xref: /petsc/src/snes/interface/snes.c (revision efca3c55b02548817e185e5069a2acfe20fa4458)
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_GSEval, SNES_NPCSolve;
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   snes->domainerror = PETSC_TRUE;
95   PetscFunctionReturn(0);
96 }
97 
98 #undef __FUNCT__
99 #define __FUNCT__ "SNESGetFunctionDomainError"
100 /*@
101    SNESGetFunctionDomainError - Gets the status of the domain error after a call to SNESComputeFunction;
102 
103    Logically Collective on SNES
104 
105    Input Parameters:
106 .  snes - the SNES context
107 
108    Output Parameters:
109 .  domainerror - Set to PETSC_TRUE if there's a domain error; PETSC_FALSE otherwise.
110 
111    Level: advanced
112 
113 .keywords: SNES, view
114 
115 .seealso: SNESSetFunctionDomainError(), SNESComputeFunction()
116 @*/
117 PetscErrorCode  SNESGetFunctionDomainError(SNES snes, PetscBool *domainerror)
118 {
119   PetscFunctionBegin;
120   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
121   PetscValidPointer(domainerror, 2);
122   *domainerror = snes->domainerror;
123   PetscFunctionReturn(0);
124 }
125 
126 #undef __FUNCT__
127 #define __FUNCT__ "SNESLoad"
128 /*@C
129   SNESLoad - Loads a SNES that has been stored in binary  with SNESView().
130 
131   Collective on PetscViewer
132 
133   Input Parameters:
134 + newdm - the newly loaded SNES, this needs to have been created with SNESCreate() or
135            some related function before a call to SNESLoad().
136 - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()
137 
138    Level: intermediate
139 
140   Notes:
141    The type is determined by the data in the file, any type set into the SNES before this call is ignored.
142 
143   Notes for advanced users:
144   Most users should not need to know the details of the binary storage
145   format, since SNESLoad() and TSView() completely hide these details.
146   But for anyone who's interested, the standard binary matrix storage
147   format is
148 .vb
149      has not yet been determined
150 .ve
151 
152 .seealso: PetscViewerBinaryOpen(), SNESView(), MatLoad(), VecLoad()
153 @*/
154 PetscErrorCode  SNESLoad(SNES snes, PetscViewer viewer)
155 {
156   PetscErrorCode ierr;
157   PetscBool      isbinary;
158   PetscInt       classid;
159   char           type[256];
160   KSP            ksp;
161   DM             dm;
162   DMSNES         dmsnes;
163 
164   PetscFunctionBegin;
165   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
166   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
167   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
168   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");
169 
170   ierr = PetscViewerBinaryRead(viewer,&classid,1,PETSC_INT);CHKERRQ(ierr);
171   if (classid != SNES_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONG,"Not SNES next in file");
172   ierr = PetscViewerBinaryRead(viewer,type,256,PETSC_CHAR);CHKERRQ(ierr);
173   ierr = SNESSetType(snes, type);CHKERRQ(ierr);
174   if (snes->ops->load) {
175     ierr = (*snes->ops->load)(snes,viewer);CHKERRQ(ierr);
176   }
177   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
178   ierr = DMGetDMSNES(dm,&dmsnes);CHKERRQ(ierr);
179   ierr = DMSNESLoad(dmsnes,viewer);CHKERRQ(ierr);
180   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
181   ierr = KSPLoad(ksp,viewer);CHKERRQ(ierr);
182   PetscFunctionReturn(0);
183 }
184 
185 #include <petscdraw.h>
186 #if defined(PETSC_HAVE_AMS)
187 #include <petscviewerams.h>
188 #endif
189 #undef __FUNCT__
190 #define __FUNCT__ "SNESView"
191 /*@C
192    SNESView - Prints the SNES data structure.
193 
194    Collective on SNES
195 
196    Input Parameters:
197 +  SNES - the SNES context
198 -  viewer - visualization context
199 
200    Options Database Key:
201 .  -snes_view - Calls SNESView() at end of SNESSolve()
202 
203    Notes:
204    The available visualization contexts include
205 +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
206 -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
207          output where only the first processor opens
208          the file.  All other processors send their
209          data to the first processor to print.
210 
211    The user can open an alternative visualization context with
212    PetscViewerASCIIOpen() - output to a specified file.
213 
214    Level: beginner
215 
216 .keywords: SNES, view
217 
218 .seealso: PetscViewerASCIIOpen()
219 @*/
220 PetscErrorCode  SNESView(SNES snes,PetscViewer viewer)
221 {
222   SNESKSPEW      *kctx;
223   PetscErrorCode ierr;
224   KSP            ksp;
225   SNESLineSearch linesearch;
226   PetscBool      iascii,isstring,isbinary,isdraw;
227   DMSNES         dmsnes;
228 #if defined(PETSC_HAVE_AMS)
229   PetscBool      isams;
230 #endif
231 
232   PetscFunctionBegin;
233   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
234   if (!viewer) {
235     ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&viewer);CHKERRQ(ierr);
236   }
237   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
238   PetscCheckSameComm(snes,1,viewer,2);
239 
240   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
241   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
242   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
243   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);CHKERRQ(ierr);
244 #if defined(PETSC_HAVE_AMS)
245   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERAMS,&isams);CHKERRQ(ierr);
246 #endif
247   if (iascii) {
248     ierr = PetscObjectPrintClassNamePrefixType((PetscObject)snes,viewer);CHKERRQ(ierr);
249     if (!snes->setupcalled) {
250       ierr = PetscViewerASCIIPrintf(viewer,"  SNES has not been set up so information may be incomplete\n");CHKERRQ(ierr);
251     }
252     if (snes->ops->view) {
253       ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
254       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
255       ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
256     }
257     ierr = PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, maximum function evaluations=%D\n",snes->max_its,snes->max_funcs);CHKERRQ(ierr);
258     ierr = PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%G, absolute=%G, solution=%G\n",snes->rtol,snes->abstol,snes->stol);CHKERRQ(ierr);
259     ierr = PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",snes->linear_its);CHKERRQ(ierr);
260     ierr = PetscViewerASCIIPrintf(viewer,"  total number of function evaluations=%D\n",snes->nfuncs);CHKERRQ(ierr);
261     if (snes->gridsequence) {
262       ierr = PetscViewerASCIIPrintf(viewer,"  total number of grid sequence refinements=%D\n",snes->gridsequence);CHKERRQ(ierr);
263     }
264     if (snes->ksp_ewconv) {
265       kctx = (SNESKSPEW*)snes->kspconvctx;
266       if (kctx) {
267         ierr = PetscViewerASCIIPrintf(viewer,"  Eisenstat-Walker computation of KSP relative tolerance (version %D)\n",kctx->version);CHKERRQ(ierr);
268         ierr = PetscViewerASCIIPrintf(viewer,"    rtol_0=%G, rtol_max=%G, threshold=%G\n",kctx->rtol_0,kctx->rtol_max,kctx->threshold);CHKERRQ(ierr);
269         ierr = PetscViewerASCIIPrintf(viewer,"    gamma=%G, alpha=%G, alpha2=%G\n",kctx->gamma,kctx->alpha,kctx->alpha2);CHKERRQ(ierr);
270       }
271     }
272     if (snes->lagpreconditioner == -1) {
273       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is never rebuilt\n");CHKERRQ(ierr);
274     } else if (snes->lagpreconditioner > 1) {
275       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is rebuilt every %D new Jacobians\n",snes->lagpreconditioner);CHKERRQ(ierr);
276     }
277     if (snes->lagjacobian == -1) {
278       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is never rebuilt\n");CHKERRQ(ierr);
279     } else if (snes->lagjacobian > 1) {
280       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is rebuilt every %D SNES iterations\n",snes->lagjacobian);CHKERRQ(ierr);
281     }
282   } else if (isstring) {
283     const char *type;
284     ierr = SNESGetType(snes,&type);CHKERRQ(ierr);
285     ierr = PetscViewerStringSPrintf(viewer," %-3.3s",type);CHKERRQ(ierr);
286   } else if (isbinary) {
287     PetscInt    classid = SNES_FILE_CLASSID;
288     MPI_Comm    comm;
289     PetscMPIInt rank;
290     char        type[256];
291 
292     ierr = PetscObjectGetComm((PetscObject)snes,&comm);CHKERRQ(ierr);
293     ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
294     if (!rank) {
295       ierr = PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);CHKERRQ(ierr);
296       ierr = PetscStrncpy(type,((PetscObject)snes)->type_name,256);CHKERRQ(ierr);
297       ierr = PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR,PETSC_FALSE);CHKERRQ(ierr);
298     }
299     if (snes->ops->view) {
300       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
301     }
302   } else if (isdraw) {
303     PetscDraw draw;
304     char      str[36];
305     PetscReal x,y,bottom,h;
306 
307     ierr   = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
308     ierr   = PetscDrawGetCurrentPoint(draw,&x,&y);CHKERRQ(ierr);
309     ierr   = PetscStrcpy(str,"SNES: ");CHKERRQ(ierr);
310     ierr   = PetscStrcat(str,((PetscObject)snes)->type_name);CHKERRQ(ierr);
311     ierr   = PetscDrawBoxedString(draw,x,y,PETSC_DRAW_BLUE,PETSC_DRAW_BLACK,str,NULL,&h);CHKERRQ(ierr);
312     bottom = y - h;
313     ierr   = PetscDrawPushCurrentPoint(draw,x,bottom);CHKERRQ(ierr);
314     if (snes->ops->view) {
315       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
316     }
317 #if defined(PETSC_HAVE_AMS)
318   } else if (isams) {
319     if (((PetscObject)snes)->amsmem == -1) {
320       ierr = PetscObjectViewAMS((PetscObject)snes,viewer);CHKERRQ(ierr);
321       PetscStackCallAMS(AMS_Memory_take_access,(((PetscObject)snes)->amsmem));
322       PetscStackCallAMS(AMS_Memory_add_field,(((PetscObject)snes)->amsmem,"its",&snes->iter,1,AMS_INT,AMS_READ,AMS_COMMON,AMS_REDUCT_UNDEF));
323       if (!snes->conv_hist) {
324         ierr = SNESSetConvergenceHistory(snes,NULL,NULL,PETSC_DECIDE,PETSC_FALSE);CHKERRQ(ierr);
325       }
326       PetscStackCallAMS(AMS_Memory_add_field,(((PetscObject)snes)->amsmem,"conv_hist",snes->conv_hist,10,AMS_DOUBLE,AMS_READ,AMS_COMMON,AMS_REDUCT_UNDEF));
327       PetscStackCallAMS(AMS_Memory_grant_access,(((PetscObject)snes)->amsmem));
328     }
329 #endif
330   }
331   if (snes->linesearch) {
332     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
333     ierr = SNESGetLineSearch(snes, &linesearch);CHKERRQ(ierr);
334     ierr = SNESLineSearchView(linesearch, viewer);CHKERRQ(ierr);
335     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
336   }
337   if (snes->pc && snes->usespc) {
338     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
339     ierr = SNESView(snes->pc, viewer);CHKERRQ(ierr);
340     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
341   }
342   ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
343   ierr = DMGetDMSNES(snes->dm,&dmsnes);CHKERRQ(ierr);
344   ierr = DMSNESView(dmsnes, viewer);CHKERRQ(ierr);
345   ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
346   if (snes->usesksp) {
347     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
348     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
349     ierr = KSPView(ksp,viewer);CHKERRQ(ierr);
350     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
351   }
352   if (isdraw) {
353     PetscDraw draw;
354     ierr = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
355     ierr = PetscDrawPopCurrentPoint(draw);CHKERRQ(ierr);
356   }
357   PetscFunctionReturn(0);
358 }
359 
360 /*
361   We retain a list of functions that also take SNES command
362   line options. These are called at the end SNESSetFromOptions()
363 */
364 #define MAXSETFROMOPTIONS 5
365 static PetscInt numberofsetfromoptions;
366 static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);
367 
368 #undef __FUNCT__
369 #define __FUNCT__ "SNESAddOptionsChecker"
370 /*@C
371   SNESAddOptionsChecker - Adds an additional function to check for SNES options.
372 
373   Not Collective
374 
375   Input Parameter:
376 . snescheck - function that checks for options
377 
378   Level: developer
379 
380 .seealso: SNESSetFromOptions()
381 @*/
382 PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
383 {
384   PetscFunctionBegin;
385   if (numberofsetfromoptions >= MAXSETFROMOPTIONS) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %D allowed", MAXSETFROMOPTIONS);
386   othersetfromoptions[numberofsetfromoptions++] = snescheck;
387   PetscFunctionReturn(0);
388 }
389 
390 extern PetscErrorCode  SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);
391 
392 #undef __FUNCT__
393 #define __FUNCT__ "SNESSetUpMatrixFree_Private"
394 static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
395 {
396   Mat            J;
397   KSP            ksp;
398   PC             pc;
399   PetscBool      match;
400   PetscErrorCode ierr;
401 
402   PetscFunctionBegin;
403   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
404 
405   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
406     Mat A = snes->jacobian, B = snes->jacobian_pre;
407     ierr = MatGetVecs(A ? A : B, NULL,&snes->vec_func);CHKERRQ(ierr);
408   }
409 
410   if (version == 1) {
411     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
412     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
413     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
414   } else if (version == 2) {
415     if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
416 #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128)
417     ierr = SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);CHKERRQ(ierr);
418 #else
419     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator rutines (version 2)");
420 #endif
421   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator rutines, only version 1 and 2");
422 
423   ierr = PetscInfo1(snes,"Setting default matrix-free operator routines (version %D)\n", version);CHKERRQ(ierr);
424   if (hasOperator) {
425 
426     /* This version replaces the user provided Jacobian matrix with a
427        matrix-free version but still employs the user-provided preconditioner matrix. */
428     ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);
429   } else {
430     /* This version replaces both the user-provided Jacobian and the user-
431      provided preconditioner Jacobian with the default matrix free version. */
432     if ((snes->pcside == PC_LEFT) && snes->pc) {
433       if (!snes->jacobian){ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);}
434     } else {
435       ierr = SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,0);CHKERRQ(ierr);
436     }
437     /* Force no preconditioner */
438     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
439     ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
440     ierr = PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);CHKERRQ(ierr);
441     if (!match) {
442       ierr = PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");CHKERRQ(ierr);
443       ierr = PCSetType(pc,PCNONE);CHKERRQ(ierr);
444     }
445   }
446   ierr = MatDestroy(&J);CHKERRQ(ierr);
447   PetscFunctionReturn(0);
448 }
449 
450 #undef __FUNCT__
451 #define __FUNCT__ "DMRestrictHook_SNESVecSol"
452 static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
453 {
454   SNES           snes = (SNES)ctx;
455   PetscErrorCode ierr;
456   Vec            Xfine,Xfine_named = NULL,Xcoarse;
457 
458   PetscFunctionBegin;
459   if (PetscLogPrintInfo) {
460     PetscInt finelevel,coarselevel,fineclevel,coarseclevel;
461     ierr = DMGetRefineLevel(dmfine,&finelevel);CHKERRQ(ierr);
462     ierr = DMGetCoarsenLevel(dmfine,&fineclevel);CHKERRQ(ierr);
463     ierr = DMGetRefineLevel(dmcoarse,&coarselevel);CHKERRQ(ierr);
464     ierr = DMGetCoarsenLevel(dmcoarse,&coarseclevel);CHKERRQ(ierr);
465     ierr = PetscInfo4(dmfine,"Restricting SNES solution vector from level %D-%D to level %D-%D\n",finelevel,fineclevel,coarselevel,coarseclevel);CHKERRQ(ierr);
466   }
467   if (dmfine == snes->dm) Xfine = snes->vec_sol;
468   else {
469     ierr  = DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);
470     Xfine = Xfine_named;
471   }
472   ierr = DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
473   ierr = MatRestrict(Restrict,Xfine,Xcoarse);CHKERRQ(ierr);
474   ierr = VecPointwiseMult(Xcoarse,Xcoarse,Rscale);CHKERRQ(ierr);
475   ierr = DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
476   if (Xfine_named) {ierr = DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);}
477   PetscFunctionReturn(0);
478 }
479 
480 #undef __FUNCT__
481 #define __FUNCT__ "DMCoarsenHook_SNESVecSol"
482 static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm,DM dmc,void *ctx)
483 {
484   PetscErrorCode ierr;
485 
486   PetscFunctionBegin;
487   ierr = DMCoarsenHookAdd(dmc,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,ctx);CHKERRQ(ierr);
488   PetscFunctionReturn(0);
489 }
490 
491 #undef __FUNCT__
492 #define __FUNCT__ "KSPComputeOperators_SNES"
493 /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
494  * safely call SNESGetDM() in their residual evaluation routine. */
495 static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,MatStructure *mstruct,void *ctx)
496 {
497   SNES           snes = (SNES)ctx;
498   PetscErrorCode ierr;
499   Mat            Asave = A,Bsave = B;
500   Vec            X,Xnamed = NULL;
501   DM             dmsave;
502   void           *ctxsave;
503   PetscErrorCode (*jac)(SNES,Vec,Mat*,Mat*,MatStructure*,void*);
504 
505   PetscFunctionBegin;
506   dmsave = snes->dm;
507   ierr   = KSPGetDM(ksp,&snes->dm);CHKERRQ(ierr);
508   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
509   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
510     ierr = DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
511     X    = Xnamed;
512     ierr = SNESGetJacobian(snes,NULL,NULL,&jac,&ctxsave);CHKERRQ(ierr);
513     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
514     if (jac == SNESComputeJacobianDefaultColor) {
515       ierr = SNESSetJacobian(snes,NULL,NULL,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
516     }
517   }
518   /* put the previous context back */
519 
520   ierr = SNESComputeJacobian(snes,X,&A,&B,mstruct);CHKERRQ(ierr);
521   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) {
522     ierr = SNESSetJacobian(snes,NULL,NULL,jac,ctxsave);CHKERRQ(ierr);
523   }
524 
525   if (A != Asave || B != Bsave) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_SUP,"No support for changing matrices at this time");
526   if (Xnamed) {
527     ierr = DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
528   }
529   snes->dm = dmsave;
530   PetscFunctionReturn(0);
531 }
532 
533 #undef __FUNCT__
534 #define __FUNCT__ "SNESSetUpMatrices"
535 /*@
536    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()
537 
538    Collective
539 
540    Input Arguments:
541 .  snes - snes to configure
542 
543    Level: developer
544 
545 .seealso: SNESSetUp()
546 @*/
547 PetscErrorCode SNESSetUpMatrices(SNES snes)
548 {
549   PetscErrorCode ierr;
550   DM             dm;
551   DMSNES         sdm;
552 
553   PetscFunctionBegin;
554   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
555   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
556   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_PLIB,"DMSNES not properly configured");
557   else if (!snes->jacobian && snes->mf) {
558     Mat  J;
559     void *functx;
560     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
561     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
562     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
563     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
564     ierr = SNESSetJacobian(snes,J,J,0,0);CHKERRQ(ierr);
565     ierr = MatDestroy(&J);CHKERRQ(ierr);
566   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
567     Mat J,B;
568     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
569     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
570     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
571     ierr = DMCreateMatrix(snes->dm,&B);CHKERRQ(ierr);
572     /* sdm->computejacobian was already set to reach here */
573     ierr = SNESSetJacobian(snes,J,B,NULL,NULL);CHKERRQ(ierr);
574     ierr = MatDestroy(&J);CHKERRQ(ierr);
575     ierr = MatDestroy(&B);CHKERRQ(ierr);
576   } else if (!snes->jacobian_pre) {
577     Mat J,B;
578     J    = snes->jacobian;
579     ierr = DMCreateMatrix(snes->dm,&B);CHKERRQ(ierr);
580     ierr = SNESSetJacobian(snes,J ? J : B,B,NULL,NULL);CHKERRQ(ierr);
581     ierr = MatDestroy(&B);CHKERRQ(ierr);
582   }
583   {
584     KSP ksp;
585     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
586     ierr = KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);CHKERRQ(ierr);
587     ierr = DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);CHKERRQ(ierr);
588   }
589   PetscFunctionReturn(0);
590 }
591 
592 #undef __FUNCT__
593 #define __FUNCT__ "SNESSetFromOptions"
594 /*@
595    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.
596 
597    Collective on SNES
598 
599    Input Parameter:
600 .  snes - the SNES context
601 
602    Options Database Keys:
603 +  -snes_type <type> - ls, tr, ngmres, ncg, richardson, qn, vi, fas
604 .  -snes_stol - convergence tolerance in terms of the norm
605                 of the change in the solution between steps
606 .  -snes_atol <abstol> - absolute tolerance of residual norm
607 .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
608 .  -snes_max_it <max_it> - maximum number of iterations
609 .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
610 .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
611 .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
612 .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
613 .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
614 .  -snes_trtol <trtol> - trust region tolerance
615 .  -snes_no_convergence_test - skip convergence test in nonlinear
616                                solver; hence iterations will continue until max_it
617                                or some other criterion is reached. Saves expense
618                                of convergence test
619 .  -snes_monitor <optional filename> - prints residual norm at each iteration. if no
620                                        filename given prints to stdout
621 .  -snes_monitor_solution - plots solution at each iteration
622 .  -snes_monitor_residual - plots residual (not its norm) at each iteration
623 .  -snes_monitor_solution_update - plots update to solution at each iteration
624 .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
625 .  -snes_monitor_lg_range - plots residual norm at each iteration
626 .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
627 .  -snes_fd_color - use finite differences with coloring to compute Jacobian
628 .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
629 -  -snes_converged_reason - print the reason for convergence/divergence after each solve
630 
631     Options Database for Eisenstat-Walker method:
632 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
633 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
634 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
635 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
636 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
637 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
638 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
639 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
640 
641    Notes:
642    To see all options, run your program with the -help option or consult
643    the <A href="../../docs/manual.pdf#nameddest=ch_snes">SNES chapter of the users manual</A>.
644 
645    Level: beginner
646 
647 .keywords: SNES, nonlinear, set, options, database
648 
649 .seealso: SNESSetOptionsPrefix()
650 @*/
651 PetscErrorCode  SNESSetFromOptions(SNES snes)
652 {
653   PetscBool      flg,pcset,persist;
654   PetscInt       i,indx,lag,grids;
655   MatStructure   matflag;
656   const char     *deft        = SNESNEWTONLS;
657   const char     *convtests[] = {"default","skip"};
658   SNESKSPEW      *kctx        = NULL;
659   char           type[256], monfilename[PETSC_MAX_PATH_LEN];
660   PetscViewer    monviewer;
661   PetscErrorCode ierr;
662   PCSide         pcside;
663   const char     *optionsprefix;
664 
665   PetscFunctionBegin;
666   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
667   if (!SNESRegisterAllCalled) {ierr = SNESRegisterAll();CHKERRQ(ierr);}
668   ierr = PetscObjectOptionsBegin((PetscObject)snes);CHKERRQ(ierr);
669   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
670   ierr = PetscOptionsList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);CHKERRQ(ierr);
671   if (flg) {
672     ierr = SNESSetType(snes,type);CHKERRQ(ierr);
673   } else if (!((PetscObject)snes)->type_name) {
674     ierr = SNESSetType(snes,deft);CHKERRQ(ierr);
675   }
676   /* not used here, but called so will go into help messaage */
677   ierr = PetscOptionsName("-snes_view","Print detailed information on solver used","SNESView",0);CHKERRQ(ierr);
678 
679   ierr = PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,0);CHKERRQ(ierr);
680   ierr = PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,0);CHKERRQ(ierr);
681 
682   ierr = PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,0);CHKERRQ(ierr);
683   ierr = PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,NULL);CHKERRQ(ierr);
684   ierr = PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,NULL);CHKERRQ(ierr);
685   ierr = PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,NULL);CHKERRQ(ierr);
686   ierr = PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,NULL);CHKERRQ(ierr);
687   ierr = PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,NULL);CHKERRQ(ierr);
688 
689   ierr = PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);CHKERRQ(ierr);
690   if (flg) {
691     ierr = SNESSetLagPreconditioner(snes,lag);CHKERRQ(ierr);
692   }
693   ierr = PetscOptionsBool("-snes_lag_preconditioner_persists","Preconditioner lagging through multiple solves","SNESSetLagPreconditionerPersists",snes->lagjac_persist,&persist,&flg);CHKERRQ(ierr);
694   if (flg) {
695     ierr = SNESSetLagPreconditionerPersists(snes,persist);CHKERRQ(ierr);
696   }
697   ierr = PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);CHKERRQ(ierr);
698   if (flg) {
699     ierr = SNESSetLagJacobian(snes,lag);CHKERRQ(ierr);
700   }
701   ierr = PetscOptionsBool("-snes_lag_jacobian_persists","Jacobian lagging through multiple solves","SNESSetLagJacobianPersists",snes->lagjac_persist,&persist,&flg);CHKERRQ(ierr);
702   if (flg) {
703     ierr = SNESSetLagJacobianPersists(snes,persist);CHKERRQ(ierr);
704   }
705 
706   ierr = PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);CHKERRQ(ierr);
707   if (flg) {
708     ierr = SNESSetGridSequence(snes,grids);CHKERRQ(ierr);
709   }
710 
711   ierr = PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);CHKERRQ(ierr);
712   if (flg) {
713     switch (indx) {
714     case 0: ierr = SNESSetConvergenceTest(snes,SNESConvergedDefault,NULL,NULL);CHKERRQ(ierr); break;
715     case 1: ierr = SNESSetConvergenceTest(snes,SNESConvergedSkip,NULL,NULL);CHKERRQ(ierr);    break;
716     }
717   }
718 
719   ierr = PetscOptionsBool("-snes_converged_reason","Print reason for converged or diverged","SNESSolve",snes->printreason,&snes->printreason,NULL);CHKERRQ(ierr);
720 
721   ierr = PetscOptionsEList("-snes_norm_schedule","SNES Norm schedule","SNESSetNormSchedule",SNESNormSchedules,5,"function",&indx,&flg);CHKERRQ(ierr);
722   if (flg) { ierr = SNESSetNormSchedule(snes,(SNESNormSchedule)indx);CHKERRQ(ierr); }
723 
724   ierr = PetscOptionsEList("-snes_function_type","SNES Norm schedule","SNESSetFunctionType",SNESFunctionTypes,2,"unpreconditioned",&indx,&flg);CHKERRQ(ierr);
725   if (flg) { ierr = SNESSetFunctionType(snes,(SNESFunctionType)indx);CHKERRQ(ierr); }
726 
727   kctx = (SNESKSPEW*)snes->kspconvctx;
728 
729   ierr = PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,NULL);CHKERRQ(ierr);
730 
731   ierr = PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,0);CHKERRQ(ierr);
732   ierr = PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,0);CHKERRQ(ierr);
733   ierr = PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,0);CHKERRQ(ierr);
734   ierr = PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,0);CHKERRQ(ierr);
735   ierr = PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,0);CHKERRQ(ierr);
736   ierr = PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,0);CHKERRQ(ierr);
737   ierr = PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,0);CHKERRQ(ierr);
738 
739   flg  = PETSC_FALSE;
740   ierr = PetscOptionsBool("-snes_check_jacobian","Check each Jacobian with a differenced one","SNESUpdateCheckJacobian",flg,&flg,NULL);CHKERRQ(ierr);
741   if (flg) {
742     ierr = SNESSetUpdate(snes,SNESUpdateCheckJacobian);CHKERRQ(ierr);
743   }
744 
745   flg  = PETSC_FALSE;
746   ierr = PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,NULL);CHKERRQ(ierr);
747   if (flg) {ierr = SNESMonitorCancel(snes);CHKERRQ(ierr);}
748 
749   ierr = PetscOptionsString("-snes_monitor","Monitor norm of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
750   if (flg) {
751     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
752     ierr = SNESMonitorSet(snes,SNESMonitorDefault,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
753   }
754 
755   ierr = PetscOptionsString("-snes_monitor_range","Monitor range of elements of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
756   if (flg) {
757     ierr = SNESMonitorSet(snes,SNESMonitorRange,0,0);CHKERRQ(ierr);
758   }
759 
760   ierr = PetscOptionsString("-snes_ratiomonitor","Monitor ratios of norms of function","SNESMonitorSetRatio","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
761   if (flg) {
762     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
763     ierr = SNESMonitorSetRatio(snes,monviewer);CHKERRQ(ierr);
764   }
765 
766   ierr = PetscOptionsString("-snes_monitor_short","Monitor norm of function (fewer digits)","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
767   if (flg) {
768     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
769     ierr = SNESMonitorSet(snes,SNESMonitorDefaultShort,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
770   }
771 
772   ierr = PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
773   if (flg) {ierr = PetscPythonMonitorSet((PetscObject)snes,monfilename);CHKERRQ(ierr);}
774 
775   flg  = PETSC_FALSE;
776   ierr = PetscOptionsBool("-snes_monitor_solution","Plot solution at each iteration","SNESMonitorSolution",flg,&flg,NULL);CHKERRQ(ierr);
777   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolution,0,0);CHKERRQ(ierr);}
778   flg  = PETSC_FALSE;
779   ierr = PetscOptionsBool("-snes_monitor_solution_update","Plot correction at each iteration","SNESMonitorSolutionUpdate",flg,&flg,NULL);CHKERRQ(ierr);
780   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolutionUpdate,0,0);CHKERRQ(ierr);}
781   flg  = PETSC_FALSE;
782   ierr = PetscOptionsBool("-snes_monitor_residual","Plot residual at each iteration","SNESMonitorResidual",flg,&flg,NULL);CHKERRQ(ierr);
783   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorResidual,0,0);CHKERRQ(ierr);}
784   flg  = PETSC_FALSE;
785   ierr = PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,NULL);CHKERRQ(ierr);
786   if (flg) {
787     PetscDrawLG ctx;
788 
789     ierr = SNESMonitorLGCreate(0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
790     ierr = SNESMonitorSet(snes,SNESMonitorLGResidualNorm,ctx,(PetscErrorCode (*)(void**))SNESMonitorLGDestroy);CHKERRQ(ierr);
791   }
792   flg  = PETSC_FALSE;
793   ierr = PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);CHKERRQ(ierr);
794   if (flg) {
795     PetscViewer ctx;
796 
797     ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
798     ierr = SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
799   }
800 
801   flg  = PETSC_FALSE;
802   ierr = PetscOptionsBool("-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",flg,&flg,NULL);CHKERRQ(ierr);
803   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorJacUpdateSpectrum,0,0);CHKERRQ(ierr);}
804 
805   flg  = PETSC_FALSE;
806   ierr = PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);CHKERRQ(ierr);
807   if (flg) {
808     void *functx;
809     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
810     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);CHKERRQ(ierr);
811     ierr = PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");CHKERRQ(ierr);
812   }
813 
814   flg  = PETSC_FALSE;
815   ierr = PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);CHKERRQ(ierr);
816   if (flg) {
817     ierr = SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);CHKERRQ(ierr);
818   }
819 
820   flg  = PETSC_FALSE;
821   ierr = PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);CHKERRQ(ierr);
822   if (flg) {
823     DM             dm;
824     DMSNES         sdm;
825     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
826     ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
827     sdm->jacobianctx = NULL;
828     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
829     ierr = PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");CHKERRQ(ierr);
830   }
831 
832   flg  = PETSC_FALSE;
833   ierr = PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf_operator,&flg);CHKERRQ(ierr);
834   if (flg && snes->mf_operator) {
835     snes->mf_operator = PETSC_TRUE;
836     snes->mf          = PETSC_TRUE;
837   }
838   flg  = PETSC_FALSE;
839   ierr = PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf,&flg);CHKERRQ(ierr);
840   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
841   ierr = PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,0);CHKERRQ(ierr);
842 
843   flg  = PETSC_FALSE;
844   ierr = SNESGetPCSide(snes,&pcside);CHKERRQ(ierr);
845   ierr = PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);CHKERRQ(ierr);
846   if (flg) {ierr = SNESSetPCSide(snes,pcside);CHKERRQ(ierr);}
847 
848 #if defined(PETSC_HAVE_AMS)
849   {
850   PetscBool set;
851   flg  = PETSC_FALSE;
852   ierr = PetscOptionsBool("-snes_ams_block","Block for AMS memory snooper at end of SNESSolve","PetscObjectAMSBlock",((PetscObject)snes)->amspublishblock,&flg,&set);CHKERRQ(ierr);
853   if (set) {
854     ierr = PetscObjectAMSSetBlock((PetscObject)snes,flg);CHKERRQ(ierr);
855   }
856   }
857 #endif
858 
859   for (i = 0; i < numberofsetfromoptions; i++) {
860     ierr = (*othersetfromoptions[i])(snes);CHKERRQ(ierr);
861   }
862 
863   if (snes->ops->setfromoptions) {
864     ierr = (*snes->ops->setfromoptions)(snes);CHKERRQ(ierr);
865   }
866 
867   /* process any options handlers added with PetscObjectAddOptionsHandler() */
868   ierr = PetscObjectProcessOptionsHandlers((PetscObject)snes);CHKERRQ(ierr);
869   ierr = PetscOptionsEnd();CHKERRQ(ierr);
870 
871   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
872   ierr = KSPGetOperators(snes->ksp,NULL,NULL,&matflag);CHKERRQ(ierr);
873   ierr = KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre,matflag);CHKERRQ(ierr);
874   ierr = KSPSetFromOptions(snes->ksp);CHKERRQ(ierr);
875 
876   if (!snes->linesearch) {
877     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
878   }
879   ierr = SNESLineSearchSetFromOptions(snes->linesearch);CHKERRQ(ierr);
880 
881   /* if someone has set the SNES PC type, create it. */
882   ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
883   ierr = PetscOptionsHasName(optionsprefix, "-npc_snes_type", &pcset);CHKERRQ(ierr);
884   if (pcset && (!snes->pc)) {
885     ierr = SNESGetPC(snes, &snes->pc);CHKERRQ(ierr);
886   }
887   PetscFunctionReturn(0);
888 }
889 
890 #undef __FUNCT__
891 #define __FUNCT__ "SNESSetComputeApplicationContext"
892 /*@C
893    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
894    the nonlinear solvers.
895 
896    Logically Collective on SNES
897 
898    Input Parameters:
899 +  snes - the SNES context
900 .  compute - function to compute the context
901 -  destroy - function to destroy the context
902 
903    Level: intermediate
904 
905    Notes:
906    This function is currently not available from Fortran.
907 
908 .keywords: SNES, nonlinear, set, application, context
909 
910 .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
911 @*/
912 PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
913 {
914   PetscFunctionBegin;
915   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
916   snes->ops->usercompute = compute;
917   snes->ops->userdestroy = destroy;
918   PetscFunctionReturn(0);
919 }
920 
921 #undef __FUNCT__
922 #define __FUNCT__ "SNESSetApplicationContext"
923 /*@
924    SNESSetApplicationContext - Sets the optional user-defined context for
925    the nonlinear solvers.
926 
927    Logically Collective on SNES
928 
929    Input Parameters:
930 +  snes - the SNES context
931 -  usrP - optional user context
932 
933    Level: intermediate
934 
935 .keywords: SNES, nonlinear, set, application, context
936 
937 .seealso: SNESGetApplicationContext()
938 @*/
939 PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
940 {
941   PetscErrorCode ierr;
942   KSP            ksp;
943 
944   PetscFunctionBegin;
945   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
946   ierr       = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
947   ierr       = KSPSetApplicationContext(ksp,usrP);CHKERRQ(ierr);
948   snes->user = usrP;
949   PetscFunctionReturn(0);
950 }
951 
952 #undef __FUNCT__
953 #define __FUNCT__ "SNESGetApplicationContext"
954 /*@
955    SNESGetApplicationContext - Gets the user-defined context for the
956    nonlinear solvers.
957 
958    Not Collective
959 
960    Input Parameter:
961 .  snes - SNES context
962 
963    Output Parameter:
964 .  usrP - user context
965 
966    Level: intermediate
967 
968 .keywords: SNES, nonlinear, get, application, context
969 
970 .seealso: SNESSetApplicationContext()
971 @*/
972 PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
973 {
974   PetscFunctionBegin;
975   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
976   *(void**)usrP = snes->user;
977   PetscFunctionReturn(0);
978 }
979 
980 #undef __FUNCT__
981 #define __FUNCT__ "SNESGetIterationNumber"
982 /*@
983    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
984    at this time.
985 
986    Not Collective
987 
988    Input Parameter:
989 .  snes - SNES context
990 
991    Output Parameter:
992 .  iter - iteration number
993 
994    Notes:
995    For example, during the computation of iteration 2 this would return 1.
996 
997    This is useful for using lagged Jacobians (where one does not recompute the
998    Jacobian at each SNES iteration). For example, the code
999 .vb
1000       ierr = SNESGetIterationNumber(snes,&it);
1001       if (!(it % 2)) {
1002         [compute Jacobian here]
1003       }
1004 .ve
1005    can be used in your ComputeJacobian() function to cause the Jacobian to be
1006    recomputed every second SNES iteration.
1007 
1008    Level: intermediate
1009 
1010 .keywords: SNES, nonlinear, get, iteration, number,
1011 
1012 .seealso:   SNESGetFunctionNorm(), SNESGetLinearSolveIterations()
1013 @*/
1014 PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
1015 {
1016   PetscFunctionBegin;
1017   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1018   PetscValidIntPointer(iter,2);
1019   *iter = snes->iter;
1020   PetscFunctionReturn(0);
1021 }
1022 
1023 #undef __FUNCT__
1024 #define __FUNCT__ "SNESSetIterationNumber"
1025 /*@
1026    SNESSetIterationNumber - Sets the current iteration number.
1027 
1028    Not Collective
1029 
1030    Input Parameter:
1031 .  snes - SNES context
1032 .  iter - iteration number
1033 
1034    Level: developer
1035 
1036 .keywords: SNES, nonlinear, set, iteration, number,
1037 
1038 .seealso:   SNESGetFunctionNorm(), SNESGetLinearSolveIterations()
1039 @*/
1040 PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
1041 {
1042   PetscErrorCode ierr;
1043 
1044   PetscFunctionBegin;
1045   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1046   ierr       = PetscObjectAMSTakeAccess((PetscObject)snes);CHKERRQ(ierr);
1047   snes->iter = iter;
1048   ierr       = PetscObjectAMSGrantAccess((PetscObject)snes);CHKERRQ(ierr);
1049   PetscFunctionReturn(0);
1050 }
1051 
1052 #undef __FUNCT__
1053 #define __FUNCT__ "SNESGetFunctionNorm"
1054 /*@
1055    SNESGetFunctionNorm - Gets the norm of the current function that was set
1056    with SNESSSetFunction().
1057 
1058    Collective on SNES
1059 
1060    Input Parameter:
1061 .  snes - SNES context
1062 
1063    Output Parameter:
1064 .  fnorm - 2-norm of function
1065 
1066    Level: intermediate
1067 
1068 .keywords: SNES, nonlinear, get, function, norm
1069 
1070 .seealso: SNESGetFunction(), SNESGetIterationNumber(), SNESGetLinearSolveIterations()
1071 @*/
1072 PetscErrorCode  SNESGetFunctionNorm(SNES snes,PetscReal *fnorm)
1073 {
1074   PetscFunctionBegin;
1075   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1076   PetscValidScalarPointer(fnorm,2);
1077   *fnorm = snes->norm;
1078   PetscFunctionReturn(0);
1079 }
1080 
1081 
1082 #undef __FUNCT__
1083 #define __FUNCT__ "SNESSetFunctionNorm"
1084 /*@
1085    SNESSetFunctionNorm - Sets the 2-norm of the current function computed using VecNorm().
1086 
1087    Collective on SNES
1088 
1089    Input Parameter:
1090 .  snes - SNES context
1091 .  fnorm - 2-norm of function
1092 
1093    Level: developer
1094 
1095 .keywords: SNES, nonlinear, set, function, norm
1096 
1097 .seealso: SNESSetFunction(), SNESSetIterationNumber(), VecNorm().
1098 @*/
1099 PetscErrorCode  SNESSetFunctionNorm(SNES snes,PetscReal fnorm)
1100 {
1101 
1102   PetscErrorCode ierr;
1103 
1104   PetscFunctionBegin;
1105   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1106   ierr       = PetscObjectAMSTakeAccess((PetscObject)snes);CHKERRQ(ierr);
1107   snes->norm = fnorm;
1108   ierr       = PetscObjectAMSGrantAccess((PetscObject)snes);CHKERRQ(ierr);
1109   PetscFunctionReturn(0);
1110 }
1111 
1112 #undef __FUNCT__
1113 #define __FUNCT__ "SNESGetNonlinearStepFailures"
1114 /*@
1115    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1116    attempted by the nonlinear solver.
1117 
1118    Not Collective
1119 
1120    Input Parameter:
1121 .  snes - SNES context
1122 
1123    Output Parameter:
1124 .  nfails - number of unsuccessful steps attempted
1125 
1126    Notes:
1127    This counter is reset to zero for each successive call to SNESSolve().
1128 
1129    Level: intermediate
1130 
1131 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1132 
1133 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1134           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
1135 @*/
1136 PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
1137 {
1138   PetscFunctionBegin;
1139   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1140   PetscValidIntPointer(nfails,2);
1141   *nfails = snes->numFailures;
1142   PetscFunctionReturn(0);
1143 }
1144 
1145 #undef __FUNCT__
1146 #define __FUNCT__ "SNESSetMaxNonlinearStepFailures"
1147 /*@
1148    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1149    attempted by the nonlinear solver before it gives up.
1150 
1151    Not Collective
1152 
1153    Input Parameters:
1154 +  snes     - SNES context
1155 -  maxFails - maximum of unsuccessful steps
1156 
1157    Level: intermediate
1158 
1159 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1160 
1161 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1162           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1163 @*/
1164 PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1165 {
1166   PetscFunctionBegin;
1167   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1168   snes->maxFailures = maxFails;
1169   PetscFunctionReturn(0);
1170 }
1171 
1172 #undef __FUNCT__
1173 #define __FUNCT__ "SNESGetMaxNonlinearStepFailures"
1174 /*@
1175    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1176    attempted by the nonlinear solver before it gives up.
1177 
1178    Not Collective
1179 
1180    Input Parameter:
1181 .  snes     - SNES context
1182 
1183    Output Parameter:
1184 .  maxFails - maximum of unsuccessful steps
1185 
1186    Level: intermediate
1187 
1188 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1189 
1190 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1191           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1192 
1193 @*/
1194 PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1195 {
1196   PetscFunctionBegin;
1197   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1198   PetscValidIntPointer(maxFails,2);
1199   *maxFails = snes->maxFailures;
1200   PetscFunctionReturn(0);
1201 }
1202 
1203 #undef __FUNCT__
1204 #define __FUNCT__ "SNESGetNumberFunctionEvals"
1205 /*@
1206    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1207      done by SNES.
1208 
1209    Not Collective
1210 
1211    Input Parameter:
1212 .  snes     - SNES context
1213 
1214    Output Parameter:
1215 .  nfuncs - number of evaluations
1216 
1217    Level: intermediate
1218 
1219    Notes: Reset every time SNESSolve is called unless SNESSetCountersReset() is used.
1220 
1221 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1222 
1223 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(), SNESSetCountersReset()
1224 @*/
1225 PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1226 {
1227   PetscFunctionBegin;
1228   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1229   PetscValidIntPointer(nfuncs,2);
1230   *nfuncs = snes->nfuncs;
1231   PetscFunctionReturn(0);
1232 }
1233 
1234 #undef __FUNCT__
1235 #define __FUNCT__ "SNESGetLinearSolveFailures"
1236 /*@
1237    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1238    linear solvers.
1239 
1240    Not Collective
1241 
1242    Input Parameter:
1243 .  snes - SNES context
1244 
1245    Output Parameter:
1246 .  nfails - number of failed solves
1247 
1248    Notes:
1249    This counter is reset to zero for each successive call to SNESSolve().
1250 
1251    Level: intermediate
1252 
1253 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1254 
1255 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1256 @*/
1257 PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
1258 {
1259   PetscFunctionBegin;
1260   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1261   PetscValidIntPointer(nfails,2);
1262   *nfails = snes->numLinearSolveFailures;
1263   PetscFunctionReturn(0);
1264 }
1265 
1266 #undef __FUNCT__
1267 #define __FUNCT__ "SNESSetMaxLinearSolveFailures"
1268 /*@
1269    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1270    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE
1271 
1272    Logically Collective on SNES
1273 
1274    Input Parameters:
1275 +  snes     - SNES context
1276 -  maxFails - maximum allowed linear solve failures
1277 
1278    Level: intermediate
1279 
1280    Notes: By default this is 0; that is SNES returns on the first failed linear solve
1281 
1282 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1283 
1284 .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1285 @*/
1286 PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1287 {
1288   PetscFunctionBegin;
1289   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1290   PetscValidLogicalCollectiveInt(snes,maxFails,2);
1291   snes->maxLinearSolveFailures = maxFails;
1292   PetscFunctionReturn(0);
1293 }
1294 
1295 #undef __FUNCT__
1296 #define __FUNCT__ "SNESGetMaxLinearSolveFailures"
1297 /*@
1298    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1299      are allowed before SNES terminates
1300 
1301    Not Collective
1302 
1303    Input Parameter:
1304 .  snes     - SNES context
1305 
1306    Output Parameter:
1307 .  maxFails - maximum of unsuccessful solves allowed
1308 
1309    Level: intermediate
1310 
1311    Notes: By default this is 1; that is SNES returns on the first failed linear solve
1312 
1313 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1314 
1315 .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1316 @*/
1317 PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1318 {
1319   PetscFunctionBegin;
1320   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1321   PetscValidIntPointer(maxFails,2);
1322   *maxFails = snes->maxLinearSolveFailures;
1323   PetscFunctionReturn(0);
1324 }
1325 
1326 #undef __FUNCT__
1327 #define __FUNCT__ "SNESGetLinearSolveIterations"
1328 /*@
1329    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1330    used by the nonlinear solver.
1331 
1332    Not Collective
1333 
1334    Input Parameter:
1335 .  snes - SNES context
1336 
1337    Output Parameter:
1338 .  lits - number of linear iterations
1339 
1340    Notes:
1341    This counter is reset to zero for each successive call to SNESSolve() unless SNESSetCountersReset() is used.
1342 
1343    Level: intermediate
1344 
1345 .keywords: SNES, nonlinear, get, number, linear, iterations
1346 
1347 .seealso:  SNESGetIterationNumber(), SNESGetFunctionNorm(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
1348 @*/
1349 PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
1350 {
1351   PetscFunctionBegin;
1352   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1353   PetscValidIntPointer(lits,2);
1354   *lits = snes->linear_its;
1355   PetscFunctionReturn(0);
1356 }
1357 
1358 #undef __FUNCT__
1359 #define __FUNCT__ "SNESSetCountersReset"
1360 /*@
1361    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1362    are reset every time SNESSolve() is called.
1363 
1364    Logically Collective on SNES
1365 
1366    Input Parameter:
1367 +  snes - SNES context
1368 -  reset - whether to reset the counters or not
1369 
1370    Notes:
1371    This is automatically called with FALSE
1372 
1373    Level: developer
1374 
1375 .keywords: SNES, nonlinear, set, reset, number, linear, iterations
1376 
1377 .seealso:  SNESGetNumberFunctionEvals(), SNESGetNumberLinearSolveIterations(), SNESGetPC()
1378 @*/
1379 PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
1380 {
1381   PetscFunctionBegin;
1382   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1383   PetscValidLogicalCollectiveBool(snes,reset,2);
1384   snes->counters_reset = reset;
1385   PetscFunctionReturn(0);
1386 }
1387 
1388 
1389 #undef __FUNCT__
1390 #define __FUNCT__ "SNESSetKSP"
1391 /*@
1392    SNESSetKSP - Sets a KSP context for the SNES object to use
1393 
1394    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm
1395 
1396    Input Parameters:
1397 +  snes - the SNES context
1398 -  ksp - the KSP context
1399 
1400    Notes:
1401    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1402    so this routine is rarely needed.
1403 
1404    The KSP object that is already in the SNES object has its reference count
1405    decreased by one.
1406 
1407    Level: developer
1408 
1409 .keywords: SNES, nonlinear, get, KSP, context
1410 
1411 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1412 @*/
1413 PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1414 {
1415   PetscErrorCode ierr;
1416 
1417   PetscFunctionBegin;
1418   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1419   PetscValidHeaderSpecific(ksp,KSP_CLASSID,2);
1420   PetscCheckSameComm(snes,1,ksp,2);
1421   ierr = PetscObjectReference((PetscObject)ksp);CHKERRQ(ierr);
1422   if (snes->ksp) {ierr = PetscObjectDereference((PetscObject)snes->ksp);CHKERRQ(ierr);}
1423   snes->ksp = ksp;
1424   PetscFunctionReturn(0);
1425 }
1426 
1427 /* -----------------------------------------------------------*/
1428 #undef __FUNCT__
1429 #define __FUNCT__ "SNESCreate"
1430 /*@
1431    SNESCreate - Creates a nonlinear solver context.
1432 
1433    Collective on MPI_Comm
1434 
1435    Input Parameters:
1436 .  comm - MPI communicator
1437 
1438    Output Parameter:
1439 .  outsnes - the new SNES context
1440 
1441    Options Database Keys:
1442 +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1443                and no preconditioning matrix
1444 .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1445                products, and a user-provided preconditioning matrix
1446                as set by SNESSetJacobian()
1447 -   -snes_fd - Uses (slow!) finite differences to compute Jacobian
1448 
1449    Level: beginner
1450 
1451 .keywords: SNES, nonlinear, create, context
1452 
1453 .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()
1454 
1455 @*/
1456 PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1457 {
1458   PetscErrorCode ierr;
1459   SNES           snes;
1460   SNESKSPEW      *kctx;
1461 
1462   PetscFunctionBegin;
1463   PetscValidPointer(outsnes,2);
1464   *outsnes = NULL;
1465   ierr = SNESInitializePackage();CHKERRQ(ierr);
1466 
1467   ierr = PetscHeaderCreate(snes,_p_SNES,struct _SNESOps,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);CHKERRQ(ierr);
1468 
1469   snes->ops->converged    = SNESConvergedDefault;
1470   snes->usesksp           = PETSC_TRUE;
1471   snes->tolerancesset     = PETSC_FALSE;
1472   snes->max_its           = 50;
1473   snes->max_funcs         = 10000;
1474   snes->norm              = 0.0;
1475   snes->normschedule      = SNES_NORM_ALWAYS;
1476   snes->functype          = SNES_FUNCTION_DEFAULT;
1477   snes->rtol              = 1.e-8;
1478   snes->ttol              = 0.0;
1479   snes->abstol            = 1.e-50;
1480   snes->stol              = 1.e-8;
1481   snes->deltatol          = 1.e-12;
1482   snes->nfuncs            = 0;
1483   snes->numFailures       = 0;
1484   snes->maxFailures       = 1;
1485   snes->linear_its        = 0;
1486   snes->lagjacobian       = 1;
1487   snes->jac_iter          = 0;
1488   snes->lagjac_persist    = PETSC_FALSE;
1489   snes->lagpreconditioner = 1;
1490   snes->pre_iter          = 0;
1491   snes->lagpre_persist    = PETSC_FALSE;
1492   snes->numbermonitors    = 0;
1493   snes->data              = 0;
1494   snes->setupcalled       = PETSC_FALSE;
1495   snes->ksp_ewconv        = PETSC_FALSE;
1496   snes->nwork             = 0;
1497   snes->work              = 0;
1498   snes->nvwork            = 0;
1499   snes->vwork             = 0;
1500   snes->conv_hist_len     = 0;
1501   snes->conv_hist_max     = 0;
1502   snes->conv_hist         = NULL;
1503   snes->conv_hist_its     = NULL;
1504   snes->conv_hist_reset   = PETSC_TRUE;
1505   snes->counters_reset    = PETSC_TRUE;
1506   snes->vec_func_init_set = PETSC_FALSE;
1507   snes->reason            = SNES_CONVERGED_ITERATING;
1508   snes->pcside            = PC_RIGHT;
1509 
1510   snes->mf          = PETSC_FALSE;
1511   snes->mf_operator = PETSC_FALSE;
1512   snes->mf_version  = 1;
1513 
1514   snes->numLinearSolveFailures = 0;
1515   snes->maxLinearSolveFailures = 1;
1516 
1517   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1518   ierr = PetscNewLog(snes,SNESKSPEW,&kctx);CHKERRQ(ierr);
1519 
1520   snes->kspconvctx  = (void*)kctx;
1521   kctx->version     = 2;
1522   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1523                              this was too large for some test cases */
1524   kctx->rtol_last   = 0.0;
1525   kctx->rtol_max    = .9;
1526   kctx->gamma       = 1.0;
1527   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1528   kctx->alpha2      = kctx->alpha;
1529   kctx->threshold   = .1;
1530   kctx->lresid_last = 0.0;
1531   kctx->norm_last   = 0.0;
1532 
1533   *outsnes = snes;
1534   PetscFunctionReturn(0);
1535 }
1536 
1537 /*MC
1538     SNESFunction - functional form used to convey the nonlinear function to be solved by SNES
1539 
1540      Synopsis:
1541      #include "petscsnes.h"
1542      SNESFunction(SNES snes,Vec x,Vec f,void *ctx);
1543 
1544      Input Parameters:
1545 +     snes - the SNES context
1546 .     x    - state at which to evaluate residual
1547 -     ctx     - optional user-defined function context, passed in with SNESSetFunction()
1548 
1549      Output Parameter:
1550 .     f  - vector to put residual (function value)
1551 
1552    Level: intermediate
1553 
1554 .seealso:   SNESSetFunction(), SNESGetFunction()
1555 M*/
1556 
1557 #undef __FUNCT__
1558 #define __FUNCT__ "SNESSetFunction"
1559 /*@C
1560    SNESSetFunction - Sets the function evaluation routine and function
1561    vector for use by the SNES routines in solving systems of nonlinear
1562    equations.
1563 
1564    Logically Collective on SNES
1565 
1566    Input Parameters:
1567 +  snes - the SNES context
1568 .  r - vector to store function value
1569 .  SNESFunction - function evaluation routine
1570 -  ctx - [optional] user-defined context for private data for the
1571          function evaluation routine (may be NULL)
1572 
1573    Notes:
1574    The Newton-like methods typically solve linear systems of the form
1575 $      f'(x) x = -f(x),
1576    where f'(x) denotes the Jacobian matrix and f(x) is the function.
1577 
1578    Level: beginner
1579 
1580 .keywords: SNES, nonlinear, set, function
1581 
1582 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
1583 @*/
1584 PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*SNESFunction)(SNES,Vec,Vec,void*),void *ctx)
1585 {
1586   PetscErrorCode ierr;
1587   DM             dm;
1588 
1589   PetscFunctionBegin;
1590   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1591   if (r) {
1592     PetscValidHeaderSpecific(r,VEC_CLASSID,2);
1593     PetscCheckSameComm(snes,1,r,2);
1594     ierr = PetscObjectReference((PetscObject)r);CHKERRQ(ierr);
1595     ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
1596 
1597     snes->vec_func = r;
1598   }
1599   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1600   ierr = DMSNESSetFunction(dm,SNESFunction,ctx);CHKERRQ(ierr);
1601   PetscFunctionReturn(0);
1602 }
1603 
1604 
1605 #undef __FUNCT__
1606 #define __FUNCT__ "SNESSetInitialFunction"
1607 /*@C
1608    SNESSetInitialFunction - Sets the function vector to be used as the
1609    function norm at the initialization of the method.  In some
1610    instances, the user has precomputed the function before calling
1611    SNESSolve.  This function allows one to avoid a redundant call
1612    to SNESComputeFunction in that case.
1613 
1614    Logically Collective on SNES
1615 
1616    Input Parameters:
1617 +  snes - the SNES context
1618 -  f - vector to store function value
1619 
1620    Notes:
1621    This should not be modified during the solution procedure.
1622 
1623    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1624 
1625    Level: developer
1626 
1627 .keywords: SNES, nonlinear, set, function
1628 
1629 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1630 @*/
1631 PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1632 {
1633   PetscErrorCode ierr;
1634   Vec            vec_func;
1635 
1636   PetscFunctionBegin;
1637   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1638   PetscValidHeaderSpecific(f,VEC_CLASSID,2);
1639   PetscCheckSameComm(snes,1,f,2);
1640   if (snes->pcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
1641     snes->vec_func_init_set = PETSC_FALSE;
1642     PetscFunctionReturn(0);
1643   }
1644   ierr = SNESGetFunction(snes,&vec_func,NULL,NULL);CHKERRQ(ierr);
1645   ierr = VecCopy(f, vec_func);CHKERRQ(ierr);
1646 
1647   snes->vec_func_init_set = PETSC_TRUE;
1648   PetscFunctionReturn(0);
1649 }
1650 
1651 #undef __FUNCT__
1652 #define __FUNCT__ "SNESSetNormSchedule"
1653 /*@
1654    SNESSetNormSchedule - Sets the SNESNormSchedule used in covergence and monitoring
1655    of the SNES method.
1656 
1657    Logically Collective on SNES
1658 
1659    Input Parameters:
1660 +  snes - the SNES context
1661 -  normschedule - the frequency of norm computation
1662 
1663    Notes:
1664    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1665    of the nonlinear function and the taking of its norm at every iteration to
1666    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1667    (SNESGS) and the like do not require the norm of the function to be computed, and therfore
1668    may either be monitored for convergence or not.  As these are often used as nonlinear
1669    preconditioners, monitoring the norm of their error is not a useful enterprise within
1670    their solution.
1671 
1672    Level: developer
1673 
1674 .keywords: SNES, nonlinear, set, function, norm, type
1675 
1676 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1677 @*/
1678 PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
1679 {
1680   PetscFunctionBegin;
1681   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1682   snes->normschedule = normschedule;
1683   PetscFunctionReturn(0);
1684 }
1685 
1686 
1687 #undef __FUNCT__
1688 #define __FUNCT__ "SNESGetNormSchedule"
1689 /*@
1690    SNESGetNormSchedule - Gets the SNESNormSchedule used in covergence and monitoring
1691    of the SNES method.
1692 
1693    Logically Collective on SNES
1694 
1695    Input Parameters:
1696 +  snes - the SNES context
1697 -  normschedule - the type of the norm used
1698 
1699    Level: advanced
1700 
1701 .keywords: SNES, nonlinear, set, function, norm, type
1702 
1703 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1704 @*/
1705 PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
1706 {
1707   PetscFunctionBegin;
1708   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1709   *normschedule = snes->normschedule;
1710   PetscFunctionReturn(0);
1711 }
1712 
1713 
1714 #undef __FUNCT__
1715 #define __FUNCT__ "SNESSetFunctionType"
1716 /*@C
1717    SNESSetFunctionType - Sets the SNESNormSchedule used in covergence and monitoring
1718    of the SNES method.
1719 
1720    Logically Collective on SNES
1721 
1722    Input Parameters:
1723 +  snes - the SNES context
1724 -  normschedule - the frequency of norm computation
1725 
1726    Notes:
1727    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1728    of the nonlinear function and the taking of its norm at every iteration to
1729    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1730    (SNESGS) and the like do not require the norm of the function to be computed, and therfore
1731    may either be monitored for convergence or not.  As these are often used as nonlinear
1732    preconditioners, monitoring the norm of their error is not a useful enterprise within
1733    their solution.
1734 
1735    Level: developer
1736 
1737 .keywords: SNES, nonlinear, set, function, norm, type
1738 
1739 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1740 @*/
1741 PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
1742 {
1743   PetscFunctionBegin;
1744   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1745   snes->functype = type;
1746   PetscFunctionReturn(0);
1747 }
1748 
1749 
1750 #undef __FUNCT__
1751 #define __FUNCT__ "SNESGetFunctionType"
1752 /*@C
1753    SNESGetFunctionType - Gets the SNESNormSchedule used in covergence and monitoring
1754    of the SNES method.
1755 
1756    Logically Collective on SNES
1757 
1758    Input Parameters:
1759 +  snes - the SNES context
1760 -  normschedule - the type of the norm used
1761 
1762    Level: advanced
1763 
1764 .keywords: SNES, nonlinear, set, function, norm, type
1765 
1766 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1767 @*/
1768 PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
1769 {
1770   PetscFunctionBegin;
1771   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1772   *type = snes->functype;
1773   PetscFunctionReturn(0);
1774 }
1775 
1776 /*MC
1777     SNESGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function
1778 
1779      Synopsis:
1780      #include "petscsnes.h"
1781 $    SNESGSFunction(SNES snes,Vec x,Vec b,void *ctx);
1782 
1783 +  X   - solution vector
1784 .  B   - RHS vector
1785 -  ctx - optional user-defined Gauss-Seidel context
1786 
1787    Level: intermediate
1788 
1789 .seealso:   SNESSetGS(), SNESGetGS()
1790 M*/
1791 
1792 #undef __FUNCT__
1793 #define __FUNCT__ "SNESSetGS"
1794 /*@C
1795    SNESSetGS - Sets the user nonlinear Gauss-Seidel routine for
1796    use with composed nonlinear solvers.
1797 
1798    Input Parameters:
1799 +  snes   - the SNES context
1800 .  SNESGSFunction - function evaluation routine
1801 -  ctx    - [optional] user-defined context for private data for the
1802             smoother evaluation routine (may be NULL)
1803 
1804    Notes:
1805    The GS routines are used by the composed nonlinear solver to generate
1806     a problem appropriate update to the solution, particularly FAS.
1807 
1808    Level: intermediate
1809 
1810 .keywords: SNES, nonlinear, set, Gauss-Seidel
1811 
1812 .seealso: SNESGetFunction(), SNESComputeGS()
1813 @*/
1814 PetscErrorCode SNESSetGS(SNES snes,PetscErrorCode (*SNESGSFunction)(SNES,Vec,Vec,void*),void *ctx)
1815 {
1816   PetscErrorCode ierr;
1817   DM             dm;
1818 
1819   PetscFunctionBegin;
1820   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1821   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1822   ierr = DMSNESSetGS(dm,SNESGSFunction,ctx);CHKERRQ(ierr);
1823   PetscFunctionReturn(0);
1824 }
1825 
1826 #undef __FUNCT__
1827 #define __FUNCT__ "SNESPicardComputeFunction"
1828 PETSC_EXTERN PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
1829 {
1830   PetscErrorCode ierr;
1831   DM             dm;
1832   DMSNES         sdm;
1833 
1834   PetscFunctionBegin;
1835   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1836   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
1837   /*  A(x)*x - b(x) */
1838   if (sdm->ops->computepfunction) {
1839     ierr = (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);CHKERRQ(ierr);
1840   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");
1841 
1842   if (sdm->ops->computepjacobian) {
1843     ierr = (*sdm->ops->computepjacobian)(snes,x,&snes->jacobian,&snes->jacobian_pre,&snes->matstruct,sdm->pctx);CHKERRQ(ierr);
1844   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard matrix.");
1845   ierr = VecScale(f,-1.0);CHKERRQ(ierr);
1846   ierr = MatMultAdd(snes->jacobian,x,f,f);CHKERRQ(ierr);
1847   PetscFunctionReturn(0);
1848 }
1849 
1850 #undef __FUNCT__
1851 #define __FUNCT__ "SNESPicardComputeJacobian"
1852 PETSC_EXTERN PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx)
1853 {
1854   PetscFunctionBegin;
1855   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
1856   *flag = snes->matstruct;
1857   PetscFunctionReturn(0);
1858 }
1859 
1860 #undef __FUNCT__
1861 #define __FUNCT__ "SNESSetPicard"
1862 /*@C
1863    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)
1864 
1865    Logically Collective on SNES
1866 
1867    Input Parameters:
1868 +  snes - the SNES context
1869 .  r - vector to store function value
1870 .  SNESFunction - function evaluation routine
1871 .  Amat - matrix with which A(x) x - b(x) is to be computed
1872 .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
1873 .  SNESJacobianFunction  - function to compute matrix value
1874 -  ctx - [optional] user-defined context for private data for the
1875          function evaluation routine (may be NULL)
1876 
1877    Notes:
1878     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
1879     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.
1880 
1881     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both
1882 
1883 $     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}
1884 $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.
1885 
1886      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.
1887 
1888    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
1889    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)
1890 
1891    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
1892    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
1893    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).
1894 
1895    Level: intermediate
1896 
1897 .keywords: SNES, nonlinear, set, function
1898 
1899 .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard()
1900 @*/
1901 PetscErrorCode  SNESSetPicard(SNES snes,Vec r,PetscErrorCode (*SNESFunction)(SNES,Vec,Vec,void*),Mat Amat, Mat Pmat, PetscErrorCode (*SNESJacobianFunction)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void *ctx)
1902 {
1903   PetscErrorCode ierr;
1904   DM             dm;
1905 
1906   PetscFunctionBegin;
1907   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1908   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
1909   ierr = DMSNESSetPicard(dm,SNESFunction,SNESJacobianFunction,ctx);CHKERRQ(ierr);
1910   ierr = SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);CHKERRQ(ierr);
1911   ierr = SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);CHKERRQ(ierr);
1912   PetscFunctionReturn(0);
1913 }
1914 
1915 #undef __FUNCT__
1916 #define __FUNCT__ "SNESGetPicard"
1917 /*@C
1918    SNESGetPicard - Returns the context for the Picard iteration
1919 
1920    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
1921 
1922    Input Parameter:
1923 .  snes - the SNES context
1924 
1925    Output Parameter:
1926 +  r - the function (or NULL)
1927 .  SNESFunction - the function (or NULL)
1928 .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
1929 .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
1930 .  SNESJacobianFunction - the function for matrix evaluation (or NULL)
1931 -  ctx - the function context (or NULL)
1932 
1933    Level: advanced
1934 
1935 .keywords: SNES, nonlinear, get, function
1936 
1937 .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
1938 @*/
1939 PetscErrorCode  SNESGetPicard(SNES snes,Vec *r,PetscErrorCode (**SNESFunction)(SNES,Vec,Vec,void*),Mat *Amat, Mat *Pmat, PetscErrorCode (**SNESJacobianFunction)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void **ctx)
1940 {
1941   PetscErrorCode ierr;
1942   DM             dm;
1943 
1944   PetscFunctionBegin;
1945   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1946   ierr = SNESGetFunction(snes,r,NULL,NULL);CHKERRQ(ierr);
1947   ierr = SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);CHKERRQ(ierr);
1948   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1949   ierr = DMSNESGetPicard(dm,SNESFunction,SNESJacobianFunction,ctx);CHKERRQ(ierr);
1950   PetscFunctionReturn(0);
1951 }
1952 
1953 #undef __FUNCT__
1954 #define __FUNCT__ "SNESSetComputeInitialGuess"
1955 /*@C
1956    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem
1957 
1958    Logically Collective on SNES
1959 
1960    Input Parameters:
1961 +  snes - the SNES context
1962 .  func - function evaluation routine
1963 -  ctx - [optional] user-defined context for private data for the
1964          function evaluation routine (may be NULL)
1965 
1966    Calling sequence of func:
1967 $    func (SNES snes,Vec x,void *ctx);
1968 
1969 .  f - function vector
1970 -  ctx - optional user-defined function context
1971 
1972    Level: intermediate
1973 
1974 .keywords: SNES, nonlinear, set, function
1975 
1976 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
1977 @*/
1978 PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
1979 {
1980   PetscFunctionBegin;
1981   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1982   if (func) snes->ops->computeinitialguess = func;
1983   if (ctx)  snes->initialguessP            = ctx;
1984   PetscFunctionReturn(0);
1985 }
1986 
1987 /* --------------------------------------------------------------- */
1988 #undef __FUNCT__
1989 #define __FUNCT__ "SNESGetRhs"
1990 /*@C
1991    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
1992    it assumes a zero right hand side.
1993 
1994    Logically Collective on SNES
1995 
1996    Input Parameter:
1997 .  snes - the SNES context
1998 
1999    Output Parameter:
2000 .  rhs - the right hand side vector or NULL if the right hand side vector is null
2001 
2002    Level: intermediate
2003 
2004 .keywords: SNES, nonlinear, get, function, right hand side
2005 
2006 .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
2007 @*/
2008 PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
2009 {
2010   PetscFunctionBegin;
2011   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2012   PetscValidPointer(rhs,2);
2013   *rhs = snes->vec_rhs;
2014   PetscFunctionReturn(0);
2015 }
2016 
2017 #undef __FUNCT__
2018 #define __FUNCT__ "SNESComputeFunction"
2019 /*@
2020    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().
2021 
2022    Collective on SNES
2023 
2024    Input Parameters:
2025 +  snes - the SNES context
2026 -  x - input vector
2027 
2028    Output Parameter:
2029 .  y - function vector, as set by SNESSetFunction()
2030 
2031    Notes:
2032    SNESComputeFunction() is typically used within nonlinear solvers
2033    implementations, so most users would not generally call this routine
2034    themselves.
2035 
2036    Level: developer
2037 
2038 .keywords: SNES, nonlinear, compute, function
2039 
2040 .seealso: SNESSetFunction(), SNESGetFunction()
2041 @*/
2042 PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
2043 {
2044   PetscErrorCode ierr;
2045   DM             dm;
2046   DMSNES         sdm;
2047 
2048   PetscFunctionBegin;
2049   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2050   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2051   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
2052   PetscCheckSameComm(snes,1,x,2);
2053   PetscCheckSameComm(snes,1,y,3);
2054   ierr = VecValidValues(x,2,PETSC_TRUE);CHKERRQ(ierr);
2055 
2056   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2057   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2058   if (sdm->ops->computefunction) {
2059     ierr = PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2060     PetscStackPush("SNES user function");
2061     ierr = (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);CHKERRQ(ierr);
2062     PetscStackPop;
2063     ierr = PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2064   } else if (snes->vec_rhs) {
2065     ierr = MatMult(snes->jacobian, x, y);CHKERRQ(ierr);
2066   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2067   if (snes->vec_rhs) {
2068     ierr = VecAXPY(y,-1.0,snes->vec_rhs);CHKERRQ(ierr);
2069   }
2070   snes->nfuncs++;
2071   ierr = VecValidValues(y,3,PETSC_FALSE);CHKERRQ(ierr);
2072   PetscFunctionReturn(0);
2073 }
2074 
2075 #undef __FUNCT__
2076 #define __FUNCT__ "SNESComputeGS"
2077 /*@
2078    SNESComputeGS - Calls the Gauss-Seidel function that has been set with  SNESSetGS().
2079 
2080    Collective on SNES
2081 
2082    Input Parameters:
2083 +  snes - the SNES context
2084 .  x - input vector
2085 -  b - rhs vector
2086 
2087    Output Parameter:
2088 .  x - new solution vector
2089 
2090    Notes:
2091    SNESComputeGS() is typically used within composed nonlinear solver
2092    implementations, so most users would not generally call this routine
2093    themselves.
2094 
2095    Level: developer
2096 
2097 .keywords: SNES, nonlinear, compute, function
2098 
2099 .seealso: SNESSetGS(), SNESComputeFunction()
2100 @*/
2101 PetscErrorCode  SNESComputeGS(SNES snes,Vec b,Vec x)
2102 {
2103   PetscErrorCode ierr;
2104   DM             dm;
2105   DMSNES         sdm;
2106 
2107   PetscFunctionBegin;
2108   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2109   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2110   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,3);
2111   PetscCheckSameComm(snes,1,x,2);
2112   if (b) PetscCheckSameComm(snes,1,b,3);
2113   if (b) {ierr = VecValidValues(b,2,PETSC_TRUE);CHKERRQ(ierr);}
2114   ierr = PetscLogEventBegin(SNES_GSEval,snes,x,b,0);CHKERRQ(ierr);
2115   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2116   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2117   if (sdm->ops->computegs) {
2118     PetscStackPush("SNES user GS");
2119     ierr = (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);CHKERRQ(ierr);
2120     PetscStackPop;
2121   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetGS() before SNESComputeGS(), likely called from SNESSolve().");
2122   ierr = PetscLogEventEnd(SNES_GSEval,snes,x,b,0);CHKERRQ(ierr);
2123   ierr = VecValidValues(x,3,PETSC_FALSE);CHKERRQ(ierr);
2124   PetscFunctionReturn(0);
2125 }
2126 
2127 #undef __FUNCT__
2128 #define __FUNCT__ "SNESComputeJacobian"
2129 /*@
2130    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().
2131 
2132    Collective on SNES and Mat
2133 
2134    Input Parameters:
2135 +  snes - the SNES context
2136 -  x - input vector
2137 
2138    Output Parameters:
2139 +  A - Jacobian matrix
2140 .  B - optional preconditioning matrix
2141 -  flag - flag indicating matrix structure (one of, SAME_NONZERO_PATTERN,DIFFERENT_NONZERO_PATTERN,SAME_PRECONDITIONER)
2142 
2143   Options Database Keys:
2144 +    -snes_lag_preconditioner <lag>
2145 .    -snes_lag_jacobian <lag>
2146 .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2147 .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2148 .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2149 .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2150 .    -snes_compare_coloring - Compute the finite differece Jacobian using coloring and display norms of difference
2151 .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
2152 .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2153 .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2154 .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2155 .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
2156 -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences
2157 
2158 
2159    Notes:
2160    Most users should not need to explicitly call this routine, as it
2161    is used internally within the nonlinear solvers.
2162 
2163    See KSPSetOperators() for important information about setting the
2164    flag parameter.
2165 
2166    Level: developer
2167 
2168 .keywords: SNES, compute, Jacobian, matrix
2169 
2170 .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2171 @*/
2172 PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat *A,Mat *B,MatStructure *flg)
2173 {
2174   PetscErrorCode ierr;
2175   PetscBool      flag;
2176   DM             dm;
2177   DMSNES         sdm;
2178 
2179   PetscFunctionBegin;
2180   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2181   PetscValidHeaderSpecific(X,VEC_CLASSID,2);
2182   PetscValidPointer(flg,5);
2183   PetscCheckSameComm(snes,1,X,2);
2184   ierr = VecValidValues(X,2,PETSC_TRUE);CHKERRQ(ierr);
2185   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2186   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2187 
2188   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");
2189 
2190   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */
2191 
2192   if (snes->lagjacobian == -2) {
2193     snes->lagjacobian = -1;
2194 
2195     ierr = PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");CHKERRQ(ierr);
2196   } else if (snes->lagjacobian == -1) {
2197     *flg = SAME_PRECONDITIONER;
2198     ierr = PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");CHKERRQ(ierr);
2199     ierr = PetscObjectTypeCompare((PetscObject)*A,MATMFFD,&flag);CHKERRQ(ierr);
2200     if (flag) {
2201       ierr = MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2202       ierr = MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2203     }
2204     PetscFunctionReturn(0);
2205   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2206     *flg = SAME_PRECONDITIONER;
2207     ierr = PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);CHKERRQ(ierr);
2208     ierr = PetscObjectTypeCompare((PetscObject)*A,MATMFFD,&flag);CHKERRQ(ierr);
2209     if (flag) {
2210       ierr = MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2211       ierr = MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2212     }
2213     PetscFunctionReturn(0);
2214   }
2215   if (snes->pc && snes->pcside == PC_LEFT) {
2216       ierr = MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2217       ierr = MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2218       PetscFunctionReturn(0);
2219   }
2220 
2221   *flg = DIFFERENT_NONZERO_PATTERN;
2222   ierr = PetscLogEventBegin(SNES_JacobianEval,snes,X,*A,*B);CHKERRQ(ierr);
2223 
2224   PetscStackPush("SNES user Jacobian function");
2225   ierr = (*sdm->ops->computejacobian)(snes,X,A,B,flg,sdm->jacobianctx);CHKERRQ(ierr);
2226   PetscStackPop;
2227 
2228   ierr = PetscLogEventEnd(SNES_JacobianEval,snes,X,*A,*B);CHKERRQ(ierr);
2229 
2230   if (snes->lagpreconditioner == -2) {
2231     ierr = PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");CHKERRQ(ierr);
2232 
2233     snes->lagpreconditioner = -1;
2234   } else if (snes->lagpreconditioner == -1) {
2235     *flg = SAME_PRECONDITIONER;
2236     ierr = PetscInfo(snes,"Reusing preconditioner because lag is -1\n");CHKERRQ(ierr);
2237   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2238     *flg = SAME_PRECONDITIONER;
2239     ierr = PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);CHKERRQ(ierr);
2240   }
2241 
2242   /* make sure user returned a correct Jacobian and preconditioner */
2243   /* PetscValidHeaderSpecific(*A,MAT_CLASSID,3);
2244     PetscValidHeaderSpecific(*B,MAT_CLASSID,4);   */
2245   {
2246     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2247     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit",&flag,NULL);CHKERRQ(ierr);
2248     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",&flag_draw,NULL);CHKERRQ(ierr);
2249     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2250     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_operator",&flag_operator,NULL);CHKERRQ(ierr);
2251     if (flag || flag_draw || flag_contour) {
2252       Mat          Bexp_mine = NULL,Bexp,FDexp;
2253       MatStructure mstruct;
2254       PetscViewer  vdraw,vstdout;
2255       PetscBool    flg;
2256       if (flag_operator) {
2257         ierr = MatComputeExplicitOperator(*A,&Bexp_mine);CHKERRQ(ierr);
2258         Bexp = Bexp_mine;
2259       } else {
2260         /* See if the preconditioning matrix can be viewed and added directly */
2261         ierr = PetscObjectTypeCompareAny((PetscObject)*B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");CHKERRQ(ierr);
2262         if (flg) Bexp = *B;
2263         else {
2264           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2265           ierr = MatComputeExplicitOperator(*B,&Bexp_mine);CHKERRQ(ierr);
2266           Bexp = Bexp_mine;
2267         }
2268       }
2269       ierr = MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);CHKERRQ(ierr);
2270       ierr = SNESComputeJacobianDefault(snes,X,&FDexp,&FDexp,&mstruct,NULL);CHKERRQ(ierr);
2271       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2272       if (flag_draw || flag_contour) {
2273         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2274         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2275       } else vdraw = NULL;
2276       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");CHKERRQ(ierr);
2277       if (flag) {ierr = MatView(Bexp,vstdout);CHKERRQ(ierr);}
2278       if (vdraw) {ierr = MatView(Bexp,vdraw);CHKERRQ(ierr);}
2279       ierr = PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");CHKERRQ(ierr);
2280       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2281       if (vdraw) {ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);}
2282       ierr = MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2283       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");CHKERRQ(ierr);
2284       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2285       if (vdraw) {              /* Always use contour for the difference */
2286         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2287         ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);
2288         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2289       }
2290       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2291       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2292       ierr = MatDestroy(&Bexp_mine);CHKERRQ(ierr);
2293       ierr = MatDestroy(&FDexp);CHKERRQ(ierr);
2294     }
2295   }
2296   {
2297     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2298     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2299     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring",&flag,NULL);CHKERRQ(ierr);
2300     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_display",&flag_display,NULL);CHKERRQ(ierr);
2301     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",&flag_draw,NULL);CHKERRQ(ierr);
2302     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2303     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",&flag_threshold,NULL);CHKERRQ(ierr);
2304     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);CHKERRQ(ierr);
2305     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);CHKERRQ(ierr);
2306     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2307       Mat            Bfd;
2308       MatStructure   mstruct;
2309       PetscViewer    vdraw,vstdout;
2310       ISColoring     iscoloring;
2311       MatFDColoring  matfdcoloring;
2312       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2313       void           *funcctx;
2314       PetscReal      norm1,norm2,normmax;
2315 
2316       ierr = MatDuplicate(*B,MAT_DO_NOT_COPY_VALUES,&Bfd);CHKERRQ(ierr);
2317       ierr = MatGetColoring(Bfd,MATCOLORINGSL,&iscoloring);CHKERRQ(ierr);
2318       ierr = MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);CHKERRQ(ierr);
2319       ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr);
2320 
2321       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2322       ierr = SNESGetFunction(snes,NULL,&func,&funcctx);CHKERRQ(ierr);
2323       ierr = MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);CHKERRQ(ierr);
2324       ierr = PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);CHKERRQ(ierr);
2325       ierr = PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");CHKERRQ(ierr);
2326       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2327       ierr = MatFDColoringApply(Bfd,matfdcoloring,X,&mstruct,snes);CHKERRQ(ierr);
2328       ierr = MatFDColoringDestroy(&matfdcoloring);CHKERRQ(ierr);
2329 
2330       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2331       if (flag_draw || flag_contour) {
2332         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2333         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2334       } else vdraw = NULL;
2335       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");CHKERRQ(ierr);
2336       if (flag_display) {ierr = MatView(*B,vstdout);CHKERRQ(ierr);}
2337       if (vdraw) {ierr = MatView(*B,vdraw);CHKERRQ(ierr);}
2338       ierr = PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");CHKERRQ(ierr);
2339       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2340       if (vdraw) {ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);}
2341       ierr = MatAYPX(Bfd,-1.0,*B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2342       ierr = MatNorm(Bfd,NORM_1,&norm1);CHKERRQ(ierr);
2343       ierr = MatNorm(Bfd,NORM_FROBENIUS,&norm2);CHKERRQ(ierr);
2344       ierr = MatNorm(Bfd,NORM_MAX,&normmax);CHKERRQ(ierr);
2345       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%G normFrob=%G normmax=%G\n",norm1,norm2,normmax);CHKERRQ(ierr);
2346       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2347       if (vdraw) {              /* Always use contour for the difference */
2348         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2349         ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);
2350         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2351       }
2352       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2353 
2354       if (flag_threshold) {
2355         PetscInt bs,rstart,rend,i;
2356         ierr = MatGetBlockSize(*B,&bs);CHKERRQ(ierr);
2357         ierr = MatGetOwnershipRange(*B,&rstart,&rend);CHKERRQ(ierr);
2358         for (i=rstart; i<rend; i++) {
2359           const PetscScalar *ba,*ca;
2360           const PetscInt    *bj,*cj;
2361           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2362           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2363           ierr = MatGetRow(*B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2364           ierr = MatGetRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2365           if (bn != cn) SETERRQ(((PetscObject)*A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2366           for (j=0; j<bn; j++) {
2367             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2368             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2369               maxentrycol = bj[j];
2370               maxentry    = PetscRealPart(ba[j]);
2371             }
2372             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2373               maxdiffcol = bj[j];
2374               maxdiff    = PetscRealPart(ca[j]);
2375             }
2376             if (rdiff > maxrdiff) {
2377               maxrdiffcol = bj[j];
2378               maxrdiff    = rdiff;
2379             }
2380           }
2381           if (maxrdiff > 1) {
2382             ierr = PetscViewerASCIIPrintf(vstdout,"row %D (maxentry=%G at %D, maxdiff=%G at %D, maxrdiff=%G at %D):",i,maxentry,maxentrycol,maxdiff,maxdiffcol,maxrdiff,maxrdiffcol);CHKERRQ(ierr);
2383             for (j=0; j<bn; j++) {
2384               PetscReal rdiff;
2385               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2386               if (rdiff > 1) {
2387                 ierr = PetscViewerASCIIPrintf(vstdout," (%D,%G:%G)",bj[j],PetscRealPart(ba[j]),PetscRealPart(ca[j]));CHKERRQ(ierr);
2388               }
2389             }
2390             ierr = PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);CHKERRQ(ierr);
2391           }
2392           ierr = MatRestoreRow(*B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2393           ierr = MatRestoreRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2394         }
2395       }
2396       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2397       ierr = MatDestroy(&Bfd);CHKERRQ(ierr);
2398     }
2399   }
2400   PetscFunctionReturn(0);
2401 }
2402 
2403 /*MC
2404     SNESJacobianFunction - function used to convey the nonlinear Jacobian of the function to be solved by SNES
2405 
2406      Synopsis:
2407      #include "petscsnes.h"
2408 $     SNESJacobianFunction(SNES snes,Vec x,Mat *Amat,Mat *Pmat,int *flag,void *ctx);
2409 
2410 +  x - input vector
2411 .  Amat - the matrix that defines the (approximate) Jacobian
2412 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2413 .  flag - flag indicating information about the preconditioner matrix
2414    structure (same as flag in KSPSetOperators()), one of SAME_NONZERO_PATTERN,DIFFERENT_NONZERO_PATTERN,SAME_PRECONDITIONER
2415 -  ctx - [optional] user-defined Jacobian context
2416 
2417    Level: intermediate
2418 
2419 .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2420 M*/
2421 
2422 #undef __FUNCT__
2423 #define __FUNCT__ "SNESSetJacobian"
2424 /*@C
2425    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2426    location to store the matrix.
2427 
2428    Logically Collective on SNES and Mat
2429 
2430    Input Parameters:
2431 +  snes - the SNES context
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 .  SNESJacobianFunction - Jacobian evaluation routine (if NULL then SNES retains any previously set value)
2435 -  ctx - [optional] user-defined context for private data for the
2436          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)
2437 
2438    Notes:
2439    See KSPSetOperators() for important information about setting the flag
2440    output parameter in the routine func().  Be sure to read this information!
2441 
2442    The routine func() takes Mat * as the matrix arguments rather than Mat.
2443    This allows the Jacobian evaluation routine to replace A and/or B with a
2444    completely new new matrix structure (not just different matrix elements)
2445    when appropriate, for instance, if the nonzero structure is changing
2446    throughout the global iterations.
2447 
2448    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
2449    each matrix.
2450 
2451    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
2452    must be a MatFDColoring.
2453 
2454    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2455    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.
2456 
2457    Level: beginner
2458 
2459 .keywords: SNES, nonlinear, set, Jacobian, matrix
2460 
2461 .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, SNESJacobianFunction, SNESSetPicard()
2462 @*/
2463 PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*SNESJacobianFunction)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void *ctx)
2464 {
2465   PetscErrorCode ierr;
2466   DM             dm;
2467 
2468   PetscFunctionBegin;
2469   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2470   if (Amat) PetscValidHeaderSpecific(Amat,MAT_CLASSID,2);
2471   if (Pmat) PetscValidHeaderSpecific(Pmat,MAT_CLASSID,3);
2472   if (Amat) PetscCheckSameComm(snes,1,Amat,2);
2473   if (Pmat) PetscCheckSameComm(snes,1,Pmat,3);
2474   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2475   ierr = DMSNESSetJacobian(dm,SNESJacobianFunction,ctx);CHKERRQ(ierr);
2476   if (Amat) {
2477     ierr = PetscObjectReference((PetscObject)Amat);CHKERRQ(ierr);
2478     ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2479 
2480     snes->jacobian = Amat;
2481   }
2482   if (Pmat) {
2483     ierr = PetscObjectReference((PetscObject)Pmat);CHKERRQ(ierr);
2484     ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2485 
2486     snes->jacobian_pre = Pmat;
2487   }
2488   PetscFunctionReturn(0);
2489 }
2490 
2491 #undef __FUNCT__
2492 #define __FUNCT__ "SNESGetJacobian"
2493 /*@C
2494    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2495    provided context for evaluating the Jacobian.
2496 
2497    Not Collective, but Mat object will be parallel if SNES object is
2498 
2499    Input Parameter:
2500 .  snes - the nonlinear solver context
2501 
2502    Output Parameters:
2503 +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
2504 .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
2505 .  SNESJacobianFunction - location to put Jacobian function (or NULL)
2506 -  ctx - location to stash Jacobian ctx (or NULL)
2507 
2508    Level: advanced
2509 
2510 .seealso: SNESSetJacobian(), SNESComputeJacobian()
2511 @*/
2512 PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**SNESJacobianFunction)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void **ctx)
2513 {
2514   PetscErrorCode ierr;
2515   DM             dm;
2516   DMSNES         sdm;
2517 
2518   PetscFunctionBegin;
2519   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2520   if (Amat) *Amat = snes->jacobian;
2521   if (Pmat) *Pmat = snes->jacobian_pre;
2522   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2523   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2524   if (SNESJacobianFunction) *SNESJacobianFunction = sdm->ops->computejacobian;
2525   if (ctx) *ctx = sdm->jacobianctx;
2526   PetscFunctionReturn(0);
2527 }
2528 
2529 #undef __FUNCT__
2530 #define __FUNCT__ "SNESSetUp"
2531 /*@
2532    SNESSetUp - Sets up the internal data structures for the later use
2533    of a nonlinear solver.
2534 
2535    Collective on SNES
2536 
2537    Input Parameters:
2538 .  snes - the SNES context
2539 
2540    Notes:
2541    For basic use of the SNES solvers the user need not explicitly call
2542    SNESSetUp(), since these actions will automatically occur during
2543    the call to SNESSolve().  However, if one wishes to control this
2544    phase separately, SNESSetUp() should be called after SNESCreate()
2545    and optional routines of the form SNESSetXXX(), but before SNESSolve().
2546 
2547    Level: advanced
2548 
2549 .keywords: SNES, nonlinear, setup
2550 
2551 .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
2552 @*/
2553 PetscErrorCode  SNESSetUp(SNES snes)
2554 {
2555   PetscErrorCode ierr;
2556   DM             dm;
2557   DMSNES         sdm;
2558   SNESLineSearch linesearch, pclinesearch;
2559   void           *lsprectx,*lspostctx;
2560   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
2561   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
2562   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2563   Vec            f,fpc;
2564   void           *funcctx;
2565   PetscErrorCode (*jac)(SNES,Vec,Mat*,Mat*,MatStructure*,void*);
2566   void           *jacctx,*appctx;
2567 
2568   PetscFunctionBegin;
2569   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2570   if (snes->setupcalled) PetscFunctionReturn(0);
2571 
2572   if (!((PetscObject)snes)->type_name) {
2573     ierr = SNESSetType(snes,SNESNEWTONLS);CHKERRQ(ierr);
2574   }
2575 
2576   ierr = SNESGetFunction(snes,&snes->vec_func,NULL,NULL);CHKERRQ(ierr);
2577 
2578   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2579   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2580   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
2581   if (!sdm->ops->computejacobian) {
2582     ierr = DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);CHKERRQ(ierr);
2583   }
2584   if (!snes->vec_func) {
2585     ierr = DMCreateGlobalVector(dm,&snes->vec_func);CHKERRQ(ierr);
2586   }
2587 
2588   if (!snes->ksp) {
2589     ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);
2590   }
2591 
2592   if (!snes->linesearch) {
2593     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
2594   }
2595   ierr = SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);CHKERRQ(ierr);
2596 
2597   if (snes->pc && (snes->pcside == PC_LEFT)) {
2598     snes->mf          = PETSC_TRUE;
2599     snes->mf_operator = PETSC_FALSE;
2600   }
2601 
2602   if (snes->mf) {
2603     ierr = SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);CHKERRQ(ierr);
2604   }
2605 
2606   if (snes->ops->usercompute && !snes->user) {
2607     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2608   }
2609 
2610   if (snes->pc) {
2611     /* copy the DM over */
2612     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2613     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
2614 
2615     ierr = SNESGetFunction(snes,&f,&func,&funcctx);CHKERRQ(ierr);
2616     ierr = VecDuplicate(f,&fpc);CHKERRQ(ierr);
2617     ierr = SNESSetFunction(snes->pc,fpc,func,funcctx);CHKERRQ(ierr);
2618     ierr = SNESGetJacobian(snes,NULL,NULL,&jac,&jacctx);CHKERRQ(ierr);
2619     ierr = SNESSetJacobian(snes->pc,NULL,NULL,jac,jacctx);CHKERRQ(ierr);
2620     ierr = SNESGetApplicationContext(snes,&appctx);CHKERRQ(ierr);
2621     ierr = SNESSetApplicationContext(snes->pc,appctx);CHKERRQ(ierr);
2622     ierr = VecDestroy(&fpc);CHKERRQ(ierr);
2623 
2624     /* copy the function pointers over */
2625     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
2626 
2627     /* default to 1 iteration */
2628     ierr = SNESSetTolerances(snes->pc,0.0,0.0,0.0,1,snes->pc->max_funcs);CHKERRQ(ierr);
2629     if (snes->pcside==PC_RIGHT) {
2630       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
2631     } else {
2632       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_NONE);CHKERRQ(ierr);
2633     }
2634     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
2635 
2636     /* copy the line search context over */
2637     ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2638     ierr = SNESGetLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
2639     ierr = SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);CHKERRQ(ierr);
2640     ierr = SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);CHKERRQ(ierr);
2641     ierr = SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);CHKERRQ(ierr);
2642     ierr = SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);CHKERRQ(ierr);
2643     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);CHKERRQ(ierr);
2644   }
2645 
2646   snes->jac_iter = 0;
2647   snes->pre_iter = 0;
2648 
2649   if (snes->ops->setup) {
2650     ierr = (*snes->ops->setup)(snes);CHKERRQ(ierr);
2651   }
2652 
2653   if (snes->pc && (snes->pcside == PC_LEFT)) {
2654     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
2655       ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2656       ierr = SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultPC);CHKERRQ(ierr);
2657     }
2658   }
2659 
2660   snes->setupcalled = PETSC_TRUE;
2661   PetscFunctionReturn(0);
2662 }
2663 
2664 #undef __FUNCT__
2665 #define __FUNCT__ "SNESReset"
2666 /*@
2667    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats
2668 
2669    Collective on SNES
2670 
2671    Input Parameter:
2672 .  snes - iterative context obtained from SNESCreate()
2673 
2674    Level: intermediate
2675 
2676    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()
2677 
2678 .keywords: SNES, destroy
2679 
2680 .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
2681 @*/
2682 PetscErrorCode  SNESReset(SNES snes)
2683 {
2684   PetscErrorCode ierr;
2685 
2686   PetscFunctionBegin;
2687   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2688   if (snes->ops->userdestroy && snes->user) {
2689     ierr       = (*snes->ops->userdestroy)((void**)&snes->user);CHKERRQ(ierr);
2690     snes->user = NULL;
2691   }
2692   if (snes->pc) {
2693     ierr = SNESReset(snes->pc);CHKERRQ(ierr);
2694   }
2695 
2696   if (snes->ops->reset) {
2697     ierr = (*snes->ops->reset)(snes);CHKERRQ(ierr);
2698   }
2699   if (snes->ksp) {
2700     ierr = KSPReset(snes->ksp);CHKERRQ(ierr);
2701   }
2702 
2703   if (snes->linesearch) {
2704     ierr = SNESLineSearchReset(snes->linesearch);CHKERRQ(ierr);
2705   }
2706 
2707   ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
2708   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
2709   ierr = VecDestroy(&snes->vec_sol_update);CHKERRQ(ierr);
2710   ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
2711   ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2712   ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2713   ierr = VecDestroyVecs(snes->nwork,&snes->work);CHKERRQ(ierr);
2714   ierr = VecDestroyVecs(snes->nvwork,&snes->vwork);CHKERRQ(ierr);
2715 
2716   snes->nwork       = snes->nvwork = 0;
2717   snes->setupcalled = PETSC_FALSE;
2718   PetscFunctionReturn(0);
2719 }
2720 
2721 #undef __FUNCT__
2722 #define __FUNCT__ "SNESDestroy"
2723 /*@
2724    SNESDestroy - Destroys the nonlinear solver context that was created
2725    with SNESCreate().
2726 
2727    Collective on SNES
2728 
2729    Input Parameter:
2730 .  snes - the SNES context
2731 
2732    Level: beginner
2733 
2734 .keywords: SNES, nonlinear, destroy
2735 
2736 .seealso: SNESCreate(), SNESSolve()
2737 @*/
2738 PetscErrorCode  SNESDestroy(SNES *snes)
2739 {
2740   PetscErrorCode ierr;
2741 
2742   PetscFunctionBegin;
2743   if (!*snes) PetscFunctionReturn(0);
2744   PetscValidHeaderSpecific((*snes),SNES_CLASSID,1);
2745   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; PetscFunctionReturn(0);}
2746 
2747   ierr = SNESReset((*snes));CHKERRQ(ierr);
2748   ierr = SNESDestroy(&(*snes)->pc);CHKERRQ(ierr);
2749 
2750   /* if memory was published with AMS then destroy it */
2751   ierr = PetscObjectAMSViewOff((PetscObject)*snes);CHKERRQ(ierr);
2752   if ((*snes)->ops->destroy) {ierr = (*((*snes))->ops->destroy)((*snes));CHKERRQ(ierr);}
2753 
2754   ierr = DMDestroy(&(*snes)->dm);CHKERRQ(ierr);
2755   ierr = KSPDestroy(&(*snes)->ksp);CHKERRQ(ierr);
2756   ierr = SNESLineSearchDestroy(&(*snes)->linesearch);CHKERRQ(ierr);
2757 
2758   ierr = PetscFree((*snes)->kspconvctx);CHKERRQ(ierr);
2759   if ((*snes)->ops->convergeddestroy) {
2760     ierr = (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);CHKERRQ(ierr);
2761   }
2762   if ((*snes)->conv_malloc) {
2763     ierr = PetscFree((*snes)->conv_hist);CHKERRQ(ierr);
2764     ierr = PetscFree((*snes)->conv_hist_its);CHKERRQ(ierr);
2765   }
2766   ierr = SNESMonitorCancel((*snes));CHKERRQ(ierr);
2767   ierr = PetscHeaderDestroy(snes);CHKERRQ(ierr);
2768   PetscFunctionReturn(0);
2769 }
2770 
2771 /* ----------- Routines to set solver parameters ---------- */
2772 
2773 #undef __FUNCT__
2774 #define __FUNCT__ "SNESSetLagPreconditioner"
2775 /*@
2776    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.
2777 
2778    Logically Collective on SNES
2779 
2780    Input Parameters:
2781 +  snes - the SNES context
2782 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2783          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2784 
2785    Options Database Keys:
2786 .    -snes_lag_preconditioner <lag>
2787 
2788    Notes:
2789    The default is 1
2790    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2791    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use
2792 
2793    Level: intermediate
2794 
2795 .keywords: SNES, nonlinear, set, convergence, tolerances
2796 
2797 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2798 
2799 @*/
2800 PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
2801 {
2802   PetscFunctionBegin;
2803   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2804   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2805   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2806   PetscValidLogicalCollectiveInt(snes,lag,2);
2807   snes->lagpreconditioner = lag;
2808   PetscFunctionReturn(0);
2809 }
2810 
2811 #undef __FUNCT__
2812 #define __FUNCT__ "SNESSetGridSequence"
2813 /*@
2814    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does
2815 
2816    Logically Collective on SNES
2817 
2818    Input Parameters:
2819 +  snes - the SNES context
2820 -  steps - the number of refinements to do, defaults to 0
2821 
2822    Options Database Keys:
2823 .    -snes_grid_sequence <steps>
2824 
2825    Level: intermediate
2826 
2827    Notes:
2828    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2829 
2830 .keywords: SNES, nonlinear, set, convergence, tolerances
2831 
2832 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2833 
2834 @*/
2835 PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
2836 {
2837   PetscFunctionBegin;
2838   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2839   PetscValidLogicalCollectiveInt(snes,steps,2);
2840   snes->gridsequence = steps;
2841   PetscFunctionReturn(0);
2842 }
2843 
2844 #undef __FUNCT__
2845 #define __FUNCT__ "SNESGetLagPreconditioner"
2846 /*@
2847    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt
2848 
2849    Not Collective
2850 
2851    Input Parameter:
2852 .  snes - the SNES context
2853 
2854    Output Parameter:
2855 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2856          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2857 
2858    Options Database Keys:
2859 .    -snes_lag_preconditioner <lag>
2860 
2861    Notes:
2862    The default is 1
2863    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2864 
2865    Level: intermediate
2866 
2867 .keywords: SNES, nonlinear, set, convergence, tolerances
2868 
2869 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()
2870 
2871 @*/
2872 PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
2873 {
2874   PetscFunctionBegin;
2875   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2876   *lag = snes->lagpreconditioner;
2877   PetscFunctionReturn(0);
2878 }
2879 
2880 #undef __FUNCT__
2881 #define __FUNCT__ "SNESSetLagJacobian"
2882 /*@
2883    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
2884      often the preconditioner is rebuilt.
2885 
2886    Logically Collective on SNES
2887 
2888    Input Parameters:
2889 +  snes - the SNES context
2890 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2891          the Jacobian is built etc. -2 means rebuild at next chance but then never again
2892 
2893    Options Database Keys:
2894 .    -snes_lag_jacobian <lag>
2895 
2896    Notes:
2897    The default is 1
2898    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2899    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
2900    at the next Newton step but never again (unless it is reset to another value)
2901 
2902    Level: intermediate
2903 
2904 .keywords: SNES, nonlinear, set, convergence, tolerances
2905 
2906 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()
2907 
2908 @*/
2909 PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
2910 {
2911   PetscFunctionBegin;
2912   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2913   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2914   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2915   PetscValidLogicalCollectiveInt(snes,lag,2);
2916   snes->lagjacobian = lag;
2917   PetscFunctionReturn(0);
2918 }
2919 
2920 #undef __FUNCT__
2921 #define __FUNCT__ "SNESGetLagJacobian"
2922 /*@
2923    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt
2924 
2925    Not Collective
2926 
2927    Input Parameter:
2928 .  snes - the SNES context
2929 
2930    Output Parameter:
2931 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2932          the Jacobian is built etc.
2933 
2934    Options Database Keys:
2935 .    -snes_lag_jacobian <lag>
2936 
2937    Notes:
2938    The default is 1
2939    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2940 
2941    Level: intermediate
2942 
2943 .keywords: SNES, nonlinear, set, convergence, tolerances
2944 
2945 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()
2946 
2947 @*/
2948 PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
2949 {
2950   PetscFunctionBegin;
2951   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2952   *lag = snes->lagjacobian;
2953   PetscFunctionReturn(0);
2954 }
2955 
2956 #undef __FUNCT__
2957 #define __FUNCT__ "SNESSetLagJacobianPersists"
2958 /*@
2959    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves
2960 
2961    Logically collective on SNES
2962 
2963    Input Parameter:
2964 +  snes - the SNES context
2965 -   flg - jacobian lagging persists if true
2966 
2967    Options Database Keys:
2968 .    -snes_lag_jacobian_persists <flg>
2969 
2970    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
2971    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
2972    timesteps may present huge efficiency gains.
2973 
2974    Level: developer
2975 
2976 .keywords: SNES, nonlinear, lag, NPC
2977 
2978 .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetPC()
2979 
2980 @*/
2981 PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
2982 {
2983   PetscFunctionBegin;
2984   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2985   PetscValidLogicalCollectiveBool(snes,flg,2);
2986   snes->lagjac_persist = flg;
2987   PetscFunctionReturn(0);
2988 }
2989 
2990 #undef __FUNCT__
2991 #define __FUNCT__ "SNESSetLagPreconditionerPersists"
2992 /*@
2993    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple solves
2994 
2995    Logically Collective on SNES
2996 
2997    Input Parameter:
2998 +  snes - the SNES context
2999 -   flg - preconditioner lagging persists if true
3000 
3001    Options Database Keys:
3002 .    -snes_lag_jacobian_persists <flg>
3003 
3004    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
3005    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
3006    several timesteps may present huge efficiency gains.
3007 
3008    Level: developer
3009 
3010 .keywords: SNES, nonlinear, lag, NPC
3011 
3012 .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetPC()
3013 
3014 @*/
3015 PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
3016 {
3017   PetscFunctionBegin;
3018   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3019   PetscValidLogicalCollectiveBool(snes,flg,2);
3020   snes->lagpre_persist = flg;
3021   PetscFunctionReturn(0);
3022 }
3023 
3024 #undef __FUNCT__
3025 #define __FUNCT__ "SNESSetTolerances"
3026 /*@
3027    SNESSetTolerances - Sets various parameters used in convergence tests.
3028 
3029    Logically Collective on SNES
3030 
3031    Input Parameters:
3032 +  snes - the SNES context
3033 .  abstol - absolute convergence tolerance
3034 .  rtol - relative convergence tolerance
3035 .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
3036 .  maxit - maximum number of iterations
3037 -  maxf - maximum number of function evaluations
3038 
3039    Options Database Keys:
3040 +    -snes_atol <abstol> - Sets abstol
3041 .    -snes_rtol <rtol> - Sets rtol
3042 .    -snes_stol <stol> - Sets stol
3043 .    -snes_max_it <maxit> - Sets maxit
3044 -    -snes_max_funcs <maxf> - Sets maxf
3045 
3046    Notes:
3047    The default maximum number of iterations is 50.
3048    The default maximum number of function evaluations is 1000.
3049 
3050    Level: intermediate
3051 
3052 .keywords: SNES, nonlinear, set, convergence, tolerances
3053 
3054 .seealso: SNESSetTrustRegionTolerance()
3055 @*/
3056 PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
3057 {
3058   PetscFunctionBegin;
3059   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3060   PetscValidLogicalCollectiveReal(snes,abstol,2);
3061   PetscValidLogicalCollectiveReal(snes,rtol,3);
3062   PetscValidLogicalCollectiveReal(snes,stol,4);
3063   PetscValidLogicalCollectiveInt(snes,maxit,5);
3064   PetscValidLogicalCollectiveInt(snes,maxf,6);
3065 
3066   if (abstol != PETSC_DEFAULT) {
3067     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %G must be non-negative",abstol);
3068     snes->abstol = abstol;
3069   }
3070   if (rtol != PETSC_DEFAULT) {
3071     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",rtol);
3072     snes->rtol = rtol;
3073   }
3074   if (stol != PETSC_DEFAULT) {
3075     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %G must be non-negative",stol);
3076     snes->stol = stol;
3077   }
3078   if (maxit != PETSC_DEFAULT) {
3079     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
3080     snes->max_its = maxit;
3081   }
3082   if (maxf != PETSC_DEFAULT) {
3083     if (maxf < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
3084     snes->max_funcs = maxf;
3085   }
3086   snes->tolerancesset = PETSC_TRUE;
3087   PetscFunctionReturn(0);
3088 }
3089 
3090 #undef __FUNCT__
3091 #define __FUNCT__ "SNESGetTolerances"
3092 /*@
3093    SNESGetTolerances - Gets various parameters used in convergence tests.
3094 
3095    Not Collective
3096 
3097    Input Parameters:
3098 +  snes - the SNES context
3099 .  atol - absolute convergence tolerance
3100 .  rtol - relative convergence tolerance
3101 .  stol -  convergence tolerance in terms of the norm
3102            of the change in the solution between steps
3103 .  maxit - maximum number of iterations
3104 -  maxf - maximum number of function evaluations
3105 
3106    Notes:
3107    The user can specify NULL for any parameter that is not needed.
3108 
3109    Level: intermediate
3110 
3111 .keywords: SNES, nonlinear, get, convergence, tolerances
3112 
3113 .seealso: SNESSetTolerances()
3114 @*/
3115 PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3116 {
3117   PetscFunctionBegin;
3118   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3119   if (atol)  *atol  = snes->abstol;
3120   if (rtol)  *rtol  = snes->rtol;
3121   if (stol)  *stol  = snes->stol;
3122   if (maxit) *maxit = snes->max_its;
3123   if (maxf)  *maxf  = snes->max_funcs;
3124   PetscFunctionReturn(0);
3125 }
3126 
3127 #undef __FUNCT__
3128 #define __FUNCT__ "SNESSetTrustRegionTolerance"
3129 /*@
3130    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.
3131 
3132    Logically Collective on SNES
3133 
3134    Input Parameters:
3135 +  snes - the SNES context
3136 -  tol - tolerance
3137 
3138    Options Database Key:
3139 .  -snes_trtol <tol> - Sets tol
3140 
3141    Level: intermediate
3142 
3143 .keywords: SNES, nonlinear, set, trust region, tolerance
3144 
3145 .seealso: SNESSetTolerances()
3146 @*/
3147 PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3148 {
3149   PetscFunctionBegin;
3150   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3151   PetscValidLogicalCollectiveReal(snes,tol,2);
3152   snes->deltatol = tol;
3153   PetscFunctionReturn(0);
3154 }
3155 
3156 /*
3157    Duplicate the lg monitors for SNES from KSP; for some reason with
3158    dynamic libraries things don't work under Sun4 if we just use
3159    macros instead of functions
3160 */
3161 #undef __FUNCT__
3162 #define __FUNCT__ "SNESMonitorLGResidualNorm"
3163 PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,void *ctx)
3164 {
3165   PetscErrorCode ierr;
3166 
3167   PetscFunctionBegin;
3168   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3169   ierr = KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);CHKERRQ(ierr);
3170   PetscFunctionReturn(0);
3171 }
3172 
3173 #undef __FUNCT__
3174 #define __FUNCT__ "SNESMonitorLGCreate"
3175 PetscErrorCode  SNESMonitorLGCreate(const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *draw)
3176 {
3177   PetscErrorCode ierr;
3178 
3179   PetscFunctionBegin;
3180   ierr = KSPMonitorLGResidualNormCreate(host,label,x,y,m,n,draw);CHKERRQ(ierr);
3181   PetscFunctionReturn(0);
3182 }
3183 
3184 #undef __FUNCT__
3185 #define __FUNCT__ "SNESMonitorLGDestroy"
3186 PetscErrorCode  SNESMonitorLGDestroy(PetscDrawLG *draw)
3187 {
3188   PetscErrorCode ierr;
3189 
3190   PetscFunctionBegin;
3191   ierr = KSPMonitorLGResidualNormDestroy(draw);CHKERRQ(ierr);
3192   PetscFunctionReturn(0);
3193 }
3194 
3195 extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
3196 #undef __FUNCT__
3197 #define __FUNCT__ "SNESMonitorLGRange"
3198 PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3199 {
3200   PetscDrawLG      lg;
3201   PetscErrorCode   ierr;
3202   PetscReal        x,y,per;
3203   PetscViewer      v = (PetscViewer)monctx;
3204   static PetscReal prev; /* should be in the context */
3205   PetscDraw        draw;
3206 
3207   PetscFunctionBegin;
3208   ierr = PetscViewerDrawGetDrawLG(v,0,&lg);CHKERRQ(ierr);
3209   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3210   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3211   ierr = PetscDrawSetTitle(draw,"Residual norm");CHKERRQ(ierr);
3212   x    = (PetscReal)n;
3213   if (rnorm > 0.0) y = log10(rnorm);
3214   else y = -15.0;
3215   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3216   if (n < 20 || !(n % 5)) {
3217     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3218   }
3219 
3220   ierr = PetscViewerDrawGetDrawLG(v,1,&lg);CHKERRQ(ierr);
3221   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3222   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3223   ierr = PetscDrawSetTitle(draw,"% elemts > .2*max elemt");CHKERRQ(ierr);
3224   ierr =  SNESMonitorRange_Private(snes,n,&per);CHKERRQ(ierr);
3225   x    = (PetscReal)n;
3226   y    = 100.0*per;
3227   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3228   if (n < 20 || !(n % 5)) {
3229     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3230   }
3231 
3232   ierr = PetscViewerDrawGetDrawLG(v,2,&lg);CHKERRQ(ierr);
3233   if (!n) {prev = rnorm;ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3234   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3235   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");CHKERRQ(ierr);
3236   x    = (PetscReal)n;
3237   y    = (prev - rnorm)/prev;
3238   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3239   if (n < 20 || !(n % 5)) {
3240     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3241   }
3242 
3243   ierr = PetscViewerDrawGetDrawLG(v,3,&lg);CHKERRQ(ierr);
3244   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3245   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3246   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");CHKERRQ(ierr);
3247   x    = (PetscReal)n;
3248   y    = (prev - rnorm)/(prev*per);
3249   if (n > 2) { /*skip initial crazy value */
3250     ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3251   }
3252   if (n < 20 || !(n % 5)) {
3253     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3254   }
3255   prev = rnorm;
3256   PetscFunctionReturn(0);
3257 }
3258 
3259 #undef __FUNCT__
3260 #define __FUNCT__ "SNESMonitor"
3261 /*@
3262    SNESMonitor - runs the user provided monitor routines, if they exist
3263 
3264    Collective on SNES
3265 
3266    Input Parameters:
3267 +  snes - nonlinear solver context obtained from SNESCreate()
3268 .  iter - iteration number
3269 -  rnorm - relative norm of the residual
3270 
3271    Notes:
3272    This routine is called by the SNES implementations.
3273    It does not typically need to be called by the user.
3274 
3275    Level: developer
3276 
3277 .seealso: SNESMonitorSet()
3278 @*/
3279 PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3280 {
3281   PetscErrorCode ierr;
3282   PetscInt       i,n = snes->numbermonitors;
3283 
3284   PetscFunctionBegin;
3285   for (i=0; i<n; i++) {
3286     ierr = (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);CHKERRQ(ierr);
3287   }
3288   PetscFunctionReturn(0);
3289 }
3290 
3291 /* ------------ Routines to set performance monitoring options ----------- */
3292 
3293 /*MC
3294     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver
3295 
3296      Synopsis:
3297      #include "petscsnes.h"
3298 $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)
3299 
3300 +    snes - the SNES context
3301 .    its - iteration number
3302 .    norm - 2-norm function value (may be estimated)
3303 -    mctx - [optional] monitoring context
3304 
3305    Level: advanced
3306 
3307 .seealso:   SNESMonitorSet(), SNESMonitorGet()
3308 M*/
3309 
3310 #undef __FUNCT__
3311 #define __FUNCT__ "SNESMonitorSet"
3312 /*@C
3313    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3314    iteration of the nonlinear solver to display the iteration's
3315    progress.
3316 
3317    Logically Collective on SNES
3318 
3319    Input Parameters:
3320 +  snes - the SNES context
3321 .  SNESMonitorFunction - monitoring routine
3322 .  mctx - [optional] user-defined context for private data for the
3323           monitor routine (use NULL if no context is desired)
3324 -  monitordestroy - [optional] routine that frees monitor context
3325           (may be NULL)
3326 
3327    Options Database Keys:
3328 +    -snes_monitor        - sets SNESMonitorDefault()
3329 .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3330                             uses SNESMonitorLGCreate()
3331 -    -snes_monitor_cancel - cancels all monitors that have
3332                             been hardwired into a code by
3333                             calls to SNESMonitorSet(), but
3334                             does not cancel those set via
3335                             the options database.
3336 
3337    Notes:
3338    Several different monitoring routines may be set by calling
3339    SNESMonitorSet() multiple times; all will be called in the
3340    order in which they were set.
3341 
3342    Fortran notes: Only a single monitor function can be set for each SNES object
3343 
3344    Level: intermediate
3345 
3346 .keywords: SNES, nonlinear, set, monitor
3347 
3348 .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
3349 @*/
3350 PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*SNESMonitorFunction)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3351 {
3352   PetscInt       i;
3353   PetscErrorCode ierr;
3354 
3355   PetscFunctionBegin;
3356   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3357   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3358   for (i=0; i<snes->numbermonitors;i++) {
3359     if (SNESMonitorFunction == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
3360       if (monitordestroy) {
3361         ierr = (*monitordestroy)(&mctx);CHKERRQ(ierr);
3362       }
3363       PetscFunctionReturn(0);
3364     }
3365   }
3366   snes->monitor[snes->numbermonitors]          = SNESMonitorFunction;
3367   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
3368   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
3369   PetscFunctionReturn(0);
3370 }
3371 
3372 #undef __FUNCT__
3373 #define __FUNCT__ "SNESMonitorCancel"
3374 /*@
3375    SNESMonitorCancel - Clears all the monitor functions for a SNES object.
3376 
3377    Logically Collective on SNES
3378 
3379    Input Parameters:
3380 .  snes - the SNES context
3381 
3382    Options Database Key:
3383 .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3384     into a code by calls to SNESMonitorSet(), but does not cancel those
3385     set via the options database
3386 
3387    Notes:
3388    There is no way to clear one specific monitor from a SNES object.
3389 
3390    Level: intermediate
3391 
3392 .keywords: SNES, nonlinear, set, monitor
3393 
3394 .seealso: SNESMonitorDefault(), SNESMonitorSet()
3395 @*/
3396 PetscErrorCode  SNESMonitorCancel(SNES snes)
3397 {
3398   PetscErrorCode ierr;
3399   PetscInt       i;
3400 
3401   PetscFunctionBegin;
3402   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3403   for (i=0; i<snes->numbermonitors; i++) {
3404     if (snes->monitordestroy[i]) {
3405       ierr = (*snes->monitordestroy[i])(&snes->monitorcontext[i]);CHKERRQ(ierr);
3406     }
3407   }
3408   snes->numbermonitors = 0;
3409   PetscFunctionReturn(0);
3410 }
3411 
3412 /*MC
3413     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver
3414 
3415      Synopsis:
3416      #include "petscsnes.h"
3417 $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)
3418 
3419 +    snes - the SNES context
3420 .    it - current iteration (0 is the first and is before any Newton step)
3421 .    cctx - [optional] convergence context
3422 .    reason - reason for convergence/divergence
3423 .    xnorm - 2-norm of current iterate
3424 .    gnorm - 2-norm of current step
3425 -    f - 2-norm of function
3426 
3427    Level: intermediate
3428 
3429 .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
3430 M*/
3431 
3432 #undef __FUNCT__
3433 #define __FUNCT__ "SNESSetConvergenceTest"
3434 /*@C
3435    SNESSetConvergenceTest - Sets the function that is to be used
3436    to test for convergence of the nonlinear iterative solution.
3437 
3438    Logically Collective on SNES
3439 
3440    Input Parameters:
3441 +  snes - the SNES context
3442 .  SNESConvergenceTestFunction - routine to test for convergence
3443 .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
3444 -  destroy - [optional] destructor for the context (may be NULL; NULL_FUNCTION in Fortran)
3445 
3446    Level: advanced
3447 
3448 .keywords: SNES, nonlinear, set, convergence, test
3449 
3450 .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
3451 @*/
3452 PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
3453 {
3454   PetscErrorCode ierr;
3455 
3456   PetscFunctionBegin;
3457   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3458   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
3459   if (snes->ops->convergeddestroy) {
3460     ierr = (*snes->ops->convergeddestroy)(snes->cnvP);CHKERRQ(ierr);
3461   }
3462   snes->ops->converged        = SNESConvergenceTestFunction;
3463   snes->ops->convergeddestroy = destroy;
3464   snes->cnvP                  = cctx;
3465   PetscFunctionReturn(0);
3466 }
3467 
3468 #undef __FUNCT__
3469 #define __FUNCT__ "SNESGetConvergedReason"
3470 /*@
3471    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.
3472 
3473    Not Collective
3474 
3475    Input Parameter:
3476 .  snes - the SNES context
3477 
3478    Output Parameter:
3479 .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3480             manual pages for the individual convergence tests for complete lists
3481 
3482    Level: intermediate
3483 
3484    Notes: Can only be called after the call the SNESSolve() is complete.
3485 
3486 .keywords: SNES, nonlinear, set, convergence, test
3487 
3488 .seealso: SNESSetConvergenceTest(), SNESConvergedReason
3489 @*/
3490 PetscErrorCode  SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
3491 {
3492   PetscFunctionBegin;
3493   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3494   PetscValidPointer(reason,2);
3495   *reason = snes->reason;
3496   PetscFunctionReturn(0);
3497 }
3498 
3499 #undef __FUNCT__
3500 #define __FUNCT__ "SNESSetConvergenceHistory"
3501 /*@
3502    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.
3503 
3504    Logically Collective on SNES
3505 
3506    Input Parameters:
3507 +  snes - iterative context obtained from SNESCreate()
3508 .  a   - array to hold history, this array will contain the function norms computed at each step
3509 .  its - integer array holds the number of linear iterations for each solve.
3510 .  na  - size of a and its
3511 -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
3512            else it continues storing new values for new nonlinear solves after the old ones
3513 
3514    Notes:
3515    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
3516    default array of length 10000 is allocated.
3517 
3518    This routine is useful, e.g., when running a code for purposes
3519    of accurate performance monitoring, when no I/O should be done
3520    during the section of code that is being timed.
3521 
3522    Level: intermediate
3523 
3524 .keywords: SNES, set, convergence, history
3525 
3526 .seealso: SNESGetConvergenceHistory()
3527 
3528 @*/
3529 PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
3530 {
3531   PetscErrorCode ierr;
3532 
3533   PetscFunctionBegin;
3534   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3535   if (a) PetscValidScalarPointer(a,2);
3536   if (its) PetscValidIntPointer(its,3);
3537   if (!a) {
3538     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
3539     ierr = PetscMalloc(na*sizeof(PetscReal),&a);CHKERRQ(ierr);
3540     ierr = PetscMalloc(na*sizeof(PetscInt),&its);CHKERRQ(ierr);
3541 
3542     snes->conv_malloc = PETSC_TRUE;
3543   }
3544   snes->conv_hist       = a;
3545   snes->conv_hist_its   = its;
3546   snes->conv_hist_max   = na;
3547   snes->conv_hist_len   = 0;
3548   snes->conv_hist_reset = reset;
3549   PetscFunctionReturn(0);
3550 }
3551 
3552 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3553 #include <engine.h>   /* MATLAB include file */
3554 #include <mex.h>      /* MATLAB include file */
3555 
3556 #undef __FUNCT__
3557 #define __FUNCT__ "SNESGetConvergenceHistoryMatlab"
3558 PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
3559 {
3560   mxArray   *mat;
3561   PetscInt  i;
3562   PetscReal *ar;
3563 
3564   PetscFunctionBegin;
3565   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
3566   ar  = (PetscReal*) mxGetData(mat);
3567   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
3568   PetscFunctionReturn(mat);
3569 }
3570 #endif
3571 
3572 #undef __FUNCT__
3573 #define __FUNCT__ "SNESGetConvergenceHistory"
3574 /*@C
3575    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.
3576 
3577    Not Collective
3578 
3579    Input Parameter:
3580 .  snes - iterative context obtained from SNESCreate()
3581 
3582    Output Parameters:
3583 .  a   - array to hold history
3584 .  its - integer array holds the number of linear iterations (or
3585          negative if not converged) for each solve.
3586 -  na  - size of a and its
3587 
3588    Notes:
3589     The calling sequence for this routine in Fortran is
3590 $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
3591 
3592    This routine is useful, e.g., when running a code for purposes
3593    of accurate performance monitoring, when no I/O should be done
3594    during the section of code that is being timed.
3595 
3596    Level: intermediate
3597 
3598 .keywords: SNES, get, convergence, history
3599 
3600 .seealso: SNESSetConvergencHistory()
3601 
3602 @*/
3603 PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
3604 {
3605   PetscFunctionBegin;
3606   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3607   if (a)   *a   = snes->conv_hist;
3608   if (its) *its = snes->conv_hist_its;
3609   if (na)  *na  = snes->conv_hist_len;
3610   PetscFunctionReturn(0);
3611 }
3612 
3613 #undef __FUNCT__
3614 #define __FUNCT__ "SNESSetUpdate"
3615 /*@C
3616   SNESSetUpdate - Sets the general-purpose update function called
3617   at the beginning of every iteration of the nonlinear solve. Specifically
3618   it is called just before the Jacobian is "evaluated".
3619 
3620   Logically Collective on SNES
3621 
3622   Input Parameters:
3623 . snes - The nonlinear solver context
3624 . func - The function
3625 
3626   Calling sequence of func:
3627 . func (SNES snes, PetscInt step);
3628 
3629 . step - The current step of the iteration
3630 
3631   Level: advanced
3632 
3633   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()
3634         This is not used by most users.
3635 
3636 .keywords: SNES, update
3637 
3638 .seealso SNESSetJacobian(), SNESSolve()
3639 @*/
3640 PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
3641 {
3642   PetscFunctionBegin;
3643   PetscValidHeaderSpecific(snes, SNES_CLASSID,1);
3644   snes->ops->update = func;
3645   PetscFunctionReturn(0);
3646 }
3647 
3648 #undef __FUNCT__
3649 #define __FUNCT__ "SNESScaleStep_Private"
3650 /*
3651    SNESScaleStep_Private - Scales a step so that its length is less than the
3652    positive parameter delta.
3653 
3654     Input Parameters:
3655 +   snes - the SNES context
3656 .   y - approximate solution of linear system
3657 .   fnorm - 2-norm of current function
3658 -   delta - trust region size
3659 
3660     Output Parameters:
3661 +   gpnorm - predicted function norm at the new point, assuming local
3662     linearization.  The value is zero if the step lies within the trust
3663     region, and exceeds zero otherwise.
3664 -   ynorm - 2-norm of the step
3665 
3666     Note:
3667     For non-trust region methods such as SNESNEWTONLS, the parameter delta
3668     is set to be the maximum allowable step size.
3669 
3670 .keywords: SNES, nonlinear, scale, step
3671 */
3672 PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
3673 {
3674   PetscReal      nrm;
3675   PetscScalar    cnorm;
3676   PetscErrorCode ierr;
3677 
3678   PetscFunctionBegin;
3679   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3680   PetscValidHeaderSpecific(y,VEC_CLASSID,2);
3681   PetscCheckSameComm(snes,1,y,2);
3682 
3683   ierr = VecNorm(y,NORM_2,&nrm);CHKERRQ(ierr);
3684   if (nrm > *delta) {
3685     nrm     = *delta/nrm;
3686     *gpnorm = (1.0 - nrm)*(*fnorm);
3687     cnorm   = nrm;
3688     ierr    = VecScale(y,cnorm);CHKERRQ(ierr);
3689     *ynorm  = *delta;
3690   } else {
3691     *gpnorm = 0.0;
3692     *ynorm  = nrm;
3693   }
3694   PetscFunctionReturn(0);
3695 }
3696 
3697 #undef __FUNCT__
3698 #define __FUNCT__ "SNESSolve"
3699 /*@C
3700    SNESSolve - Solves a nonlinear system F(x) = b.
3701    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3702 
3703    Collective on SNES
3704 
3705    Input Parameters:
3706 +  snes - the SNES context
3707 .  b - the constant part of the equation F(x) = b, or NULL to use zero.
3708 -  x - the solution vector.
3709 
3710    Notes:
3711    The user should initialize the vector,x, with the initial guess
3712    for the nonlinear solve prior to calling SNESSolve.  In particular,
3713    to employ an initial guess of zero, the user should explicitly set
3714    this vector to zero by calling VecSet().
3715 
3716    Level: beginner
3717 
3718 .keywords: SNES, nonlinear, solve
3719 
3720 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3721 @*/
3722 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3723 {
3724   PetscErrorCode    ierr;
3725   PetscBool         flg;
3726   PetscViewer       viewer;
3727   PetscInt          grid;
3728   Vec               xcreated = NULL;
3729   DM                dm;
3730   PetscViewerFormat format;
3731 
3732   PetscFunctionBegin;
3733   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3734   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3735   if (x) PetscCheckSameComm(snes,1,x,3);
3736   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3737   if (b) PetscCheckSameComm(snes,1,b,2);
3738 
3739   if (!x) {
3740     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3741     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3742     x    = xcreated;
3743   }
3744 
3745   ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_view_pre",&viewer,&format,&flg);CHKERRQ(ierr);
3746   if (flg && !PetscPreLoadingOn) {
3747     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
3748     ierr = SNESView(snes,viewer);CHKERRQ(ierr);
3749     ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
3750     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3751   }
3752 
3753   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);}
3754   for (grid=0; grid<snes->gridsequence+1; grid++) {
3755 
3756     /* set solution vector */
3757     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3758     ierr          = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3759     snes->vec_sol = x;
3760     ierr          = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3761 
3762     /* set affine vector if provided */
3763     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3764     ierr          = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3765     snes->vec_rhs = b;
3766 
3767     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
3768     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
3769     if (!snes->vec_sol_update /* && snes->vec_sol */) {
3770       ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
3771       ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);CHKERRQ(ierr);
3772     }
3773     ierr = DMShellSetGlobalVector(dm,snes->vec_sol);CHKERRQ(ierr);
3774     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3775 
3776     if (!grid) {
3777       if (snes->ops->computeinitialguess) {
3778         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3779       }
3780     }
3781 
3782     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3783     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}
3784 
3785     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3786     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3787     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3788     if (snes->domainerror) {
3789       snes->reason      = SNES_DIVERGED_FUNCTION_DOMAIN;
3790       snes->domainerror = PETSC_FALSE;
3791     }
3792     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3793 
3794     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
3795     if (snes->lagpre_persist) snes->pre_iter += snes->iter;
3796 
3797     flg  = PETSC_FALSE;
3798     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,NULL);CHKERRQ(ierr);
3799     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
3800     if (snes->printreason) {
3801       ierr = PetscViewerASCIIAddTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3802       if (snes->reason > 0) {
3803         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3804       } else {
3805         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3806       }
3807       ierr = PetscViewerASCIISubtractTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3808     }
3809 
3810     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
3811     if (grid <  snes->gridsequence) {
3812       DM  fine;
3813       Vec xnew;
3814       Mat interp;
3815 
3816       ierr = DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);CHKERRQ(ierr);
3817       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
3818       ierr = DMCreateInterpolation(snes->dm,fine,&interp,NULL);CHKERRQ(ierr);
3819       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
3820       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
3821       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
3822       ierr = MatDestroy(&interp);CHKERRQ(ierr);
3823       x    = xnew;
3824 
3825       ierr = SNESReset(snes);CHKERRQ(ierr);
3826       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
3827       ierr = DMDestroy(&fine);CHKERRQ(ierr);
3828       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);
3829     }
3830   }
3831   /* monitoring and viewing */
3832   ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_view",&viewer,&format,&flg);CHKERRQ(ierr);
3833   if (flg && !PetscPreLoadingOn) {
3834     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
3835     ierr = SNESView(snes,viewer);CHKERRQ(ierr);
3836     ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
3837     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3838   }
3839   ierr = VecViewFromOptions(snes->vec_sol,((PetscObject)snes)->prefix,"-snes_view_solution");CHKERRQ(ierr);
3840 
3841   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
3842   ierr = PetscObjectAMSBlock((PetscObject)snes);CHKERRQ(ierr);
3843   PetscFunctionReturn(0);
3844 }
3845 
3846 /* --------- Internal routines for SNES Package --------- */
3847 
3848 #undef __FUNCT__
3849 #define __FUNCT__ "SNESSetType"
3850 /*@C
3851    SNESSetType - Sets the method for the nonlinear solver.
3852 
3853    Collective on SNES
3854 
3855    Input Parameters:
3856 +  snes - the SNES context
3857 -  type - a known method
3858 
3859    Options Database Key:
3860 .  -snes_type <type> - Sets the method; use -help for a list
3861    of available methods (for instance, newtonls or newtontr)
3862 
3863    Notes:
3864    See "petsc/include/petscsnes.h" for available methods (for instance)
3865 +    SNESNEWTONLS - Newton's method with line search
3866      (systems of nonlinear equations)
3867 .    SNESNEWTONTR - Newton's method with trust region
3868      (systems of nonlinear equations)
3869 
3870   Normally, it is best to use the SNESSetFromOptions() command and then
3871   set the SNES solver type from the options database rather than by using
3872   this routine.  Using the options database provides the user with
3873   maximum flexibility in evaluating the many nonlinear solvers.
3874   The SNESSetType() routine is provided for those situations where it
3875   is necessary to set the nonlinear solver independently of the command
3876   line or options database.  This might be the case, for example, when
3877   the choice of solver changes during the execution of the program,
3878   and the user's application is taking responsibility for choosing the
3879   appropriate method.
3880 
3881     Developer Notes: SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
3882     the constructor in that list and calls it to create the spexific object.
3883 
3884   Level: intermediate
3885 
3886 .keywords: SNES, set, type
3887 
3888 .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()
3889 
3890 @*/
3891 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
3892 {
3893   PetscErrorCode ierr,(*r)(SNES);
3894   PetscBool      match;
3895 
3896   PetscFunctionBegin;
3897   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3898   PetscValidCharPointer(type,2);
3899 
3900   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
3901   if (match) PetscFunctionReturn(0);
3902 
3903   ierr =  PetscFunctionListFind(SNESList,type,&r);CHKERRQ(ierr);
3904   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
3905   /* Destroy the previous private SNES context */
3906   if (snes->ops->destroy) {
3907     ierr               = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
3908     snes->ops->destroy = NULL;
3909   }
3910   /* Reinitialize function pointers in SNESOps structure */
3911   snes->ops->setup          = 0;
3912   snes->ops->solve          = 0;
3913   snes->ops->view           = 0;
3914   snes->ops->setfromoptions = 0;
3915   snes->ops->destroy        = 0;
3916   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
3917   snes->setupcalled = PETSC_FALSE;
3918 
3919   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
3920   ierr = (*r)(snes);CHKERRQ(ierr);
3921   PetscFunctionReturn(0);
3922 }
3923 
3924 #undef __FUNCT__
3925 #define __FUNCT__ "SNESGetType"
3926 /*@C
3927    SNESGetType - Gets the SNES method type and name (as a string).
3928 
3929    Not Collective
3930 
3931    Input Parameter:
3932 .  snes - nonlinear solver context
3933 
3934    Output Parameter:
3935 .  type - SNES method (a character string)
3936 
3937    Level: intermediate
3938 
3939 .keywords: SNES, nonlinear, get, type, name
3940 @*/
3941 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
3942 {
3943   PetscFunctionBegin;
3944   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3945   PetscValidPointer(type,2);
3946   *type = ((PetscObject)snes)->type_name;
3947   PetscFunctionReturn(0);
3948 }
3949 
3950 #undef __FUNCT__
3951 #define __FUNCT__ "SNESGetSolution"
3952 /*@
3953    SNESGetSolution - Returns the vector where the approximate solution is
3954    stored. This is the fine grid solution when using SNESSetGridSequence().
3955 
3956    Not Collective, but Vec is parallel if SNES is parallel
3957 
3958    Input Parameter:
3959 .  snes - the SNES context
3960 
3961    Output Parameter:
3962 .  x - the solution
3963 
3964    Level: intermediate
3965 
3966 .keywords: SNES, nonlinear, get, solution
3967 
3968 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
3969 @*/
3970 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
3971 {
3972   PetscFunctionBegin;
3973   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3974   PetscValidPointer(x,2);
3975   *x = snes->vec_sol;
3976   PetscFunctionReturn(0);
3977 }
3978 
3979 #undef __FUNCT__
3980 #define __FUNCT__ "SNESGetSolutionUpdate"
3981 /*@
3982    SNESGetSolutionUpdate - Returns the vector where the solution update is
3983    stored.
3984 
3985    Not Collective, but Vec is parallel if SNES is parallel
3986 
3987    Input Parameter:
3988 .  snes - the SNES context
3989 
3990    Output Parameter:
3991 .  x - the solution update
3992 
3993    Level: advanced
3994 
3995 .keywords: SNES, nonlinear, get, solution, update
3996 
3997 .seealso: SNESGetSolution(), SNESGetFunction()
3998 @*/
3999 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
4000 {
4001   PetscFunctionBegin;
4002   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4003   PetscValidPointer(x,2);
4004   *x = snes->vec_sol_update;
4005   PetscFunctionReturn(0);
4006 }
4007 
4008 #undef __FUNCT__
4009 #define __FUNCT__ "SNESGetFunction"
4010 /*@C
4011    SNESGetFunction - Returns the vector where the function is stored.
4012 
4013    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
4014 
4015    Input Parameter:
4016 .  snes - the SNES context
4017 
4018    Output Parameter:
4019 +  r - the vector that is used to store residuals (or NULL if you don't want it)
4020 .  SNESFunction- the function (or NULL if you don't want it)
4021 -  ctx - the function context (or NULL if you don't want it)
4022 
4023    Level: advanced
4024 
4025 .keywords: SNES, nonlinear, get, function
4026 
4027 .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
4028 @*/
4029 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**SNESFunction)(SNES,Vec,Vec,void*),void **ctx)
4030 {
4031   PetscErrorCode ierr;
4032   DM             dm;
4033 
4034   PetscFunctionBegin;
4035   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4036   if (r) {
4037     if (!snes->vec_func) {
4038       if (snes->vec_rhs) {
4039         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
4040       } else if (snes->vec_sol) {
4041         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
4042       } else if (snes->dm) {
4043         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
4044       }
4045     }
4046     *r = snes->vec_func;
4047   }
4048   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4049   ierr = DMSNESGetFunction(dm,SNESFunction,ctx);CHKERRQ(ierr);
4050   PetscFunctionReturn(0);
4051 }
4052 
4053 /*@C
4054    SNESGetGS - Returns the GS function and context.
4055 
4056    Input Parameter:
4057 .  snes - the SNES context
4058 
4059    Output Parameter:
4060 +  SNESGSFunction - the function (or NULL)
4061 -  ctx    - the function context (or NULL)
4062 
4063    Level: advanced
4064 
4065 .keywords: SNES, nonlinear, get, function
4066 
4067 .seealso: SNESSetGS(), SNESGetFunction()
4068 @*/
4069 
4070 #undef __FUNCT__
4071 #define __FUNCT__ "SNESGetGS"
4072 PetscErrorCode SNESGetGS (SNES snes, PetscErrorCode (**SNESGSFunction)(SNES, Vec, Vec, void*), void ** ctx)
4073 {
4074   PetscErrorCode ierr;
4075   DM             dm;
4076 
4077   PetscFunctionBegin;
4078   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4079   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4080   ierr = DMSNESGetGS(dm,SNESGSFunction,ctx);CHKERRQ(ierr);
4081   PetscFunctionReturn(0);
4082 }
4083 
4084 #undef __FUNCT__
4085 #define __FUNCT__ "SNESSetOptionsPrefix"
4086 /*@C
4087    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4088    SNES options in the database.
4089 
4090    Logically Collective on SNES
4091 
4092    Input Parameter:
4093 +  snes - the SNES context
4094 -  prefix - the prefix to prepend to all option names
4095 
4096    Notes:
4097    A hyphen (-) must NOT be given at the beginning of the prefix name.
4098    The first character of all runtime options is AUTOMATICALLY the hyphen.
4099 
4100    Level: advanced
4101 
4102 .keywords: SNES, set, options, prefix, database
4103 
4104 .seealso: SNESSetFromOptions()
4105 @*/
4106 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4107 {
4108   PetscErrorCode ierr;
4109 
4110   PetscFunctionBegin;
4111   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4112   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4113   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4114   if (snes->linesearch) {
4115     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4116     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4117   }
4118   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4119   PetscFunctionReturn(0);
4120 }
4121 
4122 #undef __FUNCT__
4123 #define __FUNCT__ "SNESAppendOptionsPrefix"
4124 /*@C
4125    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4126    SNES options in the database.
4127 
4128    Logically Collective on SNES
4129 
4130    Input Parameters:
4131 +  snes - the SNES context
4132 -  prefix - the prefix to prepend to all option names
4133 
4134    Notes:
4135    A hyphen (-) must NOT be given at the beginning of the prefix name.
4136    The first character of all runtime options is AUTOMATICALLY the hyphen.
4137 
4138    Level: advanced
4139 
4140 .keywords: SNES, append, options, prefix, database
4141 
4142 .seealso: SNESGetOptionsPrefix()
4143 @*/
4144 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4145 {
4146   PetscErrorCode ierr;
4147 
4148   PetscFunctionBegin;
4149   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4150   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4151   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4152   if (snes->linesearch) {
4153     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4154     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4155   }
4156   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4157   PetscFunctionReturn(0);
4158 }
4159 
4160 #undef __FUNCT__
4161 #define __FUNCT__ "SNESGetOptionsPrefix"
4162 /*@C
4163    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4164    SNES options in the database.
4165 
4166    Not Collective
4167 
4168    Input Parameter:
4169 .  snes - the SNES context
4170 
4171    Output Parameter:
4172 .  prefix - pointer to the prefix string used
4173 
4174    Notes: On the fortran side, the user should pass in a string 'prefix' of
4175    sufficient length to hold the prefix.
4176 
4177    Level: advanced
4178 
4179 .keywords: SNES, get, options, prefix, database
4180 
4181 .seealso: SNESAppendOptionsPrefix()
4182 @*/
4183 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4184 {
4185   PetscErrorCode ierr;
4186 
4187   PetscFunctionBegin;
4188   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4189   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4190   PetscFunctionReturn(0);
4191 }
4192 
4193 
4194 #undef __FUNCT__
4195 #define __FUNCT__ "SNESRegister"
4196 /*@C
4197   SNESRegister - Adds a method to the nonlinear solver package.
4198 
4199    Not collective
4200 
4201    Input Parameters:
4202 +  name_solver - name of a new user-defined solver
4203 -  routine_create - routine to create method context
4204 
4205    Notes:
4206    SNESRegister() may be called multiple times to add several user-defined solvers.
4207 
4208    Sample usage:
4209 .vb
4210    SNESRegister("my_solver",MySolverCreate);
4211 .ve
4212 
4213    Then, your solver can be chosen with the procedural interface via
4214 $     SNESSetType(snes,"my_solver")
4215    or at runtime via the option
4216 $     -snes_type my_solver
4217 
4218    Level: advanced
4219 
4220     Note: If your function is not being put into a shared library then use SNESRegister() instead
4221 
4222 .keywords: SNES, nonlinear, register
4223 
4224 .seealso: SNESRegisterAll(), SNESRegisterDestroy()
4225 
4226   Level: advanced
4227 @*/
4228 PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
4229 {
4230   PetscErrorCode ierr;
4231 
4232   PetscFunctionBegin;
4233   ierr = PetscFunctionListAdd(&SNESList,sname,function);CHKERRQ(ierr);
4234   PetscFunctionReturn(0);
4235 }
4236 
4237 #undef __FUNCT__
4238 #define __FUNCT__ "SNESTestLocalMin"
4239 PetscErrorCode  SNESTestLocalMin(SNES snes)
4240 {
4241   PetscErrorCode ierr;
4242   PetscInt       N,i,j;
4243   Vec            u,uh,fh;
4244   PetscScalar    value;
4245   PetscReal      norm;
4246 
4247   PetscFunctionBegin;
4248   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4249   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4250   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4251 
4252   /* currently only works for sequential */
4253   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");CHKERRQ(ierr);
4254   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4255   for (i=0; i<N; i++) {
4256     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4257     ierr = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4258     for (j=-10; j<11; j++) {
4259       value = PetscSign(j)*exp(PetscAbs(j)-10.0);
4260       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4261       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4262       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4263       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4264       value = -value;
4265       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4266     }
4267   }
4268   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4269   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4270   PetscFunctionReturn(0);
4271 }
4272 
4273 #undef __FUNCT__
4274 #define __FUNCT__ "SNESKSPSetUseEW"
4275 /*@
4276    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4277    computing relative tolerance for linear solvers within an inexact
4278    Newton method.
4279 
4280    Logically Collective on SNES
4281 
4282    Input Parameters:
4283 +  snes - SNES context
4284 -  flag - PETSC_TRUE or PETSC_FALSE
4285 
4286     Options Database:
4287 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4288 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4289 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4290 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4291 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4292 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4293 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4294 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4295 
4296    Notes:
4297    Currently, the default is to use a constant relative tolerance for
4298    the inner linear solvers.  Alternatively, one can use the
4299    Eisenstat-Walker method, where the relative convergence tolerance
4300    is reset at each Newton iteration according progress of the nonlinear
4301    solver.
4302 
4303    Level: advanced
4304 
4305    Reference:
4306    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4307    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4308 
4309 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4310 
4311 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4312 @*/
4313 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
4314 {
4315   PetscFunctionBegin;
4316   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4317   PetscValidLogicalCollectiveBool(snes,flag,2);
4318   snes->ksp_ewconv = flag;
4319   PetscFunctionReturn(0);
4320 }
4321 
4322 #undef __FUNCT__
4323 #define __FUNCT__ "SNESKSPGetUseEW"
4324 /*@
4325    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4326    for computing relative tolerance for linear solvers within an
4327    inexact Newton method.
4328 
4329    Not Collective
4330 
4331    Input Parameter:
4332 .  snes - SNES context
4333 
4334    Output Parameter:
4335 .  flag - PETSC_TRUE or PETSC_FALSE
4336 
4337    Notes:
4338    Currently, the default is to use a constant relative tolerance for
4339    the inner linear solvers.  Alternatively, one can use the
4340    Eisenstat-Walker method, where the relative convergence tolerance
4341    is reset at each Newton iteration according progress of the nonlinear
4342    solver.
4343 
4344    Level: advanced
4345 
4346    Reference:
4347    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4348    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4349 
4350 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4351 
4352 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4353 @*/
4354 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4355 {
4356   PetscFunctionBegin;
4357   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4358   PetscValidPointer(flag,2);
4359   *flag = snes->ksp_ewconv;
4360   PetscFunctionReturn(0);
4361 }
4362 
4363 #undef __FUNCT__
4364 #define __FUNCT__ "SNESKSPSetParametersEW"
4365 /*@
4366    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4367    convergence criteria for the linear solvers within an inexact
4368    Newton method.
4369 
4370    Logically Collective on SNES
4371 
4372    Input Parameters:
4373 +    snes - SNES context
4374 .    version - version 1, 2 (default is 2) or 3
4375 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4376 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4377 .    gamma - multiplicative factor for version 2 rtol computation
4378              (0 <= gamma2 <= 1)
4379 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4380 .    alpha2 - power for safeguard
4381 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4382 
4383    Note:
4384    Version 3 was contributed by Luis Chacon, June 2006.
4385 
4386    Use PETSC_DEFAULT to retain the default for any of the parameters.
4387 
4388    Level: advanced
4389 
4390    Reference:
4391    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4392    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4393    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4394 
4395 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4396 
4397 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4398 @*/
4399 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4400 {
4401   SNESKSPEW *kctx;
4402 
4403   PetscFunctionBegin;
4404   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4405   kctx = (SNESKSPEW*)snes->kspconvctx;
4406   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4407   PetscValidLogicalCollectiveInt(snes,version,2);
4408   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4409   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4410   PetscValidLogicalCollectiveReal(snes,gamma,5);
4411   PetscValidLogicalCollectiveReal(snes,alpha,6);
4412   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4413   PetscValidLogicalCollectiveReal(snes,threshold,8);
4414 
4415   if (version != PETSC_DEFAULT)   kctx->version   = version;
4416   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4417   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4418   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4419   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4420   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4421   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4422 
4423   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);
4424   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",kctx->rtol_0);
4425   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",kctx->rtol_max);
4426   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%G) <= 1.0\n",kctx->gamma);
4427   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%G) <= 2.0\n",kctx->alpha);
4428   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%G) < 1.0\n",kctx->threshold);
4429   PetscFunctionReturn(0);
4430 }
4431 
4432 #undef __FUNCT__
4433 #define __FUNCT__ "SNESKSPGetParametersEW"
4434 /*@
4435    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4436    convergence criteria for the linear solvers within an inexact
4437    Newton method.
4438 
4439    Not Collective
4440 
4441    Input Parameters:
4442      snes - SNES context
4443 
4444    Output Parameters:
4445 +    version - version 1, 2 (default is 2) or 3
4446 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4447 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4448 .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
4449 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4450 .    alpha2 - power for safeguard
4451 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4452 
4453    Level: advanced
4454 
4455 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4456 
4457 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4458 @*/
4459 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4460 {
4461   SNESKSPEW *kctx;
4462 
4463   PetscFunctionBegin;
4464   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4465   kctx = (SNESKSPEW*)snes->kspconvctx;
4466   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4467   if (version)   *version   = kctx->version;
4468   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4469   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4470   if (gamma)     *gamma     = kctx->gamma;
4471   if (alpha)     *alpha     = kctx->alpha;
4472   if (alpha2)    *alpha2    = kctx->alpha2;
4473   if (threshold) *threshold = kctx->threshold;
4474   PetscFunctionReturn(0);
4475 }
4476 
4477 #undef __FUNCT__
4478 #define __FUNCT__ "KSPPreSolve_SNESEW"
4479  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4480 {
4481   PetscErrorCode ierr;
4482   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4483   PetscReal      rtol  = PETSC_DEFAULT,stol;
4484 
4485   PetscFunctionBegin;
4486   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4487   if (!snes->iter) {
4488     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
4489     ierr = VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);CHKERRQ(ierr);
4490   }
4491   else {
4492     if (kctx->version == 1) {
4493       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4494       if (rtol < 0.0) rtol = -rtol;
4495       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
4496       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4497     } else if (kctx->version == 2) {
4498       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4499       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
4500       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4501     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
4502       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4503       /* safeguard: avoid sharp decrease of rtol */
4504       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
4505       stol = PetscMax(rtol,stol);
4506       rtol = PetscMin(kctx->rtol_0,stol);
4507       /* safeguard: avoid oversolving */
4508       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
4509       stol = PetscMax(rtol,stol);
4510       rtol = PetscMin(kctx->rtol_0,stol);
4511     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4512   }
4513   /* safeguard: avoid rtol greater than one */
4514   rtol = PetscMin(rtol,kctx->rtol_max);
4515   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4516   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%G\n",snes->iter,kctx->version,rtol);CHKERRQ(ierr);
4517   PetscFunctionReturn(0);
4518 }
4519 
4520 #undef __FUNCT__
4521 #define __FUNCT__ "KSPPostSolve_SNESEW"
4522 PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4523 {
4524   PetscErrorCode ierr;
4525   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4526   PCSide         pcside;
4527   Vec            lres;
4528 
4529   PetscFunctionBegin;
4530   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4531   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4532   ierr = SNESGetFunctionNorm(snes,&kctx->norm_last);CHKERRQ(ierr);
4533   if (kctx->version == 1) {
4534     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4535     if (pcside == PC_RIGHT) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4536       /* KSP residual is true linear residual */
4537       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4538     } else {
4539       /* KSP residual is preconditioned residual */
4540       /* compute true linear residual norm */
4541       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4542       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4543       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4544       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4545       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4546     }
4547   }
4548   PetscFunctionReturn(0);
4549 }
4550 
4551 #undef __FUNCT__
4552 #define __FUNCT__ "SNESGetKSP"
4553 /*@
4554    SNESGetKSP - Returns the KSP context for a SNES solver.
4555 
4556    Not Collective, but if SNES object is parallel, then KSP object is parallel
4557 
4558    Input Parameter:
4559 .  snes - the SNES context
4560 
4561    Output Parameter:
4562 .  ksp - the KSP context
4563 
4564    Notes:
4565    The user can then directly manipulate the KSP context to set various
4566    options, etc.  Likewise, the user can then extract and manipulate the
4567    PC contexts as well.
4568 
4569    Level: beginner
4570 
4571 .keywords: SNES, nonlinear, get, KSP, context
4572 
4573 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
4574 @*/
4575 PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
4576 {
4577   PetscErrorCode ierr;
4578 
4579   PetscFunctionBegin;
4580   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4581   PetscValidPointer(ksp,2);
4582 
4583   if (!snes->ksp) {
4584     ierr = KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);CHKERRQ(ierr);
4585     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);CHKERRQ(ierr);
4586     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);CHKERRQ(ierr);
4587 
4588     ierr = KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);CHKERRQ(ierr);
4589     ierr = KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);CHKERRQ(ierr);
4590   }
4591   *ksp = snes->ksp;
4592   PetscFunctionReturn(0);
4593 }
4594 
4595 
4596 #include <petsc-private/dmimpl.h>
4597 #undef __FUNCT__
4598 #define __FUNCT__ "SNESSetDM"
4599 /*@
4600    SNESSetDM - Sets the DM that may be used by some preconditioners
4601 
4602    Logically Collective on SNES
4603 
4604    Input Parameters:
4605 +  snes - the preconditioner context
4606 -  dm - the dm
4607 
4608    Level: intermediate
4609 
4610 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4611 @*/
4612 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4613 {
4614   PetscErrorCode ierr;
4615   KSP            ksp;
4616   DMSNES         sdm;
4617 
4618   PetscFunctionBegin;
4619   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4620   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4621   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4622     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4623       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4624       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4625       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
4626     }
4627     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4628   }
4629   snes->dm     = dm;
4630   snes->dmAuto = PETSC_FALSE;
4631 
4632   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4633   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4634   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4635   if (snes->pc) {
4636     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4637     ierr = SNESSetPCSide(snes,snes->pcside);CHKERRQ(ierr);
4638   }
4639   PetscFunctionReturn(0);
4640 }
4641 
4642 #undef __FUNCT__
4643 #define __FUNCT__ "SNESGetDM"
4644 /*@
4645    SNESGetDM - Gets the DM that may be used by some preconditioners
4646 
4647    Not Collective but DM obtained is parallel on SNES
4648 
4649    Input Parameter:
4650 . snes - the preconditioner context
4651 
4652    Output Parameter:
4653 .  dm - the dm
4654 
4655    Level: intermediate
4656 
4657 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4658 @*/
4659 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4660 {
4661   PetscErrorCode ierr;
4662 
4663   PetscFunctionBegin;
4664   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4665   if (!snes->dm) {
4666     ierr         = DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);CHKERRQ(ierr);
4667     snes->dmAuto = PETSC_TRUE;
4668   }
4669   *dm = snes->dm;
4670   PetscFunctionReturn(0);
4671 }
4672 
4673 #undef __FUNCT__
4674 #define __FUNCT__ "SNESSetPC"
4675 /*@
4676   SNESSetPC - Sets the nonlinear preconditioner to be used.
4677 
4678   Collective on SNES
4679 
4680   Input Parameters:
4681 + snes - iterative context obtained from SNESCreate()
4682 - pc   - the preconditioner object
4683 
4684   Notes:
4685   Use SNESGetPC() to retrieve the preconditioner context (for example,
4686   to configure it using the API).
4687 
4688   Level: developer
4689 
4690 .keywords: SNES, set, precondition
4691 .seealso: SNESGetPC()
4692 @*/
4693 PetscErrorCode SNESSetPC(SNES snes, SNES pc)
4694 {
4695   PetscErrorCode ierr;
4696 
4697   PetscFunctionBegin;
4698   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4699   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4700   PetscCheckSameComm(snes, 1, pc, 2);
4701   ierr     = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4702   ierr     = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4703   snes->pc = pc;
4704   ierr     = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->pc);CHKERRQ(ierr);
4705   PetscFunctionReturn(0);
4706 }
4707 
4708 #undef __FUNCT__
4709 #define __FUNCT__ "SNESGetPC"
4710 /*@
4711   SNESGetPC - Returns a pointer to the nonlinear preconditioning context set with SNESSetPC().
4712 
4713   Not Collective
4714 
4715   Input Parameter:
4716 . snes - iterative context obtained from SNESCreate()
4717 
4718   Output Parameter:
4719 . pc - preconditioner context
4720 
4721   Level: developer
4722 
4723 .keywords: SNES, get, preconditioner
4724 .seealso: SNESSetPC()
4725 @*/
4726 PetscErrorCode SNESGetPC(SNES snes, SNES *pc)
4727 {
4728   PetscErrorCode ierr;
4729   const char     *optionsprefix;
4730 
4731   PetscFunctionBegin;
4732   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4733   PetscValidPointer(pc, 2);
4734   if (!snes->pc) {
4735     ierr = SNESCreate(PetscObjectComm((PetscObject)snes),&snes->pc);CHKERRQ(ierr);
4736     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4737     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
4738     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4739     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4740     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4741     ierr = SNESSetCountersReset(snes->pc,PETSC_FALSE);CHKERRQ(ierr);
4742   }
4743   *pc = snes->pc;
4744   PetscFunctionReturn(0);
4745 }
4746 
4747 #undef __FUNCT__
4748 #define __FUNCT__ "SNESSetPCSide"
4749 /*@
4750     SNESSetPCSide - Sets the preconditioning side.
4751 
4752     Logically Collective on SNES
4753 
4754     Input Parameter:
4755 .   snes - iterative context obtained from SNESCreate()
4756 
4757     Output Parameter:
4758 .   side - the preconditioning side, where side is one of
4759 .vb
4760       PC_LEFT - left preconditioning (default)
4761       PC_RIGHT - right preconditioning
4762 .ve
4763 
4764     Options Database Keys:
4765 .   -snes_pc_side <right,left>
4766 
4767     Level: intermediate
4768 
4769 .keywords: SNES, set, right, left, side, preconditioner, flag
4770 
4771 .seealso: SNESGetPCSide(), KSPSetPCSide()
4772 @*/
4773 PetscErrorCode  SNESSetPCSide(SNES snes,PCSide side)
4774 {
4775   PetscFunctionBegin;
4776   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4777   PetscValidLogicalCollectiveEnum(snes,side,2);
4778   snes->pcside = side;
4779   PetscFunctionReturn(0);
4780 }
4781 
4782 #undef __FUNCT__
4783 #define __FUNCT__ "SNESGetPCSide"
4784 /*@
4785     SNESGetPCSide - Gets the preconditioning side.
4786 
4787     Not Collective
4788 
4789     Input Parameter:
4790 .   snes - iterative context obtained from SNESCreate()
4791 
4792     Output Parameter:
4793 .   side - the preconditioning side, where side is one of
4794 .vb
4795       PC_LEFT - left preconditioning (default)
4796       PC_RIGHT - right preconditioning
4797 .ve
4798 
4799     Level: intermediate
4800 
4801 .keywords: SNES, get, right, left, side, preconditioner, flag
4802 
4803 .seealso: SNESSetPCSide(), KSPGetPCSide()
4804 @*/
4805 PetscErrorCode  SNESGetPCSide(SNES snes,PCSide *side)
4806 {
4807   PetscFunctionBegin;
4808   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4809   PetscValidPointer(side,2);
4810   *side = snes->pcside;
4811   PetscFunctionReturn(0);
4812 }
4813 
4814 #undef __FUNCT__
4815 #define __FUNCT__ "SNESSetLineSearch"
4816 /*@
4817   SNESSetLineSearch - Sets the linesearch on the SNES instance.
4818 
4819   Collective on SNES
4820 
4821   Input Parameters:
4822 + snes - iterative context obtained from SNESCreate()
4823 - linesearch   - the linesearch object
4824 
4825   Notes:
4826   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
4827   to configure it using the API).
4828 
4829   Level: developer
4830 
4831 .keywords: SNES, set, linesearch
4832 .seealso: SNESGetLineSearch()
4833 @*/
4834 PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
4835 {
4836   PetscErrorCode ierr;
4837 
4838   PetscFunctionBegin;
4839   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4840   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
4841   PetscCheckSameComm(snes, 1, linesearch, 2);
4842   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
4843   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
4844 
4845   snes->linesearch = linesearch;
4846 
4847   ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
4848   PetscFunctionReturn(0);
4849 }
4850 
4851 #undef __FUNCT__
4852 #define __FUNCT__ "SNESGetLineSearch"
4853 /*@
4854   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
4855   or creates a default line search instance associated with the SNES and returns it.
4856 
4857   Not Collective
4858 
4859   Input Parameter:
4860 . snes - iterative context obtained from SNESCreate()
4861 
4862   Output Parameter:
4863 . linesearch - linesearch context
4864 
4865   Level: developer
4866 
4867 .keywords: SNES, get, linesearch
4868 .seealso: SNESSetLineSearch()
4869 @*/
4870 PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
4871 {
4872   PetscErrorCode ierr;
4873   const char     *optionsprefix;
4874 
4875   PetscFunctionBegin;
4876   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4877   PetscValidPointer(linesearch, 2);
4878   if (!snes->linesearch) {
4879     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
4880     ierr = SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);CHKERRQ(ierr);
4881     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
4882     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
4883     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
4884     ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
4885   }
4886   *linesearch = snes->linesearch;
4887   PetscFunctionReturn(0);
4888 }
4889 
4890 #if defined(PETSC_HAVE_MATLAB_ENGINE)
4891 #include <mex.h>
4892 
4893 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
4894 
4895 #undef __FUNCT__
4896 #define __FUNCT__ "SNESComputeFunction_Matlab"
4897 /*
4898    SNESComputeFunction_Matlab - Calls the function that has been set with SNESSetFunctionMatlab().
4899 
4900    Collective on SNES
4901 
4902    Input Parameters:
4903 +  snes - the SNES context
4904 -  x - input vector
4905 
4906    Output Parameter:
4907 .  y - function vector, as set by SNESSetFunction()
4908 
4909    Notes:
4910    SNESComputeFunction() is typically used within nonlinear solvers
4911    implementations, so most users would not generally call this routine
4912    themselves.
4913 
4914    Level: developer
4915 
4916 .keywords: SNES, nonlinear, compute, function
4917 
4918 .seealso: SNESSetFunction(), SNESGetFunction()
4919 */
4920 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
4921 {
4922   PetscErrorCode    ierr;
4923   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
4924   int               nlhs  = 1,nrhs = 5;
4925   mxArray           *plhs[1],*prhs[5];
4926   long long int     lx = 0,ly = 0,ls = 0;
4927 
4928   PetscFunctionBegin;
4929   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4930   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4931   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
4932   PetscCheckSameComm(snes,1,x,2);
4933   PetscCheckSameComm(snes,1,y,3);
4934 
4935   /* call Matlab function in ctx with arguments x and y */
4936 
4937   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4938   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4939   ierr    = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
4940   prhs[0] = mxCreateDoubleScalar((double)ls);
4941   prhs[1] = mxCreateDoubleScalar((double)lx);
4942   prhs[2] = mxCreateDoubleScalar((double)ly);
4943   prhs[3] = mxCreateString(sctx->funcname);
4944   prhs[4] = sctx->ctx;
4945   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
4946   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
4947   mxDestroyArray(prhs[0]);
4948   mxDestroyArray(prhs[1]);
4949   mxDestroyArray(prhs[2]);
4950   mxDestroyArray(prhs[3]);
4951   mxDestroyArray(plhs[0]);
4952   PetscFunctionReturn(0);
4953 }
4954 
4955 #undef __FUNCT__
4956 #define __FUNCT__ "SNESSetFunctionMatlab"
4957 /*
4958    SNESSetFunctionMatlab - Sets the function evaluation routine and function
4959    vector for use by the SNES routines in solving systems of nonlinear
4960    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4961 
4962    Logically Collective on SNES
4963 
4964    Input Parameters:
4965 +  snes - the SNES context
4966 .  r - vector to store function value
4967 -  SNESFunction - function evaluation routine
4968 
4969    Notes:
4970    The Newton-like methods typically solve linear systems of the form
4971 $      f'(x) x = -f(x),
4972    where f'(x) denotes the Jacobian matrix and f(x) is the function.
4973 
4974    Level: beginner
4975 
4976    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
4977 
4978 .keywords: SNES, nonlinear, set, function
4979 
4980 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4981 */
4982 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *SNESFunction,mxArray *ctx)
4983 {
4984   PetscErrorCode    ierr;
4985   SNESMatlabContext *sctx;
4986 
4987   PetscFunctionBegin;
4988   /* currently sctx is memory bleed */
4989   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4990   ierr = PetscStrallocpy(SNESFunction,&sctx->funcname);CHKERRQ(ierr);
4991   /*
4992      This should work, but it doesn't
4993   sctx->ctx = ctx;
4994   mexMakeArrayPersistent(sctx->ctx);
4995   */
4996   sctx->ctx = mxDuplicateArray(ctx);
4997   ierr      = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
4998   PetscFunctionReturn(0);
4999 }
5000 
5001 #undef __FUNCT__
5002 #define __FUNCT__ "SNESComputeJacobian_Matlab"
5003 /*
5004    SNESComputeJacobian_Matlab - Calls the function that has been set with SNESSetJacobianMatlab().
5005 
5006    Collective on SNES
5007 
5008    Input Parameters:
5009 +  snes - the SNES context
5010 .  x - input vector
5011 .  A, B - the matrices
5012 -  ctx - user context
5013 
5014    Output Parameter:
5015 .  flag - structure of the matrix
5016 
5017    Level: developer
5018 
5019 .keywords: SNES, nonlinear, compute, function
5020 
5021 .seealso: SNESSetFunction(), SNESGetFunction()
5022 @*/
5023 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat *A,Mat *B,MatStructure *flag, void *ctx)
5024 {
5025   PetscErrorCode    ierr;
5026   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5027   int               nlhs  = 2,nrhs = 6;
5028   mxArray           *plhs[2],*prhs[6];
5029   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
5030 
5031   PetscFunctionBegin;
5032   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5033   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
5034 
5035   /* call Matlab function in ctx with arguments x and y */
5036 
5037   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5038   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5039   ierr    = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
5040   ierr    = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
5041   prhs[0] = mxCreateDoubleScalar((double)ls);
5042   prhs[1] = mxCreateDoubleScalar((double)lx);
5043   prhs[2] = mxCreateDoubleScalar((double)lA);
5044   prhs[3] = mxCreateDoubleScalar((double)lB);
5045   prhs[4] = mxCreateString(sctx->funcname);
5046   prhs[5] = sctx->ctx;
5047   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
5048   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5049   *flag   = (MatStructure) mxGetScalar(plhs[1]);CHKERRQ(ierr);
5050   mxDestroyArray(prhs[0]);
5051   mxDestroyArray(prhs[1]);
5052   mxDestroyArray(prhs[2]);
5053   mxDestroyArray(prhs[3]);
5054   mxDestroyArray(prhs[4]);
5055   mxDestroyArray(plhs[0]);
5056   mxDestroyArray(plhs[1]);
5057   PetscFunctionReturn(0);
5058 }
5059 
5060 #undef __FUNCT__
5061 #define __FUNCT__ "SNESSetJacobianMatlab"
5062 /*
5063    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
5064    vector for use by the SNES routines in solving systems of nonlinear
5065    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5066 
5067    Logically Collective on SNES
5068 
5069    Input Parameters:
5070 +  snes - the SNES context
5071 .  A,B - Jacobian matrices
5072 .  SNESJacobianFunction - function evaluation routine
5073 -  ctx - user context
5074 
5075    Level: developer
5076 
5077    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5078 
5079 .keywords: SNES, nonlinear, set, function
5080 
5081 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction(), SNESJacobianFunction
5082 */
5083 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *SNESJacobianFunction,mxArray *ctx)
5084 {
5085   PetscErrorCode    ierr;
5086   SNESMatlabContext *sctx;
5087 
5088   PetscFunctionBegin;
5089   /* currently sctx is memory bleed */
5090   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
5091   ierr = PetscStrallocpy(SNESJacobianFunction,&sctx->funcname);CHKERRQ(ierr);
5092   /*
5093      This should work, but it doesn't
5094   sctx->ctx = ctx;
5095   mexMakeArrayPersistent(sctx->ctx);
5096   */
5097   sctx->ctx = mxDuplicateArray(ctx);
5098   ierr      = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
5099   PetscFunctionReturn(0);
5100 }
5101 
5102 #undef __FUNCT__
5103 #define __FUNCT__ "SNESMonitor_Matlab"
5104 /*
5105    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
5106 
5107    Collective on SNES
5108 
5109 .seealso: SNESSetFunction(), SNESGetFunction()
5110 @*/
5111 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
5112 {
5113   PetscErrorCode    ierr;
5114   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5115   int               nlhs  = 1,nrhs = 6;
5116   mxArray           *plhs[1],*prhs[6];
5117   long long int     lx = 0,ls = 0;
5118   Vec               x  = snes->vec_sol;
5119 
5120   PetscFunctionBegin;
5121   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5122 
5123   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5124   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5125   prhs[0] = mxCreateDoubleScalar((double)ls);
5126   prhs[1] = mxCreateDoubleScalar((double)it);
5127   prhs[2] = mxCreateDoubleScalar((double)fnorm);
5128   prhs[3] = mxCreateDoubleScalar((double)lx);
5129   prhs[4] = mxCreateString(sctx->funcname);
5130   prhs[5] = sctx->ctx;
5131   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
5132   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5133   mxDestroyArray(prhs[0]);
5134   mxDestroyArray(prhs[1]);
5135   mxDestroyArray(prhs[2]);
5136   mxDestroyArray(prhs[3]);
5137   mxDestroyArray(prhs[4]);
5138   mxDestroyArray(plhs[0]);
5139   PetscFunctionReturn(0);
5140 }
5141 
5142 #undef __FUNCT__
5143 #define __FUNCT__ "SNESMonitorSetMatlab"
5144 /*
5145    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
5146 
5147    Level: developer
5148 
5149    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5150 
5151 .keywords: SNES, nonlinear, set, function
5152 
5153 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5154 */
5155 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *SNESMonitorFunction,mxArray *ctx)
5156 {
5157   PetscErrorCode    ierr;
5158   SNESMatlabContext *sctx;
5159 
5160   PetscFunctionBegin;
5161   /* currently sctx is memory bleed */
5162   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
5163   ierr = PetscStrallocpy(SNESMonitorFunction,&sctx->funcname);CHKERRQ(ierr);
5164   /*
5165      This should work, but it doesn't
5166   sctx->ctx = ctx;
5167   mexMakeArrayPersistent(sctx->ctx);
5168   */
5169   sctx->ctx = mxDuplicateArray(ctx);
5170   ierr      = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,NULL);CHKERRQ(ierr);
5171   PetscFunctionReturn(0);
5172 }
5173 
5174 #endif
5175