctxsave);CHKERRQ(ierr);
548   }
549 
550   if (A != Asave || B != Bsave) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_SUP,"No support for changing matrices at this time");
551   if (Xnamed) {
552     ierr = DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
553   }
554   snes->dm = dmsave;
555   PetscFunctionReturn(0);
556 }
557 
558 #undef __FUNCT__
559 #define __FUNCT__ "SNESSetUpMatrices"
560 /*@
561    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()
562 
563    Collective
564 
565    Input Arguments:
566 .  snes - snes to configure
567 
568    Level: developer
569 
570 .seealso: SNESSetUp()
571 @*/
572 PetscErrorCode SNESSetUpMatrices(SNES snes)
573 {
574   PetscErrorCode ierr;
575   DM             dm;
576   DMSNES         sdm;
577 
578   PetscFunctionBegin;
579   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
580   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
581   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_PLIB,"DMSNES not properly configured");
582   else if (!snes->jacobian && snes->mf) {
583     Mat  J;
584     void *functx;
585     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
586     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
587     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
588     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
589     ierr = SNESSetJacobian(snes,J,J,0,0);CHKERRQ(ierr);
590     ierr = MatDestroy(&J);CHKERRQ(ierr);
591   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
592     Mat J,B;
593     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
594     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
595     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
596     ierr = DMCreateMatrix(snes->dm,&B);CHKERRQ(ierr);
597     /* sdm->computejacobian was already set to reach here */
598     ierr = SNESSetJacobian(snes,J,B,NULL,NULL);CHKERRQ(ierr);
599     ierr = MatDestroy(&J);CHKERRQ(ierr);
600     ierr = MatDestroy(&B);CHKERRQ(ierr);
601   } else if (!snes->jacobian_pre) {
602     Mat J,B;
603     J    = snes->jacobian;
604     ierr = DMCreateMatrix(snes->dm,&B);CHKERRQ(ierr);
605     ierr = SNESSetJacobian(snes,J ? J : B,B,NULL,NULL);CHKERRQ(ierr);
606     ierr = MatDestroy(&B);CHKERRQ(ierr);
607   }
608   {
609     KSP ksp;
610     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
611     ierr = KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);CHKERRQ(ierr);
612     ierr = DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);CHKERRQ(ierr);
613   }
614   PetscFunctionReturn(0);
615 }
616 
617 #undef __FUNCT__
618 #define __FUNCT__ "SNESSetFromOptions"
619 /*@
620    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.
621 
622    Collective on SNES
623 
624    Input Parameter:
625 .  snes - the SNES context
626 
627    Options Database Keys:
628 +  -snes_type <type> - newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas, SNESType for complete list
629 .  -snes_stol - convergence tolerance in terms of the norm
630                 of the change in the solution between steps
631 .  -snes_atol <abstol> - absolute tolerance of residual norm
632 .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
633 .  -snes_max_it <max_it> - maximum number of iterations
634 .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
635 .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
636 .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
637 .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
638 .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
639 .  -snes_trtol <trtol> - trust region tolerance
640 .  -snes_no_convergence_test - skip convergence test in nonlinear
641                                solver; hence iterations will continue until max_it
642                                or some other criterion is reached. Saves expense
643                                of convergence test
644 .  -snes_monitor <optional filename> - prints residual norm at each iteration. if no
645                                        filename given prints to stdout
646 .  -snes_monitor_solution - plots solution at each iteration
647 .  -snes_monitor_residual - plots residual (not its norm) at each iteration
648 .  -snes_monitor_solution_update - plots update to solution at each iteration
649 .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
650 .  -snes_monitor_lg_range - plots residual norm at each iteration
651 .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
652 .  -snes_fd_color - use finite differences with coloring to compute Jacobian
653 .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
654 -  -snes_converged_reason - print the reason for convergence/divergence after each solve
655 
656     Options Database for Eisenstat-Walker method:
657 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
658 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
659 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
660 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
661 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
662 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
663 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
664 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
665 
666    Notes:
667    To see all options, run your program with the -help option or consult
668    Users-Manual: ch_snes
669 
670    Level: beginner
671 
672 .keywords: SNES, nonlinear, set, options, database
673 
674 .seealso: SNESSetOptionsPrefix()
675 @*/
676 PetscErrorCode  SNESSetFromOptions(SNES snes)
677 {
678   PetscBool      flg,pcset,persist,set;
679   PetscInt       i,indx,lag,grids;
680   const char     *deft        = SNESNEWTONLS;
681   const char     *convtests[] = {"default","skip"};
682   SNESKSPEW      *kctx        = NULL;
683   char           type[256], monfilename[PETSC_MAX_PATH_LEN];
684   PetscViewer    monviewer;
685   PetscErrorCode ierr;
686   PCSide         pcside;
687   const char     *optionsprefix;
688 
689   PetscFunctionBegin;
690   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
691   ierr = SNESRegisterAll();CHKERRQ(ierr);
692   ierr = PetscObjectOptionsBegin((PetscObject)snes);CHKERRQ(ierr);
693   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
694   ierr = PetscOptionsFList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);CHKERRQ(ierr);
695   if (flg) {
696     ierr = SNESSetType(snes,type);CHKERRQ(ierr);
697   } else if (!((PetscObject)snes)->type_name) {
698     ierr = SNESSetType(snes,deft);CHKERRQ(ierr);
699   }
700   ierr = PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,NULL);CHKERRQ(ierr);
701   ierr = PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,NULL);CHKERRQ(ierr);
702 
703   ierr = PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,NULL);CHKERRQ(ierr);
704   ierr = PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,NULL);CHKERRQ(ierr);
705   ierr = PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,NULL);CHKERRQ(ierr);
706   ierr = PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,NULL);CHKERRQ(ierr);
707   ierr = PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,NULL);CHKERRQ(ierr);
708   ierr = PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,NULL);CHKERRQ(ierr);
709 
710   ierr = PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);CHKERRQ(ierr);
711   if (flg) {
712     ierr = SNESSetLagPreconditioner(snes,lag);CHKERRQ(ierr);
713   }
714   ierr = PetscOptionsBool("-snes_lag_preconditioner_persists","Preconditioner lagging through multiple solves","SNESSetLagPreconditionerPersists",snes->lagjac_persist,&persist,&flg);CHKERRQ(ierr);
715   if (flg) {
716     ierr = SNESSetLagPreconditionerPersists(snes,persist);CHKERRQ(ierr);
717   }
718   ierr = PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);CHKERRQ(ierr);
719   if (flg) {
720     ierr = SNESSetLagJacobian(snes,lag);CHKERRQ(ierr);
721   }
722   ierr = PetscOptionsBool("-snes_lag_jacobian_persists","Jacobian lagging through multiple solves","SNESSetLagJacobianPersists",snes->lagjac_persist,&persist,&flg);CHKERRQ(ierr);
723   if (flg) {
724     ierr = SNESSetLagJacobianPersists(snes,persist);CHKERRQ(ierr);
725   }
726 
727   ierr = PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);CHKERRQ(ierr);
728   if (flg) {
729     ierr = SNESSetGridSequence(snes,grids);CHKERRQ(ierr);
730   }
731 
732   ierr = PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);CHKERRQ(ierr);
733   if (flg) {
734     switch (indx) {
735     case 0: ierr = SNESSetConvergenceTest(snes,SNESConvergedDefault,NULL,NULL);CHKERRQ(ierr); break;
736     case 1: ierr = SNESSetConvergenceTest(snes,SNESConvergedSkip,NULL,NULL);CHKERRQ(ierr);    break;
737     }
738   }
739 
740   ierr = PetscOptionsEList("-snes_norm_schedule","SNES Norm schedule","SNESSetNormSchedule",SNESNormSchedules,5,"function",&indx,&flg);CHKERRQ(ierr);
741   if (flg) { ierr = SNESSetNormSchedule(snes,(SNESNormSchedule)indx);CHKERRQ(ierr); }
742 
743   ierr = PetscOptionsEList("-snes_function_type","SNES Norm schedule","SNESSetFunctionType",SNESFunctionTypes,2,"unpreconditioned",&indx,&flg);CHKERRQ(ierr);
744   if (flg) { ierr = SNESSetFunctionType(snes,(SNESFunctionType)indx);CHKERRQ(ierr); }
745 
746   kctx = (SNESKSPEW*)snes->kspconvctx;
747 
748   ierr = PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,NULL);CHKERRQ(ierr);
749 
750   ierr = PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,NULL);CHKERRQ(ierr);
751   ierr = PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,NULL);CHKERRQ(ierr);
752   ierr = PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,NULL);CHKERRQ(ierr);
753   ierr = PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,NULL);CHKERRQ(ierr);
754   ierr = PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,NULL);CHKERRQ(ierr);
755   ierr = PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,NULL);CHKERRQ(ierr);
756   ierr = PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,NULL);CHKERRQ(ierr);
757 
758   flg  = PETSC_FALSE;
759   ierr = PetscOptionsBool("-snes_check_jacobian","Check each Jacobian with a differenced one","SNESUpdateCheckJacobian",flg,&flg,&set);CHKERRQ(ierr);
760   if (set && flg) {
761     ierr = SNESSetUpdate(snes,SNESUpdateCheckJacobian);CHKERRQ(ierr);
762   }
763 
764   flg  = PETSC_FALSE;
765   ierr = PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,&set);CHKERRQ(ierr);
766   if (set && flg) {ierr = SNESMonitorCancel(snes);CHKERRQ(ierr);}
767 
768   ierr = PetscOptionsString("-snes_monitor","Monitor norm of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
769   if (flg) {
770     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
771     ierr = SNESMonitorSet(snes,SNESMonitorDefault,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
772   }
773 
774   ierr = PetscOptionsString("-snes_monitor_range","Monitor range of elements of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
775   if (flg) {
776     ierr = SNESMonitorSet(snes,SNESMonitorRange,0,0);CHKERRQ(ierr);
777   }
778 
779   ierr = PetscOptionsString("-snes_ratiomonitor","Monitor ratios of norms of function","SNESMonitorSetRatio","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
780   if (flg) {
781     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
782     ierr = SNESMonitorSetRatio(snes,monviewer);CHKERRQ(ierr);
783   }
784 
785   ierr = PetscOptionsString("-snes_monitor_short","Monitor norm of function (fewer digits)","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
786   if (flg) {
787     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
788     ierr = SNESMonitorSet(snes,SNESMonitorDefaultShort,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
789   }
790 
791   ierr = PetscOptionsString("-snes_monitor_field","Monitor norm of function (split into fields)","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
792   if (flg) {
793     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
794     ierr = SNESMonitorSet(snes,SNESMonitorDefaultField,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
795   }
796 
797   ierr = PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
798   if (flg) {ierr = PetscPythonMonitorSet((PetscObject)snes,monfilename);CHKERRQ(ierr);}
799 
800   flg  = PETSC_FALSE;
801   ierr = PetscOptionsBool("-snes_monitor_solution","Plot solution at each iteration","SNESMonitorSolution",flg,&flg,NULL);CHKERRQ(ierr);
802   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolution,0,0);CHKERRQ(ierr);}
803   flg  = PETSC_FALSE;
804   ierr = PetscOptionsBool("-snes_monitor_solution_update","Plot correction at each iteration","SNESMonitorSolutionUpdate",flg,&flg,NULL);CHKERRQ(ierr);
805   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolutionUpdate,0,0);CHKERRQ(ierr);}
806   flg  = PETSC_FALSE;
807   ierr = PetscOptionsBool("-snes_monitor_residual","Plot residual at each iteration","SNESMonitorResidual",flg,&flg,NULL);CHKERRQ(ierr);
808   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorResidual,0,0);CHKERRQ(ierr);}
809   flg  = PETSC_FALSE;
810   ierr = PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,NULL);CHKERRQ(ierr);
811   if (flg) {
812     PetscObject *objs;
813 
814     ierr = SNESMonitorLGCreate(0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&objs);CHKERRQ(ierr);
815     ierr = SNESMonitorSet(snes,(PetscErrorCode (*)(SNES,PetscInt,PetscReal,void*))SNESMonitorLGResidualNorm,objs,(PetscErrorCode (*)(void**))SNESMonitorLGDestroy);CHKERRQ(ierr);
816   }
817   flg  = PETSC_FALSE;
818   ierr = PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);CHKERRQ(ierr);
819   if (flg) {
820     PetscViewer ctx;
821 
822     ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
823     ierr = SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
824   }
825 
826   flg  = PETSC_FALSE;
827   ierr = PetscOptionsBool("-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",flg,&flg,NULL);CHKERRQ(ierr);
828   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorJacUpdateSpectrum,0,0);CHKERRQ(ierr);}
829 
830 
831   ierr = PetscOptionsString("-snes_monitor_fields","Monitor norm of function per field","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
832   if (flg) {
833     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
834     ierr = SNESMonitorSet(snes,SNESMonitorFields,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
835   }
836 
837   flg  = PETSC_FALSE;
838   ierr = PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);CHKERRQ(ierr);
839   if (flg) {
840     void *functx;
841     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
842     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);CHKERRQ(ierr);
843     ierr = PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");CHKERRQ(ierr);
844   }
845 
846   flg  = PETSC_FALSE;
847   ierr = PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);CHKERRQ(ierr);
848   if (flg) {
849     ierr = SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);CHKERRQ(ierr);
850   }
851 
852   flg  = PETSC_FALSE;
853   ierr = PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);CHKERRQ(ierr);
854   if (flg) {
855     DM             dm;
856     DMSNES         sdm;
857     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
858     ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
859     sdm->jacobianctx = NULL;
860     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
861     ierr = PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");CHKERRQ(ierr);
862   }
863 
864   flg  = PETSC_FALSE;
865   ierr = PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf_operator,&flg);CHKERRQ(ierr);
866   if (flg && snes->mf_operator) {
867     snes->mf_operator = PETSC_TRUE;
868     snes->mf          = PETSC_TRUE;
869   }
870   flg  = PETSC_FALSE;
871   ierr = PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf,&flg);CHKERRQ(ierr);
872   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
873   ierr = PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,0);CHKERRQ(ierr);
874 
875   flg  = PETSC_FALSE;
876   ierr = SNESGetNPCSide(snes,&pcside);CHKERRQ(ierr);
877   ierr = PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetNPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);CHKERRQ(ierr);
878   if (flg) {ierr = SNESSetNPCSide(snes,pcside);CHKERRQ(ierr);}
879 
880 #if defined(PETSC_HAVE_SAWS)
881   /*
882     Publish convergence information using SAWs
883   */
884   flg  = PETSC_FALSE;
885   ierr = PetscOptionsBool("-snes_monitor_saws","Publish SNES progress using SAWs","SNESMonitorSet",flg,&flg,NULL);CHKERRQ(ierr);
886   if (flg) {
887     void *ctx;
888     ierr = SNESMonitorSAWsCreate(snes,&ctx);CHKERRQ(ierr);
889     ierr = SNESMonitorSet(snes,SNESMonitorSAWs,ctx,SNESMonitorSAWsDestroy);CHKERRQ(ierr);
890   }
891 #endif
892 #if defined(PETSC_HAVE_SAWS)
893   {
894   PetscBool set;
895   flg  = PETSC_FALSE;
896   ierr = PetscOptionsBool("-snes_saws_block","Block for SAWs at end of SNESSolve","PetscObjectSAWsBlock",((PetscObject)snes)->amspublishblock,&flg,&set);CHKERRQ(ierr);
897   if (set) {
898     ierr = PetscObjectSAWsSetBlock((PetscObject)snes,flg);CHKERRQ(ierr);
899   }
900   }
901 #endif
902 
903   for (i = 0; i < numberofsetfromoptions; i++) {
904     ierr = (*othersetfromoptions[i])(snes);CHKERRQ(ierr);
905   }
906 
907   if (snes->ops->setfromoptions) {
908     ierr = (*snes->ops->setfromoptions)(PetscOptionsObject,snes);CHKERRQ(ierr);
909   }
910 
911   /* process any options handlers added with PetscObjectAddOptionsHandler() */
912   ierr = PetscObjectProcessOptionsHandlers((PetscObject)snes);CHKERRQ(ierr);
913   ierr = PetscOptionsEnd();CHKERRQ(ierr);
914 
915   if (!snes->linesearch) {
916     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
917   }
918   ierr = SNESLineSearchSetFromOptions(snes->linesearch);CHKERRQ(ierr);
919 
920   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
921   ierr = KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);CHKERRQ(ierr);
922   ierr = KSPSetFromOptions(snes->ksp);CHKERRQ(ierr);
923 
924   /* if someone has set the SNES NPC type, create it. */
925   ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
926   ierr = PetscOptionsHasName(optionsprefix, "-npc_snes_type", &pcset);CHKERRQ(ierr);
927   if (pcset && (!snes->pc)) {
928     ierr = SNESGetNPC(snes, &snes->pc);CHKERRQ(ierr);
929   }
930   PetscFunctionReturn(0);
931 }
932 
933 #undef __FUNCT__
934 #define __FUNCT__ "SNESSetComputeApplicationContext"
935 /*@C
936    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
937    the nonlinear solvers.
938 
939    Logically Collective on SNES
940 
941    Input Parameters:
942 +  snes - the SNES context
943 .  compute - function to compute the context
944 -  destroy - function to destroy the context
945 
946    Level: intermediate
947 
948    Notes:
949    This function is currently not available from Fortran.
950 
951 .keywords: SNES, nonlinear, set, application, context
952 
953 .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
954 @*/
955 PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
956 {
957   PetscFunctionBegin;
958   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
959   snes->ops->usercompute = compute;
960   snes->ops->userdestroy = destroy;
961   PetscFunctionReturn(0);
962 }
963 
964 #undef __FUNCT__
965 #define __FUNCT__ "SNESSetApplicationContext"
966 /*@
967    SNESSetApplicationContext - Sets the optional user-defined context for
968    the nonlinear solvers.
969 
970    Logically Collective on SNES
971 
972    Input Parameters:
973 +  snes - the SNES context
974 -  usrP - optional user context
975 
976    Level: intermediate
977 
978 .keywords: SNES, nonlinear, set, application, context
979 
980 .seealso: SNESGetApplicationContext()
981 @*/
982 PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
983 {
984   PetscErrorCode ierr;
985   KSP            ksp;
986 
987   PetscFunctionBegin;
988   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
989   ierr       = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
990   ierr       = KSPSetApplicationContext(ksp,usrP);CHKERRQ(ierr);
991   snes->user = usrP;
992   PetscFunctionReturn(0);
993 }
994 
995 #undef __FUNCT__
996 #define __FUNCT__ "SNESGetApplicationContext"
997 /*@
998    SNESGetApplicationContext - Gets the user-defined context for the
999    nonlinear solvers.
1000 
1001    Not Collective
1002 
1003    Input Parameter:
1004 .  snes - SNES context
1005 
1006    Output Parameter:
1007 .  usrP - user context
1008 
1009    Level: intermediate
1010 
1011 .keywords: SNES, nonlinear, get, application, context
1012 
1013 .seealso: SNESSetApplicationContext()
1014 @*/
1015 PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
1016 {
1017   PetscFunctionBegin;
1018   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1019   *(void**)usrP = snes->user;
1020   PetscFunctionReturn(0);
1021 }
1022 
1023 #undef __FUNCT__
1024 #define __FUNCT__ "SNESGetIterationNumber"
1025 /*@
1026    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
1027    at this time.
1028 
1029    Not Collective
1030 
1031    Input Parameter:
1032 .  snes - SNES context
1033 
1034    Output Parameter:
1035 .  iter - iteration number
1036 
1037    Notes:
1038    For example, during the computation of iteration 2 this would return 1.
1039 
1040    This is useful for using lagged Jacobians (where one does not recompute the
1041    Jacobian at each SNES iteration). For example, the code
1042 .vb
1043       ierr = SNESGetIterationNumber(snes,&it);
1044       if (!(it % 2)) {
1045         [compute Jacobian here]
1046       }
1047 .ve
1048    can be used in your ComputeJacobian() function to cause the Jacobian to be
1049    recomputed every second SNES iteration.
1050 
1051    Level: intermediate
1052 
1053 .keywords: SNES, nonlinear, get, iteration, number,
1054 
1055 .seealso:   SNESGetLinearSolveIterations()
1056 @*/
1057 PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
1058 {
1059   PetscFunctionBegin;
1060   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1061   PetscValidIntPointer(iter,2);
1062   *iter = snes->iter;
1063   PetscFunctionReturn(0);
1064 }
1065 
1066 #undef __FUNCT__
1067 #define __FUNCT__ "SNESSetIterationNumber"
1068 /*@
1069    SNESSetIterationNumber - Sets the current iteration number.
1070 
1071    Not Collective
1072 
1073    Input Parameter:
1074 .  snes - SNES context
1075 .  iter - iteration number
1076 
1077    Level: developer
1078 
1079 .keywords: SNES, nonlinear, set, iteration, number,
1080 
1081 .seealso:   SNESGetLinearSolveIterations()
1082 @*/
1083 PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
1084 {
1085   PetscErrorCode ierr;
1086 
1087   PetscFunctionBegin;
1088   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1089   ierr       = PetscObjectSAWsTakeAccess((PetscObject)snes);CHKERRQ(ierr);
1090   snes->iter = iter;
1091   ierr       = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr);
1092   PetscFunctionReturn(0);
1093 }
1094 
1095 #undef __FUNCT__
1096 #define __FUNCT__ "SNESGetNonlinearStepFailures"
1097 /*@
1098    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1099    attempted by the nonlinear solver.
1100 
1101    Not Collective
1102 
1103    Input Parameter:
1104 .  snes - SNES context
1105 
1106    Output Parameter:
1107 .  nfails - number of unsuccessful steps attempted
1108 
1109    Notes:
1110    This counter is reset to zero for each successive call to SNESSolve().
1111 
1112    Level: intermediate
1113 
1114 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1115 
1116 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1117           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
1118 @*/
1119 PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
1120 {
1121   PetscFunctionBegin;
1122   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1123   PetscValidIntPointer(nfails,2);
1124   *nfails = snes->numFailures;
1125   PetscFunctionReturn(0);
1126 }
1127 
1128 #undef __FUNCT__
1129 #define __FUNCT__ "SNESSetMaxNonlinearStepFailures"
1130 /*@
1131    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1132    attempted by the nonlinear solver before it gives up.
1133 
1134    Not Collective
1135 
1136    Input Parameters:
1137 +  snes     - SNES context
1138 -  maxFails - maximum of unsuccessful steps
1139 
1140    Level: intermediate
1141 
1142 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1143 
1144 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1145           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1146 @*/
1147 PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1148 {
1149   PetscFunctionBegin;
1150   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1151   snes->maxFailures = maxFails;
1152   PetscFunctionReturn(0);
1153 }
1154 
1155 #undef __FUNCT__
1156 #define __FUNCT__ "SNESGetMaxNonlinearStepFailures"
1157 /*@
1158    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1159    attempted by the nonlinear solver before it gives up.
1160 
1161    Not Collective
1162 
1163    Input Parameter:
1164 .  snes     - SNES context
1165 
1166    Output Parameter:
1167 .  maxFails - maximum of unsuccessful steps
1168 
1169    Level: intermediate
1170 
1171 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1172 
1173 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1174           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1175 
1176 @*/
1177 PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1178 {
1179   PetscFunctionBegin;
1180   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1181   PetscValidIntPointer(maxFails,2);
1182   *maxFails = snes->maxFailures;
1183   PetscFunctionReturn(0);
1184 }
1185 
1186 #undef __FUNCT__
1187 #define __FUNCT__ "SNESGetNumberFunctionEvals"
1188 /*@
1189    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1190      done by SNES.
1191 
1192    Not Collective
1193 
1194    Input Parameter:
1195 .  snes     - SNES context
1196 
1197    Output Parameter:
1198 .  nfuncs - number of evaluations
1199 
1200    Level: intermediate
1201 
1202    Notes: Reset every time SNESSolve is called unless SNESSetCountersReset() is used.
1203 
1204 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1205 
1206 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(), SNESSetCountersReset()
1207 @*/
1208 PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1209 {
1210   PetscFunctionBegin;
1211   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1212   PetscValidIntPointer(nfuncs,2);
1213   *nfuncs = snes->nfuncs;
1214   PetscFunctionReturn(0);
1215 }
1216 
1217 #undef __FUNCT__
1218 #define __FUNCT__ "SNESGetLinearSolveFailures"
1219 /*@
1220    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1221    linear solvers.
1222 
1223    Not Collective
1224 
1225    Input Parameter:
1226 .  snes - SNES context
1227 
1228    Output Parameter:
1229 .  nfails - number of failed solves
1230 
1231    Level: intermediate
1232 
1233    Options Database Keys:
1234 . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated
1235 
1236    Notes:
1237    This counter is reset to zero for each successive call to SNESSolve().
1238 
1239 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1240 
1241 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1242 @*/
1243 PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
1244 {
1245   PetscFunctionBegin;
1246   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1247   PetscValidIntPointer(nfails,2);
1248   *nfails = snes->numLinearSolveFailures;
1249   PetscFunctionReturn(0);
1250 }
1251 
1252 #undef __FUNCT__
1253 #define __FUNCT__ "SNESSetMaxLinearSolveFailures"
1254 /*@
1255    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1256    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE
1257 
1258    Logically Collective on SNES
1259 
1260    Input Parameters:
1261 +  snes     - SNES context
1262 -  maxFails - maximum allowed linear solve failures
1263 
1264    Level: intermediate
1265 
1266    Options Database Keys:
1267 . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated
1268 
1269    Notes: By default this is 0; that is SNES returns on the first failed linear solve
1270 
1271 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1272 
1273 .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1274 @*/
1275 PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1276 {
1277   PetscFunctionBegin;
1278   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1279   PetscValidLogicalCollectiveInt(snes,maxFails,2);
1280   snes->maxLinearSolveFailures = maxFails;
1281   PetscFunctionReturn(0);
1282 }
1283 
1284 #undef __FUNCT__
1285 #define __FUNCT__ "SNESGetMaxLinearSolveFailures"
1286 /*@
1287    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1288      are allowed before SNES terminates
1289 
1290    Not Collective
1291 
1292    Input Parameter:
1293 .  snes     - SNES context
1294 
1295    Output Parameter:
1296 .  maxFails - maximum of unsuccessful solves allowed
1297 
1298    Level: intermediate
1299 
1300    Notes: By default this is 1; that is SNES returns on the first failed linear solve
1301 
1302 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1303 
1304 .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1305 @*/
1306 PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1307 {
1308   PetscFunctionBegin;
1309   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1310   PetscValidIntPointer(maxFails,2);
1311   *maxFails = snes->maxLinearSolveFailures;
1312   PetscFunctionReturn(0);
1313 }
1314 
1315 #undef __FUNCT__
1316 #define __FUNCT__ "SNESGetLinearSolveIterations"
1317 /*@
1318    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1319    used by the nonlinear solver.
1320 
1321    Not Collective
1322 
1323    Input Parameter:
1324 .  snes - SNES context
1325 
1326    Output Parameter:
1327 .  lits - number of linear iterations
1328 
1329    Notes:
1330    This counter is reset to zero for each successive call to SNESSolve() unless SNESSetCountersReset() is used.
1331 
1332    Level: intermediate
1333 
1334 .keywords: SNES, nonlinear, get, number, linear, iterations
1335 
1336 .seealso:  SNESGetIterationNumber(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
1337 @*/
1338 PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
1339 {
1340   PetscFunctionBegin;
1341   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1342   PetscValidIntPointer(lits,2);
1343   *lits = snes->linear_its;
1344   PetscFunctionReturn(0);
1345 }
1346 
1347 #undef __FUNCT__
1348 #define __FUNCT__ "SNESSetCountersReset"
1349 /*@
1350    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1351    are reset every time SNESSolve() is called.
1352 
1353    Logically Collective on SNES
1354 
1355    Input Parameter:
1356 +  snes - SNES context
1357 -  reset - whether to reset the counters or not
1358 
1359    Notes:
1360    This defaults to PETSC_TRUE
1361 
1362    Level: developer
1363 
1364 .keywords: SNES, nonlinear, set, reset, number, linear, iterations
1365 
1366 .seealso:  SNESGetNumberFunctionEvals(), SNESGetLinearSolveIterations(), SNESGetNPC()
1367 @*/
1368 PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
1369 {
1370   PetscFunctionBegin;
1371   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1372   PetscValidLogicalCollectiveBool(snes,reset,2);
1373   snes->counters_reset = reset;
1374   PetscFunctionReturn(0);
1375 }
1376 
1377 
1378 #undef __FUNCT__
1379 #define __FUNCT__ "SNESSetKSP"
1380 /*@
1381    SNESSetKSP - Sets a KSP context for the SNES object to use
1382 
1383    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm
1384 
1385    Input Parameters:
1386 +  snes - the SNES context
1387 -  ksp - the KSP context
1388 
1389    Notes:
1390    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1391    so this routine is rarely needed.
1392 
1393    The KSP object that is already in the SNES object has its reference count
1394    decreased by one.
1395 
1396    Level: developer
1397 
1398 .keywords: SNES, nonlinear, get, KSP, context
1399 
1400 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1401 @*/
1402 PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1403 {
1404   PetscErrorCode ierr;
1405 
1406   PetscFunctionBegin;
1407   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1408   PetscValidHeaderSpecific(ksp,KSP_CLASSID,2);
1409   PetscCheckSameComm(snes,1,ksp,2);
1410   ierr = PetscObjectReference((PetscObject)ksp);CHKERRQ(ierr);
1411   if (snes->ksp) {ierr = PetscObjectDereference((PetscObject)snes->ksp);CHKERRQ(ierr);}
1412   snes->ksp = ksp;
1413   PetscFunctionReturn(0);
1414 }
1415 
1416 /* -----------------------------------------------------------*/
1417 #undef __FUNCT__
1418 #define __FUNCT__ "SNESCreate"
1419 /*@
1420    SNESCreate - Creates a nonlinear solver context.
1421 
1422    Collective on MPI_Comm
1423 
1424    Input Parameters:
1425 .  comm - MPI communicator
1426 
1427    Output Parameter:
1428 .  outsnes - the new SNES context
1429 
1430    Options Database Keys:
1431 +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1432                and no preconditioning matrix
1433 .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1434                products, and a user-provided preconditioning matrix
1435                as set by SNESSetJacobian()
1436 -   -snes_fd - Uses (slow!) finite differences to compute Jacobian
1437 
1438    Level: beginner
1439 
1440 .keywords: SNES, nonlinear, create, context
1441 
1442 .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()
1443 
1444 @*/
1445 PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1446 {
1447   PetscErrorCode ierr;
1448   SNES           snes;
1449   SNESKSPEW      *kctx;
1450 
1451   PetscFunctionBegin;
1452   PetscValidPointer(outsnes,2);
1453   *outsnes = NULL;
1454   ierr = SNESInitializePackage();CHKERRQ(ierr);
1455 
1456   ierr = PetscHeaderCreate(snes,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);CHKERRQ(ierr);
1457 
1458   snes->ops->converged    = SNESConvergedDefault;
1459   snes->usesksp           = PETSC_TRUE;
1460   snes->tolerancesset     = PETSC_FALSE;
1461   snes->max_its           = 50;
1462   snes->max_funcs         = 10000;
1463   snes->norm              = 0.0;
1464   snes->normschedule      = SNES_NORM_ALWAYS;
1465   snes->functype          = SNES_FUNCTION_DEFAULT;
1466 #if defined(PETSC_USE_REAL_SINGLE)
1467   snes->rtol              = 1.e-5;
1468 #else
1469   snes->rtol              = 1.e-8;
1470 #endif
1471   snes->ttol              = 0.0;
1472 #if defined(PETSC_USE_REAL_SINGLE)
1473   snes->abstol            = 1.e-25;
1474 #else
1475   snes->abstol            = 1.e-50;
1476 #endif
1477   snes->stol              = 1.e-8;
1478 #if defined(PETSC_USE_REAL_SINGLE)
1479   snes->deltatol          = 1.e-6;
1480 #else
1481   snes->deltatol          = 1.e-12;
1482 #endif
1483   snes->nfuncs            = 0;
1484   snes->numFailures       = 0;
1485   snes->maxFailures       = 1;
1486   snes->linear_its        = 0;
1487   snes->lagjacobian       = 1;
1488   snes->jac_iter          = 0;
1489   snes->lagjac_persist    = PETSC_FALSE;
1490   snes->lagpreconditioner = 1;
1491   snes->pre_iter          = 0;
1492   snes->lagpre_persist    = PETSC_FALSE;
1493   snes->numbermonitors    = 0;
1494   snes->data              = 0;
1495   snes->setupcalled       = PETSC_FALSE;
1496   snes->ksp_ewconv        = PETSC_FALSE;
1497   snes->nwork             = 0;
1498   snes->work              = 0;
1499   snes->nvwork            = 0;
1500   snes->vwork             = 0;
1501   snes->conv_hist_len     = 0;
1502   snes->conv_hist_max     = 0;
1503   snes->conv_hist         = NULL;
1504   snes->conv_hist_its     = NULL;
1505   snes->conv_hist_reset   = PETSC_TRUE;
1506   snes->counters_reset    = PETSC_TRUE;
1507   snes->vec_func_init_set = PETSC_FALSE;
1508   snes->reason            = SNES_CONVERGED_ITERATING;
1509   snes->pcside            = PC_RIGHT;
1510 
1511   snes->mf          = PETSC_FALSE;
1512   snes->mf_operator = PETSC_FALSE;
1513   snes->mf_version  = 1;
1514 
1515   snes->numLinearSolveFailures = 0;
1516   snes->maxLinearSolveFailures = 1;
1517 
1518   snes->vizerotolerance = 1.e-8;
1519 
1520   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1521   ierr = PetscNewLog(snes,&kctx);CHKERRQ(ierr);
1522 
1523   snes->kspconvctx  = (void*)kctx;
1524   kctx->version     = 2;
1525   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1526                              this was too large for some test cases */
1527   kctx->rtol_last   = 0.0;
1528   kctx->rtol_max    = .9;
1529   kctx->gamma       = 1.0;
1530   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1531   kctx->alpha2      = kctx->alpha;
1532   kctx->threshold   = .1;
1533   kctx->lresid_last = 0.0;
1534   kctx->norm_last   = 0.0;
1535 
1536   *outsnes = snes;
1537   PetscFunctionReturn(0);
1538 }
1539 
1540 /*MC
1541     SNESFunction - Functional form used to convey the nonlinear function to be solved by SNES
1542 
1543      Synopsis:
1544      #include "petscsnes.h"
1545      PetscErrorCode SNESFunction(SNES snes,Vec x,Vec f,void *ctx);
1546 
1547      Input Parameters:
1548 +     snes - the SNES context
1549 .     x    - state at which to evaluate residual
1550 -     ctx     - optional user-defined function context, passed in with SNESSetFunction()
1551 
1552      Output Parameter:
1553 .     f  - vector to put residual (function value)
1554 
1555    Level: intermediate
1556 
1557 .seealso:   SNESSetFunction(), SNESGetFunction()
1558 M*/
1559 
1560 #undef __FUNCT__
1561 #define __FUNCT__ "SNESSetFunction"
1562 /*@C
1563    SNESSetFunction - Sets the function evaluation routine and function
1564    vector for use by the SNES routines in solving systems of nonlinear
1565    equations.
1566 
1567    Logically Collective on SNES
1568 
1569    Input Parameters:
1570 +  snes - the SNES context
1571 .  r - vector to store function value
1572 .  f - function evaluation routine; see SNESFunction for calling sequence details
1573 -  ctx - [optional] user-defined context for private data for the
1574          function evaluation routine (may be NULL)
1575 
1576    Notes:
1577    The Newton-like methods typically solve linear systems of the form
1578 $      f'(x) x = -f(x),
1579    where f'(x) denotes the Jacobian matrix and f(x) is the function.
1580 
1581    Level: beginner
1582 
1583 .keywords: SNES, nonlinear, set, function
1584 
1585 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
1586 @*/
1587 PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1588 {
1589   PetscErrorCode ierr;
1590   DM             dm;
1591 
1592   PetscFunctionBegin;
1593   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1594   if (r) {
1595     PetscValidHeaderSpecific(r,VEC_CLASSID,2);
1596     PetscCheckSameComm(snes,1,r,2);
1597     ierr = PetscObjectReference((PetscObject)r);CHKERRQ(ierr);
1598     ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
1599 
1600     snes->vec_func = r;
1601   }
1602   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1603   ierr = DMSNESSetFunction(dm,f,ctx);CHKERRQ(ierr);
1604   PetscFunctionReturn(0);
1605 }
1606 
1607 
1608 #undef __FUNCT__
1609 #define __FUNCT__ "SNESSetInitialFunction"
1610 /*@C
1611    SNESSetInitialFunction - Sets the function vector to be used as the
1612    function norm at the initialization of the method.  In some
1613    instances, the user has precomputed the function before calling
1614    SNESSolve.  This function allows one to avoid a redundant call
1615    to SNESComputeFunction in that case.
1616 
1617    Logically Collective on SNES
1618 
1619    Input Parameters:
1620 +  snes - the SNES context
1621 -  f - vector to store function value
1622 
1623    Notes:
1624    This should not be modified during the solution procedure.
1625 
1626    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1627 
1628    Level: developer
1629 
1630 .keywords: SNES, nonlinear, set, function
1631 
1632 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1633 @*/
1634 PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1635 {
1636   PetscErrorCode ierr;
1637   Vec            vec_func;
1638 
1639   PetscFunctionBegin;
1640   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1641   PetscValidHeaderSpecific(f,VEC_CLASSID,2);
1642   PetscCheckSameComm(snes,1,f,2);
1643   if (snes->pcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
1644     snes->vec_func_init_set = PETSC_FALSE;
1645     PetscFunctionReturn(0);
1646   }
1647   ierr = SNESGetFunction(snes,&vec_func,NULL,NULL);CHKERRQ(ierr);
1648   ierr = VecCopy(f, vec_func);CHKERRQ(ierr);
1649 
1650   snes->vec_func_init_set = PETSC_TRUE;
1651   PetscFunctionReturn(0);
1652 }
1653 
1654 #undef __FUNCT__
1655 #define __FUNCT__ "SNESSetNormSchedule"
1656 /*@
1657    SNESSetNormSchedule - Sets the SNESNormSchedule used in covergence and monitoring
1658    of the SNES method.
1659 
1660    Logically Collective on SNES
1661 
1662    Input Parameters:
1663 +  snes - the SNES context
1664 -  normschedule - the frequency of norm computation
1665 
1666    Options Database Key:
1667 .  -snes_norm_schedule <none, always, initialonly, finalonly, initalfinalonly>
1668 
1669    Notes:
1670    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1671    of the nonlinear function and the taking of its norm at every iteration to
1672    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1673    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1674    may either be monitored for convergence or not.  As these are often used as nonlinear
1675    preconditioners, monitoring the norm of their error is not a useful enterprise within
1676    their solution.
1677 
1678    Level: developer
1679 
1680 .keywords: SNES, nonlinear, set, function, norm, type
1681 
1682 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1683 @*/
1684 PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
1685 {
1686   PetscFunctionBegin;
1687   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1688   snes->normschedule = normschedule;
1689   PetscFunctionReturn(0);
1690 }
1691 
1692 
1693 #undef __FUNCT__
1694 #define __FUNCT__ "SNESGetNormSchedule"
1695 /*@
1696    SNESGetNormSchedule - Gets the SNESNormSchedule used in covergence and monitoring
1697    of the SNES method.
1698 
1699    Logically Collective on SNES
1700 
1701    Input Parameters:
1702 +  snes - the SNES context
1703 -  normschedule - the type of the norm used
1704 
1705    Level: advanced
1706 
1707 .keywords: SNES, nonlinear, set, function, norm, type
1708 
1709 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1710 @*/
1711 PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
1712 {
1713   PetscFunctionBegin;
1714   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1715   *normschedule = snes->normschedule;
1716   PetscFunctionReturn(0);
1717 }
1718 
1719 
1720 #undef __FUNCT__
1721 #define __FUNCT__ "SNESSetFunctionType"
1722 /*@C
1723    SNESSetFunctionType - Sets the SNESNormSchedule used in covergence and monitoring
1724    of the SNES method.
1725 
1726    Logically Collective on SNES
1727 
1728    Input Parameters:
1729 +  snes - the SNES context
1730 -  normschedule - the frequency of norm computation
1731 
1732    Notes:
1733    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1734    of the nonlinear function and the taking of its norm at every iteration to
1735    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1736    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1737    may either be monitored for convergence or not.  As these are often used as nonlinear
1738    preconditioners, monitoring the norm of their error is not a useful enterprise within
1739    their solution.
1740 
1741    Level: developer
1742 
1743 .keywords: SNES, nonlinear, set, function, norm, type
1744 
1745 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1746 @*/
1747 PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
1748 {
1749   PetscFunctionBegin;
1750   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1751   snes->functype = type;
1752   PetscFunctionReturn(0);
1753 }
1754 
1755 
1756 #undef __FUNCT__
1757 #define __FUNCT__ "SNESGetFunctionType"
1758 /*@C
1759    SNESGetFunctionType - Gets the SNESNormSchedule used in covergence and monitoring
1760    of the SNES method.
1761 
1762    Logically Collective on SNES
1763 
1764    Input Parameters:
1765 +  snes - the SNES context
1766 -  normschedule - the type of the norm used
1767 
1768    Level: advanced
1769 
1770 .keywords: SNES, nonlinear, set, function, norm, type
1771 
1772 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1773 @*/
1774 PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
1775 {
1776   PetscFunctionBegin;
1777   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1778   *type = snes->functype;
1779   PetscFunctionReturn(0);
1780 }
1781 
1782 /*MC
1783     SNESNGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function
1784 
1785      Synopsis:
1786      #include <petscsnes.h>
1787 $    SNESNGSFunction(SNES snes,Vec x,Vec b,void *ctx);
1788 
1789 +  X   - solution vector
1790 .  B   - RHS vector
1791 -  ctx - optional user-defined Gauss-Seidel context
1792 
1793    Level: intermediate
1794 
1795 .seealso:   SNESSetNGS(), SNESGetNGS()
1796 M*/
1797 
1798 #undef __FUNCT__
1799 #define __FUNCT__ "SNESSetNGS"
1800 /*@C
1801    SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
1802    use with composed nonlinear solvers.
1803 
1804    Input Parameters:
1805 +  snes   - the SNES context
1806 .  f - function evaluation routine to apply Gauss-Seidel see SNESNGSFunction
1807 -  ctx    - [optional] user-defined context for private data for the
1808             smoother evaluation routine (may be NULL)
1809 
1810    Notes:
1811    The NGS routines are used by the composed nonlinear solver to generate
1812     a problem appropriate update to the solution, particularly FAS.
1813 
1814    Level: intermediate
1815 
1816 .keywords: SNES, nonlinear, set, Gauss-Seidel
1817 
1818 .seealso: SNESGetFunction(), SNESComputeNGS()
1819 @*/
1820 PetscErrorCode SNESSetNGS(SNES snes,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1821 {
1822   PetscErrorCode ierr;
1823   DM             dm;
1824 
1825   PetscFunctionBegin;
1826   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1827   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1828   ierr = DMSNESSetNGS(dm,f,ctx);CHKERRQ(ierr);
1829   PetscFunctionReturn(0);
1830 }
1831 
1832 #undef __FUNCT__
1833 #define __FUNCT__ "SNESPicardComputeFunction"
1834 PETSC_EXTERN PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
1835 {
1836   PetscErrorCode ierr;
1837   DM             dm;
1838   DMSNES         sdm;
1839 
1840   PetscFunctionBegin;
1841   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1842   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
1843   /*  A(x)*x - b(x) */
1844   if (sdm->ops->computepfunction) {
1845     ierr = (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);CHKERRQ(ierr);
1846   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");
1847 
1848   if (sdm->ops->computepjacobian) {
1849     ierr = (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);CHKERRQ(ierr);
1850   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard matrix.");
1851   ierr = VecScale(f,-1.0);CHKERRQ(ierr);
1852   ierr = MatMultAdd(snes->jacobian,x,f,f);CHKERRQ(ierr);
1853   PetscFunctionReturn(0);
1854 }
1855 
1856 #undef __FUNCT__
1857 #define __FUNCT__ "SNESPicardComputeJacobian"
1858 PETSC_EXTERN PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
1859 {
1860   PetscFunctionBegin;
1861   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
1862   PetscFunctionReturn(0);
1863 }
1864 
1865 #undef __FUNCT__
1866 #define __FUNCT__ "SNESSetPicard"
1867 /*@C
1868    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)
1869 
1870    Logically Collective on SNES
1871 
1872    Input Parameters:
1873 +  snes - the SNES context
1874 .  r - vector to store function value
1875 .  b - function evaluation routine
1876 .  Amat - matrix with which A(x) x - b(x) is to be computed
1877 .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
1878 .  J  - function to compute matrix value, see SNESJacobianFunction for details on its calling sequence
1879 -  ctx - [optional] user-defined context for private data for the
1880          function evaluation routine (may be NULL)
1881 
1882    Notes:
1883     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
1884     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.
1885 
1886     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both
1887 
1888 $     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}
1889 $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.
1890 
1891      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.
1892 
1893    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
1894    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)
1895 
1896    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
1897    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
1898    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).
1899 
1900    Level: intermediate
1901 
1902 .keywords: SNES, nonlinear, set, function
1903 
1904 .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard(), SNESJacobianFunction
1905 @*/
1906 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)
1907 {
1908   PetscErrorCode ierr;
1909   DM             dm;
1910 
1911   PetscFunctionBegin;
1912   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1913   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
1914   ierr = DMSNESSetPicard(dm,b,J,ctx);CHKERRQ(ierr);
1915   ierr = SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);CHKERRQ(ierr);
1916   ierr = SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);CHKERRQ(ierr);
1917   PetscFunctionReturn(0);
1918 }
1919 
1920 #undef __FUNCT__
1921 #define __FUNCT__ "SNESGetPicard"
1922 /*@C
1923    SNESGetPicard - Returns the context for the Picard iteration
1924 
1925    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
1926 
1927    Input Parameter:
1928 .  snes - the SNES context
1929 
1930    Output Parameter:
1931 +  r - the function (or NULL)
1932 .  f - the function (or NULL); see SNESFunction for calling sequence details
1933 .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
1934 .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
1935 .  J - the function for matrix evaluation (or NULL); see SNESJacobianFunction for calling sequence details
1936 -  ctx - the function context (or NULL)
1937 
1938    Level: advanced
1939 
1940 .keywords: SNES, nonlinear, get, function
1941 
1942 .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
1943 @*/
1944 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)
1945 {
1946   PetscErrorCode ierr;
1947   DM             dm;
1948 
1949   PetscFunctionBegin;
1950   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1951   ierr = SNESGetFunction(snes,r,NULL,NULL);CHKERRQ(ierr);
1952   ierr = SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);CHKERRQ(ierr);
1953   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1954   ierr = DMSNESGetPicard(dm,f,J,ctx);CHKERRQ(ierr);
1955   PetscFunctionReturn(0);
1956 }
1957 
1958 #undef __FUNCT__
1959 #define __FUNCT__ "SNESSetComputeInitialGuess"
1960 /*@C
1961    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem
1962 
1963    Logically Collective on SNES
1964 
1965    Input Parameters:
1966 +  snes - the SNES context
1967 .  func - function evaluation routine
1968 -  ctx - [optional] user-defined context for private data for the
1969          function evaluation routine (may be NULL)
1970 
1971    Calling sequence of func:
1972 $    func (SNES snes,Vec x,void *ctx);
1973 
1974 .  f - function vector
1975 -  ctx - optional user-defined function context
1976 
1977    Level: intermediate
1978 
1979 .keywords: SNES, nonlinear, set, function
1980 
1981 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
1982 @*/
1983 PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
1984 {
1985   PetscFunctionBegin;
1986   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1987   if (func) snes->ops->computeinitialguess = func;
1988   if (ctx)  snes->initialguessP            = ctx;
1989   PetscFunctionReturn(0);
1990 }
1991 
1992 /* --------------------------------------------------------------- */
1993 #undef __FUNCT__
1994 #define __FUNCT__ "SNESGetRhs"
1995 /*@C
1996    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
1997    it assumes a zero right hand side.
1998 
1999    Logically Collective on SNES
2000 
2001    Input Parameter:
2002 .  snes - the SNES context
2003 
2004    Output Parameter:
2005 .  rhs - the right hand side vector or NULL if the right hand side vector is null
2006 
2007    Level: intermediate
2008 
2009 .keywords: SNES, nonlinear, get, function, right hand side
2010 
2011 .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
2012 @*/
2013 PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
2014 {
2015   PetscFunctionBegin;
2016   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2017   PetscValidPointer(rhs,2);
2018   *rhs = snes->vec_rhs;
2019   PetscFunctionReturn(0);
2020 }
2021 
2022 #undef __FUNCT__
2023 #define __FUNCT__ "SNESComputeFunction"
2024 /*@
2025    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().
2026 
2027    Collective on SNES
2028 
2029    Input Parameters:
2030 +  snes - the SNES context
2031 -  x - input vector
2032 
2033    Output Parameter:
2034 .  y - function vector, as set by SNESSetFunction()
2035 
2036    Notes:
2037    SNESComputeFunction() is typically used within nonlinear solvers
2038    implementations, so most users would not generally call this routine
2039    themselves.
2040 
2041    Level: developer
2042 
2043 .keywords: SNES, nonlinear, compute, function
2044 
2045 .seealso: SNESSetFunction(), SNESGetFunction()
2046 @*/
2047 PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
2048 {
2049   PetscErrorCode ierr;
2050   DM             dm;
2051   DMSNES         sdm;
2052 
2053   PetscFunctionBegin;
2054   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2055   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2056   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
2057   PetscCheckSameComm(snes,1,x,2);
2058   PetscCheckSameComm(snes,1,y,3);
2059   ierr = VecValidValues(x,2,PETSC_TRUE);CHKERRQ(ierr);
2060 
2061   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2062   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2063   if (sdm->ops->computefunction) {
2064     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2065       ierr = PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2066     }
2067     ierr = VecLockPush(x);CHKERRQ(ierr);
2068     PetscStackPush("SNES user function");
2069     ierr = (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);CHKERRQ(ierr);
2070     PetscStackPop;
2071     ierr = VecLockPop(x);CHKERRQ(ierr);
2072     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2073       ierr = PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2074     }
2075   } else if (snes->vec_rhs) {
2076     ierr = MatMult(snes->jacobian, x, y);CHKERRQ(ierr);
2077   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2078   if (snes->vec_rhs) {
2079     ierr = VecAXPY(y,-1.0,snes->vec_rhs);CHKERRQ(ierr);
2080   }
2081   snes->nfuncs++;
2082   /*
2083      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
2084      propagate the value to all processes
2085   */
2086   if (snes->domainerror) {
2087     ierr = VecSetInf(y);CHKERRQ(ierr);
2088   }
2089   PetscFunctionReturn(0);
2090 }
2091 
2092 #undef __FUNCT__
2093 #define __FUNCT__ "SNESComputeNGS"
2094 /*@
2095    SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  SNESSetNGS().
2096 
2097    Collective on SNES
2098 
2099    Input Parameters:
2100 +  snes - the SNES context
2101 .  x - input vector
2102 -  b - rhs vector
2103 
2104    Output Parameter:
2105 .  x - new solution vector
2106 
2107    Notes:
2108    SNESComputeNGS() is typically used within composed nonlinear solver
2109    implementations, so most users would not generally call this routine
2110    themselves.
2111 
2112    Level: developer
2113 
2114 .keywords: SNES, nonlinear, compute, function
2115 
2116 .seealso: SNESSetNGS(), SNESComputeFunction()
2117 @*/
2118 PetscErrorCode  SNESComputeNGS(SNES snes,Vec b,Vec x)
2119 {
2120   PetscErrorCode ierr;
2121   DM             dm;
2122   DMSNES         sdm;
2123 
2124   PetscFunctionBegin;
2125   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2126   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2127   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,3);
2128   PetscCheckSameComm(snes,1,x,2);
2129   if (b) PetscCheckSameComm(snes,1,b,3);
2130   if (b) {ierr = VecValidValues(b,2,PETSC_TRUE);CHKERRQ(ierr);}
2131   ierr = PetscLogEventBegin(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2132   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2133   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2134   if (sdm->ops->computegs) {
2135     if (b) {ierr = VecLockPush(b);CHKERRQ(ierr);}
2136     PetscStackPush("SNES user NGS");
2137     ierr = (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);CHKERRQ(ierr);
2138     PetscStackPop;
2139     if (b) {ierr = VecLockPop(b);CHKERRQ(ierr);}
2140   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
2141   ierr = PetscLogEventEnd(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2142   PetscFunctionReturn(0);
2143 }
2144 
2145 #undef __FUNCT__
2146 #define __FUNCT__ "SNESComputeJacobian"
2147 /*@
2148    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().
2149 
2150    Collective on SNES and Mat
2151 
2152    Input Parameters:
2153 +  snes - the SNES context
2154 -  x - input vector
2155 
2156    Output Parameters:
2157 +  A - Jacobian matrix
2158 -  B - optional preconditioning matrix
2159 
2160   Options Database Keys:
2161 +    -snes_lag_preconditioner <lag>
2162 .    -snes_lag_jacobian <lag>
2163 .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2164 .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2165 .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2166 .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2167 .    -snes_compare_coloring - Compute the finite differece Jacobian using coloring and display norms of difference
2168 .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
2169 .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2170 .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2171 .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2172 .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
2173 -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences
2174 
2175 
2176    Notes:
2177    Most users should not need to explicitly call this routine, as it
2178    is used internally within the nonlinear solvers.
2179 
2180    Level: developer
2181 
2182 .keywords: SNES, compute, Jacobian, matrix
2183 
2184 .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2185 @*/
2186 PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat A,Mat B)
2187 {
2188   PetscErrorCode ierr;
2189   PetscBool      flag;
2190   DM             dm;
2191   DMSNES         sdm;
2192   KSP            ksp;
2193 
2194   PetscFunctionBegin;
2195   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2196   PetscValidHeaderSpecific(X,VEC_CLASSID,2);
2197   PetscCheckSameComm(snes,1,X,2);
2198   ierr = VecValidValues(X,2,PETSC_TRUE);CHKERRQ(ierr);
2199   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2200   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2201 
2202   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");
2203 
2204   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */
2205 
2206   if (snes->lagjacobian == -2) {
2207     snes->lagjacobian = -1;
2208 
2209     ierr = PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");CHKERRQ(ierr);
2210   } else if (snes->lagjacobian == -1) {
2211     ierr = PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");CHKERRQ(ierr);
2212     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2213     if (flag) {
2214       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2215       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2216     }
2217     PetscFunctionReturn(0);
2218   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2219     ierr = PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);CHKERRQ(ierr);
2220     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2221     if (flag) {
2222       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2223       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2224     }
2225     PetscFunctionReturn(0);
2226   }
2227   if (snes->pc && snes->pcside == PC_LEFT) {
2228       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2229       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2230       PetscFunctionReturn(0);
2231   }
2232 
2233   ierr = PetscLogEventBegin(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2234   ierr = VecLockPush(X);CHKERRQ(ierr);
2235   PetscStackPush("SNES user Jacobian function");
2236   ierr = (*sdm->ops->computejacobian)(snes,X,A,B,sdm->jacobianctx);CHKERRQ(ierr);
2237   PetscStackPop;
2238   ierr = VecLockPop(X);CHKERRQ(ierr);
2239   ierr = PetscLogEventEnd(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2240 
2241   /* the next line ensures that snes->ksp exists */
2242   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
2243   if (snes->lagpreconditioner == -2) {
2244     ierr = PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");CHKERRQ(ierr);
2245     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2246     snes->lagpreconditioner = -1;
2247   } else if (snes->lagpreconditioner == -1) {
2248     ierr = PetscInfo(snes,"Reusing preconditioner because lag is -1\n");CHKERRQ(ierr);
2249     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2250   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2251     ierr = PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);CHKERRQ(ierr);
2252     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2253   } else {
2254     ierr = PetscInfo(snes,"Rebuilding preconditioner\n");CHKERRQ(ierr);
2255     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2256   }
2257 
2258   /* make sure user returned a correct Jacobian and preconditioner */
2259   /* PetscValidHeaderSpecific(A,MAT_CLASSID,3);
2260     PetscValidHeaderSpecific(B,MAT_CLASSID,4);   */
2261   {
2262     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2263     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit",&flag,NULL);CHKERRQ(ierr);
2264     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",&flag_draw,NULL);CHKERRQ(ierr);
2265     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2266     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_operator",&flag_operator,NULL);CHKERRQ(ierr);
2267     if (flag || flag_draw || flag_contour) {
2268       Mat          Bexp_mine = NULL,Bexp,FDexp;
2269       PetscViewer  vdraw,vstdout;
2270       PetscBool    flg;
2271       if (flag_operator) {
2272         ierr = MatComputeExplicitOperator(A,&Bexp_mine);CHKERRQ(ierr);
2273         Bexp = Bexp_mine;
2274       } else {
2275         /* See if the preconditioning matrix can be viewed and added directly */
2276         ierr = PetscObjectTypeCompareAny((PetscObject)B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");CHKERRQ(ierr);
2277         if (flg) Bexp = B;
2278         else {
2279           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2280           ierr = MatComputeExplicitOperator(B,&Bexp_mine);CHKERRQ(ierr);
2281           Bexp = Bexp_mine;
2282         }
2283       }
2284       ierr = MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);CHKERRQ(ierr);
2285       ierr = SNESComputeJacobianDefault(snes,X,FDexp,FDexp,NULL);CHKERRQ(ierr);
2286       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2287       if (flag_draw || flag_contour) {
2288         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2289         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2290       } else vdraw = NULL;
2291       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");CHKERRQ(ierr);
2292       if (flag) {ierr = MatView(Bexp,vstdout);CHKERRQ(ierr);}
2293       if (vdraw) {ierr = MatView(Bexp,vdraw);CHKERRQ(ierr);}
2294       ierr = PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");CHKERRQ(ierr);
2295       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2296       if (vdraw) {ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);}
2297       ierr = MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2298       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");CHKERRQ(ierr);
2299       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2300       if (vdraw) {              /* Always use contour for the difference */
2301         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2302         ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);
2303         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2304       }
2305       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2306       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2307       ierr = MatDestroy(&Bexp_mine);CHKERRQ(ierr);
2308       ierr = MatDestroy(&FDexp);CHKERRQ(ierr);
2309     }
2310   }
2311   {
2312     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2313     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2314     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring",&flag,NULL);CHKERRQ(ierr);
2315     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_display",&flag_display,NULL);CHKERRQ(ierr);
2316     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",&flag_draw,NULL);CHKERRQ(ierr);
2317     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2318     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",&flag_threshold,NULL);CHKERRQ(ierr);
2319     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);CHKERRQ(ierr);
2320     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);CHKERRQ(ierr);
2321     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2322       Mat            Bfd;
2323       PetscViewer    vdraw,vstdout;
2324       MatColoring    coloring;
2325       ISColoring     iscoloring;
2326       MatFDColoring  matfdcoloring;
2327       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2328       void           *funcctx;
2329       PetscReal      norm1,norm2,normmax;
2330 
2331       ierr = MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);CHKERRQ(ierr);
2332       ierr = MatColoringCreate(Bfd,&coloring);CHKERRQ(ierr);
2333       ierr = MatColoringSetType(coloring,MATCOLORINGSL);CHKERRQ(ierr);
2334       ierr = MatColoringSetFromOptions(coloring);CHKERRQ(ierr);
2335       ierr = MatColoringApply(coloring,&iscoloring);CHKERRQ(ierr);
2336       ierr = MatColoringDestroy(&coloring);CHKERRQ(ierr);
2337       ierr = MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);CHKERRQ(ierr);
2338       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2339       ierr = MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);CHKERRQ(ierr);
2340       ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr);
2341 
2342       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2343       ierr = SNESGetFunction(snes,NULL,&func,&funcctx);CHKERRQ(ierr);
2344       ierr = MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);CHKERRQ(ierr);
2345       ierr = PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);CHKERRQ(ierr);
2346       ierr = PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");CHKERRQ(ierr);
2347       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2348       ierr = MatFDColoringApply(Bfd,matfdcoloring,X,snes);CHKERRQ(ierr);
2349       ierr = MatFDColoringDestroy(&matfdcoloring);CHKERRQ(ierr);
2350 
2351       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2352       if (flag_draw || flag_contour) {
2353         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2354         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2355       } else vdraw = NULL;
2356       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");CHKERRQ(ierr);
2357       if (flag_display) {ierr = MatView(B,vstdout);CHKERRQ(ierr);}
2358       if (vdraw) {ierr = MatView(B,vdraw);CHKERRQ(ierr);}
2359       ierr = PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");CHKERRQ(ierr);
2360       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2361       if (vdraw) {ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);}
2362       ierr = MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2363       ierr = MatNorm(Bfd,NORM_1,&norm1);CHKERRQ(ierr);
2364       ierr = MatNorm(Bfd,NORM_FROBENIUS,&norm2);CHKERRQ(ierr);
2365       ierr = MatNorm(Bfd,NORM_MAX,&normmax);CHKERRQ(ierr);
2366       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);
2367       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2368       if (vdraw) {              /* Always use contour for the difference */
2369         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2370         ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);
2371         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2372       }
2373       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2374 
2375       if (flag_threshold) {
2376         PetscInt bs,rstart,rend,i;
2377         ierr = MatGetBlockSize(B,&bs);CHKERRQ(ierr);
2378         ierr = MatGetOwnershipRange(B,&rstart,&rend);CHKERRQ(ierr);
2379         for (i=rstart; i<rend; i++) {
2380           const PetscScalar *ba,*ca;
2381           const PetscInt    *bj,*cj;
2382           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2383           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2384           ierr = MatGetRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2385           ierr = MatGetRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2386           if (bn != cn) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2387           for (j=0; j<bn; j++) {
2388             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2389             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2390               maxentrycol = bj[j];
2391               maxentry    = PetscRealPart(ba[j]);
2392             }
2393             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2394               maxdiffcol = bj[j];
2395               maxdiff    = PetscRealPart(ca[j]);
2396             }
2397             if (rdiff > maxrdiff) {
2398               maxrdiffcol = bj[j];
2399               maxrdiff    = rdiff;
2400             }
2401           }
2402           if (maxrdiff > 1) {
2403             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);
2404             for (j=0; j<bn; j++) {
2405               PetscReal rdiff;
2406               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2407               if (rdiff > 1) {
2408                 ierr = PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));CHKERRQ(ierr);
2409               }
2410             }
2411             ierr = PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);CHKERRQ(ierr);
2412           }
2413           ierr = MatRestoreRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2414           ierr = MatRestoreRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2415         }
2416       }
2417       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2418       ierr = MatDestroy(&Bfd);CHKERRQ(ierr);
2419     }
2420   }
2421   PetscFunctionReturn(0);
2422 }
2423 
2424 /*MC
2425     SNESJacobianFunction - Function used to convey the nonlinear Jacobian of the function to be solved by SNES
2426 
2427      Synopsis:
2428      #include "petscsnes.h"
2429      PetscErrorCode SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);
2430 
2431 +  x - input vector
2432 .  Amat - the matrix that defines the (approximate) Jacobian
2433 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2434 -  ctx - [optional] user-defined Jacobian context
2435 
2436    Level: intermediate
2437 
2438 .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2439 M*/
2440 
2441 #undef __FUNCT__
2442 #define __FUNCT__ "SNESSetJacobian"
2443 /*@C
2444    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2445    location to store the matrix.
2446 
2447    Logically Collective on SNES and Mat
2448 
2449    Input Parameters:
2450 +  snes - the SNES context
2451 .  Amat - the matrix that defines the (approximate) Jacobian
2452 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2453 .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value), see SNESJacobianFunction for details
2454 -  ctx - [optional] user-defined context for private data for the
2455          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)
2456 
2457    Notes:
2458    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
2459    each matrix.
2460 
2461    If you know the operator Amat has a null space you can use MatSetNullSpace() and MatSetTransposeNullSpace() to supply the null
2462    space to Amat and the KSP solvers will automatically use that null space as needed during the solution process.
2463 
2464    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
2465    must be a MatFDColoring.
2466 
2467    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2468    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.
2469 
2470    Level: beginner
2471 
2472 .keywords: SNES, nonlinear, set, Jacobian, matrix
2473 
2474 .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J,
2475           SNESSetPicard(), SNESJacobianFunction
2476 @*/
2477 PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2478 {
2479   PetscErrorCode ierr;
2480   DM             dm;
2481 
2482   PetscFunctionBegin;
2483   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2484   if (Amat) PetscValidHeaderSpecific(Amat,MAT_CLASSID,2);
2485   if (Pmat) PetscValidHeaderSpecific(Pmat,MAT_CLASSID,3);
2486   if (Amat) PetscCheckSameComm(snes,1,Amat,2);
2487   if (Pmat) PetscCheckSameComm(snes,1,Pmat,3);
2488   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2489   ierr = DMSNESSetJacobian(dm,J,ctx);CHKERRQ(ierr);
2490   if (Amat) {
2491     ierr = PetscObjectReference((PetscObject)Amat);CHKERRQ(ierr);
2492     ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2493 
2494     snes->jacobian = Amat;
2495   }
2496   if (Pmat) {
2497     ierr = PetscObjectReference((PetscObject)Pmat);CHKERRQ(ierr);
2498     ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2499 
2500     snes->jacobian_pre = Pmat;
2501   }
2502   PetscFunctionReturn(0);
2503 }
2504 
2505 #undef __FUNCT__
2506 #define __FUNCT__ "SNESGetJacobian"
2507 /*@C
2508    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2509    provided context for evaluating the Jacobian.
2510 
2511    Not Collective, but Mat object will be parallel if SNES object is
2512 
2513    Input Parameter:
2514 .  snes - the nonlinear solver context
2515 
2516    Output Parameters:
2517 +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
2518 .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
2519 .  J - location to put Jacobian function (or NULL), see SNESJacobianFunction for details on its calling sequence
2520 -  ctx - location to stash Jacobian ctx (or NULL)
2521 
2522    Level: advanced
2523 
2524 .seealso: SNESSetJacobian(), SNESComputeJacobian(), SNESJacobianFunction, SNESGetFunction()
2525 @*/
2526 PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
2527 {
2528   PetscErrorCode ierr;
2529   DM             dm;
2530   DMSNES         sdm;
2531 
2532   PetscFunctionBegin;
2533   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2534   if (Amat) *Amat = snes->jacobian;
2535   if (Pmat) *Pmat = snes->jacobian_pre;
2536   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2537   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2538   if (J) *J = sdm->ops->computejacobian;
2539   if (ctx) *ctx = sdm->jacobianctx;
2540   PetscFunctionReturn(0);
2541 }
2542 
2543 #undef __FUNCT__
2544 #define __FUNCT__ "SNESSetUp"
2545 /*@
2546    SNESSetUp - Sets up the internal data structures for the later use
2547    of a nonlinear solver.
2548 
2549    Collective on SNES
2550 
2551    Input Parameters:
2552 .  snes - the SNES context
2553 
2554    Notes:
2555    For basic use of the SNES solvers the user need not explicitly call
2556    SNESSetUp(), since these actions will automatically occur during
2557    the call to SNESSolve().  However, if one wishes to control this
2558    phase separately, SNESSetUp() should be called after SNESCreate()
2559    and optional routines of the form SNESSetXXX(), but before SNESSolve().
2560 
2561    Level: advanced
2562 
2563 .keywords: SNES, nonlinear, setup
2564 
2565 .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
2566 @*/
2567 PetscErrorCode  SNESSetUp(SNES snes)
2568 {
2569   PetscErrorCode ierr;
2570   DM             dm;
2571   DMSNES         sdm;
2572   SNESLineSearch linesearch, pclinesearch;
2573   void           *lsprectx,*lspostctx;
2574   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
2575   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
2576   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2577   Vec            f,fpc;
2578   void           *funcctx;
2579   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
2580   void           *jacctx,*appctx;
2581   Mat            j,jpre;
2582 
2583   PetscFunctionBegin;
2584   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2585   if (snes->setupcalled) PetscFunctionReturn(0);
2586 
2587   if (!((PetscObject)snes)->type_name) {
2588     ierr = SNESSetType(snes,SNESNEWTONLS);CHKERRQ(ierr);
2589   }
2590 
2591   ierr = SNESGetFunction(snes,&snes->vec_func,NULL,NULL);CHKERRQ(ierr);
2592 
2593   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2594   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2595   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
2596   if (!sdm->ops->computejacobian) {
2597     ierr = DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);CHKERRQ(ierr);
2598   }
2599   if (!snes->vec_func) {
2600     ierr = DMCreateGlobalVector(dm,&snes->vec_func);CHKERRQ(ierr);
2601   }
2602 
2603   if (!snes->ksp) {
2604     ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);
2605   }
2606 
2607   if (!snes->linesearch) {
2608     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
2609   }
2610   ierr = SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);CHKERRQ(ierr);
2611 
2612   if (snes->pc && (snes->pcside == PC_LEFT)) {
2613     snes->mf          = PETSC_TRUE;
2614     snes->mf_operator = PETSC_FALSE;
2615   }
2616 
2617   if (snes->pc) {
2618     /* copy the DM over */
2619     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2620     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
2621 
2622     ierr = SNESGetFunction(snes,&f,&func,&funcctx);CHKERRQ(ierr);
2623     ierr = VecDuplicate(f,&fpc);CHKERRQ(ierr);
2624     ierr = SNESSetFunction(snes->pc,fpc,func,funcctx);CHKERRQ(ierr);
2625     ierr = SNESGetJacobian(snes,&j,&jpre,&jac,&jacctx);CHKERRQ(ierr);
2626     ierr = SNESSetJacobian(snes->pc,j,jpre,jac,jacctx);CHKERRQ(ierr);
2627     ierr = SNESGetApplicationContext(snes,&appctx);CHKERRQ(ierr);
2628     ierr = SNESSetApplicationContext(snes->pc,appctx);CHKERRQ(ierr);
2629     ierr = VecDestroy(&fpc);CHKERRQ(ierr);
2630 
2631     /* copy the function pointers over */
2632     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
2633 
2634     /* default to 1 iteration */
2635     ierr = SNESSetTolerances(snes->pc,0.0,0.0,0.0,1,snes->pc->max_funcs);CHKERRQ(ierr);
2636     if (snes->pcside==PC_RIGHT) {
2637       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
2638     } else {
2639       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_NONE);CHKERRQ(ierr);
2640     }
2641     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
2642 
2643     /* copy the line search context over */
2644     ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2645     ierr = SNESGetLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
2646     ierr = SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);CHKERRQ(ierr);
2647     ierr = SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);CHKERRQ(ierr);
2648     ierr = SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);CHKERRQ(ierr);
2649     ierr = SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);CHKERRQ(ierr);
2650     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);CHKERRQ(ierr);
2651   }
2652   if (snes->mf) {
2653     ierr = SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);CHKERRQ(ierr);
2654   }
2655   if (snes->ops->usercompute && !snes->user) {
2656     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2657   }
2658 
2659   snes->jac_iter = 0;
2660   snes->pre_iter = 0;
2661 
2662   if (snes->ops->setup) {
2663     ierr = (*snes->ops->setup)(snes);CHKERRQ(ierr);
2664   }
2665 
2666   if (snes->pc && (snes->pcside == PC_LEFT)) {
2667     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
2668       ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2669       ierr = SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultNPC);CHKERRQ(ierr);
2670     }
2671   }
2672 
2673   snes->setupcalled = PETSC_TRUE;
2674   PetscFunctionReturn(0);
2675 }
2676 
2677 #undef __FUNCT__
2678 #define __FUNCT__ "SNESReset"
2679 /*@
2680    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats
2681 
2682    Collective on SNES
2683 
2684    Input Parameter:
2685 .  snes - iterative context obtained from SNESCreate()
2686 
2687    Level: intermediate
2688 
2689    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()
2690 
2691 .keywords: SNES, destroy
2692 
2693 .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
2694 @*/
2695 PetscErrorCode  SNESReset(SNES snes)
2696 {
2697   PetscErrorCode ierr;
2698 
2699   PetscFunctionBegin;
2700   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2701   if (snes->ops->userdestroy && snes->user) {
2702     ierr       = (*snes->ops->userdestroy)((void**)&snes->user);CHKERRQ(ierr);
2703     snes->user = NULL;
2704   }
2705   if (snes->pc) {
2706     ierr = SNESReset(snes->pc);CHKERRQ(ierr);
2707   }
2708 
2709   if (snes->ops->reset) {
2710     ierr = (*snes->ops->reset)(snes);CHKERRQ(ierr);
2711   }
2712   if (snes->ksp) {
2713     ierr = KSPReset(snes->ksp);CHKERRQ(ierr);
2714   }
2715 
2716   if (snes->linesearch) {
2717     ierr = SNESLineSearchReset(snes->linesearch);CHKERRQ(ierr);
2718   }
2719 
2720   ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
2721   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
2722   ierr = VecDestroy(&snes->vec_sol_update);CHKERRQ(ierr);
2723   ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
2724   ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2725   ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2726   ierr = VecDestroyVecs(snes->nwork,&snes->work);CHKERRQ(ierr);
2727   ierr = VecDestroyVecs(snes->nvwork,&snes->vwork);CHKERRQ(ierr);
2728 
2729   snes->nwork       = snes->nvwork = 0;
2730   snes->setupcalled = PETSC_FALSE;
2731   PetscFunctionReturn(0);
2732 }
2733 
2734 #undef __FUNCT__
2735 #define __FUNCT__ "SNESDestroy"
2736 /*@
2737    SNESDestroy - Destroys the nonlinear solver context that was created
2738    with SNESCreate().
2739 
2740    Collective on SNES
2741 
2742    Input Parameter:
2743 .  snes - the SNES context
2744 
2745    Level: beginner
2746 
2747 .keywords: SNES, nonlinear, destroy
2748 
2749 .seealso: SNESCreate(), SNESSolve()
2750 @*/
2751 PetscErrorCode  SNESDestroy(SNES *snes)
2752 {
2753   PetscErrorCode ierr;
2754 
2755   PetscFunctionBegin;
2756   if (!*snes) PetscFunctionReturn(0);
2757   PetscValidHeaderSpecific((*snes),SNES_CLASSID,1);
2758   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; PetscFunctionReturn(0);}
2759 
2760   ierr = SNESReset((*snes));CHKERRQ(ierr);
2761   ierr = SNESDestroy(&(*snes)->pc);CHKERRQ(ierr);
2762 
2763   /* if memory was published with SAWs then destroy it */
2764   ierr = PetscObjectSAWsViewOff((PetscObject)*snes);CHKERRQ(ierr);
2765   if ((*snes)->ops->destroy) {ierr = (*((*snes))->ops->destroy)((*snes));CHKERRQ(ierr);}
2766 
2767   ierr = DMDestroy(&(*snes)->dm);CHKERRQ(ierr);
2768   ierr = KSPDestroy(&(*snes)->ksp);CHKERRQ(ierr);
2769   ierr = SNESLineSearchDestroy(&(*snes)->linesearch);CHKERRQ(ierr);
2770 
2771   ierr = PetscFree((*snes)->kspconvctx);CHKERRQ(ierr);
2772   if ((*snes)->ops->convergeddestroy) {
2773     ierr = (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);CHKERRQ(ierr);
2774   }
2775   if ((*snes)->conv_malloc) {
2776     ierr = PetscFree((*snes)->conv_hist);CHKERRQ(ierr);
2777     ierr = PetscFree((*snes)->conv_hist_its);CHKERRQ(ierr);
2778   }
2779   ierr = SNESMonitorCancel((*snes));CHKERRQ(ierr);
2780   ierr = PetscHeaderDestroy(snes);CHKERRQ(ierr);
2781   PetscFunctionReturn(0);
2782 }
2783 
2784 /* ----------- Routines to set solver parameters ---------- */
2785 
2786 #undef __FUNCT__
2787 #define __FUNCT__ "SNESSetLagPreconditioner"
2788 /*@
2789    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.
2790 
2791    Logically Collective on SNES
2792 
2793    Input Parameters:
2794 +  snes - the SNES context
2795 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2796          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2797 
2798    Options Database Keys:
2799 .    -snes_lag_preconditioner <lag>
2800 
2801    Notes:
2802    The default is 1
2803    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2804    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use
2805 
2806    Level: intermediate
2807 
2808 .keywords: SNES, nonlinear, set, convergence, tolerances
2809 
2810 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2811 
2812 @*/
2813 PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
2814 {
2815   PetscFunctionBegin;
2816   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2817   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2818   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2819   PetscValidLogicalCollectiveInt(snes,lag,2);
2820   snes->lagpreconditioner = lag;
2821   PetscFunctionReturn(0);
2822 }
2823 
2824 #undef __FUNCT__
2825 #define __FUNCT__ "SNESSetGridSequence"
2826 /*@
2827    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does
2828 
2829    Logically Collective on SNES
2830 
2831    Input Parameters:
2832 +  snes - the SNES context
2833 -  steps - the number of refinements to do, defaults to 0
2834 
2835    Options Database Keys:
2836 .    -snes_grid_sequence <steps>
2837 
2838    Level: intermediate
2839 
2840    Notes:
2841    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2842 
2843 .keywords: SNES, nonlinear, set, convergence, tolerances
2844 
2845 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetGridSequence()
2846 
2847 @*/
2848 PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
2849 {
2850   PetscFunctionBegin;
2851   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2852   PetscValidLogicalCollectiveInt(snes,steps,2);
2853   snes->gridsequence = steps;
2854   PetscFunctionReturn(0);
2855 }
2856 
2857 #undef __FUNCT__
2858 #define __FUNCT__ "SNESGetGridSequence"
2859 /*@
2860    SNESGetGridSequence - gets the number of steps of grid sequencing that SNES does
2861 
2862    Logically Collective on SNES
2863 
2864    Input Parameter:
2865 .  snes - the SNES context
2866 
2867    Output Parameter:
2868 .  steps - the number of refinements to do, defaults to 0
2869 
2870    Options Database Keys:
2871 .    -snes_grid_sequence <steps>
2872 
2873    Level: intermediate
2874 
2875    Notes:
2876    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2877 
2878 .keywords: SNES, nonlinear, set, convergence, tolerances
2879 
2880 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESSetGridSequence()
2881 
2882 @*/
2883 PetscErrorCode  SNESGetGridSequence(SNES snes,PetscInt *steps)
2884 {
2885   PetscFunctionBegin;
2886   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2887   *steps = snes->gridsequence;
2888   PetscFunctionReturn(0);
2889 }
2890 
2891 #undef __FUNCT__
2892 #define __FUNCT__ "SNESGetLagPreconditioner"
2893 /*@
2894    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt
2895 
2896    Not Collective
2897 
2898    Input Parameter:
2899 .  snes - the SNES context
2900 
2901    Output Parameter:
2902 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2903          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2904 
2905    Options Database Keys:
2906 .    -snes_lag_preconditioner <lag>
2907 
2908    Notes:
2909    The default is 1
2910    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2911 
2912    Level: intermediate
2913 
2914 .keywords: SNES, nonlinear, set, convergence, tolerances
2915 
2916 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()
2917 
2918 @*/
2919 PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
2920 {
2921   PetscFunctionBegin;
2922   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2923   *lag = snes->lagpreconditioner;
2924   PetscFunctionReturn(0);
2925 }
2926 
2927 #undef __FUNCT__
2928 #define __FUNCT__ "SNESSetLagJacobian"
2929 /*@
2930    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
2931      often the preconditioner is rebuilt.
2932 
2933    Logically Collective on SNES
2934 
2935    Input Parameters:
2936 +  snes - the SNES context
2937 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2938          the Jacobian is built etc. -2 means rebuild at next chance but then never again
2939 
2940    Options Database Keys:
2941 .    -snes_lag_jacobian <lag>
2942 
2943    Notes:
2944    The default is 1
2945    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2946    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
2947    at the next Newton step but never again (unless it is reset to another value)
2948 
2949    Level: intermediate
2950 
2951 .keywords: SNES, nonlinear, set, convergence, tolerances
2952 
2953 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()
2954 
2955 @*/
2956 PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
2957 {
2958   PetscFunctionBegin;
2959   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2960   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2961   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2962   PetscValidLogicalCollectiveInt(snes,lag,2);
2963   snes->lagjacobian = lag;
2964   PetscFunctionReturn(0);
2965 }
2966 
2967 #undef __FUNCT__
2968 #define __FUNCT__ "SNESGetLagJacobian"
2969 /*@
2970    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt
2971 
2972    Not Collective
2973 
2974    Input Parameter:
2975 .  snes - the SNES context
2976 
2977    Output Parameter:
2978 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2979          the Jacobian is built etc.
2980 
2981    Options Database Keys:
2982 .    -snes_lag_jacobian <lag>
2983 
2984    Notes:
2985    The default is 1
2986    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2987 
2988    Level: intermediate
2989 
2990 .keywords: SNES, nonlinear, set, convergence, tolerances
2991 
2992 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()
2993 
2994 @*/
2995 PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
2996 {
2997   PetscFunctionBegin;
2998   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2999   *lag = snes->lagjacobian;
3000   PetscFunctionReturn(0);
3001 }
3002 
3003 #undef __FUNCT__
3004 #define __FUNCT__ "SNESSetLagJacobianPersists"
3005 /*@
3006    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves
3007 
3008    Logically collective on SNES
3009 
3010    Input Parameter:
3011 +  snes - the SNES context
3012 -   flg - jacobian lagging persists if true
3013 
3014    Options Database Keys:
3015 .    -snes_lag_jacobian_persists <flg>
3016 
3017    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
3018    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
3019    timesteps may present huge efficiency gains.
3020 
3021    Level: developer
3022 
3023 .keywords: SNES, nonlinear, lag
3024 
3025 .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
3026 
3027 @*/
3028 PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
3029 {
3030   PetscFunctionBegin;
3031   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3032   PetscValidLogicalCollectiveBool(snes,flg,2);
3033   snes->lagjac_persist = flg;
3034   PetscFunctionReturn(0);
3035 }
3036 
3037 #undef __FUNCT__
3038 #define __FUNCT__ "SNESSetLagPreconditionerPersists"
3039 /*@
3040    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple solves
3041 
3042    Logically Collective on SNES
3043 
3044    Input Parameter:
3045 +  snes - the SNES context
3046 -   flg - preconditioner lagging persists if true
3047 
3048    Options Database Keys:
3049 .    -snes_lag_jacobian_persists <flg>
3050 
3051    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
3052    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
3053    several timesteps may present huge efficiency gains.
3054 
3055    Level: developer
3056 
3057 .keywords: SNES, nonlinear, lag
3058 
3059 .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
3060 
3061 @*/
3062 PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
3063 {
3064   PetscFunctionBegin;
3065   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3066   PetscValidLogicalCollectiveBool(snes,flg,2);
3067   snes->lagpre_persist = flg;
3068   PetscFunctionReturn(0);
3069 }
3070 
3071 #undef __FUNCT__
3072 #define __FUNCT__ "SNESSetTolerances"
3073 /*@
3074    SNESSetTolerances - Sets various parameters used in convergence tests.
3075 
3076    Logically Collective on SNES
3077 
3078    Input Parameters:
3079 +  snes - the SNES context
3080 .  abstol - absolute convergence tolerance
3081 .  rtol - relative convergence tolerance
3082 .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
3083 .  maxit - maximum number of iterations
3084 -  maxf - maximum number of function evaluations
3085 
3086    Options Database Keys:
3087 +    -snes_atol <abstol> - Sets abstol
3088 .    -snes_rtol <rtol> - Sets rtol
3089 .    -snes_stol <stol> - Sets stol
3090 .    -snes_max_it <maxit> - Sets maxit
3091 -    -snes_max_funcs <maxf> - Sets maxf
3092 
3093    Notes:
3094    The default maximum number of iterations is 50.
3095    The default maximum number of function evaluations is 1000.
3096 
3097    Level: intermediate
3098 
3099 .keywords: SNES, nonlinear, set, convergence, tolerances
3100 
3101 .seealso: SNESSetTrustRegionTolerance()
3102 @*/
3103 PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
3104 {
3105   PetscFunctionBegin;
3106   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3107   PetscValidLogicalCollectiveReal(snes,abstol,2);
3108   PetscValidLogicalCollectiveReal(snes,rtol,3);
3109   PetscValidLogicalCollectiveReal(snes,stol,4);
3110   PetscValidLogicalCollectiveInt(snes,maxit,5);
3111   PetscValidLogicalCollectiveInt(snes,maxf,6);
3112 
3113   if (abstol != PETSC_DEFAULT) {
3114     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %g must be non-negative",(double)abstol);
3115     snes->abstol = abstol;
3116   }
3117   if (rtol != PETSC_DEFAULT) {
3118     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);
3119     snes->rtol = rtol;
3120   }
3121   if (stol != PETSC_DEFAULT) {
3122     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %g must be non-negative",(double)stol);
3123     snes->stol = stol;
3124   }
3125   if (maxit != PETSC_DEFAULT) {
3126     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
3127     snes->max_its = maxit;
3128   }
3129   if (maxf != PETSC_DEFAULT) {
3130     if (maxf < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
3131     snes->max_funcs = maxf;
3132   }
3133   snes->tolerancesset = PETSC_TRUE;
3134   PetscFunctionReturn(0);
3135 }
3136 
3137 #undef __FUNCT__
3138 #define __FUNCT__ "SNESGetTolerances"
3139 /*@
3140    SNESGetTolerances - Gets various parameters used in convergence tests.
3141 
3142    Not Collective
3143 
3144    Input Parameters:
3145 +  snes - the SNES context
3146 .  atol - absolute convergence tolerance
3147 .  rtol - relative convergence tolerance
3148 .  stol -  convergence tolerance in terms of the norm
3149            of the change in the solution between steps
3150 .  maxit - maximum number of iterations
3151 -  maxf - maximum number of function evaluations
3152 
3153    Notes:
3154    The user can specify NULL for any parameter that is not needed.
3155 
3156    Level: intermediate
3157 
3158 .keywords: SNES, nonlinear, get, convergence, tolerances
3159 
3160 .seealso: SNESSetTolerances()
3161 @*/
3162 PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3163 {
3164   PetscFunctionBegin;
3165   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3166   if (atol)  *atol  = snes->abstol;
3167   if (rtol)  *rtol  = snes->rtol;
3168   if (stol)  *stol  = snes->stol;
3169   if (maxit) *maxit = snes->max_its;
3170   if (maxf)  *maxf  = snes->max_funcs;
3171   PetscFunctionReturn(0);
3172 }
3173 
3174 #undef __FUNCT__
3175 #define __FUNCT__ "SNESSetTrustRegionTolerance"
3176 /*@
3177    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.
3178 
3179    Logically Collective on SNES
3180 
3181    Input Parameters:
3182 +  snes - the SNES context
3183 -  tol - tolerance
3184 
3185    Options Database Key:
3186 .  -snes_trtol <tol> - Sets tol
3187 
3188    Level: intermediate
3189 
3190 .keywords: SNES, nonlinear, set, trust region, tolerance
3191 
3192 .seealso: SNESSetTolerances()
3193 @*/
3194 PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3195 {
3196   PetscFunctionBegin;
3197   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3198   PetscValidLogicalCollectiveReal(snes,tol,2);
3199   snes->deltatol = tol;
3200   PetscFunctionReturn(0);
3201 }
3202 
3203 /*
3204    Duplicate the lg monitors for SNES from KSP; for some reason with
3205    dynamic libraries things don't work under Sun4 if we just use
3206    macros instead of functions
3207 */
3208 #undef __FUNCT__
3209 #define __FUNCT__ "SNESMonitorLGResidualNorm"
3210 PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,PetscObject *objs)
3211 {
3212   PetscErrorCode ierr;
3213 
3214   PetscFunctionBegin;
3215   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3216   ierr = KSPMonitorLGResidualNorm((KSP)snes,it,norm,objs);CHKERRQ(ierr);
3217   PetscFunctionReturn(0);
3218 }
3219 
3220 #undef __FUNCT__
3221 #define __FUNCT__ "SNESMonitorLGCreate"
3222 PetscErrorCode  SNESMonitorLGCreate(const char host[],const char label[],int x,int y,int m,int n,PetscObject **draw)
3223 {
3224   PetscErrorCode ierr;
3225 
3226   PetscFunctionBegin;
3227   ierr = KSPMonitorLGResidualNormCreate(host,label,x,y,m,n,draw);CHKERRQ(ierr);
3228   PetscFunctionReturn(0);
3229 }
3230 
3231 #undef __FUNCT__
3232 #define __FUNCT__ "SNESMonitorLGDestroy"
3233 PetscErrorCode  SNESMonitorLGDestroy(PetscObject **objs)
3234 {
3235   PetscErrorCode ierr;
3236 
3237   PetscFunctionBegin;
3238   ierr = KSPMonitorLGResidualNormDestroy(objs);CHKERRQ(ierr);
3239   PetscFunctionReturn(0);
3240 }
3241 
3242 extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
3243 #undef __FUNCT__
3244 #define __FUNCT__ "SNESMonitorLGRange"
3245 PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3246 {
3247   PetscDrawLG      lg;
3248   PetscErrorCode   ierr;
3249   PetscReal        x,y,per;
3250   PetscViewer      v = (PetscViewer)monctx;
3251   static PetscReal prev; /* should be in the context */
3252   PetscDraw        draw;
3253 
3254   PetscFunctionBegin;
3255   PetscValidHeaderSpecific(v,PETSC_VIEWER_CLASSID,4);
3256   ierr = PetscViewerDrawGetDrawLG(v,0,&lg);CHKERRQ(ierr);
3257   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3258   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3259   ierr = PetscDrawSetTitle(draw,"Residual norm");CHKERRQ(ierr);
3260   x    = (PetscReal)n;
3261   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
3262   else y = -15.0;
3263   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3264   if (n < 20 || !(n % 5)) {
3265     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3266   }
3267 
3268   ierr = PetscViewerDrawGetDrawLG(v,1,&lg);CHKERRQ(ierr);
3269   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3270   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3271   ierr = PetscDrawSetTitle(draw,"% elemts > .2*max elemt");CHKERRQ(ierr);
3272   ierr =  SNESMonitorRange_Private(snes,n,&per);CHKERRQ(ierr);
3273   x    = (PetscReal)n;
3274   y    = 100.0*per;
3275   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3276   if (n < 20 || !(n % 5)) {
3277     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3278   }
3279 
3280   ierr = PetscViewerDrawGetDrawLG(v,2,&lg);CHKERRQ(ierr);
3281   if (!n) {prev = rnorm;ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3282   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3283   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");CHKERRQ(ierr);
3284   x    = (PetscReal)n;
3285   y    = (prev - rnorm)/prev;
3286   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3287   if (n < 20 || !(n % 5)) {
3288     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3289   }
3290 
3291   ierr = PetscViewerDrawGetDrawLG(v,3,&lg);CHKERRQ(ierr);
3292   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3293   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3294   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");CHKERRQ(ierr);
3295   x    = (PetscReal)n;
3296   y    = (prev - rnorm)/(prev*per);
3297   if (n > 2) { /*skip initial crazy value */
3298     ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3299   }
3300   if (n < 20 || !(n % 5)) {
3301     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3302   }
3303   prev = rnorm;
3304   PetscFunctionReturn(0);
3305 }
3306 
3307 #undef __FUNCT__
3308 #define __FUNCT__ "SNESMonitor"
3309 /*@
3310    SNESMonitor - runs the user provided monitor routines, if they exist
3311 
3312    Collective on SNES
3313 
3314    Input Parameters:
3315 +  snes - nonlinear solver context obtained from SNESCreate()
3316 .  iter - iteration number
3317 -  rnorm - relative norm of the residual
3318 
3319    Notes:
3320    This routine is called by the SNES implementations.
3321    It does not typically need to be called by the user.
3322 
3323    Level: developer
3324 
3325 .seealso: SNESMonitorSet()
3326 @*/
3327 PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3328 {
3329   PetscErrorCode ierr;
3330   PetscInt       i,n = snes->numbermonitors;
3331 
3332   PetscFunctionBegin;
3333   ierr = VecLockPush(snes->vec_sol);CHKERRQ(ierr);
3334   for (i=0; i<n; i++) {
3335     ierr = (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);CHKERRQ(ierr);
3336   }
3337   ierr = VecLockPop(snes->vec_sol);CHKERRQ(ierr);
3338   PetscFunctionReturn(0);
3339 }
3340 
3341 /* ------------ Routines to set performance monitoring options ----------- */
3342 
3343 /*MC
3344     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver
3345 
3346      Synopsis:
3347      #include <petscsnes.h>
3348 $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)
3349 
3350 +    snes - the SNES context
3351 .    its - iteration number
3352 .    norm - 2-norm function value (may be estimated)
3353 -    mctx - [optional] monitoring context
3354 
3355    Level: advanced
3356 
3357 .seealso:   SNESMonitorSet(), SNESMonitorGet()
3358 M*/
3359 
3360 #undef __FUNCT__
3361 #define __FUNCT__ "SNESMonitorSet"
3362 /*@C
3363    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3364    iteration of the nonlinear solver to display the iteration's
3365    progress.
3366 
3367    Logically Collective on SNES
3368 
3369    Input Parameters:
3370 +  snes - the SNES context
3371 .  f - the monitor function, see SNESMonitorFunction for the calling sequence
3372 .  mctx - [optional] user-defined context for private data for the
3373           monitor routine (use NULL if no context is desired)
3374 -  monitordestroy - [optional] routine that frees monitor context
3375           (may be NULL)
3376 
3377    Options Database Keys:
3378 +    -snes_monitor        - sets SNESMonitorDefault()
3379 .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3380                             uses SNESMonitorLGCreate()
3381 -    -snes_monitor_cancel - cancels all monitors that have
3382                             been hardwired into a code by
3383                             calls to SNESMonitorSet(), but
3384                             does not cancel those set via
3385                             the options database.
3386 
3387    Notes:
3388    Several different monitoring routines may be set by calling
3389    SNESMonitorSet() multiple times; all will be called in the
3390    order in which they were set.
3391 
3392    Fortran notes: Only a single monitor function can be set for each SNES object
3393 
3394    Level: intermediate
3395 
3396 .keywords: SNES, nonlinear, set, monitor
3397 
3398 .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
3399 @*/
3400 PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*f)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3401 {
3402   PetscInt       i;
3403   PetscErrorCode ierr;
3404 
3405   PetscFunctionBegin;
3406   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3407   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3408   for (i=0; i<snes->numbermonitors;i++) {
3409     if (f == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
3410       if (monitordestroy) {
3411         ierr = (*monitordestroy)(&mctx);CHKERRQ(ierr);
3412       }
3413       PetscFunctionReturn(0);
3414     }
3415   }
3416   snes->monitor[snes->numbermonitors]          = f;
3417   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
3418   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
3419   PetscFunctionReturn(0);
3420 }
3421 
3422 #undef __FUNCT__
3423 #define __FUNCT__ "SNESMonitorCancel"
3424 /*@
3425    SNESMonitorCancel - Clears all the monitor functions for a SNES object.
3426 
3427    Logically Collective on SNES
3428 
3429    Input Parameters:
3430 .  snes - the SNES context
3431 
3432    Options Database Key:
3433 .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3434     into a code by calls to SNESMonitorSet(), but does not cancel those
3435     set via the options database
3436 
3437    Notes:
3438    There is no way to clear one specific monitor from a SNES object.
3439 
3440    Level: intermediate
3441 
3442 .keywords: SNES, nonlinear, set, monitor
3443 
3444 .seealso: SNESMonitorDefault(), SNESMonitorSet()
3445 @*/
3446 PetscErrorCode  SNESMonitorCancel(SNES snes)
3447 {
3448   PetscErrorCode ierr;
3449   PetscInt       i;
3450 
3451   PetscFunctionBegin;
3452   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3453   for (i=0; i<snes->numbermonitors; i++) {
3454     if (snes->monitordestroy[i]) {
3455       ierr = (*snes->monitordestroy[i])(&snes->monitorcontext[i]);CHKERRQ(ierr);
3456     }
3457   }
3458   snes->numbermonitors = 0;
3459   PetscFunctionReturn(0);
3460 }
3461 
3462 /*MC
3463     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver
3464 
3465      Synopsis:
3466      #include <petscsnes.h>
3467 $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)
3468 
3469 +    snes - the SNES context
3470 .    it - current iteration (0 is the first and is before any Newton step)
3471 .    cctx - [optional] convergence context
3472 .    reason - reason for convergence/divergence
3473 .    xnorm - 2-norm of current iterate
3474 .    gnorm - 2-norm of current step
3475 -    f - 2-norm of function
3476 
3477    Level: intermediate
3478 
3479 .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
3480 M*/
3481 
3482 #undef __FUNCT__
3483 #define __FUNCT__ "SNESSetConvergenceTest"
3484 /*@C
3485    SNESSetConvergenceTest - Sets the function that is to be used
3486    to test for convergence of the nonlinear iterative solution.
3487 
3488    Logically Collective on SNES
3489 
3490    Input Parameters:
3491 +  snes - the SNES context
3492 .  SNESConvergenceTestFunction - routine to test for convergence
3493 .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
3494 -  destroy - [optional] destructor for the context (may be NULL; NULL_FUNCTION in Fortran)
3495 
3496    Level: advanced
3497 
3498 .keywords: SNES, nonlinear, set, convergence, test
3499 
3500 .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
3501 @*/
3502 PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
3503 {
3504   PetscErrorCode ierr;
3505 
3506   PetscFunctionBegin;
3507   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3508   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
3509   if (snes->ops->convergeddestroy) {
3510     ierr = (*snes->ops->convergeddestroy)(snes->cnvP);CHKERRQ(ierr);
3511   }
3512   snes->ops->converged        = SNESConvergenceTestFunction;
3513   snes->ops->convergeddestroy = destroy;
3514   snes->cnvP                  = cctx;
3515   PetscFunctionReturn(0);
3516 }
3517 
3518 #undef __FUNCT__
3519 #define __FUNCT__ "SNESGetConvergedReason"
3520 /*@
3521    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.
3522 
3523    Not Collective
3524 
3525    Input Parameter:
3526 .  snes - the SNES context
3527 
3528    Output Parameter:
3529 .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3530             manual pages for the individual convergence tests for complete lists
3531 
3532    Level: intermediate
3533 
3534    Notes: Can only be called after the call the SNESSolve() is complete.
3535 
3536 .keywords: SNES, nonlinear, set, convergence, test
3537 
3538 .seealso: SNESSetConvergenceTest(), SNESConvergedReason
3539 @*/
3540 PetscErrorCode  SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
3541 {
3542   PetscFunctionBegin;
3543   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3544   PetscValidPointer(reason,2);
3545   *reason = snes->reason;
3546   PetscFunctionReturn(0);
3547 }
3548 
3549 #undef __FUNCT__
3550 #define __FUNCT__ "SNESSetConvergenceHistory"
3551 /*@
3552    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.
3553 
3554    Logically Collective on SNES
3555 
3556    Input Parameters:
3557 +  snes - iterative context obtained from SNESCreate()
3558 .  a   - array to hold history, this array will contain the function norms computed at each step
3559 .  its - integer array holds the number of linear iterations for each solve.
3560 .  na  - size of a and its
3561 -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
3562            else it continues storing new values for new nonlinear solves after the old ones
3563 
3564    Notes:
3565    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
3566    default array of length 10000 is allocated.
3567 
3568    This routine is useful, e.g., when running a code for purposes
3569    of accurate performance monitoring, when no I/O should be done
3570    during the section of code that is being timed.
3571 
3572    Level: intermediate
3573 
3574 .keywords: SNES, set, convergence, history
3575 
3576 .seealso: SNESGetConvergenceHistory()
3577 
3578 @*/
3579 PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
3580 {
3581   PetscErrorCode ierr;
3582 
3583   PetscFunctionBegin;
3584   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3585   if (a) PetscValidScalarPointer(a,2);
3586   if (its) PetscValidIntPointer(its,3);
3587   if (!a) {
3588     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
3589     ierr = PetscCalloc1(na,&a);CHKERRQ(ierr);
3590     ierr = PetscCalloc1(na,&its);CHKERRQ(ierr);
3591 
3592     snes->conv_malloc = PETSC_TRUE;
3593   }
3594   snes->conv_hist       = a;
3595   snes->conv_hist_its   = its;
3596   snes->conv_hist_max   = na;
3597   snes->conv_hist_len   = 0;
3598   snes->conv_hist_reset = reset;
3599   PetscFunctionReturn(0);
3600 }
3601 
3602 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3603 #include <engine.h>   /* MATLAB include file */
3604 #include <mex.h>      /* MATLAB include file */
3605 
3606 #undef __FUNCT__
3607 #define __FUNCT__ "SNESGetConvergenceHistoryMatlab"
3608 PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
3609 {
3610   mxArray   *mat;
3611   PetscInt  i;
3612   PetscReal *ar;
3613 
3614   PetscFunctionBegin;
3615   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
3616   ar  = (PetscReal*) mxGetData(mat);
3617   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
3618   PetscFunctionReturn(mat);
3619 }
3620 #endif
3621 
3622 #undef __FUNCT__
3623 #define __FUNCT__ "SNESGetConvergenceHistory"
3624 /*@C
3625    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.
3626 
3627    Not Collective
3628 
3629    Input Parameter:
3630 .  snes - iterative context obtained from SNESCreate()
3631 
3632    Output Parameters:
3633 .  a   - array to hold history
3634 .  its - integer array holds the number of linear iterations (or
3635          negative if not converged) for each solve.
3636 -  na  - size of a and its
3637 
3638    Notes:
3639     The calling sequence for this routine in Fortran is
3640 $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
3641 
3642    This routine is useful, e.g., when running a code for purposes
3643    of accurate performance monitoring, when no I/O should be done
3644    during the section of code that is being timed.
3645 
3646    Level: intermediate
3647 
3648 .keywords: SNES, get, convergence, history
3649 
3650 .seealso: SNESSetConvergencHistory()
3651 
3652 @*/
3653 PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
3654 {
3655   PetscFunctionBegin;
3656   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3657   if (a)   *a   = snes->conv_hist;
3658   if (its) *its = snes->conv_hist_its;
3659   if (na)  *na  = snes->conv_hist_len;
3660   PetscFunctionReturn(0);
3661 }
3662 
3663 #undef __FUNCT__
3664 #define __FUNCT__ "SNESSetUpdate"
3665 /*@C
3666   SNESSetUpdate - Sets the general-purpose update function called
3667   at the beginning of every iteration of the nonlinear solve. Specifically
3668   it is called just before the Jacobian is "evaluated".
3669 
3670   Logically Collective on SNES
3671 
3672   Input Parameters:
3673 . snes - The nonlinear solver context
3674 . func - The function
3675 
3676   Calling sequence of func:
3677 . func (SNES snes, PetscInt step);
3678 
3679 . step - The current step of the iteration
3680 
3681   Level: advanced
3682 
3683   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()
3684         This is not used by most users.
3685 
3686 .keywords: SNES, update
3687 
3688 .seealso SNESSetJacobian(), SNESSolve()
3689 @*/
3690 PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
3691 {
3692   PetscFunctionBegin;
3693   PetscValidHeaderSpecific(snes, SNES_CLASSID,1);
3694   snes->ops->update = func;
3695   PetscFunctionReturn(0);
3696 }
3697 
3698 #undef __FUNCT__
3699 #define __FUNCT__ "SNESScaleStep_Private"
3700 /*
3701    SNESScaleStep_Private - Scales a step so that its length is less than the
3702    positive parameter delta.
3703 
3704     Input Parameters:
3705 +   snes - the SNES context
3706 .   y - approximate solution of linear system
3707 .   fnorm - 2-norm of current function
3708 -   delta - trust region size
3709 
3710     Output Parameters:
3711 +   gpnorm - predicted function norm at the new point, assuming local
3712     linearization.  The value is zero if the step lies within the trust
3713     region, and exceeds zero otherwise.
3714 -   ynorm - 2-norm of the step
3715 
3716     Note:
3717     For non-trust region methods such as SNESNEWTONLS, the parameter delta
3718     is set to be the maximum allowable step size.
3719 
3720 .keywords: SNES, nonlinear, scale, step
3721 */
3722 PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
3723 {
3724   PetscReal      nrm;
3725   PetscScalar    cnorm;
3726   PetscErrorCode ierr;
3727 
3728   PetscFunctionBegin;
3729   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3730   PetscValidHeaderSpecific(y,VEC_CLASSID,2);
3731   PetscCheckSameComm(snes,1,y,2);
3732 
3733   ierr = VecNorm(y,NORM_2,&nrm);CHKERRQ(ierr);
3734   if (nrm > *delta) {
3735     nrm     = *delta/nrm;
3736     *gpnorm = (1.0 - nrm)*(*fnorm);
3737     cnorm   = nrm;
3738     ierr    = VecScale(y,cnorm);CHKERRQ(ierr);
3739     *ynorm  = *delta;
3740   } else {
3741     *gpnorm = 0.0;
3742     *ynorm  = nrm;
3743   }
3744   PetscFunctionReturn(0);
3745 }
3746 
3747 #undef __FUNCT__
3748 #define __FUNCT__ "SNESReasonView"
3749 /*@
3750    SNESReasonView - Displays the reason a SNES solve converged or diverged to a viewer
3751 
3752    Collective on SNES
3753 
3754    Parameter:
3755 +  snes - iterative context obtained from SNESCreate()
3756 -  viewer - the viewer to display the reason
3757 
3758 
3759    Options Database Keys:
3760 .  -snes_converged_reason - print reason for converged or diverged, also prints number of iterations
3761 
3762    Level: beginner
3763 
3764 .keywords: SNES, solve, linear system
3765 
3766 .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault()
3767 
3768 @*/
3769 PetscErrorCode  SNESReasonView(SNES snes,PetscViewer viewer)
3770 {
3771   PetscErrorCode ierr;
3772   PetscBool      isAscii;
3773 
3774   PetscFunctionBegin;
3775   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isAscii);CHKERRQ(ierr);
3776   if (isAscii) {
3777     ierr = PetscViewerASCIIAddTab(viewer,((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3778     if (snes->reason > 0) {
3779       if (((PetscObject) snes)->prefix) {
3780         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve converged due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3781       } else {
3782         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3783       }
3784     } else {
3785       if (((PetscObject) snes)->prefix) {
3786         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);
3787       } else {
3788         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3789       }
3790     }
3791     ierr = PetscViewerASCIISubtractTab(viewer,((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3792   }
3793   PetscFunctionReturn(0);
3794 }
3795 
3796 #undef __FUNCT__
3797 #define __FUNCT__ "SNESReasonViewFromOptions"
3798 /*@C
3799   SNESReasonViewFromOptions - Processes command line options to determine if/how a SNESReason is to be viewed.
3800 
3801   Collective on SNES
3802 
3803   Input Parameters:
3804 . snes   - the SNES object
3805 
3806   Level: intermediate
3807 
3808 @*/
3809 PetscErrorCode SNESReasonViewFromOptions(SNES snes)
3810 {
3811   PetscErrorCode    ierr;
3812   PetscViewer       viewer;
3813   PetscBool         flg;
3814   static PetscBool  incall = PETSC_FALSE;
3815   PetscViewerFormat format;
3816 
3817   PetscFunctionBegin;
3818   if (incall) PetscFunctionReturn(0);
3819   incall = PETSC_TRUE;
3820   ierr   = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_converged_reason",&viewer,&format,&flg);CHKERRQ(ierr);
3821   if (flg) {
3822     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
3823     ierr = SNESReasonView(snes,viewer);CHKERRQ(ierr);
3824     ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
3825     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3826   }
3827   incall = PETSC_FALSE;
3828   PetscFunctionReturn(0);
3829 }
3830 
3831 #undef __FUNCT__
3832 #define __FUNCT__ "SNESSolve"
3833 /*@C
3834    SNESSolve - Solves a nonlinear system F(x) = b.
3835    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3836 
3837    Collective on SNES
3838 
3839    Input Parameters:
3840 +  snes - the SNES context
3841 .  b - the constant part of the equation F(x) = b, or NULL to use zero.
3842 -  x - the solution vector.
3843 
3844    Notes:
3845    The user should initialize the vector,x, with the initial guess
3846    for the nonlinear solve prior to calling SNESSolve.  In particular,
3847    to employ an initial guess of zero, the user should explicitly set
3848    this vector to zero by calling VecSet().
3849 
3850    Level: beginner
3851 
3852 .keywords: SNES, nonlinear, solve
3853 
3854 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3855 @*/
3856 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3857 {
3858   PetscErrorCode    ierr;
3859   PetscBool         flg;
3860   PetscInt          grid;
3861   Vec               xcreated = NULL;
3862   DM                dm;
3863 
3864   PetscFunctionBegin;
3865   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3866   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3867   if (x) PetscCheckSameComm(snes,1,x,3);
3868   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3869   if (b) PetscCheckSameComm(snes,1,b,2);
3870 
3871   if (!x) {
3872     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3873     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3874     x    = xcreated;
3875   }
3876   ierr = SNESViewFromOptions(snes,NULL,"-snes_view_pre");CHKERRQ(ierr);
3877 
3878   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);}
3879   for (grid=0; grid<snes->gridsequence+1; grid++) {
3880 
3881     /* set solution vector */
3882     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3883     ierr          = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3884     snes->vec_sol = x;
3885     ierr          = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3886 
3887     /* set affine vector if provided */
3888     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3889     ierr          = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3890     snes->vec_rhs = b;
3891 
3892     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
3893     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
3894     if (!snes->vec_sol_update /* && snes->vec_sol */) {
3895       ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
3896       ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);CHKERRQ(ierr);
3897     }
3898     ierr = DMShellSetGlobalVector(dm,snes->vec_sol);CHKERRQ(ierr);
3899     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3900 
3901     if (!grid) {
3902       if (snes->ops->computeinitialguess) {
3903         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3904       }
3905     }
3906 
3907     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3908     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}
3909 
3910     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3911     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3912     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3913     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3914     snes->domainerror = PETSC_FALSE; /* clear the flag if it has been set */
3915 
3916     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
3917     if (snes->lagpre_persist) snes->pre_iter += snes->iter;
3918 
3919     flg  = PETSC_FALSE;
3920     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,NULL);CHKERRQ(ierr);
3921     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
3922     ierr = SNESReasonViewFromOptions(snes);CHKERRQ(ierr);
3923 
3924     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
3925     if (grid <  snes->gridsequence) {
3926       DM  fine;
3927       Vec xnew;
3928       Mat interp;
3929 
3930       ierr = DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);CHKERRQ(ierr);
3931       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
3932       ierr = DMCreateInterpolation(snes->dm,fine,&interp,NULL);CHKERRQ(ierr);
3933       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
3934       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
3935       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
3936       ierr = MatDestroy(&interp);CHKERRQ(ierr);
3937       x    = xnew;
3938 
3939       ierr = SNESReset(snes);CHKERRQ(ierr);
3940       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
3941       ierr = DMDestroy(&fine);CHKERRQ(ierr);
3942       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);
3943     }
3944   }
3945   ierr = SNESViewFromOptions(snes,NULL,"-snes_view");CHKERRQ(ierr);
3946   ierr = VecViewFromOptions(snes->vec_sol,(PetscObject)snes,"-snes_view_solution");CHKERRQ(ierr);
3947 
3948   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
3949   ierr = PetscObjectSAWsBlock((PetscObject)snes);CHKERRQ(ierr);
3950   PetscFunctionReturn(0);
3951 }
3952 
3953 /* --------- Internal routines for SNES Package --------- */
3954 
3955 #undef __FUNCT__
3956 #define __FUNCT__ "SNESSetType"
3957 /*@C
3958    SNESSetType - Sets the method for the nonlinear solver.
3959 
3960    Collective on SNES
3961 
3962    Input Parameters:
3963 +  snes - the SNES context
3964 -  type - a known method
3965 
3966    Options Database Key:
3967 .  -snes_type <type> - Sets the method; use -help for a list
3968    of available methods (for instance, newtonls or newtontr)
3969 
3970    Notes:
3971    See "petsc/include/petscsnes.h" for available methods (for instance)
3972 +    SNESNEWTONLS - Newton's method with line search
3973      (systems of nonlinear equations)
3974 .    SNESNEWTONTR - Newton's method with trust region
3975      (systems of nonlinear equations)
3976 
3977   Normally, it is best to use the SNESSetFromOptions() command and then
3978   set the SNES solver type from the options database rather than by using
3979   this routine.  Using the options database provides the user with
3980   maximum flexibility in evaluating the many nonlinear solvers.
3981   The SNESSetType() routine is provided for those situations where it
3982   is necessary to set the nonlinear solver independently of the command
3983   line or options database.  This might be the case, for example, when
3984   the choice of solver changes during the execution of the program,
3985   and the user's application is taking responsibility for choosing the
3986   appropriate method.
3987 
3988     Developer Notes: SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
3989     the constructor in that list and calls it to create the spexific object.
3990 
3991   Level: intermediate
3992 
3993 .keywords: SNES, set, type
3994 
3995 .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()
3996 
3997 @*/
3998 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
3999 {
4000   PetscErrorCode ierr,(*r)(SNES);
4001   PetscBool      match;
4002 
4003   PetscFunctionBegin;
4004   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4005   PetscValidCharPointer(type,2);
4006 
4007   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
4008   if (match) PetscFunctionReturn(0);
4009 
4010   ierr =  PetscFunctionListFind(SNESList,type,&r);CHKERRQ(ierr);
4011   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
4012   /* Destroy the previous private SNES context */
4013   if (snes->ops->destroy) {
4014     ierr               = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
4015     snes->ops->destroy = NULL;
4016   }
4017   /* Reinitialize function pointers in SNESOps structure */
4018   snes->ops->setup          = 0;
4019   snes->ops->solve          = 0;
4020   snes->ops->view           = 0;
4021   snes->ops->setfromoptions = 0;
4022   snes->ops->destroy        = 0;
4023   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
4024   snes->setupcalled = PETSC_FALSE;
4025 
4026   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
4027   ierr = (*r)(snes);CHKERRQ(ierr);
4028   PetscFunctionReturn(0);
4029 }
4030 
4031 #undef __FUNCT__
4032 #define __FUNCT__ "SNESGetType"
4033 /*@C
4034    SNESGetType - Gets the SNES method type and name (as a string).
4035 
4036    Not Collective
4037 
4038    Input Parameter:
4039 .  snes - nonlinear solver context
4040 
4041    Output Parameter:
4042 .  type - SNES method (a character string)
4043 
4044    Level: intermediate
4045 
4046 .keywords: SNES, nonlinear, get, type, name
4047 @*/
4048 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
4049 {
4050   PetscFunctionBegin;
4051   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4052   PetscValidPointer(type,2);
4053   *type = ((PetscObject)snes)->type_name;
4054   PetscFunctionReturn(0);
4055 }
4056 
4057 #undef __FUNCT__
4058 #define __FUNCT__ "SNESSetSolution"
4059 /*@
4060   SNESSetSolution - Sets the solution vector for use by the SNES routines.
4061 
4062   Logically Collective on SNES and Vec
4063 
4064   Input Parameters:
4065 + snes - the SNES context obtained from SNESCreate()
4066 - u    - the solution vector
4067 
4068   Level: beginner
4069 
4070 .keywords: SNES, set, solution
4071 @*/
4072 PetscErrorCode SNESSetSolution(SNES snes, Vec u)
4073 {
4074   DM             dm;
4075   PetscErrorCode ierr;
4076 
4077   PetscFunctionBegin;
4078   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4079   PetscValidHeaderSpecific(u, VEC_CLASSID, 2);
4080   ierr = PetscObjectReference((PetscObject) u);CHKERRQ(ierr);
4081   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
4082 
4083   snes->vec_sol = u;
4084 
4085   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
4086   ierr = DMShellSetGlobalVector(dm, u);CHKERRQ(ierr);
4087   PetscFunctionReturn(0);
4088 }
4089 
4090 #undef __FUNCT__
4091 #define __FUNCT__ "SNESGetSolution"
4092 /*@
4093    SNESGetSolution - Returns the vector where the approximate solution is
4094    stored. This is the fine grid solution when using SNESSetGridSequence().
4095 
4096    Not Collective, but Vec is parallel if SNES is parallel
4097 
4098    Input Parameter:
4099 .  snes - the SNES context
4100 
4101    Output Parameter:
4102 .  x - the solution
4103 
4104    Level: intermediate
4105 
4106 .keywords: SNES, nonlinear, get, solution
4107 
4108 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
4109 @*/
4110 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
4111 {
4112   PetscFunctionBegin;
4113   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4114   PetscValidPointer(x,2);
4115   *x = snes->vec_sol;
4116   PetscFunctionReturn(0);
4117 }
4118 
4119 #undef __FUNCT__
4120 #define __FUNCT__ "SNESGetSolutionUpdate"
4121 /*@
4122    SNESGetSolutionUpdate - Returns the vector where the solution update is
4123    stored.
4124 
4125    Not Collective, but Vec is parallel if SNES is parallel
4126 
4127    Input Parameter:
4128 .  snes - the SNES context
4129 
4130    Output Parameter:
4131 .  x - the solution update
4132 
4133    Level: advanced
4134 
4135 .keywords: SNES, nonlinear, get, solution, update
4136 
4137 .seealso: SNESGetSolution(), SNESGetFunction()
4138 @*/
4139 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
4140 {
4141   PetscFunctionBegin;
4142   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4143   PetscValidPointer(x,2);
4144   *x = snes->vec_sol_update;
4145   PetscFunctionReturn(0);
4146 }
4147 
4148 #undef __FUNCT__
4149 #define __FUNCT__ "SNESGetFunction"
4150 /*@C
4151    SNESGetFunction - Returns the vector where the function is stored.
4152 
4153    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
4154 
4155    Input Parameter:
4156 .  snes - the SNES context
4157 
4158    Output Parameter:
4159 +  r - the vector that is used to store residuals (or NULL if you don't want it)
4160 .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
4161 -  ctx - the function context (or NULL if you don't want it)
4162 
4163    Level: advanced
4164 
4165 .keywords: SNES, nonlinear, get, function
4166 
4167 .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
4168 @*/
4169 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
4170 {
4171   PetscErrorCode ierr;
4172   DM             dm;
4173 
4174   PetscFunctionBegin;
4175   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4176   if (r) {
4177     if (!snes->vec_func) {
4178       if (snes->vec_rhs) {
4179         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
4180       } else if (snes->vec_sol) {
4181         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
4182       } else if (snes->dm) {
4183         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
4184       }
4185     }
4186     *r = snes->vec_func;
4187   }
4188   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4189   ierr = DMSNESGetFunction(dm,f,ctx);CHKERRQ(ierr);
4190   PetscFunctionReturn(0);
4191 }
4192 
4193 /*@C
4194    SNESGetNGS - Returns the NGS function and context.
4195 
4196    Input Parameter:
4197 .  snes - the SNES context
4198 
4199    Output Parameter:
4200 +  f - the function (or NULL) see SNESNGSFunction for details
4201 -  ctx    - the function context (or NULL)
4202 
4203    Level: advanced
4204 
4205 .keywords: SNES, nonlinear, get, function
4206 
4207 .seealso: SNESSetNGS(), SNESGetFunction()
4208 @*/
4209 
4210 #undef __FUNCT__
4211 #define __FUNCT__ "SNESGetNGS"
4212 PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
4213 {
4214   PetscErrorCode ierr;
4215   DM             dm;
4216 
4217   PetscFunctionBegin;
4218   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4219   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4220   ierr = DMSNESGetNGS(dm,f,ctx);CHKERRQ(ierr);
4221   PetscFunctionReturn(0);
4222 }
4223 
4224 #undef __FUNCT__
4225 #define __FUNCT__ "SNESSetOptionsPrefix"
4226 /*@C
4227    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4228    SNES options in the database.
4229 
4230    Logically Collective on SNES
4231 
4232    Input Parameter:
4233 +  snes - the SNES context
4234 -  prefix - the prefix to prepend to all option names
4235 
4236    Notes:
4237    A hyphen (-) must NOT be given at the beginning of the prefix name.
4238    The first character of all runtime options is AUTOMATICALLY the hyphen.
4239 
4240    Level: advanced
4241 
4242 .keywords: SNES, set, options, prefix, database
4243 
4244 .seealso: SNESSetFromOptions()
4245 @*/
4246 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4247 {
4248   PetscErrorCode ierr;
4249 
4250   PetscFunctionBegin;
4251   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4252   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4253   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4254   if (snes->linesearch) {
4255     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4256     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4257   }
4258   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4259   PetscFunctionReturn(0);
4260 }
4261 
4262 #undef __FUNCT__
4263 #define __FUNCT__ "SNESAppendOptionsPrefix"
4264 /*@C
4265    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4266    SNES options in the database.
4267 
4268    Logically Collective on SNES
4269 
4270    Input Parameters:
4271 +  snes - the SNES context
4272 -  prefix - the prefix to prepend to all option names
4273 
4274    Notes:
4275    A hyphen (-) must NOT be given at the beginning of the prefix name.
4276    The first character of all runtime options is AUTOMATICALLY the hyphen.
4277 
4278    Level: advanced
4279 
4280 .keywords: SNES, append, options, prefix, database
4281 
4282 .seealso: SNESGetOptionsPrefix()
4283 @*/
4284 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4285 {
4286   PetscErrorCode ierr;
4287 
4288   PetscFunctionBegin;
4289   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4290   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4291   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4292   if (snes->linesearch) {
4293     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4294     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4295   }
4296   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4297   PetscFunctionReturn(0);
4298 }
4299 
4300 #undef __FUNCT__
4301 #define __FUNCT__ "SNESGetOptionsPrefix"
4302 /*@C
4303    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4304    SNES options in the database.
4305 
4306    Not Collective
4307 
4308    Input Parameter:
4309 .  snes - the SNES context
4310 
4311    Output Parameter:
4312 .  prefix - pointer to the prefix string used
4313 
4314    Notes: On the fortran side, the user should pass in a string 'prefix' of
4315    sufficient length to hold the prefix.
4316 
4317    Level: advanced
4318 
4319 .keywords: SNES, get, options, prefix, database
4320 
4321 .seealso: SNESAppendOptionsPrefix()
4322 @*/
4323 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4324 {
4325   PetscErrorCode ierr;
4326 
4327   PetscFunctionBegin;
4328   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4329   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4330   PetscFunctionReturn(0);
4331 }
4332 
4333 
4334 #undef __FUNCT__
4335 #define __FUNCT__ "SNESRegister"
4336 /*@C
4337   SNESRegister - Adds a method to the nonlinear solver package.
4338 
4339    Not collective
4340 
4341    Input Parameters:
4342 +  name_solver - name of a new user-defined solver
4343 -  routine_create - routine to create method context
4344 
4345    Notes:
4346    SNESRegister() may be called multiple times to add several user-defined solvers.
4347 
4348    Sample usage:
4349 .vb
4350    SNESRegister("my_solver",MySolverCreate);
4351 .ve
4352 
4353    Then, your solver can be chosen with the procedural interface via
4354 $     SNESSetType(snes,"my_solver")
4355    or at runtime via the option
4356 $     -snes_type my_solver
4357 
4358    Level: advanced
4359 
4360     Note: If your function is not being put into a shared library then use SNESRegister() instead
4361 
4362 .keywords: SNES, nonlinear, register
4363 
4364 .seealso: SNESRegisterAll(), SNESRegisterDestroy()
4365 
4366   Level: advanced
4367 @*/
4368 PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
4369 {
4370   PetscErrorCode ierr;
4371 
4372   PetscFunctionBegin;
4373   ierr = PetscFunctionListAdd(&SNESList,sname,function);CHKERRQ(ierr);
4374   PetscFunctionReturn(0);
4375 }
4376 
4377 #undef __FUNCT__
4378 #define __FUNCT__ "SNESTestLocalMin"
4379 PetscErrorCode  SNESTestLocalMin(SNES snes)
4380 {
4381   PetscErrorCode ierr;
4382   PetscInt       N,i,j;
4383   Vec            u,uh,fh;
4384   PetscScalar    value;
4385   PetscReal      norm;
4386 
4387   PetscFunctionBegin;
4388   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4389   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4390   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4391 
4392   /* currently only works for sequential */
4393   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");CHKERRQ(ierr);
4394   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4395   for (i=0; i<N; i++) {
4396     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4397     ierr = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4398     for (j=-10; j<11; j++) {
4399       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
4400       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4401       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4402       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4403       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4404       value = -value;
4405       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4406     }
4407   }
4408   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4409   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4410   PetscFunctionReturn(0);
4411 }
4412 
4413 #undef __FUNCT__
4414 #define __FUNCT__ "SNESKSPSetUseEW"
4415 /*@
4416    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4417    computing relative tolerance for linear solvers within an inexact
4418    Newton method.
4419 
4420    Logically Collective on SNES
4421 
4422    Input Parameters:
4423 +  snes - SNES context
4424 -  flag - PETSC_TRUE or PETSC_FALSE
4425 
4426     Options Database:
4427 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4428 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4429 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4430 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4431 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4432 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4433 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4434 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4435 
4436    Notes:
4437    Currently, the default is to use a constant relative tolerance for
4438    the inner linear solvers.  Alternatively, one can use the
4439    Eisenstat-Walker method, where the relative convergence tolerance
4440    is reset at each Newton iteration according progress of the nonlinear
4441    solver.
4442 
4443    Level: advanced
4444 
4445    Reference:
4446    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4447    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4448 
4449 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4450 
4451 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4452 @*/
4453 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
4454 {
4455   PetscFunctionBegin;
4456   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4457   PetscValidLogicalCollectiveBool(snes,flag,2);
4458   snes->ksp_ewconv = flag;
4459   PetscFunctionReturn(0);
4460 }
4461 
4462 #undef __FUNCT__
4463 #define __FUNCT__ "SNESKSPGetUseEW"
4464 /*@
4465    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4466    for computing relative tolerance for linear solvers within an
4467    inexact Newton method.
4468 
4469    Not Collective
4470 
4471    Input Parameter:
4472 .  snes - SNES context
4473 
4474    Output Parameter:
4475 .  flag - PETSC_TRUE or PETSC_FALSE
4476 
4477    Notes:
4478    Currently, the default is to use a constant relative tolerance for
4479    the inner linear solvers.  Alternatively, one can use the
4480    Eisenstat-Walker method, where the relative convergence tolerance
4481    is reset at each Newton iteration according progress of the nonlinear
4482    solver.
4483 
4484    Level: advanced
4485 
4486    Reference:
4487    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4488    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4489 
4490 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4491 
4492 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4493 @*/
4494 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4495 {
4496   PetscFunctionBegin;
4497   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4498   PetscValidPointer(flag,2);
4499   *flag = snes->ksp_ewconv;
4500   PetscFunctionReturn(0);
4501 }
4502 
4503 #undef __FUNCT__
4504 #define __FUNCT__ "SNESKSPSetParametersEW"
4505 /*@
4506    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4507    convergence criteria for the linear solvers within an inexact
4508    Newton method.
4509 
4510    Logically Collective on SNES
4511 
4512    Input Parameters:
4513 +    snes - SNES context
4514 .    version - version 1, 2 (default is 2) or 3
4515 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4516 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4517 .    gamma - multiplicative factor for version 2 rtol computation
4518              (0 <= gamma2 <= 1)
4519 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4520 .    alpha2 - power for safeguard
4521 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4522 
4523    Note:
4524    Version 3 was contributed by Luis Chacon, June 2006.
4525 
4526    Use PETSC_DEFAULT to retain the default for any of the parameters.
4527 
4528    Level: advanced
4529 
4530    Reference:
4531    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4532    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4533    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4534 
4535 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4536 
4537 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4538 @*/
4539 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4540 {
4541   SNESKSPEW *kctx;
4542 
4543   PetscFunctionBegin;
4544   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4545   kctx = (SNESKSPEW*)snes->kspconvctx;
4546   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4547   PetscValidLogicalCollectiveInt(snes,version,2);
4548   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4549   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4550   PetscValidLogicalCollectiveReal(snes,gamma,5);
4551   PetscValidLogicalCollectiveReal(snes,alpha,6);
4552   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4553   PetscValidLogicalCollectiveReal(snes,threshold,8);
4554 
4555   if (version != PETSC_DEFAULT)   kctx->version   = version;
4556   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4557   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4558   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4559   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4560   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4561   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4562 
4563   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);
4564   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);
4565   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);
4566   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);
4567   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);
4568   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);
4569   PetscFunctionReturn(0);
4570 }
4571 
4572 #undef __FUNCT__
4573 #define __FUNCT__ "SNESKSPGetParametersEW"
4574 /*@
4575    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4576    convergence criteria for the linear solvers within an inexact
4577    Newton method.
4578 
4579    Not Collective
4580 
4581    Input Parameters:
4582      snes - SNES context
4583 
4584    Output Parameters:
4585 +    version - version 1, 2 (default is 2) or 3
4586 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4587 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4588 .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
4589 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4590 .    alpha2 - power for safeguard
4591 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4592 
4593    Level: advanced
4594 
4595 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4596 
4597 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4598 @*/
4599 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4600 {
4601   SNESKSPEW *kctx;
4602 
4603   PetscFunctionBegin;
4604   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4605   kctx = (SNESKSPEW*)snes->kspconvctx;
4606   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4607   if (version)   *version   = kctx->version;
4608   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4609   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4610   if (gamma)     *gamma     = kctx->gamma;
4611   if (alpha)     *alpha     = kctx->alpha;
4612   if (alpha2)    *alpha2    = kctx->alpha2;
4613   if (threshold) *threshold = kctx->threshold;
4614   PetscFunctionReturn(0);
4615 }
4616 
4617 #undef __FUNCT__
4618 #define __FUNCT__ "KSPPreSolve_SNESEW"
4619  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4620 {
4621   PetscErrorCode ierr;
4622   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4623   PetscReal      rtol  = PETSC_DEFAULT,stol;
4624 
4625   PetscFunctionBegin;
4626   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4627   if (!snes->iter) {
4628     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
4629     ierr = VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);CHKERRQ(ierr);
4630   }
4631   else {
4632     if (kctx->version == 1) {
4633       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4634       if (rtol < 0.0) rtol = -rtol;
4635       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
4636       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4637     } else if (kctx->version == 2) {
4638       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4639       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
4640       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4641     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
4642       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4643       /* safeguard: avoid sharp decrease of rtol */
4644       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
4645       stol = PetscMax(rtol,stol);
4646       rtol = PetscMin(kctx->rtol_0,stol);
4647       /* safeguard: avoid oversolving */
4648       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
4649       stol = PetscMax(rtol,stol);
4650       rtol = PetscMin(kctx->rtol_0,stol);
4651     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4652   }
4653   /* safeguard: avoid rtol greater than one */
4654   rtol = PetscMin(rtol,kctx->rtol_max);
4655   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4656   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);CHKERRQ(ierr);
4657   PetscFunctionReturn(0);
4658 }
4659 
4660 #undef __FUNCT__
4661 #define __FUNCT__ "KSPPostSolve_SNESEW"
4662 PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4663 {
4664   PetscErrorCode ierr;
4665   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4666   PCSide         pcside;
4667   Vec            lres;
4668 
4669   PetscFunctionBegin;
4670   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4671   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4672   kctx->norm_last = snes->norm;
4673   if (kctx->version == 1) {
4674     PC        pc;
4675     PetscBool isNone;
4676 
4677     ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
4678     ierr = PetscObjectTypeCompare((PetscObject) pc, PCNONE, &isNone);CHKERRQ(ierr);
4679     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4680      if (pcside == PC_RIGHT || isNone) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4681       /* KSP residual is true linear residual */
4682       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4683     } else {
4684       /* KSP residual is preconditioned residual */
4685       /* compute true linear residual norm */
4686       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4687       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4688       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4689       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4690       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4691     }
4692   }
4693   PetscFunctionReturn(0);
4694 }
4695 
4696 #undef __FUNCT__
4697 #define __FUNCT__ "SNESGetKSP"
4698 /*@
4699    SNESGetKSP - Returns the KSP context for a SNES solver.
4700 
4701    Not Collective, but if SNES object is parallel, then KSP object is parallel
4702 
4703    Input Parameter:
4704 .  snes - the SNES context
4705 
4706    Output Parameter:
4707 .  ksp - the KSP context
4708 
4709    Notes:
4710    The user can then directly manipulate the KSP context to set various
4711    options, etc.  Likewise, the user can then extract and manipulate the
4712    PC contexts as well.
4713 
4714    Level: beginner
4715 
4716 .keywords: SNES, nonlinear, get, KSP, context
4717 
4718 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
4719 @*/
4720 PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
4721 {
4722   PetscErrorCode ierr;
4723 
4724   PetscFunctionBegin;
4725   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4726   PetscValidPointer(ksp,2);
4727 
4728   if (!snes->ksp) {
4729     PetscBool monitor = PETSC_FALSE;
4730 
4731     ierr = KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);CHKERRQ(ierr);
4732     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);CHKERRQ(ierr);
4733     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);CHKERRQ(ierr);
4734 
4735     ierr = KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);CHKERRQ(ierr);
4736     ierr = KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);CHKERRQ(ierr);
4737 
4738     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-ksp_monitor_snes",&monitor,NULL);CHKERRQ(ierr);
4739     if (monitor) {
4740       ierr = KSPMonitorSet(snes->ksp,KSPMonitorSNES,snes,NULL);CHKERRQ(ierr);
4741     }
4742     monitor = PETSC_FALSE;
4743     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-ksp_monitor_snes_lg",&monitor,NULL);CHKERRQ(ierr);
4744     if (monitor) {
4745       PetscObject *objs;
4746       ierr = KSPMonitorSNESLGResidualNormCreate(0,0,PETSC_DECIDE,PETSC_DECIDE,600,600,&objs);CHKERRQ(ierr);
4747       objs[0] = (PetscObject) snes;
4748       ierr = KSPMonitorSet(snes->ksp,(PetscErrorCode (*)(KSP,PetscInt,PetscReal,void*))KSPMonitorSNESLGResidualNorm,objs,(PetscErrorCode (*)(void**))KSPMonitorSNESLGResidualNormDestroy);CHKERRQ(ierr);
4749     }
4750   }
4751   *ksp = snes->ksp;
4752   PetscFunctionReturn(0);
4753 }
4754 
4755 
4756 #include <petsc/private/dmimpl.h>
4757 #undef __FUNCT__
4758 #define __FUNCT__ "SNESSetDM"
4759 /*@
4760    SNESSetDM - Sets the DM that may be used by some preconditioners
4761 
4762    Logically Collective on SNES
4763 
4764    Input Parameters:
4765 +  snes - the preconditioner context
4766 -  dm - the dm
4767 
4768    Level: intermediate
4769 
4770 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4771 @*/
4772 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4773 {
4774   PetscErrorCode ierr;
4775   KSP            ksp;
4776   DMSNES         sdm;
4777 
4778   PetscFunctionBegin;
4779   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4780   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4781   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4782     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4783       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4784       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4785       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
4786     }
4787     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4788   }
4789   snes->dm     = dm;
4790   snes->dmAuto = PETSC_FALSE;
4791 
4792   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4793   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4794   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4795   if (snes->pc) {
4796     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4797     ierr = SNESSetNPCSide(snes,snes->pcside);CHKERRQ(ierr);
4798   }
4799   PetscFunctionReturn(0);
4800 }
4801 
4802 #undef __FUNCT__
4803 #define __FUNCT__ "SNESGetDM"
4804 /*@
4805    SNESGetDM - Gets the DM that may be used by some preconditioners
4806 
4807    Not Collective but DM obtained is parallel on SNES
4808 
4809    Input Parameter:
4810 . snes - the preconditioner context
4811 
4812    Output Parameter:
4813 .  dm - the dm
4814 
4815    Level: intermediate
4816 
4817 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4818 @*/
4819 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4820 {
4821   PetscErrorCode ierr;
4822 
4823   PetscFunctionBegin;
4824   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4825   if (!snes->dm) {
4826     ierr         = DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);CHKERRQ(ierr);
4827     snes->dmAuto = PETSC_TRUE;
4828   }
4829   *dm = snes->dm;
4830   PetscFunctionReturn(0);
4831 }
4832 
4833 #undef __FUNCT__
4834 #define __FUNCT__ "SNESSetNPC"
4835 /*@
4836   SNESSetNPC - Sets the nonlinear preconditioner to be used.
4837 
4838   Collective on SNES
4839 
4840   Input Parameters:
4841 + snes - iterative context obtained from SNESCreate()
4842 - pc   - the preconditioner object
4843 
4844   Notes:
4845   Use SNESGetNPC() to retrieve the preconditioner context (for example,
4846   to configure it using the API).
4847 
4848   Level: developer
4849 
4850 .keywords: SNES, set, precondition
4851 .seealso: SNESGetNPC(), SNESHasNPC()
4852 @*/
4853 PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
4854 {
4855   PetscErrorCode ierr;
4856 
4857   PetscFunctionBegin;
4858   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4859   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4860   PetscCheckSameComm(snes, 1, pc, 2);
4861   ierr     = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4862   ierr     = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4863   snes->pc = pc;
4864   ierr     = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->pc);CHKERRQ(ierr);
4865   PetscFunctionReturn(0);
4866 }
4867 
4868 #undef __FUNCT__
4869 #define __FUNCT__ "SNESGetNPC"
4870 /*@
4871   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.
4872 
4873   Not Collective
4874 
4875   Input Parameter:
4876 . snes - iterative context obtained from SNESCreate()
4877 
4878   Output Parameter:
4879 . pc - preconditioner context
4880 
4881   Notes: If a SNES was previously set with SNESSetNPC() then that SNES is returned.
4882 
4883   Level: developer
4884 
4885 .keywords: SNES, get, preconditioner
4886 .seealso: SNESSetNPC(), SNESHasNPC()
4887 @*/
4888 PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
4889 {
4890   PetscErrorCode ierr;
4891   const char     *optionsprefix;
4892 
4893   PetscFunctionBegin;
4894   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4895   PetscValidPointer(pc, 2);
4896   if (!snes->pc) {
4897     ierr = SNESCreate(PetscObjectComm((PetscObject)snes),&snes->pc);CHKERRQ(ierr);
4898     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4899     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
4900     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4901     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4902     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4903     ierr = SNESSetCountersReset(snes->pc,PETSC_FALSE);CHKERRQ(ierr);
4904   }
4905   *pc = snes->pc;
4906   PetscFunctionReturn(0);
4907 }
4908 
4909 #undef __FUNCT__
4910 #define __FUNCT__ "SNESHasNPC"
4911 /*@
4912   SNESHasNPC - Returns whether a nonlinear preconditioner exists
4913 
4914   Not Collective
4915 
4916   Input Parameter:
4917 . snes - iterative context obtained from SNESCreate()
4918 
4919   Output Parameter:
4920 . has_npc - whether the SNES has an NPC or not
4921 
4922   Level: developer
4923 
4924 .keywords: SNES, has, preconditioner
4925 .seealso: SNESSetNPC(), SNESGetNPC()
4926 @*/
4927 PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
4928 {
4929   PetscFunctionBegin;
4930   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4931   *has_npc = (PetscBool) (snes->pc != NULL);
4932   PetscFunctionReturn(0);
4933 }
4934 
4935 #undef __FUNCT__
4936 #define __FUNCT__ "SNESSetNPCSide"
4937 /*@
4938     SNESSetNPCSide - Sets the preconditioning side.
4939 
4940     Logically Collective on SNES
4941 
4942     Input Parameter:
4943 .   snes - iterative context obtained from SNESCreate()
4944 
4945     Output Parameter:
4946 .   side - the preconditioning side, where side is one of
4947 .vb
4948       PC_LEFT - left preconditioning (default)
4949       PC_RIGHT - right preconditioning
4950 .ve
4951 
4952     Options Database Keys:
4953 .   -snes_pc_side <right,left>
4954 
4955     Level: intermediate
4956 
4957 .keywords: SNES, set, right, left, side, preconditioner, flag
4958 
4959 .seealso: SNESGetNPCSide(), KSPSetPCSide()
4960 @*/
4961 PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
4962 {
4963   PetscFunctionBegin;
4964   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4965   PetscValidLogicalCollectiveEnum(snes,side,2);
4966   snes->pcside = side;
4967   PetscFunctionReturn(0);
4968 }
4969 
4970 #undef __FUNCT__
4971 #define __FUNCT__ "SNESGetNPCSide"
4972 /*@
4973     SNESGetNPCSide - Gets the preconditioning side.
4974 
4975     Not Collective
4976 
4977     Input Parameter:
4978 .   snes - iterative context obtained from SNESCreate()
4979 
4980     Output Parameter:
4981 .   side - the preconditioning side, where side is one of
4982 .vb
4983       PC_LEFT - left preconditioning (default)
4984       PC_RIGHT - right preconditioning
4985 .ve
4986 
4987     Level: intermediate
4988 
4989 .keywords: SNES, get, right, left, side, preconditioner, flag
4990 
4991 .seealso: SNESSetNPCSide(), KSPGetPCSide()
4992 @*/
4993 PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
4994 {
4995   PetscFunctionBegin;
4996   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4997   PetscValidPointer(side,2);
4998   *side = snes->pcside;
4999   PetscFunctionReturn(0);
5000 }
5001 
5002 #undef __FUNCT__
5003 #define __FUNCT__ "SNESSetLineSearch"
5004 /*@
5005   SNESSetLineSearch - Sets the linesearch on the SNES instance.
5006 
5007   Collective on SNES
5008 
5009   Input Parameters:
5010 + snes - iterative context obtained from SNESCreate()
5011 - linesearch   - the linesearch object
5012 
5013   Notes:
5014   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
5015   to configure it using the API).
5016 
5017   Level: developer
5018 
5019 .keywords: SNES, set, linesearch
5020 .seealso: SNESGetLineSearch()
5021 @*/
5022 PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
5023 {
5024   PetscErrorCode ierr;
5025 
5026   PetscFunctionBegin;
5027   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
5028   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
5029   PetscCheckSameComm(snes, 1, linesearch, 2);
5030   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
5031   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
5032 
5033   snes->linesearch = linesearch;
5034 
5035   ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
5036   PetscFunctionReturn(0);
5037 }
5038 
5039 #undef __FUNCT__
5040 #define __FUNCT__ "SNESGetLineSearch"
5041 /*@
5042   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
5043   or creates a default line search instance associated with the SNES and returns it.
5044 
5045   Not Collective
5046 
5047   Input Parameter:
5048 . snes - iterative context obtained from SNESCreate()
5049 
5050   Output Parameter:
5051 . linesearch - linesearch context
5052 
5053   Level: beginner
5054 
5055 .keywords: SNES, get, linesearch
5056 .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
5057 @*/
5058 PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
5059 {
5060   PetscErrorCode ierr;
5061   const char     *optionsprefix;
5062 
5063   PetscFunctionBegin;
5064   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
5065   PetscValidPointer(linesearch, 2);
5066   if (!snes->linesearch) {
5067     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
5068     ierr = SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);CHKERRQ(ierr);
5069     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
5070     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
5071     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
5072     ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
5073   }
5074   *linesearch = snes->linesearch;
5075   PetscFunctionReturn(0);
5076 }
5077 
5078 #if defined(PETSC_HAVE_MATLAB_ENGINE)
5079 #include <mex.h>
5080 
5081 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
5082 
5083 #undef __FUNCT__
5084 #define __FUNCT__ "SNESComputeFunction_Matlab"
5085 /*
5086    SNESComputeFunction_Matlab - Calls the function that has been set with SNESSetFunctionMatlab().
5087 
5088    Collective on SNES
5089 
5090    Input Parameters:
5091 +  snes - the SNES context
5092 -  x - input vector
5093 
5094    Output Parameter:
5095 .  y - function vector, as set by SNESSetFunction()
5096 
5097    Notes:
5098    SNESComputeFunction() is typically used within nonlinear solvers
5099    implementations, so most users would not generally call this routine
5100    themselves.
5101 
5102    Level: developer
5103 
5104 .keywords: SNES, nonlinear, compute, function
5105 
5106 .seealso: SNESSetFunction(), SNESGetFunction()
5107 */
5108 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
5109 {
5110   PetscErrorCode    ierr;
5111   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5112   int               nlhs  = 1,nrhs = 5;
5113   mxArray           *plhs[1],*prhs[5];
5114   long long int     lx = 0,ly = 0,ls = 0;
5115 
5116   PetscFunctionBegin;
5117   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5118   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
5119   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
5120   PetscCheckSameComm(snes,1,x,2);
5121   PetscCheckSameComm(snes,1,y,3);
5122 
5123   /* call Matlab function in ctx with arguments x and y */
5124 
5125   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5126   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5127   ierr    = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
5128   prhs[0] = mxCreateDoubleScalar((double)ls);
5129   prhs[1] = mxCreateDoubleScalar((double)lx);
5130   prhs[2] = mxCreateDoubleScalar((double)ly);
5131   prhs[3] = mxCreateString(sctx->funcname);
5132   prhs[4] = sctx->ctx;
5133   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
5134   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5135   mxDestroyArray(prhs[0]);
5136   mxDestroyArray(prhs[1]);
5137   mxDestroyArray(prhs[2]);
5138   mxDestroyArray(prhs[3]);
5139   mxDestroyArray(plhs[0]);
5140   PetscFunctionReturn(0);
5141 }
5142 
5143 #undef __FUNCT__
5144 #define __FUNCT__ "SNESSetFunctionMatlab"
5145 /*
5146    SNESSetFunctionMatlab - Sets the function evaluation routine and function
5147    vector for use by the SNES routines in solving systems of nonlinear
5148    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5149 
5150    Logically Collective on SNES
5151 
5152    Input Parameters:
5153 +  snes - the SNES context
5154 .  r - vector to store function value
5155 -  f - function evaluation routine
5156 
5157    Notes:
5158    The Newton-like methods typically solve linear systems of the form
5159 $      f'(x) x = -f(x),
5160    where f'(x) denotes the Jacobian matrix and f(x) is the function.
5161 
5162    Level: beginner
5163 
5164    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5165 
5166 .keywords: SNES, nonlinear, set, function
5167 
5168 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5169 */
5170 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *f,mxArray *ctx)
5171 {
5172   PetscErrorCode    ierr;
5173   SNESMatlabContext *sctx;
5174 
5175   PetscFunctionBegin;
5176   /* currently sctx is memory bleed */
5177   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5178   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5179   /*
5180      This should work, but it doesn't
5181   sctx->ctx = ctx;
5182   mexMakeArrayPersistent(sctx->ctx);
5183   */
5184   sctx->ctx = mxDuplicateArray(ctx);
5185   ierr      = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
5186   PetscFunctionReturn(0);
5187 }
5188 
5189 #undef __FUNCT__
5190 #define __FUNCT__ "SNESComputeJacobian_Matlab"
5191 /*
5192    SNESComputeJacobian_Matlab - Calls the function that has been set with SNESSetJacobianMatlab().
5193 
5194    Collective on SNES
5195 
5196    Input Parameters:
5197 +  snes - the SNES context
5198 .  x - input vector
5199 .  A, B - the matrices
5200 -  ctx - user context
5201 
5202    Level: developer
5203 
5204 .keywords: SNES, nonlinear, compute, function
5205 
5206 .seealso: SNESSetFunction(), SNESGetFunction()
5207 @*/
5208 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat A,Mat B,void *ctx)
5209 {
5210   PetscErrorCode    ierr;
5211   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5212   int               nlhs  = 2,nrhs = 6;
5213   mxArray           *plhs[2],*prhs[6];
5214   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
5215 
5216   PetscFunctionBegin;
5217   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5218   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
5219 
5220   /* call Matlab function in ctx with arguments x and y */
5221 
5222   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5223   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5224   ierr    = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
5225   ierr    = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
5226   prhs[0] = mxCreateDoubleScalar((double)ls);
5227   prhs[1] = mxCreateDoubleScalar((double)lx);
5228   prhs[2] = mxCreateDoubleScalar((double)lA);
5229   prhs[3] = mxCreateDoubleScalar((double)lB);
5230   prhs[4] = mxCreateString(sctx->funcname);
5231   prhs[5] = sctx->ctx;
5232   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
5233   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5234   mxDestroyArray(prhs[0]);
5235   mxDestroyArray(prhs[1]);
5236   mxDestroyArray(prhs[2]);
5237   mxDestroyArray(prhs[3]);
5238   mxDestroyArray(prhs[4]);
5239   mxDestroyArray(plhs[0]);
5240   mxDestroyArray(plhs[1]);
5241   PetscFunctionReturn(0);
5242 }
5243 
5244 #undef __FUNCT__
5245 #define __FUNCT__ "SNESSetJacobianMatlab"
5246 /*
5247    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
5248    vector for use by the SNES routines in solving systems of nonlinear
5249    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5250 
5251    Logically Collective on SNES
5252 
5253    Input Parameters:
5254 +  snes - the SNES context
5255 .  A,B - Jacobian matrices
5256 .  J - function evaluation routine
5257 -  ctx - user context
5258 
5259    Level: developer
5260 
5261    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5262 
5263 .keywords: SNES, nonlinear, set, function
5264 
5265 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction(), J
5266 */
5267 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *J,mxArray *ctx)
5268 {
5269   PetscErrorCode    ierr;
5270   SNESMatlabContext *sctx;
5271 
5272   PetscFunctionBegin;
5273   /* currently sctx is memory bleed */
5274   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5275   ierr = PetscStrallocpy(J,&sctx->funcname);CHKERRQ(ierr);
5276   /*
5277      This should work, but it doesn't
5278   sctx->ctx = ctx;
5279   mexMakeArrayPersistent(sctx->ctx);
5280   */
5281   sctx->ctx = mxDuplicateArray(ctx);
5282   ierr      = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
5283   PetscFunctionReturn(0);
5284 }
5285 
5286 #undef __FUNCT__
5287 #define __FUNCT__ "SNESMonitor_Matlab"
5288 /*
5289    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
5290 
5291    Collective on SNES
5292 
5293 .seealso: SNESSetFunction(), SNESGetFunction()
5294 @*/
5295 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
5296 {
5297   PetscErrorCode    ierr;
5298   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5299   int               nlhs  = 1,nrhs = 6;
5300   mxArray           *plhs[1],*prhs[6];
5301   long long int     lx = 0,ls = 0;
5302   Vec               x  = snes->vec_sol;
5303 
5304   PetscFunctionBegin;
5305   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5306 
5307   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5308   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5309   prhs[0] = mxCreateDoubleScalar((double)ls);
5310   prhs[1] = mxCreateDoubleScalar((double)it);
5311   prhs[2] = mxCreateDoubleScalar((double)fnorm);
5312   prhs[3] = mxCreateDoubleScalar((double)lx);
5313   prhs[4] = mxCreateString(sctx->funcname);
5314   prhs[5] = sctx->ctx;
5315   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
5316   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5317   mxDestroyArray(prhs[0]);
5318   mxDestroyArray(prhs[1]);
5319   mxDestroyArray(prhs[2]);
5320   mxDestroyArray(prhs[3]);
5321   mxDestroyArray(prhs[4]);
5322   mxDestroyArray(plhs[0]);
5323   PetscFunctionReturn(0);
5324 }
5325 
5326 #undef __FUNCT__
5327 #define __FUNCT__ "SNESMonitorSetMatlab"
5328 /*
5329    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
5330 
5331    Level: developer
5332 
5333    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5334 
5335 .keywords: SNES, nonlinear, set, function
5336 
5337 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5338 */
5339 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *f,mxArray *ctx)
5340 {
5341   PetscErrorCode    ierr;
5342   SNESMatlabContext *sctx;
5343 
5344   PetscFunctionBegin;
5345   /* currently sctx is memory bleed */
5346   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5347   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5348   /*
5349      This should work, but it doesn't
5350   sctx->ctx = ctx;
5351   mexMakeArrayPersistent(sctx->ctx);
5352   */
5353   sctx->ctx = mxDuplicateArray(ctx);
5354   ierr      = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,NULL);CHKERRQ(ierr);
5355   PetscFunctionReturn(0);
5356 }
5357 
5358 #endif
5359