xref: /petsc/src/snes/interface/snes.c (revision fe998a80077c9ee0917a39496df43fc256e1b478)
1 
2 #include <petsc-private/snesimpl.h>      /*I "petscsnes.h"  I*/
3 #include <petscdmshell.h>
4 
5 PetscBool         SNESRegisterAllCalled = PETSC_FALSE;
6 PetscFunctionList SNESList              = NULL;
7 
8 /* Logging support */
9 PetscClassId  SNES_CLASSID, DMSNES_CLASSID;
10 PetscLogEvent SNES_Solve, SNES_FunctionEval, SNES_JacobianEval, SNES_NGSEval, SNES_NGSFuncEval, SNES_NPCSolve;
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_SAWS)
187 #include <petscviewersaws.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_SAWS)
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_SAWS)
245   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&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",(double)snes->rtol,(double)snes->abstol,(double)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",(double)kctx->rtol_0,(double)kctx->rtol_max,(double)kctx->threshold);CHKERRQ(ierr);
269         ierr = PetscViewerASCIIPrintf(viewer,"    gamma=%g, alpha=%g, alpha2=%g\n",(double)kctx->gamma,(double)kctx->alpha,(double)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,sizeof(type));CHKERRQ(ierr);
297       ierr = PetscViewerBinaryWrite(viewer,type,sizeof(type),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_SAWS)
318   } else if (isams) {
319     PetscMPIInt rank;
320     const char *name;
321 
322     ierr = PetscObjectGetName((PetscObject)snes,&name);CHKERRQ(ierr);
323     ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRQ(ierr);
324     if (!((PetscObject)snes)->amsmem && !rank) {
325       char       dir[1024];
326 
327       ierr = PetscObjectViewSAWs((PetscObject)snes,viewer);CHKERRQ(ierr);
328       ierr = PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);CHKERRQ(ierr);
329       PetscStackCallSAWs(SAWs_Register,(dir,&snes->iter,1,SAWs_READ,SAWs_INT));
330       if (!snes->conv_hist) {
331         ierr = SNESSetConvergenceHistory(snes,NULL,NULL,PETSC_DECIDE,PETSC_TRUE);CHKERRQ(ierr);
332       }
333       ierr = PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/conv_hist",name);CHKERRQ(ierr);
334       PetscStackCallSAWs(SAWs_Register,(dir,snes->conv_hist,10,SAWs_READ,SAWs_DOUBLE));
335     }
336 #endif
337   }
338   if (snes->linesearch) {
339     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
340     ierr = SNESGetLineSearch(snes, &linesearch);CHKERRQ(ierr);
341     ierr = SNESLineSearchView(linesearch, viewer);CHKERRQ(ierr);
342     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
343   }
344   if (snes->pc && snes->usespc) {
345     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
346     ierr = SNESView(snes->pc, viewer);CHKERRQ(ierr);
347     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
348   }
349   ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
350   ierr = DMGetDMSNES(snes->dm,&dmsnes);CHKERRQ(ierr);
351   ierr = DMSNESView(dmsnes, viewer);CHKERRQ(ierr);
352   ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
353   if (snes->usesksp) {
354     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
355     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
356     ierr = KSPView(ksp,viewer);CHKERRQ(ierr);
357     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
358   }
359   if (isdraw) {
360     PetscDraw draw;
361     ierr = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
362     ierr = PetscDrawPopCurrentPoint(draw);CHKERRQ(ierr);
363   }
364   PetscFunctionReturn(0);
365 }
366 
367 /*
368   We retain a list of functions that also take SNES command
369   line options. These are called at the end SNESSetFromOptions()
370 */
371 #define MAXSETFROMOPTIONS 5
372 static PetscInt numberofsetfromoptions;
373 static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);
374 
375 #undef __FUNCT__
376 #define __FUNCT__ "SNESAddOptionsChecker"
377 /*@C
378   SNESAddOptionsChecker - Adds an additional function to check for SNES options.
379 
380   Not Collective
381 
382   Input Parameter:
383 . snescheck - function that checks for options
384 
385   Level: developer
386 
387 .seealso: SNESSetFromOptions()
388 @*/
389 PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
390 {
391   PetscFunctionBegin;
392   if (numberofsetfromoptions >= MAXSETFROMOPTIONS) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %D allowed", MAXSETFROMOPTIONS);
393   othersetfromoptions[numberofsetfromoptions++] = snescheck;
394   PetscFunctionReturn(0);
395 }
396 
397 extern PetscErrorCode  SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);
398 
399 #undef __FUNCT__
400 #define __FUNCT__ "SNESSetUpMatrixFree_Private"
401 static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
402 {
403   Mat            J;
404   KSP            ksp;
405   PC             pc;
406   PetscBool      match;
407   PetscErrorCode ierr;
408 
409   PetscFunctionBegin;
410   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
411 
412   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
413     Mat A = snes->jacobian, B = snes->jacobian_pre;
414     ierr = MatCreateVecs(A ? A : B, NULL,&snes->vec_func);CHKERRQ(ierr);
415   }
416 
417   if (version == 1) {
418     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
419     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
420     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
421   } else if (version == 2) {
422     if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
423 #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128)
424     ierr = SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);CHKERRQ(ierr);
425 #else
426     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator rutines (version 2)");
427 #endif
428   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator rutines, only version 1 and 2");
429 
430   ierr = PetscInfo1(snes,"Setting default matrix-free operator routines (version %D)\n", version);CHKERRQ(ierr);
431   if (hasOperator) {
432 
433     /* This version replaces the user provided Jacobian matrix with a
434        matrix-free version but still employs the user-provided preconditioner matrix. */
435     ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);
436   } else {
437     /* This version replaces both the user-provided Jacobian and the user-
438      provided preconditioner Jacobian with the default matrix free version. */
439     if ((snes->pcside == PC_LEFT) && snes->pc) {
440       if (!snes->jacobian){ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);}
441     } else {
442       ierr = SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,0);CHKERRQ(ierr);
443     }
444     /* Force no preconditioner */
445     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
446     ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
447     ierr = PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);CHKERRQ(ierr);
448     if (!match) {
449       ierr = PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");CHKERRQ(ierr);
450       ierr = PCSetType(pc,PCNONE);CHKERRQ(ierr);
451     }
452   }
453   ierr = MatDestroy(&J);CHKERRQ(ierr);
454   PetscFunctionReturn(0);
455 }
456 
457 #undef __FUNCT__
458 #define __FUNCT__ "DMRestrictHook_SNESVecSol"
459 static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
460 {
461   SNES           snes = (SNES)ctx;
462   PetscErrorCode ierr;
463   Vec            Xfine,Xfine_named = NULL,Xcoarse;
464 
465   PetscFunctionBegin;
466   if (PetscLogPrintInfo) {
467     PetscInt finelevel,coarselevel,fineclevel,coarseclevel;
468     ierr = DMGetRefineLevel(dmfine,&finelevel);CHKERRQ(ierr);
469     ierr = DMGetCoarsenLevel(dmfine,&fineclevel);CHKERRQ(ierr);
470     ierr = DMGetRefineLevel(dmcoarse,&coarselevel);CHKERRQ(ierr);
471     ierr = DMGetCoarsenLevel(dmcoarse,&coarseclevel);CHKERRQ(ierr);
472     ierr = PetscInfo4(dmfine,"Restricting SNES solution vector from level %D-%D to level %D-%D\n",finelevel,fineclevel,coarselevel,coarseclevel);CHKERRQ(ierr);
473   }
474   if (dmfine == snes->dm) Xfine = snes->vec_sol;
475   else {
476     ierr  = DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);
477     Xfine = Xfine_named;
478   }
479   ierr = DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
480   ierr = MatRestrict(Restrict,Xfine,Xcoarse);CHKERRQ(ierr);
481   ierr = VecPointwiseMult(Xcoarse,Xcoarse,Rscale);CHKERRQ(ierr);
482   ierr = DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
483   if (Xfine_named) {ierr = DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);}
484   PetscFunctionReturn(0);
485 }
486 
487 #undef __FUNCT__
488 #define __FUNCT__ "DMCoarsenHook_SNESVecSol"
489 static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm,DM dmc,void *ctx)
490 {
491   PetscErrorCode ierr;
492 
493   PetscFunctionBegin;
494   ierr = DMCoarsenHookAdd(dmc,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,ctx);CHKERRQ(ierr);
495   PetscFunctionReturn(0);
496 }
497 
498 #undef __FUNCT__
499 #define __FUNCT__ "KSPComputeOperators_SNES"
500 /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
501  * safely call SNESGetDM() in their residual evaluation routine. */
502 static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,void *ctx)
503 {
504   SNES           snes = (SNES)ctx;
505   PetscErrorCode ierr;
506   Mat            Asave = A,Bsave = B;
507   Vec            X,Xnamed = NULL;
508   DM             dmsave;
509   void           *ctxsave;
510   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
511 
512   PetscFunctionBegin;
513   dmsave = snes->dm;
514   ierr   = KSPGetDM(ksp,&snes->dm);CHKERRQ(ierr);
515   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
516   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
517     ierr = DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
518     X    = Xnamed;
519     ierr = SNESGetJacobian(snes,NULL,NULL,&jac,&ctxsave);CHKERRQ(ierr);
520     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
521     if (jac == SNESComputeJacobianDefaultColor) {
522       ierr = SNESSetJacobian(snes,NULL,NULL,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
523     }
524   }
525   /* put the previous context back */
526 
527   ierr = SNESComputeJacobian(snes,X,A,B);CHKERRQ(ierr);
528   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) {
529     ierr = SNESSetJacobian(snes,NULL,NULL,jac,ctxsave);CHKERRQ(ierr);
530   }
531 
532   if (A != Asave || B != Bsave) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_SUP,"No support for changing matrices at this time");
533   if (Xnamed) {
534     ierr = DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
535   }
536   snes->dm = dmsave;
537   PetscFunctionReturn(0);
538 }
539 
540 #undef __FUNCT__
541 #define __FUNCT__ "SNESSetUpMatrices"
542 /*@
543    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()
544 
545    Collective
546 
547    Input Arguments:
548 .  snes - snes to configure
549 
550    Level: developer
551 
552 .seealso: SNESSetUp()
553 @*/
554 PetscErrorCode SNESSetUpMatrices(SNES snes)
555 {
556   PetscErrorCode ierr;
557   DM             dm;
558   DMSNES         sdm;
559 
560   PetscFunctionBegin;
561   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
562   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
563   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_PLIB,"DMSNES not properly configured");
564   else if (!snes->jacobian && snes->mf) {
565     Mat  J;
566     void *functx;
567     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
568     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
569     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
570     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
571     ierr = SNESSetJacobian(snes,J,J,0,0);CHKERRQ(ierr);
572     ierr = MatDestroy(&J);CHKERRQ(ierr);
573   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
574     Mat J,B;
575     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
576     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
577     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
578     ierr = DMCreateMatrix(snes->dm,&B);CHKERRQ(ierr);
579     /* sdm->computejacobian was already set to reach here */
580     ierr = SNESSetJacobian(snes,J,B,NULL,NULL);CHKERRQ(ierr);
581     ierr = MatDestroy(&J);CHKERRQ(ierr);
582     ierr = MatDestroy(&B);CHKERRQ(ierr);
583   } else if (!snes->jacobian_pre) {
584     Mat J,B;
585     J    = snes->jacobian;
586     ierr = DMCreateMatrix(snes->dm,&B);CHKERRQ(ierr);
587     ierr = SNESSetJacobian(snes,J ? J : B,B,NULL,NULL);CHKERRQ(ierr);
588     ierr = MatDestroy(&B);CHKERRQ(ierr);
589   }
590   {
591     KSP ksp;
592     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
593     ierr = KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);CHKERRQ(ierr);
594     ierr = DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);CHKERRQ(ierr);
595   }
596   PetscFunctionReturn(0);
597 }
598 
599 #undef __FUNCT__
600 #define __FUNCT__ "SNESSetFromOptions"
601 /*@
602    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.
603 
604    Collective on SNES
605 
606    Input Parameter:
607 .  snes - the SNES context
608 
609    Options Database Keys:
610 +  -snes_type <type> - newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas, SNESType for complete list
611 .  -snes_stol - convergence tolerance in terms of the norm
612                 of the change in the solution between steps
613 .  -snes_atol <abstol> - absolute tolerance of residual norm
614 .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
615 .  -snes_max_it <max_it> - maximum number of iterations
616 .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
617 .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
618 .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
619 .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
620 .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
621 .  -snes_trtol <trtol> - trust region tolerance
622 .  -snes_no_convergence_test - skip convergence test in nonlinear
623                                solver; hence iterations will continue until max_it
624                                or some other criterion is reached. Saves expense
625                                of convergence test
626 .  -snes_monitor <optional filename> - prints residual norm at each iteration. if no
627                                        filename given prints to stdout
628 .  -snes_monitor_solution - plots solution at each iteration
629 .  -snes_monitor_residual - plots residual (not its norm) at each iteration
630 .  -snes_monitor_solution_update - plots update to solution at each iteration
631 .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
632 .  -snes_monitor_lg_range - plots residual norm at each iteration
633 .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
634 .  -snes_fd_color - use finite differences with coloring to compute Jacobian
635 .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
636 -  -snes_converged_reason - print the reason for convergence/divergence after each solve
637 
638     Options Database for Eisenstat-Walker method:
639 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
640 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
641 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
642 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
643 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
644 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
645 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
646 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
647 
648    Notes:
649    To see all options, run your program with the -help option or consult
650    Users-Manual: ch_snes
651 
652    Level: beginner
653 
654 .keywords: SNES, nonlinear, set, options, database
655 
656 .seealso: SNESSetOptionsPrefix()
657 @*/
658 PetscErrorCode  SNESSetFromOptions(SNES snes)
659 {
660   PetscBool      flg,pcset,persist,set;
661   PetscInt       i,indx,lag,grids;
662   const char     *deft        = SNESNEWTONLS;
663   const char     *convtests[] = {"default","skip"};
664   SNESKSPEW      *kctx        = NULL;
665   char           type[256], monfilename[PETSC_MAX_PATH_LEN];
666   PetscViewer    monviewer;
667   PetscErrorCode ierr;
668   PCSide         pcside;
669   const char     *optionsprefix;
670 
671   PetscFunctionBegin;
672   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
673   if (!SNESRegisterAllCalled) {ierr = SNESRegisterAll();CHKERRQ(ierr);}
674   ierr = PetscObjectOptionsBegin((PetscObject)snes);CHKERRQ(ierr);
675   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
676   ierr = PetscOptionsFList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);CHKERRQ(ierr);
677   if (flg) {
678     ierr = SNESSetType(snes,type);CHKERRQ(ierr);
679   } else if (!((PetscObject)snes)->type_name) {
680     ierr = SNESSetType(snes,deft);CHKERRQ(ierr);
681   }
682   ierr = PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,NULL);CHKERRQ(ierr);
683   ierr = PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,NULL);CHKERRQ(ierr);
684 
685   ierr = PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,NULL);CHKERRQ(ierr);
686   ierr = PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,NULL);CHKERRQ(ierr);
687   ierr = PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,NULL);CHKERRQ(ierr);
688   ierr = PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,NULL);CHKERRQ(ierr);
689   ierr = PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,NULL);CHKERRQ(ierr);
690   ierr = PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,NULL);CHKERRQ(ierr);
691 
692   ierr = PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);CHKERRQ(ierr);
693   if (flg) {
694     ierr = SNESSetLagPreconditioner(snes,lag);CHKERRQ(ierr);
695   }
696   ierr = PetscOptionsBool("-snes_lag_preconditioner_persists","Preconditioner lagging through multiple solves","SNESSetLagPreconditionerPersists",snes->lagjac_persist,&persist,&flg);CHKERRQ(ierr);
697   if (flg) {
698     ierr = SNESSetLagPreconditionerPersists(snes,persist);CHKERRQ(ierr);
699   }
700   ierr = PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);CHKERRQ(ierr);
701   if (flg) {
702     ierr = SNESSetLagJacobian(snes,lag);CHKERRQ(ierr);
703   }
704   ierr = PetscOptionsBool("-snes_lag_jacobian_persists","Jacobian lagging through multiple solves","SNESSetLagJacobianPersists",snes->lagjac_persist,&persist,&flg);CHKERRQ(ierr);
705   if (flg) {
706     ierr = SNESSetLagJacobianPersists(snes,persist);CHKERRQ(ierr);
707   }
708 
709   ierr = PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);CHKERRQ(ierr);
710   if (flg) {
711     ierr = SNESSetGridSequence(snes,grids);CHKERRQ(ierr);
712   }
713 
714   ierr = PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);CHKERRQ(ierr);
715   if (flg) {
716     switch (indx) {
717     case 0: ierr = SNESSetConvergenceTest(snes,SNESConvergedDefault,NULL,NULL);CHKERRQ(ierr); break;
718     case 1: ierr = SNESSetConvergenceTest(snes,SNESConvergedSkip,NULL,NULL);CHKERRQ(ierr);    break;
719     }
720   }
721 
722   ierr = PetscOptionsEList("-snes_norm_schedule","SNES Norm schedule","SNESSetNormSchedule",SNESNormSchedules,5,"function",&indx,&flg);CHKERRQ(ierr);
723   if (flg) { ierr = SNESSetNormSchedule(snes,(SNESNormSchedule)indx);CHKERRQ(ierr); }
724 
725   ierr = PetscOptionsEList("-snes_function_type","SNES Norm schedule","SNESSetFunctionType",SNESFunctionTypes,2,"unpreconditioned",&indx,&flg);CHKERRQ(ierr);
726   if (flg) { ierr = SNESSetFunctionType(snes,(SNESFunctionType)indx);CHKERRQ(ierr); }
727 
728   kctx = (SNESKSPEW*)snes->kspconvctx;
729 
730   ierr = PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,NULL);CHKERRQ(ierr);
731 
732   ierr = PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,NULL);CHKERRQ(ierr);
733   ierr = PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,NULL);CHKERRQ(ierr);
734   ierr = PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,NULL);CHKERRQ(ierr);
735   ierr = PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,NULL);CHKERRQ(ierr);
736   ierr = PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,NULL);CHKERRQ(ierr);
737   ierr = PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,NULL);CHKERRQ(ierr);
738   ierr = PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,NULL);CHKERRQ(ierr);
739 
740   flg  = PETSC_FALSE;
741   ierr = PetscOptionsBool("-snes_check_jacobian","Check each Jacobian with a differenced one","SNESUpdateCheckJacobian",flg,&flg,&set);CHKERRQ(ierr);
742   if (set && flg) {
743     ierr = SNESSetUpdate(snes,SNESUpdateCheckJacobian);CHKERRQ(ierr);
744   }
745 
746   flg  = PETSC_FALSE;
747   ierr = PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,&set);CHKERRQ(ierr);
748   if (set && flg) {ierr = SNESMonitorCancel(snes);CHKERRQ(ierr);}
749 
750   ierr = PetscOptionsString("-snes_monitor","Monitor norm of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
751   if (flg) {
752     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
753     ierr = SNESMonitorSet(snes,SNESMonitorDefault,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
754   }
755 
756   ierr = PetscOptionsString("-snes_monitor_range","Monitor range of elements of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
757   if (flg) {
758     ierr = SNESMonitorSet(snes,SNESMonitorRange,0,0);CHKERRQ(ierr);
759   }
760 
761   ierr = PetscOptionsString("-snes_ratiomonitor","Monitor ratios of norms of function","SNESMonitorSetRatio","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
762   if (flg) {
763     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
764     ierr = SNESMonitorSetRatio(snes,monviewer);CHKERRQ(ierr);
765   }
766 
767   ierr = PetscOptionsString("-snes_monitor_short","Monitor norm of function (fewer digits)","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
768   if (flg) {
769     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
770     ierr = SNESMonitorSet(snes,SNESMonitorDefaultShort,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
771   }
772 
773   ierr = PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
774   if (flg) {ierr = PetscPythonMonitorSet((PetscObject)snes,monfilename);CHKERRQ(ierr);}
775 
776   flg  = PETSC_FALSE;
777   ierr = PetscOptionsBool("-snes_monitor_solution","Plot solution at each iteration","SNESMonitorSolution",flg,&flg,NULL);CHKERRQ(ierr);
778   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolution,0,0);CHKERRQ(ierr);}
779   flg  = PETSC_FALSE;
780   ierr = PetscOptionsBool("-snes_monitor_solution_update","Plot correction at each iteration","SNESMonitorSolutionUpdate",flg,&flg,NULL);CHKERRQ(ierr);
781   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolutionUpdate,0,0);CHKERRQ(ierr);}
782   flg  = PETSC_FALSE;
783   ierr = PetscOptionsBool("-snes_monitor_residual","Plot residual at each iteration","SNESMonitorResidual",flg,&flg,NULL);CHKERRQ(ierr);
784   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorResidual,0,0);CHKERRQ(ierr);}
785   flg  = PETSC_FALSE;
786   ierr = PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,NULL);CHKERRQ(ierr);
787   if (flg) {
788     PetscObject *objs;
789 
790     ierr = SNESMonitorLGCreate(0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&objs);CHKERRQ(ierr);
791     ierr = SNESMonitorSet(snes,(PetscErrorCode (*)(SNES,PetscInt,PetscReal,void*))SNESMonitorLGResidualNorm,objs,(PetscErrorCode (*)(void**))SNESMonitorLGDestroy);CHKERRQ(ierr);
792   }
793   flg  = PETSC_FALSE;
794   ierr = PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);CHKERRQ(ierr);
795   if (flg) {
796     PetscViewer ctx;
797 
798     ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
799     ierr = SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
800   }
801 
802   flg  = PETSC_FALSE;
803   ierr = PetscOptionsBool("-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",flg,&flg,NULL);CHKERRQ(ierr);
804   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorJacUpdateSpectrum,0,0);CHKERRQ(ierr);}
805 
806 
807   ierr = PetscOptionsString("-snes_monitor_fields","Monitor norm of function per field","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
808   if (flg) {
809     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
810     ierr = SNESMonitorSet(snes,SNESMonitorFields,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
811   }
812 
813   flg  = PETSC_FALSE;
814   ierr = PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);CHKERRQ(ierr);
815   if (flg) {
816     void *functx;
817     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
818     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);CHKERRQ(ierr);
819     ierr = PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");CHKERRQ(ierr);
820   }
821 
822   flg  = PETSC_FALSE;
823   ierr = PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);CHKERRQ(ierr);
824   if (flg) {
825     ierr = SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);CHKERRQ(ierr);
826   }
827 
828   flg  = PETSC_FALSE;
829   ierr = PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);CHKERRQ(ierr);
830   if (flg) {
831     DM             dm;
832     DMSNES         sdm;
833     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
834     ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
835     sdm->jacobianctx = NULL;
836     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
837     ierr = PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");CHKERRQ(ierr);
838   }
839 
840   flg  = PETSC_FALSE;
841   ierr = PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf_operator,&flg);CHKERRQ(ierr);
842   if (flg && snes->mf_operator) {
843     snes->mf_operator = PETSC_TRUE;
844     snes->mf          = PETSC_TRUE;
845   }
846   flg  = PETSC_FALSE;
847   ierr = PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf,&flg);CHKERRQ(ierr);
848   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
849   ierr = PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,0);CHKERRQ(ierr);
850 
851   flg  = PETSC_FALSE;
852   ierr = SNESGetNPCSide(snes,&pcside);CHKERRQ(ierr);
853   ierr = PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetNPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);CHKERRQ(ierr);
854   if (flg) {ierr = SNESSetNPCSide(snes,pcside);CHKERRQ(ierr);}
855 
856 #if defined(PETSC_HAVE_SAWS)
857   /*
858     Publish convergence information using SAWs
859   */
860   flg  = PETSC_FALSE;
861   ierr = PetscOptionsBool("-snes_monitor_saws","Publish SNES progress using SAWs","SNESMonitorSet",flg,&flg,NULL);CHKERRQ(ierr);
862   if (flg) {
863     void *ctx;
864     ierr = SNESMonitorSAWsCreate(snes,&ctx);CHKERRQ(ierr);
865     ierr = SNESMonitorSet(snes,SNESMonitorSAWs,ctx,SNESMonitorSAWsDestroy);CHKERRQ(ierr);
866   }
867 #endif
868 #if defined(PETSC_HAVE_SAWS)
869   {
870   PetscBool set;
871   flg  = PETSC_FALSE;
872   ierr = PetscOptionsBool("-snes_saws_block","Block for SAWs at end of SNESSolve","PetscObjectSAWsBlock",((PetscObject)snes)->amspublishblock,&flg,&set);CHKERRQ(ierr);
873   if (set) {
874     ierr = PetscObjectSAWsSetBlock((PetscObject)snes,flg);CHKERRQ(ierr);
875   }
876   }
877 #endif
878 
879   for (i = 0; i < numberofsetfromoptions; i++) {
880     ierr = (*othersetfromoptions[i])(snes);CHKERRQ(ierr);
881   }
882 
883   if (snes->ops->setfromoptions) {
884     ierr = (*snes->ops->setfromoptions)(snes);CHKERRQ(ierr);
885   }
886 
887   /* process any options handlers added with PetscObjectAddOptionsHandler() */
888   ierr = PetscObjectProcessOptionsHandlers((PetscObject)snes);CHKERRQ(ierr);
889   ierr = PetscOptionsEnd();CHKERRQ(ierr);
890 
891   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
892   ierr = KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);CHKERRQ(ierr);
893   ierr = KSPSetFromOptions(snes->ksp);CHKERRQ(ierr);
894 
895   if (!snes->linesearch) {
896     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
897   }
898   ierr = SNESLineSearchSetFromOptions(snes->linesearch);CHKERRQ(ierr);
899 
900   /* if someone has set the SNES NPC type, create it. */
901   ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
902   ierr = PetscOptionsHasName(optionsprefix, "-npc_snes_type", &pcset);CHKERRQ(ierr);
903   if (pcset && (!snes->pc)) {
904     ierr = SNESGetNPC(snes, &snes->pc);CHKERRQ(ierr);
905   }
906   PetscFunctionReturn(0);
907 }
908 
909 #undef __FUNCT__
910 #define __FUNCT__ "SNESSetComputeApplicationContext"
911 /*@C
912    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
913    the nonlinear solvers.
914 
915    Logically Collective on SNES
916 
917    Input Parameters:
918 +  snes - the SNES context
919 .  compute - function to compute the context
920 -  destroy - function to destroy the context
921 
922    Level: intermediate
923 
924    Notes:
925    This function is currently not available from Fortran.
926 
927 .keywords: SNES, nonlinear, set, application, context
928 
929 .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
930 @*/
931 PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
932 {
933   PetscFunctionBegin;
934   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
935   snes->ops->usercompute = compute;
936   snes->ops->userdestroy = destroy;
937   PetscFunctionReturn(0);
938 }
939 
940 #undef __FUNCT__
941 #define __FUNCT__ "SNESSetApplicationContext"
942 /*@
943    SNESSetApplicationContext - Sets the optional user-defined context for
944    the nonlinear solvers.
945 
946    Logically Collective on SNES
947 
948    Input Parameters:
949 +  snes - the SNES context
950 -  usrP - optional user context
951 
952    Level: intermediate
953 
954 .keywords: SNES, nonlinear, set, application, context
955 
956 .seealso: SNESGetApplicationContext()
957 @*/
958 PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
959 {
960   PetscErrorCode ierr;
961   KSP            ksp;
962 
963   PetscFunctionBegin;
964   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
965   ierr       = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
966   ierr       = KSPSetApplicationContext(ksp,usrP);CHKERRQ(ierr);
967   snes->user = usrP;
968   PetscFunctionReturn(0);
969 }
970 
971 #undef __FUNCT__
972 #define __FUNCT__ "SNESGetApplicationContext"
973 /*@
974    SNESGetApplicationContext - Gets the user-defined context for the
975    nonlinear solvers.
976 
977    Not Collective
978 
979    Input Parameter:
980 .  snes - SNES context
981 
982    Output Parameter:
983 .  usrP - user context
984 
985    Level: intermediate
986 
987 .keywords: SNES, nonlinear, get, application, context
988 
989 .seealso: SNESSetApplicationContext()
990 @*/
991 PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
992 {
993   PetscFunctionBegin;
994   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
995   *(void**)usrP = snes->user;
996   PetscFunctionReturn(0);
997 }
998 
999 #undef __FUNCT__
1000 #define __FUNCT__ "SNESGetIterationNumber"
1001 /*@
1002    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
1003    at this time.
1004 
1005    Not Collective
1006 
1007    Input Parameter:
1008 .  snes - SNES context
1009 
1010    Output Parameter:
1011 .  iter - iteration number
1012 
1013    Notes:
1014    For example, during the computation of iteration 2 this would return 1.
1015 
1016    This is useful for using lagged Jacobians (where one does not recompute the
1017    Jacobian at each SNES iteration). For example, the code
1018 .vb
1019       ierr = SNESGetIterationNumber(snes,&it);
1020       if (!(it % 2)) {
1021         [compute Jacobian here]
1022       }
1023 .ve
1024    can be used in your ComputeJacobian() function to cause the Jacobian to be
1025    recomputed every second SNES iteration.
1026 
1027    Level: intermediate
1028 
1029 .keywords: SNES, nonlinear, get, iteration, number,
1030 
1031 .seealso:   SNESGetLinearSolveIterations()
1032 @*/
1033 PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
1034 {
1035   PetscFunctionBegin;
1036   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1037   PetscValidIntPointer(iter,2);
1038   *iter = snes->iter;
1039   PetscFunctionReturn(0);
1040 }
1041 
1042 #undef __FUNCT__
1043 #define __FUNCT__ "SNESSetIterationNumber"
1044 /*@
1045    SNESSetIterationNumber - Sets the current iteration number.
1046 
1047    Not Collective
1048 
1049    Input Parameter:
1050 .  snes - SNES context
1051 .  iter - iteration number
1052 
1053    Level: developer
1054 
1055 .keywords: SNES, nonlinear, set, iteration, number,
1056 
1057 .seealso:   SNESGetLinearSolveIterations()
1058 @*/
1059 PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
1060 {
1061   PetscErrorCode ierr;
1062 
1063   PetscFunctionBegin;
1064   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1065   ierr       = PetscObjectSAWsTakeAccess((PetscObject)snes);CHKERRQ(ierr);
1066   snes->iter = iter;
1067   ierr       = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr);
1068   PetscFunctionReturn(0);
1069 }
1070 
1071 #undef __FUNCT__
1072 #define __FUNCT__ "SNESGetNonlinearStepFailures"
1073 /*@
1074    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1075    attempted by the nonlinear solver.
1076 
1077    Not Collective
1078 
1079    Input Parameter:
1080 .  snes - SNES context
1081 
1082    Output Parameter:
1083 .  nfails - number of unsuccessful steps attempted
1084 
1085    Notes:
1086    This counter is reset to zero for each successive call to SNESSolve().
1087 
1088    Level: intermediate
1089 
1090 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1091 
1092 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1093           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
1094 @*/
1095 PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
1096 {
1097   PetscFunctionBegin;
1098   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1099   PetscValidIntPointer(nfails,2);
1100   *nfails = snes->numFailures;
1101   PetscFunctionReturn(0);
1102 }
1103 
1104 #undef __FUNCT__
1105 #define __FUNCT__ "SNESSetMaxNonlinearStepFailures"
1106 /*@
1107    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1108    attempted by the nonlinear solver before it gives up.
1109 
1110    Not Collective
1111 
1112    Input Parameters:
1113 +  snes     - SNES context
1114 -  maxFails - maximum of unsuccessful steps
1115 
1116    Level: intermediate
1117 
1118 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1119 
1120 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1121           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1122 @*/
1123 PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1124 {
1125   PetscFunctionBegin;
1126   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1127   snes->maxFailures = maxFails;
1128   PetscFunctionReturn(0);
1129 }
1130 
1131 #undef __FUNCT__
1132 #define __FUNCT__ "SNESGetMaxNonlinearStepFailures"
1133 /*@
1134    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1135    attempted by the nonlinear solver before it gives up.
1136 
1137    Not Collective
1138 
1139    Input Parameter:
1140 .  snes     - SNES context
1141 
1142    Output Parameter:
1143 .  maxFails - maximum of unsuccessful steps
1144 
1145    Level: intermediate
1146 
1147 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1148 
1149 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1150           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1151 
1152 @*/
1153 PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1154 {
1155   PetscFunctionBegin;
1156   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1157   PetscValidIntPointer(maxFails,2);
1158   *maxFails = snes->maxFailures;
1159   PetscFunctionReturn(0);
1160 }
1161 
1162 #undef __FUNCT__
1163 #define __FUNCT__ "SNESGetNumberFunctionEvals"
1164 /*@
1165    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1166      done by SNES.
1167 
1168    Not Collective
1169 
1170    Input Parameter:
1171 .  snes     - SNES context
1172 
1173    Output Parameter:
1174 .  nfuncs - number of evaluations
1175 
1176    Level: intermediate
1177 
1178    Notes: Reset every time SNESSolve is called unless SNESSetCountersReset() is used.
1179 
1180 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1181 
1182 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(), SNESSetCountersReset()
1183 @*/
1184 PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1185 {
1186   PetscFunctionBegin;
1187   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1188   PetscValidIntPointer(nfuncs,2);
1189   *nfuncs = snes->nfuncs;
1190   PetscFunctionReturn(0);
1191 }
1192 
1193 #undef __FUNCT__
1194 #define __FUNCT__ "SNESGetLinearSolveFailures"
1195 /*@
1196    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1197    linear solvers.
1198 
1199    Not Collective
1200 
1201    Input Parameter:
1202 .  snes - SNES context
1203 
1204    Output Parameter:
1205 .  nfails - number of failed solves
1206 
1207    Notes:
1208    This counter is reset to zero for each successive call to SNESSolve().
1209 
1210    Level: intermediate
1211 
1212 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1213 
1214 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1215 @*/
1216 PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
1217 {
1218   PetscFunctionBegin;
1219   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1220   PetscValidIntPointer(nfails,2);
1221   *nfails = snes->numLinearSolveFailures;
1222   PetscFunctionReturn(0);
1223 }
1224 
1225 #undef __FUNCT__
1226 #define __FUNCT__ "SNESSetMaxLinearSolveFailures"
1227 /*@
1228    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1229    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE
1230 
1231    Logically Collective on SNES
1232 
1233    Input Parameters:
1234 +  snes     - SNES context
1235 -  maxFails - maximum allowed linear solve failures
1236 
1237    Level: intermediate
1238 
1239    Notes: By default this is 0; that is SNES returns on the first failed linear solve
1240 
1241 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1242 
1243 .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1244 @*/
1245 PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1246 {
1247   PetscFunctionBegin;
1248   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1249   PetscValidLogicalCollectiveInt(snes,maxFails,2);
1250   snes->maxLinearSolveFailures = maxFails;
1251   PetscFunctionReturn(0);
1252 }
1253 
1254 #undef __FUNCT__
1255 #define __FUNCT__ "SNESGetMaxLinearSolveFailures"
1256 /*@
1257    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1258      are allowed before SNES terminates
1259 
1260    Not Collective
1261 
1262    Input Parameter:
1263 .  snes     - SNES context
1264 
1265    Output Parameter:
1266 .  maxFails - maximum of unsuccessful solves allowed
1267 
1268    Level: intermediate
1269 
1270    Notes: By default this is 1; that is SNES returns on the first failed linear solve
1271 
1272 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1273 
1274 .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1275 @*/
1276 PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1277 {
1278   PetscFunctionBegin;
1279   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1280   PetscValidIntPointer(maxFails,2);
1281   *maxFails = snes->maxLinearSolveFailures;
1282   PetscFunctionReturn(0);
1283 }
1284 
1285 #undef __FUNCT__
1286 #define __FUNCT__ "SNESGetLinearSolveIterations"
1287 /*@
1288    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1289    used by the nonlinear solver.
1290 
1291    Not Collective
1292 
1293    Input Parameter:
1294 .  snes - SNES context
1295 
1296    Output Parameter:
1297 .  lits - number of linear iterations
1298 
1299    Notes:
1300    This counter is reset to zero for each successive call to SNESSolve() unless SNESSetCountersReset() is used.
1301 
1302    Level: intermediate
1303 
1304 .keywords: SNES, nonlinear, get, number, linear, iterations
1305 
1306 .seealso:  SNESGetIterationNumber(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
1307 @*/
1308 PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
1309 {
1310   PetscFunctionBegin;
1311   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1312   PetscValidIntPointer(lits,2);
1313   *lits = snes->linear_its;
1314   PetscFunctionReturn(0);
1315 }
1316 
1317 #undef __FUNCT__
1318 #define __FUNCT__ "SNESSetCountersReset"
1319 /*@
1320    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1321    are reset every time SNESSolve() is called.
1322 
1323    Logically Collective on SNES
1324 
1325    Input Parameter:
1326 +  snes - SNES context
1327 -  reset - whether to reset the counters or not
1328 
1329    Notes:
1330    This is automatically called with FALSE
1331 
1332    Level: developer
1333 
1334 .keywords: SNES, nonlinear, set, reset, number, linear, iterations
1335 
1336 .seealso:  SNESGetNumberFunctionEvals(), SNESGetNumberLinearSolveIterations(), SNESGetNPC()
1337 @*/
1338 PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
1339 {
1340   PetscFunctionBegin;
1341   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1342   PetscValidLogicalCollectiveBool(snes,reset,2);
1343   snes->counters_reset = reset;
1344   PetscFunctionReturn(0);
1345 }
1346 
1347 
1348 #undef __FUNCT__
1349 #define __FUNCT__ "SNESSetKSP"
1350 /*@
1351    SNESSetKSP - Sets a KSP context for the SNES object to use
1352 
1353    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm
1354 
1355    Input Parameters:
1356 +  snes - the SNES context
1357 -  ksp - the KSP context
1358 
1359    Notes:
1360    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1361    so this routine is rarely needed.
1362 
1363    The KSP object that is already in the SNES object has its reference count
1364    decreased by one.
1365 
1366    Level: developer
1367 
1368 .keywords: SNES, nonlinear, get, KSP, context
1369 
1370 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1371 @*/
1372 PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1373 {
1374   PetscErrorCode ierr;
1375 
1376   PetscFunctionBegin;
1377   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1378   PetscValidHeaderSpecific(ksp,KSP_CLASSID,2);
1379   PetscCheckSameComm(snes,1,ksp,2);
1380   ierr = PetscObjectReference((PetscObject)ksp);CHKERRQ(ierr);
1381   if (snes->ksp) {ierr = PetscObjectDereference((PetscObject)snes->ksp);CHKERRQ(ierr);}
1382   snes->ksp = ksp;
1383   PetscFunctionReturn(0);
1384 }
1385 
1386 /* -----------------------------------------------------------*/
1387 #undef __FUNCT__
1388 #define __FUNCT__ "SNESCreate"
1389 /*@
1390    SNESCreate - Creates a nonlinear solver context.
1391 
1392    Collective on MPI_Comm
1393 
1394    Input Parameters:
1395 .  comm - MPI communicator
1396 
1397    Output Parameter:
1398 .  outsnes - the new SNES context
1399 
1400    Options Database Keys:
1401 +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1402                and no preconditioning matrix
1403 .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1404                products, and a user-provided preconditioning matrix
1405                as set by SNESSetJacobian()
1406 -   -snes_fd - Uses (slow!) finite differences to compute Jacobian
1407 
1408    Level: beginner
1409 
1410 .keywords: SNES, nonlinear, create, context
1411 
1412 .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()
1413 
1414 @*/
1415 PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1416 {
1417   PetscErrorCode ierr;
1418   SNES           snes;
1419   SNESKSPEW      *kctx;
1420 
1421   PetscFunctionBegin;
1422   PetscValidPointer(outsnes,2);
1423   *outsnes = NULL;
1424   ierr = SNESInitializePackage();CHKERRQ(ierr);
1425 
1426   ierr = PetscHeaderCreate(snes,_p_SNES,struct _SNESOps,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);CHKERRQ(ierr);
1427 
1428   snes->ops->converged    = SNESConvergedDefault;
1429   snes->usesksp           = PETSC_TRUE;
1430   snes->tolerancesset     = PETSC_FALSE;
1431   snes->max_its           = 50;
1432   snes->max_funcs         = 10000;
1433   snes->norm              = 0.0;
1434   snes->normschedule      = SNES_NORM_ALWAYS;
1435   snes->functype          = SNES_FUNCTION_DEFAULT;
1436 #if defined(PETSC_USE_REAL_SINGLE)
1437   snes->rtol              = 1.e-5;
1438 #else
1439   snes->rtol              = 1.e-8;
1440 #endif
1441   snes->ttol              = 0.0;
1442 #if defined(PETSC_USE_REAL_SINGLE)
1443   snes->abstol            = 1.e-25;
1444 #else
1445   snes->abstol            = 1.e-50;
1446 #endif
1447   snes->stol              = 1.e-8;
1448 #if defined(PETSC_USE_REAL_SINGLE)
1449   snes->deltatol          = 1.e-6;
1450 #else
1451   snes->deltatol          = 1.e-12;
1452 #endif
1453   snes->nfuncs            = 0;
1454   snes->numFailures       = 0;
1455   snes->maxFailures       = 1;
1456   snes->linear_its        = 0;
1457   snes->lagjacobian       = 1;
1458   snes->jac_iter          = 0;
1459   snes->lagjac_persist    = PETSC_FALSE;
1460   snes->lagpreconditioner = 1;
1461   snes->pre_iter          = 0;
1462   snes->lagpre_persist    = PETSC_FALSE;
1463   snes->numbermonitors    = 0;
1464   snes->data              = 0;
1465   snes->setupcalled       = PETSC_FALSE;
1466   snes->ksp_ewconv        = PETSC_FALSE;
1467   snes->nwork             = 0;
1468   snes->work              = 0;
1469   snes->nvwork            = 0;
1470   snes->vwork             = 0;
1471   snes->conv_hist_len     = 0;
1472   snes->conv_hist_max     = 0;
1473   snes->conv_hist         = NULL;
1474   snes->conv_hist_its     = NULL;
1475   snes->conv_hist_reset   = PETSC_TRUE;
1476   snes->counters_reset    = PETSC_TRUE;
1477   snes->vec_func_init_set = PETSC_FALSE;
1478   snes->reason            = SNES_CONVERGED_ITERATING;
1479   snes->pcside            = PC_RIGHT;
1480 
1481   snes->mf          = PETSC_FALSE;
1482   snes->mf_operator = PETSC_FALSE;
1483   snes->mf_version  = 1;
1484 
1485   snes->numLinearSolveFailures = 0;
1486   snes->maxLinearSolveFailures = 1;
1487 
1488   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1489   ierr = PetscNewLog(snes,&kctx);CHKERRQ(ierr);
1490 
1491   snes->kspconvctx  = (void*)kctx;
1492   kctx->version     = 2;
1493   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1494                              this was too large for some test cases */
1495   kctx->rtol_last   = 0.0;
1496   kctx->rtol_max    = .9;
1497   kctx->gamma       = 1.0;
1498   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1499   kctx->alpha2      = kctx->alpha;
1500   kctx->threshold   = .1;
1501   kctx->lresid_last = 0.0;
1502   kctx->norm_last   = 0.0;
1503 
1504   *outsnes = snes;
1505   PetscFunctionReturn(0);
1506 }
1507 
1508 /*MC
1509     SNESFunction - functional form used to convey the nonlinear function to be solved by SNES
1510 
1511      Synopsis:
1512      #include <petscsnes.h>
1513      SNESFunction(SNES snes,Vec x,Vec f,void *ctx);
1514 
1515      Input Parameters:
1516 +     snes - the SNES context
1517 .     x    - state at which to evaluate residual
1518 -     ctx     - optional user-defined function context, passed in with SNESSetFunction()
1519 
1520      Output Parameter:
1521 .     f  - vector to put residual (function value)
1522 
1523    Level: intermediate
1524 
1525 .seealso:   SNESSetFunction(), SNESGetFunction()
1526 M*/
1527 
1528 #undef __FUNCT__
1529 #define __FUNCT__ "SNESSetFunction"
1530 /*@C
1531    SNESSetFunction - Sets the function evaluation routine and function
1532    vector for use by the SNES routines in solving systems of nonlinear
1533    equations.
1534 
1535    Logically Collective on SNES
1536 
1537    Input Parameters:
1538 +  snes - the SNES context
1539 .  r - vector to store function value
1540 .  f - function evaluation routine; see SNESFunction for calling sequence details
1541 -  ctx - [optional] user-defined context for private data for the
1542          function evaluation routine (may be NULL)
1543 
1544    Notes:
1545    The Newton-like methods typically solve linear systems of the form
1546 $      f'(x) x = -f(x),
1547    where f'(x) denotes the Jacobian matrix and f(x) is the function.
1548 
1549    Level: beginner
1550 
1551 .keywords: SNES, nonlinear, set, function
1552 
1553 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
1554 @*/
1555 PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1556 {
1557   PetscErrorCode ierr;
1558   DM             dm;
1559 
1560   PetscFunctionBegin;
1561   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1562   if (r) {
1563     PetscValidHeaderSpecific(r,VEC_CLASSID,2);
1564     PetscCheckSameComm(snes,1,r,2);
1565     ierr = PetscObjectReference((PetscObject)r);CHKERRQ(ierr);
1566     ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
1567 
1568     snes->vec_func = r;
1569   }
1570   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1571   ierr = DMSNESSetFunction(dm,f,ctx);CHKERRQ(ierr);
1572   PetscFunctionReturn(0);
1573 }
1574 
1575 
1576 #undef __FUNCT__
1577 #define __FUNCT__ "SNESSetInitialFunction"
1578 /*@C
1579    SNESSetInitialFunction - Sets the function vector to be used as the
1580    function norm at the initialization of the method.  In some
1581    instances, the user has precomputed the function before calling
1582    SNESSolve.  This function allows one to avoid a redundant call
1583    to SNESComputeFunction in that case.
1584 
1585    Logically Collective on SNES
1586 
1587    Input Parameters:
1588 +  snes - the SNES context
1589 -  f - vector to store function value
1590 
1591    Notes:
1592    This should not be modified during the solution procedure.
1593 
1594    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1595 
1596    Level: developer
1597 
1598 .keywords: SNES, nonlinear, set, function
1599 
1600 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1601 @*/
1602 PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1603 {
1604   PetscErrorCode ierr;
1605   Vec            vec_func;
1606 
1607   PetscFunctionBegin;
1608   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1609   PetscValidHeaderSpecific(f,VEC_CLASSID,2);
1610   PetscCheckSameComm(snes,1,f,2);
1611   if (snes->pcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
1612     snes->vec_func_init_set = PETSC_FALSE;
1613     PetscFunctionReturn(0);
1614   }
1615   ierr = SNESGetFunction(snes,&vec_func,NULL,NULL);CHKERRQ(ierr);
1616   ierr = VecCopy(f, vec_func);CHKERRQ(ierr);
1617 
1618   snes->vec_func_init_set = PETSC_TRUE;
1619   PetscFunctionReturn(0);
1620 }
1621 
1622 #undef __FUNCT__
1623 #define __FUNCT__ "SNESSetNormSchedule"
1624 /*@
1625    SNESSetNormSchedule - Sets the SNESNormSchedule used in covergence and monitoring
1626    of the SNES method.
1627 
1628    Logically Collective on SNES
1629 
1630    Input Parameters:
1631 +  snes - the SNES context
1632 -  normschedule - the frequency of norm computation
1633 
1634    Options Database Key:
1635 .  -snes_norm_schedule <none, always, initialonly, finalonly, initalfinalonly>
1636 
1637    Notes:
1638    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1639    of the nonlinear function and the taking of its norm at every iteration to
1640    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1641    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1642    may either be monitored for convergence or not.  As these are often used as nonlinear
1643    preconditioners, monitoring the norm of their error is not a useful enterprise within
1644    their solution.
1645 
1646    Level: developer
1647 
1648 .keywords: SNES, nonlinear, set, function, norm, type
1649 
1650 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1651 @*/
1652 PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
1653 {
1654   PetscFunctionBegin;
1655   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1656   snes->normschedule = normschedule;
1657   PetscFunctionReturn(0);
1658 }
1659 
1660 
1661 #undef __FUNCT__
1662 #define __FUNCT__ "SNESGetNormSchedule"
1663 /*@
1664    SNESGetNormSchedule - Gets the SNESNormSchedule used in covergence and monitoring
1665    of the SNES method.
1666 
1667    Logically Collective on SNES
1668 
1669    Input Parameters:
1670 +  snes - the SNES context
1671 -  normschedule - the type of the norm used
1672 
1673    Level: advanced
1674 
1675 .keywords: SNES, nonlinear, set, function, norm, type
1676 
1677 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1678 @*/
1679 PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
1680 {
1681   PetscFunctionBegin;
1682   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1683   *normschedule = snes->normschedule;
1684   PetscFunctionReturn(0);
1685 }
1686 
1687 
1688 #undef __FUNCT__
1689 #define __FUNCT__ "SNESSetFunctionType"
1690 /*@C
1691    SNESSetFunctionType - Sets the SNESNormSchedule used in covergence and monitoring
1692    of the SNES method.
1693 
1694    Logically Collective on SNES
1695 
1696    Input Parameters:
1697 +  snes - the SNES context
1698 -  normschedule - the frequency of norm computation
1699 
1700    Notes:
1701    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1702    of the nonlinear function and the taking of its norm at every iteration to
1703    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1704    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1705    may either be monitored for convergence or not.  As these are often used as nonlinear
1706    preconditioners, monitoring the norm of their error is not a useful enterprise within
1707    their solution.
1708 
1709    Level: developer
1710 
1711 .keywords: SNES, nonlinear, set, function, norm, type
1712 
1713 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1714 @*/
1715 PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
1716 {
1717   PetscFunctionBegin;
1718   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1719   snes->functype = type;
1720   PetscFunctionReturn(0);
1721 }
1722 
1723 
1724 #undef __FUNCT__
1725 #define __FUNCT__ "SNESGetFunctionType"
1726 /*@C
1727    SNESGetFunctionType - Gets the SNESNormSchedule used in covergence and monitoring
1728    of the SNES method.
1729 
1730    Logically Collective on SNES
1731 
1732    Input Parameters:
1733 +  snes - the SNES context
1734 -  normschedule - the type of the norm used
1735 
1736    Level: advanced
1737 
1738 .keywords: SNES, nonlinear, set, function, norm, type
1739 
1740 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1741 @*/
1742 PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
1743 {
1744   PetscFunctionBegin;
1745   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1746   *type = snes->functype;
1747   PetscFunctionReturn(0);
1748 }
1749 
1750 /*MC
1751     SNESNGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function
1752 
1753      Synopsis:
1754      #include <petscsnes.h>
1755 $    SNESNGSFunction(SNES snes,Vec x,Vec b,void *ctx);
1756 
1757 +  X   - solution vector
1758 .  B   - RHS vector
1759 -  ctx - optional user-defined Gauss-Seidel context
1760 
1761    Level: intermediate
1762 
1763 .seealso:   SNESSetNGS(), SNESGetNGS()
1764 M*/
1765 
1766 #undef __FUNCT__
1767 #define __FUNCT__ "SNESSetNGS"
1768 /*@C
1769    SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
1770    use with composed nonlinear solvers.
1771 
1772    Input Parameters:
1773 +  snes   - the SNES context
1774 .  f - function evaluation routine to apply Gauss-Seidel see SNESNGSFunction
1775 -  ctx    - [optional] user-defined context for private data for the
1776             smoother evaluation routine (may be NULL)
1777 
1778    Notes:
1779    The NGS routines are used by the composed nonlinear solver to generate
1780     a problem appropriate update to the solution, particularly FAS.
1781 
1782    Level: intermediate
1783 
1784 .keywords: SNES, nonlinear, set, Gauss-Seidel
1785 
1786 .seealso: SNESGetFunction(), SNESComputeNGS()
1787 @*/
1788 PetscErrorCode SNESSetNGS(SNES snes,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1789 {
1790   PetscErrorCode ierr;
1791   DM             dm;
1792 
1793   PetscFunctionBegin;
1794   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1795   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1796   ierr = DMSNESSetNGS(dm,f,ctx);CHKERRQ(ierr);
1797   PetscFunctionReturn(0);
1798 }
1799 
1800 #undef __FUNCT__
1801 #define __FUNCT__ "SNESPicardComputeFunction"
1802 PETSC_EXTERN PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
1803 {
1804   PetscErrorCode ierr;
1805   DM             dm;
1806   DMSNES         sdm;
1807 
1808   PetscFunctionBegin;
1809   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1810   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
1811   /*  A(x)*x - b(x) */
1812   if (sdm->ops->computepfunction) {
1813     ierr = (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);CHKERRQ(ierr);
1814   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");
1815 
1816   if (sdm->ops->computepjacobian) {
1817     ierr = (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);CHKERRQ(ierr);
1818   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard matrix.");
1819   ierr = VecScale(f,-1.0);CHKERRQ(ierr);
1820   ierr = MatMultAdd(snes->jacobian,x,f,f);CHKERRQ(ierr);
1821   PetscFunctionReturn(0);
1822 }
1823 
1824 #undef __FUNCT__
1825 #define __FUNCT__ "SNESPicardComputeJacobian"
1826 PETSC_EXTERN PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
1827 {
1828   PetscFunctionBegin;
1829   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
1830   PetscFunctionReturn(0);
1831 }
1832 
1833 #undef __FUNCT__
1834 #define __FUNCT__ "SNESSetPicard"
1835 /*@C
1836    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)
1837 
1838    Logically Collective on SNES
1839 
1840    Input Parameters:
1841 +  snes - the SNES context
1842 .  r - vector to store function value
1843 .  b - function evaluation routine
1844 .  Amat - matrix with which A(x) x - b(x) is to be computed
1845 .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
1846 .  J  - function to compute matrix value
1847 -  ctx - [optional] user-defined context for private data for the
1848          function evaluation routine (may be NULL)
1849 
1850    Notes:
1851     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
1852     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.
1853 
1854     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both
1855 
1856 $     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}
1857 $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.
1858 
1859      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.
1860 
1861    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
1862    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)
1863 
1864    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
1865    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
1866    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).
1867 
1868    Level: intermediate
1869 
1870 .keywords: SNES, nonlinear, set, function
1871 
1872 .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard()
1873 @*/
1874 PetscErrorCode  SNESSetPicard(SNES snes,Vec r,PetscErrorCode (*b)(SNES,Vec,Vec,void*),Mat Amat, Mat Pmat, PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
1875 {
1876   PetscErrorCode ierr;
1877   DM             dm;
1878 
1879   PetscFunctionBegin;
1880   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1881   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
1882   ierr = DMSNESSetPicard(dm,b,J,ctx);CHKERRQ(ierr);
1883   ierr = SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);CHKERRQ(ierr);
1884   ierr = SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);CHKERRQ(ierr);
1885   PetscFunctionReturn(0);
1886 }
1887 
1888 #undef __FUNCT__
1889 #define __FUNCT__ "SNESGetPicard"
1890 /*@C
1891    SNESGetPicard - Returns the context for the Picard iteration
1892 
1893    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
1894 
1895    Input Parameter:
1896 .  snes - the SNES context
1897 
1898    Output Parameter:
1899 +  r - the function (or NULL)
1900 .  f - the function (or NULL); see SNESFunction for calling sequence details
1901 .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
1902 .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
1903 .  J - the function for matrix evaluation (or NULL); see SNESJacobianFunction for calling sequence details
1904 -  ctx - the function context (or NULL)
1905 
1906    Level: advanced
1907 
1908 .keywords: SNES, nonlinear, get, function
1909 
1910 .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
1911 @*/
1912 PetscErrorCode  SNESGetPicard(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),Mat *Amat, Mat *Pmat, PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
1913 {
1914   PetscErrorCode ierr;
1915   DM             dm;
1916 
1917   PetscFunctionBegin;
1918   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1919   ierr = SNESGetFunction(snes,r,NULL,NULL);CHKERRQ(ierr);
1920   ierr = SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);CHKERRQ(ierr);
1921   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1922   ierr = DMSNESGetPicard(dm,f,J,ctx);CHKERRQ(ierr);
1923   PetscFunctionReturn(0);
1924 }
1925 
1926 #undef __FUNCT__
1927 #define __FUNCT__ "SNESSetComputeInitialGuess"
1928 /*@C
1929    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem
1930 
1931    Logically Collective on SNES
1932 
1933    Input Parameters:
1934 +  snes - the SNES context
1935 .  func - function evaluation routine
1936 -  ctx - [optional] user-defined context for private data for the
1937          function evaluation routine (may be NULL)
1938 
1939    Calling sequence of func:
1940 $    func (SNES snes,Vec x,void *ctx);
1941 
1942 .  f - function vector
1943 -  ctx - optional user-defined function context
1944 
1945    Level: intermediate
1946 
1947 .keywords: SNES, nonlinear, set, function
1948 
1949 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
1950 @*/
1951 PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
1952 {
1953   PetscFunctionBegin;
1954   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1955   if (func) snes->ops->computeinitialguess = func;
1956   if (ctx)  snes->initialguessP            = ctx;
1957   PetscFunctionReturn(0);
1958 }
1959 
1960 /* --------------------------------------------------------------- */
1961 #undef __FUNCT__
1962 #define __FUNCT__ "SNESGetRhs"
1963 /*@C
1964    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
1965    it assumes a zero right hand side.
1966 
1967    Logically Collective on SNES
1968 
1969    Input Parameter:
1970 .  snes - the SNES context
1971 
1972    Output Parameter:
1973 .  rhs - the right hand side vector or NULL if the right hand side vector is null
1974 
1975    Level: intermediate
1976 
1977 .keywords: SNES, nonlinear, get, function, right hand side
1978 
1979 .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
1980 @*/
1981 PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
1982 {
1983   PetscFunctionBegin;
1984   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1985   PetscValidPointer(rhs,2);
1986   *rhs = snes->vec_rhs;
1987   PetscFunctionReturn(0);
1988 }
1989 
1990 #undef __FUNCT__
1991 #define __FUNCT__ "SNESComputeFunction"
1992 /*@
1993    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().
1994 
1995    Collective on SNES
1996 
1997    Input Parameters:
1998 +  snes - the SNES context
1999 -  x - input vector
2000 
2001    Output Parameter:
2002 .  y - function vector, as set by SNESSetFunction()
2003 
2004    Notes:
2005    SNESComputeFunction() is typically used within nonlinear solvers
2006    implementations, so most users would not generally call this routine
2007    themselves.
2008 
2009    Level: developer
2010 
2011 .keywords: SNES, nonlinear, compute, function
2012 
2013 .seealso: SNESSetFunction(), SNESGetFunction()
2014 @*/
2015 PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
2016 {
2017   PetscErrorCode ierr;
2018   DM             dm;
2019   DMSNES         sdm;
2020 
2021   PetscFunctionBegin;
2022   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2023   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2024   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
2025   PetscCheckSameComm(snes,1,x,2);
2026   PetscCheckSameComm(snes,1,y,3);
2027   ierr = VecValidValues(x,2,PETSC_TRUE);CHKERRQ(ierr);
2028 
2029   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2030   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2031   if (sdm->ops->computefunction) {
2032     ierr = PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2033     PetscStackPush("SNES user function");
2034     ierr = (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);CHKERRQ(ierr);
2035     PetscStackPop;
2036     ierr = PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2037   } else if (snes->vec_rhs) {
2038     ierr = MatMult(snes->jacobian, x, y);CHKERRQ(ierr);
2039   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2040   if (snes->vec_rhs) {
2041     ierr = VecAXPY(y,-1.0,snes->vec_rhs);CHKERRQ(ierr);
2042   }
2043   snes->nfuncs++;
2044   ierr = VecValidValues(y,3,PETSC_FALSE);CHKERRQ(ierr);
2045   PetscFunctionReturn(0);
2046 }
2047 
2048 #undef __FUNCT__
2049 #define __FUNCT__ "SNESComputeNGS"
2050 /*@
2051    SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  SNESSetNGS().
2052 
2053    Collective on SNES
2054 
2055    Input Parameters:
2056 +  snes - the SNES context
2057 .  x - input vector
2058 -  b - rhs vector
2059 
2060    Output Parameter:
2061 .  x - new solution vector
2062 
2063    Notes:
2064    SNESComputeNGS() is typically used within composed nonlinear solver
2065    implementations, so most users would not generally call this routine
2066    themselves.
2067 
2068    Level: developer
2069 
2070 .keywords: SNES, nonlinear, compute, function
2071 
2072 .seealso: SNESSetNGS(), SNESComputeFunction()
2073 @*/
2074 PetscErrorCode  SNESComputeNGS(SNES snes,Vec b,Vec x)
2075 {
2076   PetscErrorCode ierr;
2077   DM             dm;
2078   DMSNES         sdm;
2079 
2080   PetscFunctionBegin;
2081   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2082   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2083   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,3);
2084   PetscCheckSameComm(snes,1,x,2);
2085   if (b) PetscCheckSameComm(snes,1,b,3);
2086   if (b) {ierr = VecValidValues(b,2,PETSC_TRUE);CHKERRQ(ierr);}
2087   ierr = PetscLogEventBegin(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2088   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2089   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2090   if (sdm->ops->computegs) {
2091     PetscStackPush("SNES user NGS");
2092     ierr = (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);CHKERRQ(ierr);
2093     PetscStackPop;
2094   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
2095   ierr = PetscLogEventEnd(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2096   ierr = VecValidValues(x,3,PETSC_FALSE);CHKERRQ(ierr);
2097   PetscFunctionReturn(0);
2098 }
2099 
2100 #undef __FUNCT__
2101 #define __FUNCT__ "SNESComputeJacobian"
2102 /*@
2103    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().
2104 
2105    Collective on SNES and Mat
2106 
2107    Input Parameters:
2108 +  snes - the SNES context
2109 -  x - input vector
2110 
2111    Output Parameters:
2112 +  A - Jacobian matrix
2113 -  B - optional preconditioning matrix
2114 
2115   Options Database Keys:
2116 +    -snes_lag_preconditioner <lag>
2117 .    -snes_lag_jacobian <lag>
2118 .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2119 .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2120 .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2121 .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2122 .    -snes_compare_coloring - Compute the finite differece Jacobian using coloring and display norms of difference
2123 .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
2124 .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2125 .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2126 .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2127 .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
2128 -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences
2129 
2130 
2131    Notes:
2132    Most users should not need to explicitly call this routine, as it
2133    is used internally within the nonlinear solvers.
2134 
2135    Level: developer
2136 
2137 .keywords: SNES, compute, Jacobian, matrix
2138 
2139 .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2140 @*/
2141 PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat A,Mat B)
2142 {
2143   PetscErrorCode ierr;
2144   PetscBool      flag;
2145   DM             dm;
2146   DMSNES         sdm;
2147   KSP            ksp;
2148 
2149   PetscFunctionBegin;
2150   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2151   PetscValidHeaderSpecific(X,VEC_CLASSID,2);
2152   PetscCheckSameComm(snes,1,X,2);
2153   ierr = VecValidValues(X,2,PETSC_TRUE);CHKERRQ(ierr);
2154   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2155   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2156 
2157   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");
2158 
2159   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */
2160 
2161   if (snes->lagjacobian == -2) {
2162     snes->lagjacobian = -1;
2163 
2164     ierr = PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");CHKERRQ(ierr);
2165   } else if (snes->lagjacobian == -1) {
2166     ierr = PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");CHKERRQ(ierr);
2167     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2168     if (flag) {
2169       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2170       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2171     }
2172     PetscFunctionReturn(0);
2173   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2174     ierr = PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);CHKERRQ(ierr);
2175     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2176     if (flag) {
2177       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2178       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2179     }
2180     PetscFunctionReturn(0);
2181   }
2182   if (snes->pc && snes->pcside == PC_LEFT) {
2183       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2184       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2185       PetscFunctionReturn(0);
2186   }
2187 
2188   ierr = PetscLogEventBegin(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2189 
2190   PetscStackPush("SNES user Jacobian function");
2191   ierr = (*sdm->ops->computejacobian)(snes,X,A,B,sdm->jacobianctx);CHKERRQ(ierr);
2192   PetscStackPop;
2193 
2194   ierr = PetscLogEventEnd(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2195 
2196   /* the next line ensures that snes->ksp exists */
2197   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
2198   if (snes->lagpreconditioner == -2) {
2199     ierr = PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");CHKERRQ(ierr);
2200     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2201     snes->lagpreconditioner = -1;
2202   } else if (snes->lagpreconditioner == -1) {
2203     ierr = PetscInfo(snes,"Reusing preconditioner because lag is -1\n");CHKERRQ(ierr);
2204     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2205   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2206     ierr = PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);CHKERRQ(ierr);
2207     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2208   } else {
2209     ierr = PetscInfo(snes,"Rebuilding preconditioner\n");CHKERRQ(ierr);
2210     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2211   }
2212 
2213   /* make sure user returned a correct Jacobian and preconditioner */
2214   /* PetscValidHeaderSpecific(A,MAT_CLASSID,3);
2215     PetscValidHeaderSpecific(B,MAT_CLASSID,4);   */
2216   {
2217     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2218     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit",&flag,NULL);CHKERRQ(ierr);
2219     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",&flag_draw,NULL);CHKERRQ(ierr);
2220     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2221     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_operator",&flag_operator,NULL);CHKERRQ(ierr);
2222     if (flag || flag_draw || flag_contour) {
2223       Mat          Bexp_mine = NULL,Bexp,FDexp;
2224       PetscViewer  vdraw,vstdout;
2225       PetscBool    flg;
2226       if (flag_operator) {
2227         ierr = MatComputeExplicitOperator(A,&Bexp_mine);CHKERRQ(ierr);
2228         Bexp = Bexp_mine;
2229       } else {
2230         /* See if the preconditioning matrix can be viewed and added directly */
2231         ierr = PetscObjectTypeCompareAny((PetscObject)B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");CHKERRQ(ierr);
2232         if (flg) Bexp = B;
2233         else {
2234           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2235           ierr = MatComputeExplicitOperator(B,&Bexp_mine);CHKERRQ(ierr);
2236           Bexp = Bexp_mine;
2237         }
2238       }
2239       ierr = MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);CHKERRQ(ierr);
2240       ierr = SNESComputeJacobianDefault(snes,X,FDexp,FDexp,NULL);CHKERRQ(ierr);
2241       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2242       if (flag_draw || flag_contour) {
2243         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2244         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2245       } else vdraw = NULL;
2246       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");CHKERRQ(ierr);
2247       if (flag) {ierr = MatView(Bexp,vstdout);CHKERRQ(ierr);}
2248       if (vdraw) {ierr = MatView(Bexp,vdraw);CHKERRQ(ierr);}
2249       ierr = PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");CHKERRQ(ierr);
2250       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2251       if (vdraw) {ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);}
2252       ierr = MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2253       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");CHKERRQ(ierr);
2254       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2255       if (vdraw) {              /* Always use contour for the difference */
2256         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2257         ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);
2258         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2259       }
2260       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2261       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2262       ierr = MatDestroy(&Bexp_mine);CHKERRQ(ierr);
2263       ierr = MatDestroy(&FDexp);CHKERRQ(ierr);
2264     }
2265   }
2266   {
2267     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2268     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2269     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring",&flag,NULL);CHKERRQ(ierr);
2270     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_display",&flag_display,NULL);CHKERRQ(ierr);
2271     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",&flag_draw,NULL);CHKERRQ(ierr);
2272     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2273     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",&flag_threshold,NULL);CHKERRQ(ierr);
2274     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);CHKERRQ(ierr);
2275     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);CHKERRQ(ierr);
2276     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2277       Mat            Bfd;
2278       PetscViewer    vdraw,vstdout;
2279       MatColoring    coloring;
2280       ISColoring     iscoloring;
2281       MatFDColoring  matfdcoloring;
2282       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2283       void           *funcctx;
2284       PetscReal      norm1,norm2,normmax;
2285 
2286       ierr = MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);CHKERRQ(ierr);
2287       ierr = MatColoringCreate(Bfd,&coloring);CHKERRQ(ierr);
2288       ierr = MatColoringSetType(coloring,MATCOLORINGSL);CHKERRQ(ierr);
2289       ierr = MatColoringSetFromOptions(coloring);CHKERRQ(ierr);
2290       ierr = MatColoringApply(coloring,&iscoloring);CHKERRQ(ierr);
2291       ierr = MatColoringDestroy(&coloring);CHKERRQ(ierr);
2292       ierr = MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);CHKERRQ(ierr);
2293       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2294       ierr = MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);CHKERRQ(ierr);
2295       ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr);
2296 
2297       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2298       ierr = SNESGetFunction(snes,NULL,&func,&funcctx);CHKERRQ(ierr);
2299       ierr = MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);CHKERRQ(ierr);
2300       ierr = PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);CHKERRQ(ierr);
2301       ierr = PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");CHKERRQ(ierr);
2302       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2303       ierr = MatFDColoringApply(Bfd,matfdcoloring,X,snes);CHKERRQ(ierr);
2304       ierr = MatFDColoringDestroy(&matfdcoloring);CHKERRQ(ierr);
2305 
2306       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2307       if (flag_draw || flag_contour) {
2308         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2309         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2310       } else vdraw = NULL;
2311       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");CHKERRQ(ierr);
2312       if (flag_display) {ierr = MatView(B,vstdout);CHKERRQ(ierr);}
2313       if (vdraw) {ierr = MatView(B,vdraw);CHKERRQ(ierr);}
2314       ierr = PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");CHKERRQ(ierr);
2315       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2316       if (vdraw) {ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);}
2317       ierr = MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2318       ierr = MatNorm(Bfd,NORM_1,&norm1);CHKERRQ(ierr);
2319       ierr = MatNorm(Bfd,NORM_FROBENIUS,&norm2);CHKERRQ(ierr);
2320       ierr = MatNorm(Bfd,NORM_MAX,&normmax);CHKERRQ(ierr);
2321       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%g normFrob=%g normmax=%g\n",(double)norm1,(double)norm2,(double)normmax);CHKERRQ(ierr);
2322       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2323       if (vdraw) {              /* Always use contour for the difference */
2324         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2325         ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);
2326         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2327       }
2328       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2329 
2330       if (flag_threshold) {
2331         PetscInt bs,rstart,rend,i;
2332         ierr = MatGetBlockSize(B,&bs);CHKERRQ(ierr);
2333         ierr = MatGetOwnershipRange(B,&rstart,&rend);CHKERRQ(ierr);
2334         for (i=rstart; i<rend; i++) {
2335           const PetscScalar *ba,*ca;
2336           const PetscInt    *bj,*cj;
2337           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2338           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2339           ierr = MatGetRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2340           ierr = MatGetRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2341           if (bn != cn) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2342           for (j=0; j<bn; j++) {
2343             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2344             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2345               maxentrycol = bj[j];
2346               maxentry    = PetscRealPart(ba[j]);
2347             }
2348             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2349               maxdiffcol = bj[j];
2350               maxdiff    = PetscRealPart(ca[j]);
2351             }
2352             if (rdiff > maxrdiff) {
2353               maxrdiffcol = bj[j];
2354               maxrdiff    = rdiff;
2355             }
2356           }
2357           if (maxrdiff > 1) {
2358             ierr = PetscViewerASCIIPrintf(vstdout,"row %D (maxentry=%g at %D, maxdiff=%g at %D, maxrdiff=%g at %D):",i,(double)maxentry,maxentrycol,(double)maxdiff,maxdiffcol,(double)maxrdiff,maxrdiffcol);CHKERRQ(ierr);
2359             for (j=0; j<bn; j++) {
2360               PetscReal rdiff;
2361               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2362               if (rdiff > 1) {
2363                 ierr = PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));CHKERRQ(ierr);
2364               }
2365             }
2366             ierr = PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);CHKERRQ(ierr);
2367           }
2368           ierr = MatRestoreRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2369           ierr = MatRestoreRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2370         }
2371       }
2372       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2373       ierr = MatDestroy(&Bfd);CHKERRQ(ierr);
2374     }
2375   }
2376   PetscFunctionReturn(0);
2377 }
2378 
2379 /*MC
2380     SNESJacobianFunction - function used to convey the nonlinear Jacobian of the function to be solved by SNES
2381 
2382      Synopsis:
2383      #include <petscsnes.h>
2384 $     SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);
2385 
2386 +  x - input vector
2387 .  Amat - the matrix that defines the (approximate) Jacobian
2388 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2389 -  ctx - [optional] user-defined Jacobian context
2390 
2391    Level: intermediate
2392 
2393 .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2394 M*/
2395 
2396 #undef __FUNCT__
2397 #define __FUNCT__ "SNESSetJacobian"
2398 /*@C
2399    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2400    location to store the matrix.
2401 
2402    Logically Collective on SNES and Mat
2403 
2404    Input Parameters:
2405 +  snes - the SNES context
2406 .  Amat - the matrix that defines the (approximate) Jacobian
2407 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2408 .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value)
2409 -  ctx - [optional] user-defined context for private data for the
2410          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)
2411 
2412    Notes:
2413    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
2414    each matrix.
2415 
2416    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
2417    must be a MatFDColoring.
2418 
2419    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2420    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.
2421 
2422    Level: beginner
2423 
2424 .keywords: SNES, nonlinear, set, Jacobian, matrix
2425 
2426 .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J, SNESSetPicard()
2427 @*/
2428 PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2429 {
2430   PetscErrorCode ierr;
2431   DM             dm;
2432 
2433   PetscFunctionBegin;
2434   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2435   if (Amat) PetscValidHeaderSpecific(Amat,MAT_CLASSID,2);
2436   if (Pmat) PetscValidHeaderSpecific(Pmat,MAT_CLASSID,3);
2437   if (Amat) PetscCheckSameComm(snes,1,Amat,2);
2438   if (Pmat) PetscCheckSameComm(snes,1,Pmat,3);
2439   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2440   ierr = DMSNESSetJacobian(dm,J,ctx);CHKERRQ(ierr);
2441   if (Amat) {
2442     ierr = PetscObjectReference((PetscObject)Amat);CHKERRQ(ierr);
2443     ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2444 
2445     snes->jacobian = Amat;
2446   }
2447   if (Pmat) {
2448     ierr = PetscObjectReference((PetscObject)Pmat);CHKERRQ(ierr);
2449     ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2450 
2451     snes->jacobian_pre = Pmat;
2452   }
2453   PetscFunctionReturn(0);
2454 }
2455 
2456 #undef __FUNCT__
2457 #define __FUNCT__ "SNESGetJacobian"
2458 /*@C
2459    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2460    provided context for evaluating the Jacobian.
2461 
2462    Not Collective, but Mat object will be parallel if SNES object is
2463 
2464    Input Parameter:
2465 .  snes - the nonlinear solver context
2466 
2467    Output Parameters:
2468 +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
2469 .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
2470 .  J - location to put Jacobian function (or NULL)
2471 -  ctx - location to stash Jacobian ctx (or NULL)
2472 
2473    Level: advanced
2474 
2475 .seealso: SNESSetJacobian(), SNESComputeJacobian()
2476 @*/
2477 PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
2478 {
2479   PetscErrorCode ierr;
2480   DM             dm;
2481   DMSNES         sdm;
2482 
2483   PetscFunctionBegin;
2484   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2485   if (Amat) *Amat = snes->jacobian;
2486   if (Pmat) *Pmat = snes->jacobian_pre;
2487   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2488   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2489   if (J) *J = sdm->ops->computejacobian;
2490   if (ctx) *ctx = sdm->jacobianctx;
2491   PetscFunctionReturn(0);
2492 }
2493 
2494 #undef __FUNCT__
2495 #define __FUNCT__ "SNESSetUp"
2496 /*@
2497    SNESSetUp - Sets up the internal data structures for the later use
2498    of a nonlinear solver.
2499 
2500    Collective on SNES
2501 
2502    Input Parameters:
2503 .  snes - the SNES context
2504 
2505    Notes:
2506    For basic use of the SNES solvers the user need not explicitly call
2507    SNESSetUp(), since these actions will automatically occur during
2508    the call to SNESSolve().  However, if one wishes to control this
2509    phase separately, SNESSetUp() should be called after SNESCreate()
2510    and optional routines of the form SNESSetXXX(), but before SNESSolve().
2511 
2512    Level: advanced
2513 
2514 .keywords: SNES, nonlinear, setup
2515 
2516 .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
2517 @*/
2518 PetscErrorCode  SNESSetUp(SNES snes)
2519 {
2520   PetscErrorCode ierr;
2521   DM             dm;
2522   DMSNES         sdm;
2523   SNESLineSearch linesearch, pclinesearch;
2524   void           *lsprectx,*lspostctx;
2525   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
2526   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
2527   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2528   Vec            f,fpc;
2529   void           *funcctx;
2530   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
2531   void           *jacctx,*appctx;
2532   Mat            j,jpre;
2533 
2534   PetscFunctionBegin;
2535   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2536   if (snes->setupcalled) PetscFunctionReturn(0);
2537 
2538   if (!((PetscObject)snes)->type_name) {
2539     ierr = SNESSetType(snes,SNESNEWTONLS);CHKERRQ(ierr);
2540   }
2541 
2542   ierr = SNESGetFunction(snes,&snes->vec_func,NULL,NULL);CHKERRQ(ierr);
2543 
2544   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2545   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2546   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
2547   if (!sdm->ops->computejacobian) {
2548     ierr = DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);CHKERRQ(ierr);
2549   }
2550   if (!snes->vec_func) {
2551     ierr = DMCreateGlobalVector(dm,&snes->vec_func);CHKERRQ(ierr);
2552   }
2553 
2554   if (!snes->ksp) {
2555     ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);
2556   }
2557 
2558   if (!snes->linesearch) {
2559     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
2560   }
2561   ierr = SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);CHKERRQ(ierr);
2562 
2563   if (snes->pc && (snes->pcside == PC_LEFT)) {
2564     snes->mf          = PETSC_TRUE;
2565     snes->mf_operator = PETSC_FALSE;
2566   }
2567 
2568   if (snes->pc) {
2569     /* copy the DM over */
2570     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2571     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
2572 
2573     ierr = SNESGetFunction(snes,&f,&func,&funcctx);CHKERRQ(ierr);
2574     ierr = VecDuplicate(f,&fpc);CHKERRQ(ierr);
2575     ierr = SNESSetFunction(snes->pc,fpc,func,funcctx);CHKERRQ(ierr);
2576     ierr = SNESGetJacobian(snes,&j,&jpre,&jac,&jacctx);CHKERRQ(ierr);
2577     ierr = SNESSetJacobian(snes->pc,j,jpre,jac,jacctx);CHKERRQ(ierr);
2578     ierr = SNESGetApplicationContext(snes,&appctx);CHKERRQ(ierr);
2579     ierr = SNESSetApplicationContext(snes->pc,appctx);CHKERRQ(ierr);
2580     ierr = VecDestroy(&fpc);CHKERRQ(ierr);
2581 
2582     /* copy the function pointers over */
2583     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
2584 
2585     /* default to 1 iteration */
2586     ierr = SNESSetTolerances(snes->pc,0.0,0.0,0.0,1,snes->pc->max_funcs);CHKERRQ(ierr);
2587     if (snes->pcside==PC_RIGHT) {
2588       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
2589     } else {
2590       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_NONE);CHKERRQ(ierr);
2591     }
2592     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
2593 
2594     /* copy the line search context over */
2595     ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2596     ierr = SNESGetLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
2597     ierr = SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);CHKERRQ(ierr);
2598     ierr = SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);CHKERRQ(ierr);
2599     ierr = SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);CHKERRQ(ierr);
2600     ierr = SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);CHKERRQ(ierr);
2601     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);CHKERRQ(ierr);
2602   }
2603   if (snes->mf) {
2604     ierr = SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);CHKERRQ(ierr);
2605   }
2606   if (snes->ops->usercompute && !snes->user) {
2607     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2608   }
2609 
2610   snes->jac_iter = 0;
2611   snes->pre_iter = 0;
2612 
2613   if (snes->ops->setup) {
2614     ierr = (*snes->ops->setup)(snes);CHKERRQ(ierr);
2615   }
2616 
2617   if (snes->pc && (snes->pcside == PC_LEFT)) {
2618     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
2619       ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2620       ierr = SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultNPC);CHKERRQ(ierr);
2621     }
2622   }
2623 
2624   snes->setupcalled = PETSC_TRUE;
2625   PetscFunctionReturn(0);
2626 }
2627 
2628 #undef __FUNCT__
2629 #define __FUNCT__ "SNESReset"
2630 /*@
2631    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats
2632 
2633    Collective on SNES
2634 
2635    Input Parameter:
2636 .  snes - iterative context obtained from SNESCreate()
2637 
2638    Level: intermediate
2639 
2640    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()
2641 
2642 .keywords: SNES, destroy
2643 
2644 .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
2645 @*/
2646 PetscErrorCode  SNESReset(SNES snes)
2647 {
2648   PetscErrorCode ierr;
2649 
2650   PetscFunctionBegin;
2651   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2652   if (snes->ops->userdestroy && snes->user) {
2653     ierr       = (*snes->ops->userdestroy)((void**)&snes->user);CHKERRQ(ierr);
2654     snes->user = NULL;
2655   }
2656   if (snes->pc) {
2657     ierr = SNESReset(snes->pc);CHKERRQ(ierr);
2658   }
2659 
2660   if (snes->ops->reset) {
2661     ierr = (*snes->ops->reset)(snes);CHKERRQ(ierr);
2662   }
2663   if (snes->ksp) {
2664     ierr = KSPReset(snes->ksp);CHKERRQ(ierr);
2665   }
2666 
2667   if (snes->linesearch) {
2668     ierr = SNESLineSearchReset(snes->linesearch);CHKERRQ(ierr);
2669   }
2670 
2671   ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
2672   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
2673   ierr = VecDestroy(&snes->vec_sol_update);CHKERRQ(ierr);
2674   ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
2675   ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2676   ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2677   ierr = VecDestroyVecs(snes->nwork,&snes->work);CHKERRQ(ierr);
2678   ierr = VecDestroyVecs(snes->nvwork,&snes->vwork);CHKERRQ(ierr);
2679 
2680   snes->nwork       = snes->nvwork = 0;
2681   snes->setupcalled = PETSC_FALSE;
2682   PetscFunctionReturn(0);
2683 }
2684 
2685 #undef __FUNCT__
2686 #define __FUNCT__ "SNESDestroy"
2687 /*@
2688    SNESDestroy - Destroys the nonlinear solver context that was created
2689    with SNESCreate().
2690 
2691    Collective on SNES
2692 
2693    Input Parameter:
2694 .  snes - the SNES context
2695 
2696    Level: beginner
2697 
2698 .keywords: SNES, nonlinear, destroy
2699 
2700 .seealso: SNESCreate(), SNESSolve()
2701 @*/
2702 PetscErrorCode  SNESDestroy(SNES *snes)
2703 {
2704   PetscErrorCode ierr;
2705 
2706   PetscFunctionBegin;
2707   if (!*snes) PetscFunctionReturn(0);
2708   PetscValidHeaderSpecific((*snes),SNES_CLASSID,1);
2709   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; PetscFunctionReturn(0);}
2710 
2711   ierr = SNESReset((*snes));CHKERRQ(ierr);
2712   ierr = SNESDestroy(&(*snes)->pc);CHKERRQ(ierr);
2713 
2714   /* if memory was published with SAWs then destroy it */
2715   ierr = PetscObjectSAWsViewOff((PetscObject)*snes);CHKERRQ(ierr);
2716   if ((*snes)->ops->destroy) {ierr = (*((*snes))->ops->destroy)((*snes));CHKERRQ(ierr);}
2717 
2718   ierr = DMDestroy(&(*snes)->dm);CHKERRQ(ierr);
2719   ierr = KSPDestroy(&(*snes)->ksp);CHKERRQ(ierr);
2720   ierr = SNESLineSearchDestroy(&(*snes)->linesearch);CHKERRQ(ierr);
2721 
2722   ierr = PetscFree((*snes)->kspconvctx);CHKERRQ(ierr);
2723   if ((*snes)->ops->convergeddestroy) {
2724     ierr = (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);CHKERRQ(ierr);
2725   }
2726   if ((*snes)->conv_malloc) {
2727     ierr = PetscFree((*snes)->conv_hist);CHKERRQ(ierr);
2728     ierr = PetscFree((*snes)->conv_hist_its);CHKERRQ(ierr);
2729   }
2730   ierr = SNESMonitorCancel((*snes));CHKERRQ(ierr);
2731   ierr = PetscHeaderDestroy(snes);CHKERRQ(ierr);
2732   PetscFunctionReturn(0);
2733 }
2734 
2735 /* ----------- Routines to set solver parameters ---------- */
2736 
2737 #undef __FUNCT__
2738 #define __FUNCT__ "SNESSetLagPreconditioner"
2739 /*@
2740    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.
2741 
2742    Logically Collective on SNES
2743 
2744    Input Parameters:
2745 +  snes - the SNES context
2746 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2747          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2748 
2749    Options Database Keys:
2750 .    -snes_lag_preconditioner <lag>
2751 
2752    Notes:
2753    The default is 1
2754    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2755    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use
2756 
2757    Level: intermediate
2758 
2759 .keywords: SNES, nonlinear, set, convergence, tolerances
2760 
2761 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2762 
2763 @*/
2764 PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
2765 {
2766   PetscFunctionBegin;
2767   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2768   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2769   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2770   PetscValidLogicalCollectiveInt(snes,lag,2);
2771   snes->lagpreconditioner = lag;
2772   PetscFunctionReturn(0);
2773 }
2774 
2775 #undef __FUNCT__
2776 #define __FUNCT__ "SNESSetGridSequence"
2777 /*@
2778    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does
2779 
2780    Logically Collective on SNES
2781 
2782    Input Parameters:
2783 +  snes - the SNES context
2784 -  steps - the number of refinements to do, defaults to 0
2785 
2786    Options Database Keys:
2787 .    -snes_grid_sequence <steps>
2788 
2789    Level: intermediate
2790 
2791    Notes:
2792    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2793 
2794 .keywords: SNES, nonlinear, set, convergence, tolerances
2795 
2796 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2797 
2798 @*/
2799 PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
2800 {
2801   PetscFunctionBegin;
2802   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2803   PetscValidLogicalCollectiveInt(snes,steps,2);
2804   snes->gridsequence = steps;
2805   PetscFunctionReturn(0);
2806 }
2807 
2808 #undef __FUNCT__
2809 #define __FUNCT__ "SNESGetLagPreconditioner"
2810 /*@
2811    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt
2812 
2813    Not Collective
2814 
2815    Input Parameter:
2816 .  snes - the SNES context
2817 
2818    Output Parameter:
2819 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2820          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2821 
2822    Options Database Keys:
2823 .    -snes_lag_preconditioner <lag>
2824 
2825    Notes:
2826    The default is 1
2827    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2828 
2829    Level: intermediate
2830 
2831 .keywords: SNES, nonlinear, set, convergence, tolerances
2832 
2833 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()
2834 
2835 @*/
2836 PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
2837 {
2838   PetscFunctionBegin;
2839   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2840   *lag = snes->lagpreconditioner;
2841   PetscFunctionReturn(0);
2842 }
2843 
2844 #undef __FUNCT__
2845 #define __FUNCT__ "SNESSetLagJacobian"
2846 /*@
2847    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
2848      often the preconditioner is rebuilt.
2849 
2850    Logically Collective on SNES
2851 
2852    Input Parameters:
2853 +  snes - the SNES context
2854 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2855          the Jacobian is built etc. -2 means rebuild at next chance but then never again
2856 
2857    Options Database Keys:
2858 .    -snes_lag_jacobian <lag>
2859 
2860    Notes:
2861    The default is 1
2862    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2863    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
2864    at the next Newton step but never again (unless it is reset to another value)
2865 
2866    Level: intermediate
2867 
2868 .keywords: SNES, nonlinear, set, convergence, tolerances
2869 
2870 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()
2871 
2872 @*/
2873 PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
2874 {
2875   PetscFunctionBegin;
2876   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2877   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2878   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2879   PetscValidLogicalCollectiveInt(snes,lag,2);
2880   snes->lagjacobian = lag;
2881   PetscFunctionReturn(0);
2882 }
2883 
2884 #undef __FUNCT__
2885 #define __FUNCT__ "SNESGetLagJacobian"
2886 /*@
2887    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt
2888 
2889    Not Collective
2890 
2891    Input Parameter:
2892 .  snes - the SNES context
2893 
2894    Output Parameter:
2895 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2896          the Jacobian is built etc.
2897 
2898    Options Database Keys:
2899 .    -snes_lag_jacobian <lag>
2900 
2901    Notes:
2902    The default is 1
2903    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2904 
2905    Level: intermediate
2906 
2907 .keywords: SNES, nonlinear, set, convergence, tolerances
2908 
2909 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()
2910 
2911 @*/
2912 PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
2913 {
2914   PetscFunctionBegin;
2915   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2916   *lag = snes->lagjacobian;
2917   PetscFunctionReturn(0);
2918 }
2919 
2920 #undef __FUNCT__
2921 #define __FUNCT__ "SNESSetLagJacobianPersists"
2922 /*@
2923    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves
2924 
2925    Logically collective on SNES
2926 
2927    Input Parameter:
2928 +  snes - the SNES context
2929 -   flg - jacobian lagging persists if true
2930 
2931    Options Database Keys:
2932 .    -snes_lag_jacobian_persists <flg>
2933 
2934    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
2935    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
2936    timesteps may present huge efficiency gains.
2937 
2938    Level: developer
2939 
2940 .keywords: SNES, nonlinear, lag
2941 
2942 .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
2943 
2944 @*/
2945 PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
2946 {
2947   PetscFunctionBegin;
2948   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2949   PetscValidLogicalCollectiveBool(snes,flg,2);
2950   snes->lagjac_persist = flg;
2951   PetscFunctionReturn(0);
2952 }
2953 
2954 #undef __FUNCT__
2955 #define __FUNCT__ "SNESSetLagPreconditionerPersists"
2956 /*@
2957    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple solves
2958 
2959    Logically Collective on SNES
2960 
2961    Input Parameter:
2962 +  snes - the SNES context
2963 -   flg - preconditioner lagging persists if true
2964 
2965    Options Database Keys:
2966 .    -snes_lag_jacobian_persists <flg>
2967 
2968    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
2969    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
2970    several timesteps may present huge efficiency gains.
2971 
2972    Level: developer
2973 
2974 .keywords: SNES, nonlinear, lag
2975 
2976 .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
2977 
2978 @*/
2979 PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
2980 {
2981   PetscFunctionBegin;
2982   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2983   PetscValidLogicalCollectiveBool(snes,flg,2);
2984   snes->lagpre_persist = flg;
2985   PetscFunctionReturn(0);
2986 }
2987 
2988 #undef __FUNCT__
2989 #define __FUNCT__ "SNESSetTolerances"
2990 /*@
2991    SNESSetTolerances - Sets various parameters used in convergence tests.
2992 
2993    Logically Collective on SNES
2994 
2995    Input Parameters:
2996 +  snes - the SNES context
2997 .  abstol - absolute convergence tolerance
2998 .  rtol - relative convergence tolerance
2999 .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
3000 .  maxit - maximum number of iterations
3001 -  maxf - maximum number of function evaluations
3002 
3003    Options Database Keys:
3004 +    -snes_atol <abstol> - Sets abstol
3005 .    -snes_rtol <rtol> - Sets rtol
3006 .    -snes_stol <stol> - Sets stol
3007 .    -snes_max_it <maxit> - Sets maxit
3008 -    -snes_max_funcs <maxf> - Sets maxf
3009 
3010    Notes:
3011    The default maximum number of iterations is 50.
3012    The default maximum number of function evaluations is 1000.
3013 
3014    Level: intermediate
3015 
3016 .keywords: SNES, nonlinear, set, convergence, tolerances
3017 
3018 .seealso: SNESSetTrustRegionTolerance()
3019 @*/
3020 PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
3021 {
3022   PetscFunctionBegin;
3023   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3024   PetscValidLogicalCollectiveReal(snes,abstol,2);
3025   PetscValidLogicalCollectiveReal(snes,rtol,3);
3026   PetscValidLogicalCollectiveReal(snes,stol,4);
3027   PetscValidLogicalCollectiveInt(snes,maxit,5);
3028   PetscValidLogicalCollectiveInt(snes,maxf,6);
3029 
3030   if (abstol != PETSC_DEFAULT) {
3031     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %g must be non-negative",(double)abstol);
3032     snes->abstol = abstol;
3033   }
3034   if (rtol != PETSC_DEFAULT) {
3035     if (rtol < 0.0 || 1.0 <= rtol) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Relative tolerance %g must be non-negative and less than 1.0",(double)rtol);
3036     snes->rtol = rtol;
3037   }
3038   if (stol != PETSC_DEFAULT) {
3039     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %g must be non-negative",(double)stol);
3040     snes->stol = stol;
3041   }
3042   if (maxit != PETSC_DEFAULT) {
3043     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
3044     snes->max_its = maxit;
3045   }
3046   if (maxf != PETSC_DEFAULT) {
3047     if (maxf < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
3048     snes->max_funcs = maxf;
3049   }
3050   snes->tolerancesset = PETSC_TRUE;
3051   PetscFunctionReturn(0);
3052 }
3053 
3054 #undef __FUNCT__
3055 #define __FUNCT__ "SNESGetTolerances"
3056 /*@
3057    SNESGetTolerances - Gets various parameters used in convergence tests.
3058 
3059    Not Collective
3060 
3061    Input Parameters:
3062 +  snes - the SNES context
3063 .  atol - absolute convergence tolerance
3064 .  rtol - relative convergence tolerance
3065 .  stol -  convergence tolerance in terms of the norm
3066            of the change in the solution between steps
3067 .  maxit - maximum number of iterations
3068 -  maxf - maximum number of function evaluations
3069 
3070    Notes:
3071    The user can specify NULL for any parameter that is not needed.
3072 
3073    Level: intermediate
3074 
3075 .keywords: SNES, nonlinear, get, convergence, tolerances
3076 
3077 .seealso: SNESSetTolerances()
3078 @*/
3079 PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3080 {
3081   PetscFunctionBegin;
3082   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3083   if (atol)  *atol  = snes->abstol;
3084   if (rtol)  *rtol  = snes->rtol;
3085   if (stol)  *stol  = snes->stol;
3086   if (maxit) *maxit = snes->max_its;
3087   if (maxf)  *maxf  = snes->max_funcs;
3088   PetscFunctionReturn(0);
3089 }
3090 
3091 #undef __FUNCT__
3092 #define __FUNCT__ "SNESSetTrustRegionTolerance"
3093 /*@
3094    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.
3095 
3096    Logically Collective on SNES
3097 
3098    Input Parameters:
3099 +  snes - the SNES context
3100 -  tol - tolerance
3101 
3102    Options Database Key:
3103 .  -snes_trtol <tol> - Sets tol
3104 
3105    Level: intermediate
3106 
3107 .keywords: SNES, nonlinear, set, trust region, tolerance
3108 
3109 .seealso: SNESSetTolerances()
3110 @*/
3111 PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3112 {
3113   PetscFunctionBegin;
3114   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3115   PetscValidLogicalCollectiveReal(snes,tol,2);
3116   snes->deltatol = tol;
3117   PetscFunctionReturn(0);
3118 }
3119 
3120 /*
3121    Duplicate the lg monitors for SNES from KSP; for some reason with
3122    dynamic libraries things don't work under Sun4 if we just use
3123    macros instead of functions
3124 */
3125 #undef __FUNCT__
3126 #define __FUNCT__ "SNESMonitorLGResidualNorm"
3127 PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,PetscObject *objs)
3128 {
3129   PetscErrorCode ierr;
3130 
3131   PetscFunctionBegin;
3132   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3133   ierr = KSPMonitorLGResidualNorm((KSP)snes,it,norm,objs);CHKERRQ(ierr);
3134   PetscFunctionReturn(0);
3135 }
3136 
3137 #undef __FUNCT__
3138 #define __FUNCT__ "SNESMonitorLGCreate"
3139 PetscErrorCode  SNESMonitorLGCreate(const char host[],const char label[],int x,int y,int m,int n,PetscObject **draw)
3140 {
3141   PetscErrorCode ierr;
3142 
3143   PetscFunctionBegin;
3144   ierr = KSPMonitorLGResidualNormCreate(host,label,x,y,m,n,draw);CHKERRQ(ierr);
3145   PetscFunctionReturn(0);
3146 }
3147 
3148 #undef __FUNCT__
3149 #define __FUNCT__ "SNESMonitorLGDestroy"
3150 PetscErrorCode  SNESMonitorLGDestroy(PetscObject **objs)
3151 {
3152   PetscErrorCode ierr;
3153 
3154   PetscFunctionBegin;
3155   ierr = KSPMonitorLGResidualNormDestroy(objs);CHKERRQ(ierr);
3156   PetscFunctionReturn(0);
3157 }
3158 
3159 extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
3160 #undef __FUNCT__
3161 #define __FUNCT__ "SNESMonitorLGRange"
3162 PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3163 {
3164   PetscDrawLG      lg;
3165   PetscErrorCode   ierr;
3166   PetscReal        x,y,per;
3167   PetscViewer      v = (PetscViewer)monctx;
3168   static PetscReal prev; /* should be in the context */
3169   PetscDraw        draw;
3170 
3171   PetscFunctionBegin;
3172   ierr = PetscViewerDrawGetDrawLG(v,0,&lg);CHKERRQ(ierr);
3173   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3174   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3175   ierr = PetscDrawSetTitle(draw,"Residual norm");CHKERRQ(ierr);
3176   x    = (PetscReal)n;
3177   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
3178   else y = -15.0;
3179   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3180   if (n < 20 || !(n % 5)) {
3181     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3182   }
3183 
3184   ierr = PetscViewerDrawGetDrawLG(v,1,&lg);CHKERRQ(ierr);
3185   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3186   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3187   ierr = PetscDrawSetTitle(draw,"% elemts > .2*max elemt");CHKERRQ(ierr);
3188   ierr =  SNESMonitorRange_Private(snes,n,&per);CHKERRQ(ierr);
3189   x    = (PetscReal)n;
3190   y    = 100.0*per;
3191   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3192   if (n < 20 || !(n % 5)) {
3193     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3194   }
3195 
3196   ierr = PetscViewerDrawGetDrawLG(v,2,&lg);CHKERRQ(ierr);
3197   if (!n) {prev = rnorm;ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3198   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3199   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");CHKERRQ(ierr);
3200   x    = (PetscReal)n;
3201   y    = (prev - rnorm)/prev;
3202   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3203   if (n < 20 || !(n % 5)) {
3204     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3205   }
3206 
3207   ierr = PetscViewerDrawGetDrawLG(v,3,&lg);CHKERRQ(ierr);
3208   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3209   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3210   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");CHKERRQ(ierr);
3211   x    = (PetscReal)n;
3212   y    = (prev - rnorm)/(prev*per);
3213   if (n > 2) { /*skip initial crazy value */
3214     ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3215   }
3216   if (n < 20 || !(n % 5)) {
3217     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3218   }
3219   prev = rnorm;
3220   PetscFunctionReturn(0);
3221 }
3222 
3223 #undef __FUNCT__
3224 #define __FUNCT__ "SNESMonitor"
3225 /*@
3226    SNESMonitor - runs the user provided monitor routines, if they exist
3227 
3228    Collective on SNES
3229 
3230    Input Parameters:
3231 +  snes - nonlinear solver context obtained from SNESCreate()
3232 .  iter - iteration number
3233 -  rnorm - relative norm of the residual
3234 
3235    Notes:
3236    This routine is called by the SNES implementations.
3237    It does not typically need to be called by the user.
3238 
3239    Level: developer
3240 
3241 .seealso: SNESMonitorSet()
3242 @*/
3243 PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3244 {
3245   PetscErrorCode ierr;
3246   PetscInt       i,n = snes->numbermonitors;
3247 
3248   PetscFunctionBegin;
3249   for (i=0; i<n; i++) {
3250     ierr = (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);CHKERRQ(ierr);
3251   }
3252   PetscFunctionReturn(0);
3253 }
3254 
3255 /* ------------ Routines to set performance monitoring options ----------- */
3256 
3257 /*MC
3258     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver
3259 
3260      Synopsis:
3261      #include <petscsnes.h>
3262 $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)
3263 
3264 +    snes - the SNES context
3265 .    its - iteration number
3266 .    norm - 2-norm function value (may be estimated)
3267 -    mctx - [optional] monitoring context
3268 
3269    Level: advanced
3270 
3271 .seealso:   SNESMonitorSet(), SNESMonitorGet()
3272 M*/
3273 
3274 #undef __FUNCT__
3275 #define __FUNCT__ "SNESMonitorSet"
3276 /*@C
3277    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3278    iteration of the nonlinear solver to display the iteration's
3279    progress.
3280 
3281    Logically Collective on SNES
3282 
3283    Input Parameters:
3284 +  snes - the SNES context
3285 .  f - the monitor function, see SNESMonitorFunction for the calling sequence
3286 .  mctx - [optional] user-defined context for private data for the
3287           monitor routine (use NULL if no context is desired)
3288 -  monitordestroy - [optional] routine that frees monitor context
3289           (may be NULL)
3290 
3291    Options Database Keys:
3292 +    -snes_monitor        - sets SNESMonitorDefault()
3293 .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3294                             uses SNESMonitorLGCreate()
3295 -    -snes_monitor_cancel - cancels all monitors that have
3296                             been hardwired into a code by
3297                             calls to SNESMonitorSet(), but
3298                             does not cancel those set via
3299                             the options database.
3300 
3301    Notes:
3302    Several different monitoring routines may be set by calling
3303    SNESMonitorSet() multiple times; all will be called in the
3304    order in which they were set.
3305 
3306    Fortran notes: Only a single monitor function can be set for each SNES object
3307 
3308    Level: intermediate
3309 
3310 .keywords: SNES, nonlinear, set, monitor
3311 
3312 .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
3313 @*/
3314 PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*f)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3315 {
3316   PetscInt       i;
3317   PetscErrorCode ierr;
3318 
3319   PetscFunctionBegin;
3320   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3321   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3322   for (i=0; i<snes->numbermonitors;i++) {
3323     if (f == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
3324       if (monitordestroy) {
3325         ierr = (*monitordestroy)(&mctx);CHKERRQ(ierr);
3326       }
3327       PetscFunctionReturn(0);
3328     }
3329   }
3330   snes->monitor[snes->numbermonitors]          = f;
3331   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
3332   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
3333   PetscFunctionReturn(0);
3334 }
3335 
3336 #undef __FUNCT__
3337 #define __FUNCT__ "SNESMonitorCancel"
3338 /*@
3339    SNESMonitorCancel - Clears all the monitor functions for a SNES object.
3340 
3341    Logically Collective on SNES
3342 
3343    Input Parameters:
3344 .  snes - the SNES context
3345 
3346    Options Database Key:
3347 .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3348     into a code by calls to SNESMonitorSet(), but does not cancel those
3349     set via the options database
3350 
3351    Notes:
3352    There is no way to clear one specific monitor from a SNES object.
3353 
3354    Level: intermediate
3355 
3356 .keywords: SNES, nonlinear, set, monitor
3357 
3358 .seealso: SNESMonitorDefault(), SNESMonitorSet()
3359 @*/
3360 PetscErrorCode  SNESMonitorCancel(SNES snes)
3361 {
3362   PetscErrorCode ierr;
3363   PetscInt       i;
3364 
3365   PetscFunctionBegin;
3366   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3367   for (i=0; i<snes->numbermonitors; i++) {
3368     if (snes->monitordestroy[i]) {
3369       ierr = (*snes->monitordestroy[i])(&snes->monitorcontext[i]);CHKERRQ(ierr);
3370     }
3371   }
3372   snes->numbermonitors = 0;
3373   PetscFunctionReturn(0);
3374 }
3375 
3376 /*MC
3377     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver
3378 
3379      Synopsis:
3380      #include <petscsnes.h>
3381 $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)
3382 
3383 +    snes - the SNES context
3384 .    it - current iteration (0 is the first and is before any Newton step)
3385 .    cctx - [optional] convergence context
3386 .    reason - reason for convergence/divergence
3387 .    xnorm - 2-norm of current iterate
3388 .    gnorm - 2-norm of current step
3389 -    f - 2-norm of function
3390 
3391    Level: intermediate
3392 
3393 .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
3394 M*/
3395 
3396 #undef __FUNCT__
3397 #define __FUNCT__ "SNESSetConvergenceTest"
3398 /*@C
3399    SNESSetConvergenceTest - Sets the function that is to be used
3400    to test for convergence of the nonlinear iterative solution.
3401 
3402    Logically Collective on SNES
3403 
3404    Input Parameters:
3405 +  snes - the SNES context
3406 .  SNESConvergenceTestFunction - routine to test for convergence
3407 .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
3408 -  destroy - [optional] destructor for the context (may be NULL; NULL_FUNCTION in Fortran)
3409 
3410    Level: advanced
3411 
3412 .keywords: SNES, nonlinear, set, convergence, test
3413 
3414 .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
3415 @*/
3416 PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
3417 {
3418   PetscErrorCode ierr;
3419 
3420   PetscFunctionBegin;
3421   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3422   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
3423   if (snes->ops->convergeddestroy) {
3424     ierr = (*snes->ops->convergeddestroy)(snes->cnvP);CHKERRQ(ierr);
3425   }
3426   snes->ops->converged        = SNESConvergenceTestFunction;
3427   snes->ops->convergeddestroy = destroy;
3428   snes->cnvP                  = cctx;
3429   PetscFunctionReturn(0);
3430 }
3431 
3432 #undef __FUNCT__
3433 #define __FUNCT__ "SNESGetConvergedReason"
3434 /*@
3435    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.
3436 
3437    Not Collective
3438 
3439    Input Parameter:
3440 .  snes - the SNES context
3441 
3442    Output Parameter:
3443 .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3444             manual pages for the individual convergence tests for complete lists
3445 
3446    Level: intermediate
3447 
3448    Notes: Can only be called after the call the SNESSolve() is complete.
3449 
3450 .keywords: SNES, nonlinear, set, convergence, test
3451 
3452 .seealso: SNESSetConvergenceTest(), SNESConvergedReason
3453 @*/
3454 PetscErrorCode  SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
3455 {
3456   PetscFunctionBegin;
3457   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3458   PetscValidPointer(reason,2);
3459   *reason = snes->reason;
3460   PetscFunctionReturn(0);
3461 }
3462 
3463 #undef __FUNCT__
3464 #define __FUNCT__ "SNESSetConvergenceHistory"
3465 /*@
3466    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.
3467 
3468    Logically Collective on SNES
3469 
3470    Input Parameters:
3471 +  snes - iterative context obtained from SNESCreate()
3472 .  a   - array to hold history, this array will contain the function norms computed at each step
3473 .  its - integer array holds the number of linear iterations for each solve.
3474 .  na  - size of a and its
3475 -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
3476            else it continues storing new values for new nonlinear solves after the old ones
3477 
3478    Notes:
3479    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
3480    default array of length 10000 is allocated.
3481 
3482    This routine is useful, e.g., when running a code for purposes
3483    of accurate performance monitoring, when no I/O should be done
3484    during the section of code that is being timed.
3485 
3486    Level: intermediate
3487 
3488 .keywords: SNES, set, convergence, history
3489 
3490 .seealso: SNESGetConvergenceHistory()
3491 
3492 @*/
3493 PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
3494 {
3495   PetscErrorCode ierr;
3496 
3497   PetscFunctionBegin;
3498   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3499   if (a) PetscValidScalarPointer(a,2);
3500   if (its) PetscValidIntPointer(its,3);
3501   if (!a) {
3502     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
3503     ierr = PetscCalloc1(na,&a);CHKERRQ(ierr);
3504     ierr = PetscCalloc1(na,&its);CHKERRQ(ierr);
3505 
3506     snes->conv_malloc = PETSC_TRUE;
3507   }
3508   snes->conv_hist       = a;
3509   snes->conv_hist_its   = its;
3510   snes->conv_hist_max   = na;
3511   snes->conv_hist_len   = 0;
3512   snes->conv_hist_reset = reset;
3513   PetscFunctionReturn(0);
3514 }
3515 
3516 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3517 #include <engine.h>   /* MATLAB include file */
3518 #include <mex.h>      /* MATLAB include file */
3519 
3520 #undef __FUNCT__
3521 #define __FUNCT__ "SNESGetConvergenceHistoryMatlab"
3522 PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
3523 {
3524   mxArray   *mat;
3525   PetscInt  i;
3526   PetscReal *ar;
3527 
3528   PetscFunctionBegin;
3529   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
3530   ar  = (PetscReal*) mxGetData(mat);
3531   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
3532   PetscFunctionReturn(mat);
3533 }
3534 #endif
3535 
3536 #undef __FUNCT__
3537 #define __FUNCT__ "SNESGetConvergenceHistory"
3538 /*@C
3539    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.
3540 
3541    Not Collective
3542 
3543    Input Parameter:
3544 .  snes - iterative context obtained from SNESCreate()
3545 
3546    Output Parameters:
3547 .  a   - array to hold history
3548 .  its - integer array holds the number of linear iterations (or
3549          negative if not converged) for each solve.
3550 -  na  - size of a and its
3551 
3552    Notes:
3553     The calling sequence for this routine in Fortran is
3554 $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
3555 
3556    This routine is useful, e.g., when running a code for purposes
3557    of accurate performance monitoring, when no I/O should be done
3558    during the section of code that is being timed.
3559 
3560    Level: intermediate
3561 
3562 .keywords: SNES, get, convergence, history
3563 
3564 .seealso: SNESSetConvergencHistory()
3565 
3566 @*/
3567 PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
3568 {
3569   PetscFunctionBegin;
3570   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3571   if (a)   *a   = snes->conv_hist;
3572   if (its) *its = snes->conv_hist_its;
3573   if (na)  *na  = snes->conv_hist_len;
3574   PetscFunctionReturn(0);
3575 }
3576 
3577 #undef __FUNCT__
3578 #define __FUNCT__ "SNESSetUpdate"
3579 /*@C
3580   SNESSetUpdate - Sets the general-purpose update function called
3581   at the beginning of every iteration of the nonlinear solve. Specifically
3582   it is called just before the Jacobian is "evaluated".
3583 
3584   Logically Collective on SNES
3585 
3586   Input Parameters:
3587 . snes - The nonlinear solver context
3588 . func - The function
3589 
3590   Calling sequence of func:
3591 . func (SNES snes, PetscInt step);
3592 
3593 . step - The current step of the iteration
3594 
3595   Level: advanced
3596 
3597   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()
3598         This is not used by most users.
3599 
3600 .keywords: SNES, update
3601 
3602 .seealso SNESSetJacobian(), SNESSolve()
3603 @*/
3604 PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
3605 {
3606   PetscFunctionBegin;
3607   PetscValidHeaderSpecific(snes, SNES_CLASSID,1);
3608   snes->ops->update = func;
3609   PetscFunctionReturn(0);
3610 }
3611 
3612 #undef __FUNCT__
3613 #define __FUNCT__ "SNESScaleStep_Private"
3614 /*
3615    SNESScaleStep_Private - Scales a step so that its length is less than the
3616    positive parameter delta.
3617 
3618     Input Parameters:
3619 +   snes - the SNES context
3620 .   y - approximate solution of linear system
3621 .   fnorm - 2-norm of current function
3622 -   delta - trust region size
3623 
3624     Output Parameters:
3625 +   gpnorm - predicted function norm at the new point, assuming local
3626     linearization.  The value is zero if the step lies within the trust
3627     region, and exceeds zero otherwise.
3628 -   ynorm - 2-norm of the step
3629 
3630     Note:
3631     For non-trust region methods such as SNESNEWTONLS, the parameter delta
3632     is set to be the maximum allowable step size.
3633 
3634 .keywords: SNES, nonlinear, scale, step
3635 */
3636 PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
3637 {
3638   PetscReal      nrm;
3639   PetscScalar    cnorm;
3640   PetscErrorCode ierr;
3641 
3642   PetscFunctionBegin;
3643   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3644   PetscValidHeaderSpecific(y,VEC_CLASSID,2);
3645   PetscCheckSameComm(snes,1,y,2);
3646 
3647   ierr = VecNorm(y,NORM_2,&nrm);CHKERRQ(ierr);
3648   if (nrm > *delta) {
3649     nrm     = *delta/nrm;
3650     *gpnorm = (1.0 - nrm)*(*fnorm);
3651     cnorm   = nrm;
3652     ierr    = VecScale(y,cnorm);CHKERRQ(ierr);
3653     *ynorm  = *delta;
3654   } else {
3655     *gpnorm = 0.0;
3656     *ynorm  = nrm;
3657   }
3658   PetscFunctionReturn(0);
3659 }
3660 
3661 #undef __FUNCT__
3662 #define __FUNCT__ "SNESReasonView"
3663 /*@
3664    SNESReasonView - Displays the reason a SNES solve converged or diverged to a viewer
3665 
3666    Collective on SNES
3667 
3668    Parameter:
3669 +  snes - iterative context obtained from SNESCreate()
3670 -  viewer - the viewer to display the reason
3671 
3672 
3673    Options Database Keys:
3674 .  -snes_converged_reason - print reason for converged or diverged, also prints number of iterations
3675 
3676    Level: beginner
3677 
3678 .keywords: SNES, solve, linear system
3679 
3680 .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault()
3681 
3682 @*/
3683 PetscErrorCode  SNESReasonView(SNES snes,PetscViewer viewer)
3684 {
3685   PetscErrorCode ierr;
3686   PetscBool      isAscii;
3687 
3688   PetscFunctionBegin;
3689   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isAscii);CHKERRQ(ierr);
3690   if (isAscii) {
3691     ierr = PetscViewerASCIIAddTab(viewer,((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3692     if (snes->reason > 0) {
3693       if (((PetscObject) snes)->prefix) {
3694         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve converged due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3695       } else {
3696         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3697       }
3698     } else {
3699       if (((PetscObject) snes)->prefix) {
3700         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve did not converge due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3701       } else {
3702         ierr = PetscViewerASCIIPrintf(viewer,"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3703       }
3704     }
3705     ierr = PetscViewerASCIISubtractTab(viewer,((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3706   }
3707   PetscFunctionReturn(0);
3708 }
3709 
3710 #undef __FUNCT__
3711 #define __FUNCT__ "SNESReasonViewFromOptions"
3712 /*@C
3713   SNESReasonViewFromOptions - Processes command line options to determine if/how a SNESReason is to be viewed.
3714 
3715   Collective on SNES
3716 
3717   Input Parameters:
3718 . snes   - the SNES object
3719 
3720   Level: intermediate
3721 
3722 @*/
3723 PetscErrorCode SNESReasonViewFromOptions(SNES snes)
3724 {
3725   PetscErrorCode    ierr;
3726   PetscViewer       viewer;
3727   PetscBool         flg;
3728   static PetscBool  incall = PETSC_FALSE;
3729   PetscViewerFormat format;
3730 
3731   PetscFunctionBegin;
3732   if (incall) PetscFunctionReturn(0);
3733   incall = PETSC_TRUE;
3734   ierr   = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_converged_reason",&viewer,&format,&flg);CHKERRQ(ierr);
3735   if (flg) {
3736     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
3737     ierr = SNESReasonView(snes,viewer);CHKERRQ(ierr);
3738     ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
3739     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3740   }
3741   incall = PETSC_FALSE;
3742   PetscFunctionReturn(0);
3743 }
3744 
3745 #undef __FUNCT__
3746 #define __FUNCT__ "SNESSolve"
3747 /*@C
3748    SNESSolve - Solves a nonlinear system F(x) = b.
3749    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3750 
3751    Collective on SNES
3752 
3753    Input Parameters:
3754 +  snes - the SNES context
3755 .  b - the constant part of the equation F(x) = b, or NULL to use zero.
3756 -  x - the solution vector.
3757 
3758    Notes:
3759    The user should initialize the vector,x, with the initial guess
3760    for the nonlinear solve prior to calling SNESSolve.  In particular,
3761    to employ an initial guess of zero, the user should explicitly set
3762    this vector to zero by calling VecSet().
3763 
3764    Level: beginner
3765 
3766 .keywords: SNES, nonlinear, solve
3767 
3768 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3769 @*/
3770 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3771 {
3772   PetscErrorCode    ierr;
3773   PetscBool         flg;
3774   PetscInt          grid;
3775   Vec               xcreated = NULL;
3776   DM                dm;
3777 
3778   PetscFunctionBegin;
3779   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3780   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3781   if (x) PetscCheckSameComm(snes,1,x,3);
3782   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3783   if (b) PetscCheckSameComm(snes,1,b,2);
3784 
3785   if (!x) {
3786     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3787     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3788     x    = xcreated;
3789   }
3790   ierr = SNESViewFromOptions(snes,NULL,"-snes_view_pre");CHKERRQ(ierr);
3791 
3792   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);}
3793   for (grid=0; grid<snes->gridsequence+1; grid++) {
3794 
3795     /* set solution vector */
3796     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3797     ierr          = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3798     snes->vec_sol = x;
3799     ierr          = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3800 
3801     /* set affine vector if provided */
3802     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3803     ierr          = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3804     snes->vec_rhs = b;
3805 
3806     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
3807     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
3808     if (!snes->vec_sol_update /* && snes->vec_sol */) {
3809       ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
3810       ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);CHKERRQ(ierr);
3811     }
3812     ierr = DMShellSetGlobalVector(dm,snes->vec_sol);CHKERRQ(ierr);
3813     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3814 
3815     if (!grid) {
3816       if (snes->ops->computeinitialguess) {
3817         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3818       }
3819     }
3820 
3821     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3822     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}
3823 
3824     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3825     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3826     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3827     if (snes->domainerror) {
3828       snes->reason      = SNES_DIVERGED_FUNCTION_DOMAIN;
3829       snes->domainerror = PETSC_FALSE;
3830     }
3831     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3832 
3833     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
3834     if (snes->lagpre_persist) snes->pre_iter += snes->iter;
3835 
3836     flg  = PETSC_FALSE;
3837     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,NULL);CHKERRQ(ierr);
3838     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
3839     ierr = SNESReasonViewFromOptions(snes);CHKERRQ(ierr);
3840 
3841     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
3842     if (grid <  snes->gridsequence) {
3843       DM  fine;
3844       Vec xnew;
3845       Mat interp;
3846 
3847       ierr = DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);CHKERRQ(ierr);
3848       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
3849       ierr = DMCreateInterpolation(snes->dm,fine,&interp,NULL);CHKERRQ(ierr);
3850       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
3851       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
3852       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
3853       ierr = MatDestroy(&interp);CHKERRQ(ierr);
3854       x    = xnew;
3855 
3856       ierr = SNESReset(snes);CHKERRQ(ierr);
3857       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
3858       ierr = DMDestroy(&fine);CHKERRQ(ierr);
3859       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);
3860     }
3861   }
3862   ierr = SNESViewFromOptions(snes,NULL,"-snes_view");CHKERRQ(ierr);
3863   ierr = VecViewFromOptions(snes->vec_sol,((PetscObject)snes)->prefix,"-snes_view_solution");CHKERRQ(ierr);
3864 
3865   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
3866   ierr = PetscObjectSAWsBlock((PetscObject)snes);CHKERRQ(ierr);
3867   PetscFunctionReturn(0);
3868 }
3869 
3870 /* --------- Internal routines for SNES Package --------- */
3871 
3872 #undef __FUNCT__
3873 #define __FUNCT__ "SNESSetType"
3874 /*@C
3875    SNESSetType - Sets the method for the nonlinear solver.
3876 
3877    Collective on SNES
3878 
3879    Input Parameters:
3880 +  snes - the SNES context
3881 -  type - a known method
3882 
3883    Options Database Key:
3884 .  -snes_type <type> - Sets the method; use -help for a list
3885    of available methods (for instance, newtonls or newtontr)
3886 
3887    Notes:
3888    See "petsc/include/petscsnes.h" for available methods (for instance)
3889 +    SNESNEWTONLS - Newton's method with line search
3890      (systems of nonlinear equations)
3891 .    SNESNEWTONTR - Newton's method with trust region
3892      (systems of nonlinear equations)
3893 
3894   Normally, it is best to use the SNESSetFromOptions() command and then
3895   set the SNES solver type from the options database rather than by using
3896   this routine.  Using the options database provides the user with
3897   maximum flexibility in evaluating the many nonlinear solvers.
3898   The SNESSetType() routine is provided for those situations where it
3899   is necessary to set the nonlinear solver independently of the command
3900   line or options database.  This might be the case, for example, when
3901   the choice of solver changes during the execution of the program,
3902   and the user's application is taking responsibility for choosing the
3903   appropriate method.
3904 
3905     Developer Notes: SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
3906     the constructor in that list and calls it to create the spexific object.
3907 
3908   Level: intermediate
3909 
3910 .keywords: SNES, set, type
3911 
3912 .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()
3913 
3914 @*/
3915 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
3916 {
3917   PetscErrorCode ierr,(*r)(SNES);
3918   PetscBool      match;
3919 
3920   PetscFunctionBegin;
3921   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3922   PetscValidCharPointer(type,2);
3923 
3924   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
3925   if (match) PetscFunctionReturn(0);
3926 
3927   ierr =  PetscFunctionListFind(SNESList,type,&r);CHKERRQ(ierr);
3928   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
3929   /* Destroy the previous private SNES context */
3930   if (snes->ops->destroy) {
3931     ierr               = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
3932     snes->ops->destroy = NULL;
3933   }
3934   /* Reinitialize function pointers in SNESOps structure */
3935   snes->ops->setup          = 0;
3936   snes->ops->solve          = 0;
3937   snes->ops->view           = 0;
3938   snes->ops->setfromoptions = 0;
3939   snes->ops->destroy        = 0;
3940   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
3941   snes->setupcalled = PETSC_FALSE;
3942 
3943   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
3944   ierr = (*r)(snes);CHKERRQ(ierr);
3945   PetscFunctionReturn(0);
3946 }
3947 
3948 #undef __FUNCT__
3949 #define __FUNCT__ "SNESGetType"
3950 /*@C
3951    SNESGetType - Gets the SNES method type and name (as a string).
3952 
3953    Not Collective
3954 
3955    Input Parameter:
3956 .  snes - nonlinear solver context
3957 
3958    Output Parameter:
3959 .  type - SNES method (a character string)
3960 
3961    Level: intermediate
3962 
3963 .keywords: SNES, nonlinear, get, type, name
3964 @*/
3965 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
3966 {
3967   PetscFunctionBegin;
3968   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3969   PetscValidPointer(type,2);
3970   *type = ((PetscObject)snes)->type_name;
3971   PetscFunctionReturn(0);
3972 }
3973 
3974 #undef __FUNCT__
3975 #define __FUNCT__ "SNESGetSolution"
3976 /*@
3977    SNESGetSolution - Returns the vector where the approximate solution is
3978    stored. This is the fine grid solution when using SNESSetGridSequence().
3979 
3980    Not Collective, but Vec is parallel if SNES is parallel
3981 
3982    Input Parameter:
3983 .  snes - the SNES context
3984 
3985    Output Parameter:
3986 .  x - the solution
3987 
3988    Level: intermediate
3989 
3990 .keywords: SNES, nonlinear, get, solution
3991 
3992 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
3993 @*/
3994 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
3995 {
3996   PetscFunctionBegin;
3997   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3998   PetscValidPointer(x,2);
3999   *x = snes->vec_sol;
4000   PetscFunctionReturn(0);
4001 }
4002 
4003 #undef __FUNCT__
4004 #define __FUNCT__ "SNESGetSolutionUpdate"
4005 /*@
4006    SNESGetSolutionUpdate - Returns the vector where the solution update is
4007    stored.
4008 
4009    Not Collective, but Vec is parallel if SNES is parallel
4010 
4011    Input Parameter:
4012 .  snes - the SNES context
4013 
4014    Output Parameter:
4015 .  x - the solution update
4016 
4017    Level: advanced
4018 
4019 .keywords: SNES, nonlinear, get, solution, update
4020 
4021 .seealso: SNESGetSolution(), SNESGetFunction()
4022 @*/
4023 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
4024 {
4025   PetscFunctionBegin;
4026   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4027   PetscValidPointer(x,2);
4028   *x = snes->vec_sol_update;
4029   PetscFunctionReturn(0);
4030 }
4031 
4032 #undef __FUNCT__
4033 #define __FUNCT__ "SNESGetFunction"
4034 /*@C
4035    SNESGetFunction - Returns the vector where the function is stored.
4036 
4037    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
4038 
4039    Input Parameter:
4040 .  snes - the SNES context
4041 
4042    Output Parameter:
4043 +  r - the vector that is used to store residuals (or NULL if you don't want it)
4044 .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
4045 -  ctx - the function context (or NULL if you don't want it)
4046 
4047    Level: advanced
4048 
4049 .keywords: SNES, nonlinear, get, function
4050 
4051 .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
4052 @*/
4053 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
4054 {
4055   PetscErrorCode ierr;
4056   DM             dm;
4057 
4058   PetscFunctionBegin;
4059   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4060   if (r) {
4061     if (!snes->vec_func) {
4062       if (snes->vec_rhs) {
4063         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
4064       } else if (snes->vec_sol) {
4065         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
4066       } else if (snes->dm) {
4067         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
4068       }
4069     }
4070     *r = snes->vec_func;
4071   }
4072   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4073   ierr = DMSNESGetFunction(dm,f,ctx);CHKERRQ(ierr);
4074   PetscFunctionReturn(0);
4075 }
4076 
4077 /*@C
4078    SNESGetNGS - Returns the NGS function and context.
4079 
4080    Input Parameter:
4081 .  snes - the SNES context
4082 
4083    Output Parameter:
4084 +  f - the function (or NULL) see SNESNGSFunction for details
4085 -  ctx    - the function context (or NULL)
4086 
4087    Level: advanced
4088 
4089 .keywords: SNES, nonlinear, get, function
4090 
4091 .seealso: SNESSetNGS(), SNESGetFunction()
4092 @*/
4093 
4094 #undef __FUNCT__
4095 #define __FUNCT__ "SNESGetNGS"
4096 PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
4097 {
4098   PetscErrorCode ierr;
4099   DM             dm;
4100 
4101   PetscFunctionBegin;
4102   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4103   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4104   ierr = DMSNESGetNGS(dm,f,ctx);CHKERRQ(ierr);
4105   PetscFunctionReturn(0);
4106 }
4107 
4108 #undef __FUNCT__
4109 #define __FUNCT__ "SNESSetOptionsPrefix"
4110 /*@C
4111    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4112    SNES options in the database.
4113 
4114    Logically Collective on SNES
4115 
4116    Input Parameter:
4117 +  snes - the SNES context
4118 -  prefix - the prefix to prepend to all option names
4119 
4120    Notes:
4121    A hyphen (-) must NOT be given at the beginning of the prefix name.
4122    The first character of all runtime options is AUTOMATICALLY the hyphen.
4123 
4124    Level: advanced
4125 
4126 .keywords: SNES, set, options, prefix, database
4127 
4128 .seealso: SNESSetFromOptions()
4129 @*/
4130 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4131 {
4132   PetscErrorCode ierr;
4133 
4134   PetscFunctionBegin;
4135   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4136   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4137   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4138   if (snes->linesearch) {
4139     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4140     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4141   }
4142   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4143   PetscFunctionReturn(0);
4144 }
4145 
4146 #undef __FUNCT__
4147 #define __FUNCT__ "SNESAppendOptionsPrefix"
4148 /*@C
4149    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4150    SNES options in the database.
4151 
4152    Logically Collective on SNES
4153 
4154    Input Parameters:
4155 +  snes - the SNES context
4156 -  prefix - the prefix to prepend to all option names
4157 
4158    Notes:
4159    A hyphen (-) must NOT be given at the beginning of the prefix name.
4160    The first character of all runtime options is AUTOMATICALLY the hyphen.
4161 
4162    Level: advanced
4163 
4164 .keywords: SNES, append, options, prefix, database
4165 
4166 .seealso: SNESGetOptionsPrefix()
4167 @*/
4168 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4169 {
4170   PetscErrorCode ierr;
4171 
4172   PetscFunctionBegin;
4173   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4174   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4175   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4176   if (snes->linesearch) {
4177     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4178     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4179   }
4180   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4181   PetscFunctionReturn(0);
4182 }
4183 
4184 #undef __FUNCT__
4185 #define __FUNCT__ "SNESGetOptionsPrefix"
4186 /*@C
4187    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4188    SNES options in the database.
4189 
4190    Not Collective
4191 
4192    Input Parameter:
4193 .  snes - the SNES context
4194 
4195    Output Parameter:
4196 .  prefix - pointer to the prefix string used
4197 
4198    Notes: On the fortran side, the user should pass in a string 'prefix' of
4199    sufficient length to hold the prefix.
4200 
4201    Level: advanced
4202 
4203 .keywords: SNES, get, options, prefix, database
4204 
4205 .seealso: SNESAppendOptionsPrefix()
4206 @*/
4207 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4208 {
4209   PetscErrorCode ierr;
4210 
4211   PetscFunctionBegin;
4212   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4213   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4214   PetscFunctionReturn(0);
4215 }
4216 
4217 
4218 #undef __FUNCT__
4219 #define __FUNCT__ "SNESRegister"
4220 /*@C
4221   SNESRegister - Adds a method to the nonlinear solver package.
4222 
4223    Not collective
4224 
4225    Input Parameters:
4226 +  name_solver - name of a new user-defined solver
4227 -  routine_create - routine to create method context
4228 
4229    Notes:
4230    SNESRegister() may be called multiple times to add several user-defined solvers.
4231 
4232    Sample usage:
4233 .vb
4234    SNESRegister("my_solver",MySolverCreate);
4235 .ve
4236 
4237    Then, your solver can be chosen with the procedural interface via
4238 $     SNESSetType(snes,"my_solver")
4239    or at runtime via the option
4240 $     -snes_type my_solver
4241 
4242    Level: advanced
4243 
4244     Note: If your function is not being put into a shared library then use SNESRegister() instead
4245 
4246 .keywords: SNES, nonlinear, register
4247 
4248 .seealso: SNESRegisterAll(), SNESRegisterDestroy()
4249 
4250   Level: advanced
4251 @*/
4252 PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
4253 {
4254   PetscErrorCode ierr;
4255 
4256   PetscFunctionBegin;
4257   ierr = PetscFunctionListAdd(&SNESList,sname,function);CHKERRQ(ierr);
4258   PetscFunctionReturn(0);
4259 }
4260 
4261 #undef __FUNCT__
4262 #define __FUNCT__ "SNESTestLocalMin"
4263 PetscErrorCode  SNESTestLocalMin(SNES snes)
4264 {
4265   PetscErrorCode ierr;
4266   PetscInt       N,i,j;
4267   Vec            u,uh,fh;
4268   PetscScalar    value;
4269   PetscReal      norm;
4270 
4271   PetscFunctionBegin;
4272   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4273   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4274   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4275 
4276   /* currently only works for sequential */
4277   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");CHKERRQ(ierr);
4278   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4279   for (i=0; i<N; i++) {
4280     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4281     ierr = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4282     for (j=-10; j<11; j++) {
4283       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
4284       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4285       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4286       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4287       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4288       value = -value;
4289       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4290     }
4291   }
4292   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4293   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4294   PetscFunctionReturn(0);
4295 }
4296 
4297 #undef __FUNCT__
4298 #define __FUNCT__ "SNESKSPSetUseEW"
4299 /*@
4300    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4301    computing relative tolerance for linear solvers within an inexact
4302    Newton method.
4303 
4304    Logically Collective on SNES
4305 
4306    Input Parameters:
4307 +  snes - SNES context
4308 -  flag - PETSC_TRUE or PETSC_FALSE
4309 
4310     Options Database:
4311 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4312 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4313 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4314 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4315 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4316 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4317 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4318 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4319 
4320    Notes:
4321    Currently, the default is to use a constant relative tolerance for
4322    the inner linear solvers.  Alternatively, one can use the
4323    Eisenstat-Walker method, where the relative convergence tolerance
4324    is reset at each Newton iteration according progress of the nonlinear
4325    solver.
4326 
4327    Level: advanced
4328 
4329    Reference:
4330    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4331    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4332 
4333 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4334 
4335 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4336 @*/
4337 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
4338 {
4339   PetscFunctionBegin;
4340   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4341   PetscValidLogicalCollectiveBool(snes,flag,2);
4342   snes->ksp_ewconv = flag;
4343   PetscFunctionReturn(0);
4344 }
4345 
4346 #undef __FUNCT__
4347 #define __FUNCT__ "SNESKSPGetUseEW"
4348 /*@
4349    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4350    for computing relative tolerance for linear solvers within an
4351    inexact Newton method.
4352 
4353    Not Collective
4354 
4355    Input Parameter:
4356 .  snes - SNES context
4357 
4358    Output Parameter:
4359 .  flag - PETSC_TRUE or PETSC_FALSE
4360 
4361    Notes:
4362    Currently, the default is to use a constant relative tolerance for
4363    the inner linear solvers.  Alternatively, one can use the
4364    Eisenstat-Walker method, where the relative convergence tolerance
4365    is reset at each Newton iteration according progress of the nonlinear
4366    solver.
4367 
4368    Level: advanced
4369 
4370    Reference:
4371    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4372    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4373 
4374 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4375 
4376 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4377 @*/
4378 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4379 {
4380   PetscFunctionBegin;
4381   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4382   PetscValidPointer(flag,2);
4383   *flag = snes->ksp_ewconv;
4384   PetscFunctionReturn(0);
4385 }
4386 
4387 #undef __FUNCT__
4388 #define __FUNCT__ "SNESKSPSetParametersEW"
4389 /*@
4390    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4391    convergence criteria for the linear solvers within an inexact
4392    Newton method.
4393 
4394    Logically Collective on SNES
4395 
4396    Input Parameters:
4397 +    snes - SNES context
4398 .    version - version 1, 2 (default is 2) or 3
4399 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4400 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4401 .    gamma - multiplicative factor for version 2 rtol computation
4402              (0 <= gamma2 <= 1)
4403 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4404 .    alpha2 - power for safeguard
4405 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4406 
4407    Note:
4408    Version 3 was contributed by Luis Chacon, June 2006.
4409 
4410    Use PETSC_DEFAULT to retain the default for any of the parameters.
4411 
4412    Level: advanced
4413 
4414    Reference:
4415    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4416    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4417    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4418 
4419 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4420 
4421 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4422 @*/
4423 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4424 {
4425   SNESKSPEW *kctx;
4426 
4427   PetscFunctionBegin;
4428   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4429   kctx = (SNESKSPEW*)snes->kspconvctx;
4430   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4431   PetscValidLogicalCollectiveInt(snes,version,2);
4432   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4433   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4434   PetscValidLogicalCollectiveReal(snes,gamma,5);
4435   PetscValidLogicalCollectiveReal(snes,alpha,6);
4436   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4437   PetscValidLogicalCollectiveReal(snes,threshold,8);
4438 
4439   if (version != PETSC_DEFAULT)   kctx->version   = version;
4440   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4441   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4442   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4443   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4444   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4445   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4446 
4447   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);
4448   if (kctx->rtol_0 < 0.0 || kctx->rtol_0 >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_0 < 1.0: %g",(double)kctx->rtol_0);
4449   if (kctx->rtol_max < 0.0 || kctx->rtol_max >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_max (%g) < 1.0\n",(double)kctx->rtol_max);
4450   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%g) <= 1.0\n",(double)kctx->gamma);
4451   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%g) <= 2.0\n",(double)kctx->alpha);
4452   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%g) < 1.0\n",(double)kctx->threshold);
4453   PetscFunctionReturn(0);
4454 }
4455 
4456 #undef __FUNCT__
4457 #define __FUNCT__ "SNESKSPGetParametersEW"
4458 /*@
4459    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4460    convergence criteria for the linear solvers within an inexact
4461    Newton method.
4462 
4463    Not Collective
4464 
4465    Input Parameters:
4466      snes - SNES context
4467 
4468    Output Parameters:
4469 +    version - version 1, 2 (default is 2) or 3
4470 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4471 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4472 .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
4473 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4474 .    alpha2 - power for safeguard
4475 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4476 
4477    Level: advanced
4478 
4479 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4480 
4481 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4482 @*/
4483 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4484 {
4485   SNESKSPEW *kctx;
4486 
4487   PetscFunctionBegin;
4488   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4489   kctx = (SNESKSPEW*)snes->kspconvctx;
4490   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4491   if (version)   *version   = kctx->version;
4492   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4493   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4494   if (gamma)     *gamma     = kctx->gamma;
4495   if (alpha)     *alpha     = kctx->alpha;
4496   if (alpha2)    *alpha2    = kctx->alpha2;
4497   if (threshold) *threshold = kctx->threshold;
4498   PetscFunctionReturn(0);
4499 }
4500 
4501 #undef __FUNCT__
4502 #define __FUNCT__ "KSPPreSolve_SNESEW"
4503  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4504 {
4505   PetscErrorCode ierr;
4506   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4507   PetscReal      rtol  = PETSC_DEFAULT,stol;
4508 
4509   PetscFunctionBegin;
4510   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4511   if (!snes->iter) {
4512     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
4513     ierr = VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);CHKERRQ(ierr);
4514   }
4515   else {
4516     if (kctx->version == 1) {
4517       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4518       if (rtol < 0.0) rtol = -rtol;
4519       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
4520       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4521     } else if (kctx->version == 2) {
4522       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4523       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
4524       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4525     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
4526       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4527       /* safeguard: avoid sharp decrease of rtol */
4528       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
4529       stol = PetscMax(rtol,stol);
4530       rtol = PetscMin(kctx->rtol_0,stol);
4531       /* safeguard: avoid oversolving */
4532       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
4533       stol = PetscMax(rtol,stol);
4534       rtol = PetscMin(kctx->rtol_0,stol);
4535     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4536   }
4537   /* safeguard: avoid rtol greater than one */
4538   rtol = PetscMin(rtol,kctx->rtol_max);
4539   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4540   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);CHKERRQ(ierr);
4541   PetscFunctionReturn(0);
4542 }
4543 
4544 #undef __FUNCT__
4545 #define __FUNCT__ "KSPPostSolve_SNESEW"
4546 PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4547 {
4548   PetscErrorCode ierr;
4549   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4550   PCSide         pcside;
4551   Vec            lres;
4552 
4553   PetscFunctionBegin;
4554   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4555   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4556   kctx->norm_last = snes->norm;
4557   if (kctx->version == 1) {
4558     PC        pc;
4559     PetscBool isNone;
4560 
4561     ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
4562     ierr = PetscObjectTypeCompare((PetscObject) pc, PCNONE, &isNone);CHKERRQ(ierr);
4563     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4564      if (pcside == PC_RIGHT || isNone) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4565       /* KSP residual is true linear residual */
4566       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4567     } else {
4568       /* KSP residual is preconditioned residual */
4569       /* compute true linear residual norm */
4570       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4571       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4572       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4573       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4574       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4575     }
4576   }
4577   PetscFunctionReturn(0);
4578 }
4579 
4580 #undef __FUNCT__
4581 #define __FUNCT__ "SNESGetKSP"
4582 /*@
4583    SNESGetKSP - Returns the KSP context for a SNES solver.
4584 
4585    Not Collective, but if SNES object is parallel, then KSP object is parallel
4586 
4587    Input Parameter:
4588 .  snes - the SNES context
4589 
4590    Output Parameter:
4591 .  ksp - the KSP context
4592 
4593    Notes:
4594    The user can then directly manipulate the KSP context to set various
4595    options, etc.  Likewise, the user can then extract and manipulate the
4596    PC contexts as well.
4597 
4598    Level: beginner
4599 
4600 .keywords: SNES, nonlinear, get, KSP, context
4601 
4602 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
4603 @*/
4604 PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
4605 {
4606   PetscErrorCode ierr;
4607 
4608   PetscFunctionBegin;
4609   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4610   PetscValidPointer(ksp,2);
4611 
4612   if (!snes->ksp) {
4613     PetscBool monitor = PETSC_FALSE;
4614 
4615     ierr = KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);CHKERRQ(ierr);
4616     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);CHKERRQ(ierr);
4617     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);CHKERRQ(ierr);
4618 
4619     ierr = KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);CHKERRQ(ierr);
4620     ierr = KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);CHKERRQ(ierr);
4621 
4622     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-ksp_monitor_snes",&monitor,NULL);CHKERRQ(ierr);
4623     if (monitor) {
4624       ierr = KSPMonitorSet(snes->ksp,KSPMonitorSNES,snes,NULL);CHKERRQ(ierr);
4625     }
4626     monitor = PETSC_FALSE;
4627     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-ksp_monitor_snes_lg",&monitor,NULL);CHKERRQ(ierr);
4628     if (monitor) {
4629       PetscObject *objs;
4630       ierr = KSPMonitorSNESLGResidualNormCreate(0,0,PETSC_DECIDE,PETSC_DECIDE,600,600,&objs);CHKERRQ(ierr);
4631       objs[0] = (PetscObject) snes;
4632       ierr = KSPMonitorSet(snes->ksp,(PetscErrorCode (*)(KSP,PetscInt,PetscReal,void*))KSPMonitorSNESLGResidualNorm,objs,(PetscErrorCode (*)(void**))KSPMonitorSNESLGResidualNormDestroy);CHKERRQ(ierr);
4633     }
4634   }
4635   *ksp = snes->ksp;
4636   PetscFunctionReturn(0);
4637 }
4638 
4639 
4640 #include <petsc-private/dmimpl.h>
4641 #undef __FUNCT__
4642 #define __FUNCT__ "SNESSetDM"
4643 /*@
4644    SNESSetDM - Sets the DM that may be used by some preconditioners
4645 
4646    Logically Collective on SNES
4647 
4648    Input Parameters:
4649 +  snes - the preconditioner context
4650 -  dm - the dm
4651 
4652    Level: intermediate
4653 
4654 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4655 @*/
4656 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4657 {
4658   PetscErrorCode ierr;
4659   KSP            ksp;
4660   DMSNES         sdm;
4661 
4662   PetscFunctionBegin;
4663   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4664   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4665   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4666     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4667       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4668       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4669       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
4670     }
4671     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4672   }
4673   snes->dm     = dm;
4674   snes->dmAuto = PETSC_FALSE;
4675 
4676   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4677   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4678   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4679   if (snes->pc) {
4680     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4681     ierr = SNESSetNPCSide(snes,snes->pcside);CHKERRQ(ierr);
4682   }
4683   PetscFunctionReturn(0);
4684 }
4685 
4686 #undef __FUNCT__
4687 #define __FUNCT__ "SNESGetDM"
4688 /*@
4689    SNESGetDM - Gets the DM that may be used by some preconditioners
4690 
4691    Not Collective but DM obtained is parallel on SNES
4692 
4693    Input Parameter:
4694 . snes - the preconditioner context
4695 
4696    Output Parameter:
4697 .  dm - the dm
4698 
4699    Level: intermediate
4700 
4701 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4702 @*/
4703 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4704 {
4705   PetscErrorCode ierr;
4706 
4707   PetscFunctionBegin;
4708   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4709   if (!snes->dm) {
4710     ierr         = DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);CHKERRQ(ierr);
4711     snes->dmAuto = PETSC_TRUE;
4712   }
4713   *dm = snes->dm;
4714   PetscFunctionReturn(0);
4715 }
4716 
4717 #undef __FUNCT__
4718 #define __FUNCT__ "SNESSetNPC"
4719 /*@
4720   SNESSetNPC - Sets the nonlinear preconditioner to be used.
4721 
4722   Collective on SNES
4723 
4724   Input Parameters:
4725 + snes - iterative context obtained from SNESCreate()
4726 - pc   - the preconditioner object
4727 
4728   Notes:
4729   Use SNESGetNPC() to retrieve the preconditioner context (for example,
4730   to configure it using the API).
4731 
4732   Level: developer
4733 
4734 .keywords: SNES, set, precondition
4735 .seealso: SNESGetNPC(), SNESHasNPC()
4736 @*/
4737 PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
4738 {
4739   PetscErrorCode ierr;
4740 
4741   PetscFunctionBegin;
4742   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4743   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4744   PetscCheckSameComm(snes, 1, pc, 2);
4745   ierr     = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4746   ierr     = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4747   snes->pc = pc;
4748   ierr     = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->pc);CHKERRQ(ierr);
4749   PetscFunctionReturn(0);
4750 }
4751 
4752 #undef __FUNCT__
4753 #define __FUNCT__ "SNESGetNPC"
4754 /*@
4755   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.
4756 
4757   Not Collective
4758 
4759   Input Parameter:
4760 . snes - iterative context obtained from SNESCreate()
4761 
4762   Output Parameter:
4763 . pc - preconditioner context
4764 
4765   Notes: If a SNES was previously set with SNESSetNPC() then that SNES is returned.
4766 
4767   Level: developer
4768 
4769 .keywords: SNES, get, preconditioner
4770 .seealso: SNESSetNPC(), SNESHasNPC()
4771 @*/
4772 PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
4773 {
4774   PetscErrorCode ierr;
4775   const char     *optionsprefix;
4776 
4777   PetscFunctionBegin;
4778   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4779   PetscValidPointer(pc, 2);
4780   if (!snes->pc) {
4781     ierr = SNESCreate(PetscObjectComm((PetscObject)snes),&snes->pc);CHKERRQ(ierr);
4782     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4783     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
4784     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4785     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4786     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4787     ierr = SNESSetCountersReset(snes->pc,PETSC_FALSE);CHKERRQ(ierr);
4788   }
4789   *pc = snes->pc;
4790   PetscFunctionReturn(0);
4791 }
4792 
4793 #undef __FUNCT__
4794 #define __FUNCT__ "SNESHasNPC"
4795 /*@
4796   SNESHasNPC - Returns whether a nonlinear preconditioner exists
4797 
4798   Not Collective
4799 
4800   Input Parameter:
4801 . snes - iterative context obtained from SNESCreate()
4802 
4803   Output Parameter:
4804 . has_npc - whether the SNES has an NPC or not
4805 
4806   Level: developer
4807 
4808 .keywords: SNES, has, preconditioner
4809 .seealso: SNESSetNPC(), SNESGetNPC()
4810 @*/
4811 PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
4812 {
4813   PetscFunctionBegin;
4814   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4815   *has_npc = (PetscBool) (snes->pc != NULL);
4816   PetscFunctionReturn(0);
4817 }
4818 
4819 #undef __FUNCT__
4820 #define __FUNCT__ "SNESSetNPCSide"
4821 /*@
4822     SNESSetNPCSide - Sets the preconditioning side.
4823 
4824     Logically Collective on SNES
4825 
4826     Input Parameter:
4827 .   snes - iterative context obtained from SNESCreate()
4828 
4829     Output Parameter:
4830 .   side - the preconditioning side, where side is one of
4831 .vb
4832       PC_LEFT - left preconditioning (default)
4833       PC_RIGHT - right preconditioning
4834 .ve
4835 
4836     Options Database Keys:
4837 .   -snes_pc_side <right,left>
4838 
4839     Level: intermediate
4840 
4841 .keywords: SNES, set, right, left, side, preconditioner, flag
4842 
4843 .seealso: SNESGetNPCSide(), KSPSetPCSide()
4844 @*/
4845 PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
4846 {
4847   PetscFunctionBegin;
4848   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4849   PetscValidLogicalCollectiveEnum(snes,side,2);
4850   snes->pcside = side;
4851   PetscFunctionReturn(0);
4852 }
4853 
4854 #undef __FUNCT__
4855 #define __FUNCT__ "SNESGetNPCSide"
4856 /*@
4857     SNESGetNPCSide - Gets the preconditioning side.
4858 
4859     Not Collective
4860 
4861     Input Parameter:
4862 .   snes - iterative context obtained from SNESCreate()
4863 
4864     Output Parameter:
4865 .   side - the preconditioning side, where side is one of
4866 .vb
4867       PC_LEFT - left preconditioning (default)
4868       PC_RIGHT - right preconditioning
4869 .ve
4870 
4871     Level: intermediate
4872 
4873 .keywords: SNES, get, right, left, side, preconditioner, flag
4874 
4875 .seealso: SNESSetNPCSide(), KSPGetPCSide()
4876 @*/
4877 PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
4878 {
4879   PetscFunctionBegin;
4880   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4881   PetscValidPointer(side,2);
4882   *side = snes->pcside;
4883   PetscFunctionReturn(0);
4884 }
4885 
4886 #undef __FUNCT__
4887 #define __FUNCT__ "SNESSetLineSearch"
4888 /*@
4889   SNESSetLineSearch - Sets the linesearch on the SNES instance.
4890 
4891   Collective on SNES
4892 
4893   Input Parameters:
4894 + snes - iterative context obtained from SNESCreate()
4895 - linesearch   - the linesearch object
4896 
4897   Notes:
4898   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
4899   to configure it using the API).
4900 
4901   Level: developer
4902 
4903 .keywords: SNES, set, linesearch
4904 .seealso: SNESGetLineSearch()
4905 @*/
4906 PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
4907 {
4908   PetscErrorCode ierr;
4909 
4910   PetscFunctionBegin;
4911   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4912   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
4913   PetscCheckSameComm(snes, 1, linesearch, 2);
4914   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
4915   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
4916 
4917   snes->linesearch = linesearch;
4918 
4919   ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
4920   PetscFunctionReturn(0);
4921 }
4922 
4923 #undef __FUNCT__
4924 #define __FUNCT__ "SNESGetLineSearch"
4925 /*@
4926   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
4927   or creates a default line search instance associated with the SNES and returns it.
4928 
4929   Not Collective
4930 
4931   Input Parameter:
4932 . snes - iterative context obtained from SNESCreate()
4933 
4934   Output Parameter:
4935 . linesearch - linesearch context
4936 
4937   Level: beginner
4938 
4939 .keywords: SNES, get, linesearch
4940 .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
4941 @*/
4942 PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
4943 {
4944   PetscErrorCode ierr;
4945   const char     *optionsprefix;
4946 
4947   PetscFunctionBegin;
4948   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4949   PetscValidPointer(linesearch, 2);
4950   if (!snes->linesearch) {
4951     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
4952     ierr = SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);CHKERRQ(ierr);
4953     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
4954     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
4955     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
4956     ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
4957   }
4958   *linesearch = snes->linesearch;
4959   PetscFunctionReturn(0);
4960 }
4961 
4962 #if defined(PETSC_HAVE_MATLAB_ENGINE)
4963 #include <mex.h>
4964 
4965 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
4966 
4967 #undef __FUNCT__
4968 #define __FUNCT__ "SNESComputeFunction_Matlab"
4969 /*
4970    SNESComputeFunction_Matlab - Calls the function that has been set with SNESSetFunctionMatlab().
4971 
4972    Collective on SNES
4973 
4974    Input Parameters:
4975 +  snes - the SNES context
4976 -  x - input vector
4977 
4978    Output Parameter:
4979 .  y - function vector, as set by SNESSetFunction()
4980 
4981    Notes:
4982    SNESComputeFunction() is typically used within nonlinear solvers
4983    implementations, so most users would not generally call this routine
4984    themselves.
4985 
4986    Level: developer
4987 
4988 .keywords: SNES, nonlinear, compute, function
4989 
4990 .seealso: SNESSetFunction(), SNESGetFunction()
4991 */
4992 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
4993 {
4994   PetscErrorCode    ierr;
4995   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
4996   int               nlhs  = 1,nrhs = 5;
4997   mxArray           *plhs[1],*prhs[5];
4998   long long int     lx = 0,ly = 0,ls = 0;
4999 
5000   PetscFunctionBegin;
5001   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5002   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
5003   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
5004   PetscCheckSameComm(snes,1,x,2);
5005   PetscCheckSameComm(snes,1,y,3);
5006 
5007   /* call Matlab function in ctx with arguments x and y */
5008 
5009   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5010   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5011   ierr    = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
5012   prhs[0] = mxCreateDoubleScalar((double)ls);
5013   prhs[1] = mxCreateDoubleScalar((double)lx);
5014   prhs[2] = mxCreateDoubleScalar((double)ly);
5015   prhs[3] = mxCreateString(sctx->funcname);
5016   prhs[4] = sctx->ctx;
5017   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
5018   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5019   mxDestroyArray(prhs[0]);
5020   mxDestroyArray(prhs[1]);
5021   mxDestroyArray(prhs[2]);
5022   mxDestroyArray(prhs[3]);
5023   mxDestroyArray(plhs[0]);
5024   PetscFunctionReturn(0);
5025 }
5026 
5027 #undef __FUNCT__
5028 #define __FUNCT__ "SNESSetFunctionMatlab"
5029 /*
5030    SNESSetFunctionMatlab - Sets the function evaluation routine and function
5031    vector for use by the SNES routines in solving systems of nonlinear
5032    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5033 
5034    Logically Collective on SNES
5035 
5036    Input Parameters:
5037 +  snes - the SNES context
5038 .  r - vector to store function value
5039 -  f - function evaluation routine
5040 
5041    Notes:
5042    The Newton-like methods typically solve linear systems of the form
5043 $      f'(x) x = -f(x),
5044    where f'(x) denotes the Jacobian matrix and f(x) is the function.
5045 
5046    Level: beginner
5047 
5048    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5049 
5050 .keywords: SNES, nonlinear, set, function
5051 
5052 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5053 */
5054 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *f,mxArray *ctx)
5055 {
5056   PetscErrorCode    ierr;
5057   SNESMatlabContext *sctx;
5058 
5059   PetscFunctionBegin;
5060   /* currently sctx is memory bleed */
5061   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5062   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5063   /*
5064      This should work, but it doesn't
5065   sctx->ctx = ctx;
5066   mexMakeArrayPersistent(sctx->ctx);
5067   */
5068   sctx->ctx = mxDuplicateArray(ctx);
5069   ierr      = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
5070   PetscFunctionReturn(0);
5071 }
5072 
5073 #undef __FUNCT__
5074 #define __FUNCT__ "SNESComputeJacobian_Matlab"
5075 /*
5076    SNESComputeJacobian_Matlab - Calls the function that has been set with SNESSetJacobianMatlab().
5077 
5078    Collective on SNES
5079 
5080    Input Parameters:
5081 +  snes - the SNES context
5082 .  x - input vector
5083 .  A, B - the matrices
5084 -  ctx - user context
5085 
5086    Level: developer
5087 
5088 .keywords: SNES, nonlinear, compute, function
5089 
5090 .seealso: SNESSetFunction(), SNESGetFunction()
5091 @*/
5092 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat A,Mat B,void *ctx)
5093 {
5094   PetscErrorCode    ierr;
5095   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5096   int               nlhs  = 2,nrhs = 6;
5097   mxArray           *plhs[2],*prhs[6];
5098   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
5099 
5100   PetscFunctionBegin;
5101   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5102   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
5103 
5104   /* call Matlab function in ctx with arguments x and y */
5105 
5106   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5107   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5108   ierr    = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
5109   ierr    = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
5110   prhs[0] = mxCreateDoubleScalar((double)ls);
5111   prhs[1] = mxCreateDoubleScalar((double)lx);
5112   prhs[2] = mxCreateDoubleScalar((double)lA);
5113   prhs[3] = mxCreateDoubleScalar((double)lB);
5114   prhs[4] = mxCreateString(sctx->funcname);
5115   prhs[5] = sctx->ctx;
5116   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
5117   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5118   mxDestroyArray(prhs[0]);
5119   mxDestroyArray(prhs[1]);
5120   mxDestroyArray(prhs[2]);
5121   mxDestroyArray(prhs[3]);
5122   mxDestroyArray(prhs[4]);
5123   mxDestroyArray(plhs[0]);
5124   mxDestroyArray(plhs[1]);
5125   PetscFunctionReturn(0);
5126 }
5127 
5128 #undef __FUNCT__
5129 #define __FUNCT__ "SNESSetJacobianMatlab"
5130 /*
5131    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
5132    vector for use by the SNES routines in solving systems of nonlinear
5133    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5134 
5135    Logically Collective on SNES
5136 
5137    Input Parameters:
5138 +  snes - the SNES context
5139 .  A,B - Jacobian matrices
5140 .  J - function evaluation routine
5141 -  ctx - user context
5142 
5143    Level: developer
5144 
5145    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5146 
5147 .keywords: SNES, nonlinear, set, function
5148 
5149 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction(), J
5150 */
5151 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *J,mxArray *ctx)
5152 {
5153   PetscErrorCode    ierr;
5154   SNESMatlabContext *sctx;
5155 
5156   PetscFunctionBegin;
5157   /* currently sctx is memory bleed */
5158   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5159   ierr = PetscStrallocpy(J,&sctx->funcname);CHKERRQ(ierr);
5160   /*
5161      This should work, but it doesn't
5162   sctx->ctx = ctx;
5163   mexMakeArrayPersistent(sctx->ctx);
5164   */
5165   sctx->ctx = mxDuplicateArray(ctx);
5166   ierr      = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
5167   PetscFunctionReturn(0);
5168 }
5169 
5170 #undef __FUNCT__
5171 #define __FUNCT__ "SNESMonitor_Matlab"
5172 /*
5173    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
5174 
5175    Collective on SNES
5176 
5177 .seealso: SNESSetFunction(), SNESGetFunction()
5178 @*/
5179 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
5180 {
5181   PetscErrorCode    ierr;
5182   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5183   int               nlhs  = 1,nrhs = 6;
5184   mxArray           *plhs[1],*prhs[6];
5185   long long int     lx = 0,ls = 0;
5186   Vec               x  = snes->vec_sol;
5187 
5188   PetscFunctionBegin;
5189   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5190 
5191   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5192   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5193   prhs[0] = mxCreateDoubleScalar((double)ls);
5194   prhs[1] = mxCreateDoubleScalar((double)it);
5195   prhs[2] = mxCreateDoubleScalar((double)fnorm);
5196   prhs[3] = mxCreateDoubleScalar((double)lx);
5197   prhs[4] = mxCreateString(sctx->funcname);
5198   prhs[5] = sctx->ctx;
5199   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
5200   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5201   mxDestroyArray(prhs[0]);
5202   mxDestroyArray(prhs[1]);
5203   mxDestroyArray(prhs[2]);
5204   mxDestroyArray(prhs[3]);
5205   mxDestroyArray(prhs[4]);
5206   mxDestroyArray(plhs[0]);
5207   PetscFunctionReturn(0);
5208 }
5209 
5210 #undef __FUNCT__
5211 #define __FUNCT__ "SNESMonitorSetMatlab"
5212 /*
5213    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
5214 
5215    Level: developer
5216 
5217    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5218 
5219 .keywords: SNES, nonlinear, set, function
5220 
5221 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5222 */
5223 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *f,mxArray *ctx)
5224 {
5225   PetscErrorCode    ierr;
5226   SNESMatlabContext *sctx;
5227 
5228   PetscFunctionBegin;
5229   /* currently sctx is memory bleed */
5230   ierr = PetscNew(&sctx);CHKERRQ(ierr);
5231   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5232   /*
5233      This should work, but it doesn't
5234   sctx->ctx = ctx;
5235   mexMakeArrayPersistent(sctx->ctx);
5236   */
5237   sctx->ctx = mxDuplicateArray(ctx);
5238   ierr      = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,NULL);CHKERRQ(ierr);
5239   PetscFunctionReturn(0);
5240 }
5241 
5242 #endif
5243