xref: /petsc/src/snes/interface/snes.c (revision ffb7e86ce04a759bf35c9adf63a5002355bf1185)
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 = MatGetVecs(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;
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,0);CHKERRQ(ierr);
683   ierr = PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,0);CHKERRQ(ierr);
684 
685   ierr = PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,0);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 = PetscOptionsBool("-snes_converged_reason","Print reason for converged or diverged","SNESSolve",snes->printreason,&snes->printreason,NULL);CHKERRQ(ierr);
723 
724   ierr = PetscOptionsEList("-snes_norm_schedule","SNES Norm schedule","SNESSetNormSchedule",SNESNormSchedules,5,"function",&indx,&flg);CHKERRQ(ierr);
725   if (flg) { ierr = SNESSetNormSchedule(snes,(SNESNormSchedule)indx);CHKERRQ(ierr); }
726 
727   ierr = PetscOptionsEList("-snes_function_type","SNES Norm schedule","SNESSetFunctionType",SNESFunctionTypes,2,"unpreconditioned",&indx,&flg);CHKERRQ(ierr);
728   if (flg) { ierr = SNESSetFunctionType(snes,(SNESFunctionType)indx);CHKERRQ(ierr); }
729 
730   kctx = (SNESKSPEW*)snes->kspconvctx;
731 
732   ierr = PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,NULL);CHKERRQ(ierr);
733 
734   ierr = PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,0);CHKERRQ(ierr);
735   ierr = PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,0);CHKERRQ(ierr);
736   ierr = PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,0);CHKERRQ(ierr);
737   ierr = PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,0);CHKERRQ(ierr);
738   ierr = PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,0);CHKERRQ(ierr);
739   ierr = PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,0);CHKERRQ(ierr);
740   ierr = PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,0);CHKERRQ(ierr);
741 
742   flg  = PETSC_FALSE;
743   ierr = PetscOptionsBool("-snes_check_jacobian","Check each Jacobian with a differenced one","SNESUpdateCheckJacobian",flg,&flg,NULL);CHKERRQ(ierr);
744   if (flg) {
745     ierr = SNESSetUpdate(snes,SNESUpdateCheckJacobian);CHKERRQ(ierr);
746   }
747 
748   flg  = PETSC_FALSE;
749   ierr = PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,NULL);CHKERRQ(ierr);
750   if (flg) {ierr = SNESMonitorCancel(snes);CHKERRQ(ierr);}
751 
752   ierr = PetscOptionsString("-snes_monitor","Monitor norm of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
753   if (flg) {
754     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
755     ierr = SNESMonitorSet(snes,SNESMonitorDefault,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
756   }
757 
758   ierr = PetscOptionsString("-snes_monitor_range","Monitor range of elements of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
759   if (flg) {
760     ierr = SNESMonitorSet(snes,SNESMonitorRange,0,0);CHKERRQ(ierr);
761   }
762 
763   ierr = PetscOptionsString("-snes_ratiomonitor","Monitor ratios of norms of function","SNESMonitorSetRatio","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
764   if (flg) {
765     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
766     ierr = SNESMonitorSetRatio(snes,monviewer);CHKERRQ(ierr);
767   }
768 
769   ierr = PetscOptionsString("-snes_monitor_short","Monitor norm of function (fewer digits)","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
770   if (flg) {
771     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
772     ierr = SNESMonitorSet(snes,SNESMonitorDefaultShort,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
773   }
774 
775   ierr = PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
776   if (flg) {ierr = PetscPythonMonitorSet((PetscObject)snes,monfilename);CHKERRQ(ierr);}
777 
778   flg  = PETSC_FALSE;
779   ierr = PetscOptionsBool("-snes_monitor_solution","Plot solution at each iteration","SNESMonitorSolution",flg,&flg,NULL);CHKERRQ(ierr);
780   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolution,0,0);CHKERRQ(ierr);}
781   flg  = PETSC_FALSE;
782   ierr = PetscOptionsBool("-snes_monitor_solution_update","Plot correction at each iteration","SNESMonitorSolutionUpdate",flg,&flg,NULL);CHKERRQ(ierr);
783   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolutionUpdate,0,0);CHKERRQ(ierr);}
784   flg  = PETSC_FALSE;
785   ierr = PetscOptionsBool("-snes_monitor_residual","Plot residual at each iteration","SNESMonitorResidual",flg,&flg,NULL);CHKERRQ(ierr);
786   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorResidual,0,0);CHKERRQ(ierr);}
787   flg  = PETSC_FALSE;
788   ierr = PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,NULL);CHKERRQ(ierr);
789   if (flg) {
790     PetscDrawLG ctx;
791 
792     ierr = SNESMonitorLGCreate(0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
793     ierr = SNESMonitorSet(snes,SNESMonitorLGResidualNorm,ctx,(PetscErrorCode (*)(void**))SNESMonitorLGDestroy);CHKERRQ(ierr);
794   }
795   flg  = PETSC_FALSE;
796   ierr = PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);CHKERRQ(ierr);
797   if (flg) {
798     PetscViewer ctx;
799 
800     ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
801     ierr = SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
802   }
803 
804   flg  = PETSC_FALSE;
805   ierr = PetscOptionsBool("-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",flg,&flg,NULL);CHKERRQ(ierr);
806   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorJacUpdateSpectrum,0,0);CHKERRQ(ierr);}
807 
808 
809   ierr = PetscOptionsString("-snes_monitor_fields","Monitor norm of function per field","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
810   if (flg) {
811     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
812     ierr = SNESMonitorSet(snes,SNESMonitorFields,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
813   }
814 
815   flg  = PETSC_FALSE;
816   ierr = PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);CHKERRQ(ierr);
817   if (flg) {
818     void *functx;
819     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
820     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);CHKERRQ(ierr);
821     ierr = PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");CHKERRQ(ierr);
822   }
823 
824   flg  = PETSC_FALSE;
825   ierr = PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);CHKERRQ(ierr);
826   if (flg) {
827     ierr = SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);CHKERRQ(ierr);
828   }
829 
830   flg  = PETSC_FALSE;
831   ierr = PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);CHKERRQ(ierr);
832   if (flg) {
833     DM             dm;
834     DMSNES         sdm;
835     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
836     ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
837     sdm->jacobianctx = NULL;
838     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
839     ierr = PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");CHKERRQ(ierr);
840   }
841 
842   flg  = PETSC_FALSE;
843   ierr = PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf_operator,&flg);CHKERRQ(ierr);
844   if (flg && snes->mf_operator) {
845     snes->mf_operator = PETSC_TRUE;
846     snes->mf          = PETSC_TRUE;
847   }
848   flg  = PETSC_FALSE;
849   ierr = PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf,&flg);CHKERRQ(ierr);
850   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
851   ierr = PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,0);CHKERRQ(ierr);
852 
853   flg  = PETSC_FALSE;
854   ierr = SNESGetNPCSide(snes,&pcside);CHKERRQ(ierr);
855   ierr = PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetNPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);CHKERRQ(ierr);
856   if (flg) {ierr = SNESSetNPCSide(snes,pcside);CHKERRQ(ierr);}
857 
858 #if defined(PETSC_HAVE_SAWS)
859   /*
860     Publish convergence information using SAWs
861   */
862   flg  = PETSC_FALSE;
863   ierr = PetscOptionsBool("-snes_monitor_saws","Publish SNES progress using SAWs","SNESMonitorSet",flg,&flg,NULL);CHKERRQ(ierr);
864   if (flg) {
865     void *ctx;
866     ierr = SNESMonitorSAWsCreate(snes,&ctx);CHKERRQ(ierr);
867     ierr = SNESMonitorSet(snes,SNESMonitorSAWs,ctx,SNESMonitorSAWsDestroy);CHKERRQ(ierr);
868   }
869 #endif
870 #if defined(PETSC_HAVE_SAWS)
871   {
872   PetscBool set;
873   flg  = PETSC_FALSE;
874   ierr = PetscOptionsBool("-snes_saws_block","Block for SAWs at end of SNESSolve","PetscObjectSAWsBlock",((PetscObject)snes)->amspublishblock,&flg,&set);CHKERRQ(ierr);
875   if (set) {
876     ierr = PetscObjectSAWsSetBlock((PetscObject)snes,flg);CHKERRQ(ierr);
877   }
878   }
879 #endif
880 
881   for (i = 0; i < numberofsetfromoptions; i++) {
882     ierr = (*othersetfromoptions[i])(snes);CHKERRQ(ierr);
883   }
884 
885   if (snes->ops->setfromoptions) {
886     ierr = (*snes->ops->setfromoptions)(snes);CHKERRQ(ierr);
887   }
888 
889   /* process any options handlers added with PetscObjectAddOptionsHandler() */
890   ierr = PetscObjectProcessOptionsHandlers((PetscObject)snes);CHKERRQ(ierr);
891   ierr = PetscOptionsEnd();CHKERRQ(ierr);
892 
893   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
894   ierr = KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);CHKERRQ(ierr);
895   ierr = KSPSetFromOptions(snes->ksp);CHKERRQ(ierr);
896 
897   if (!snes->linesearch) {
898     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
899   }
900   ierr = SNESLineSearchSetFromOptions(snes->linesearch);CHKERRQ(ierr);
901 
902   /* if someone has set the SNES NPC type, create it. */
903   ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
904   ierr = PetscOptionsHasName(optionsprefix, "-npc_snes_type", &pcset);CHKERRQ(ierr);
905   if (pcset && (!snes->pc)) {
906     ierr = SNESGetNPC(snes, &snes->pc);CHKERRQ(ierr);
907   }
908   PetscFunctionReturn(0);
909 }
910 
911 #undef __FUNCT__
912 #define __FUNCT__ "SNESSetComputeApplicationContext"
913 /*@C
914    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
915    the nonlinear solvers.
916 
917    Logically Collective on SNES
918 
919    Input Parameters:
920 +  snes - the SNES context
921 .  compute - function to compute the context
922 -  destroy - function to destroy the context
923 
924    Level: intermediate
925 
926    Notes:
927    This function is currently not available from Fortran.
928 
929 .keywords: SNES, nonlinear, set, application, context
930 
931 .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
932 @*/
933 PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
934 {
935   PetscFunctionBegin;
936   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
937   snes->ops->usercompute = compute;
938   snes->ops->userdestroy = destroy;
939   PetscFunctionReturn(0);
940 }
941 
942 #undef __FUNCT__
943 #define __FUNCT__ "SNESSetApplicationContext"
944 /*@
945    SNESSetApplicationContext - Sets the optional user-defined context for
946    the nonlinear solvers.
947 
948    Logically Collective on SNES
949 
950    Input Parameters:
951 +  snes - the SNES context
952 -  usrP - optional user context
953 
954    Level: intermediate
955 
956 .keywords: SNES, nonlinear, set, application, context
957 
958 .seealso: SNESGetApplicationContext()
959 @*/
960 PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
961 {
962   PetscErrorCode ierr;
963   KSP            ksp;
964 
965   PetscFunctionBegin;
966   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
967   ierr       = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
968   ierr       = KSPSetApplicationContext(ksp,usrP);CHKERRQ(ierr);
969   snes->user = usrP;
970   PetscFunctionReturn(0);
971 }
972 
973 #undef __FUNCT__
974 #define __FUNCT__ "SNESGetApplicationContext"
975 /*@
976    SNESGetApplicationContext - Gets the user-defined context for the
977    nonlinear solvers.
978 
979    Not Collective
980 
981    Input Parameter:
982 .  snes - SNES context
983 
984    Output Parameter:
985 .  usrP - user context
986 
987    Level: intermediate
988 
989 .keywords: SNES, nonlinear, get, application, context
990 
991 .seealso: SNESSetApplicationContext()
992 @*/
993 PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
994 {
995   PetscFunctionBegin;
996   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
997   *(void**)usrP = snes->user;
998   PetscFunctionReturn(0);
999 }
1000 
1001 #undef __FUNCT__
1002 #define __FUNCT__ "SNESGetIterationNumber"
1003 /*@
1004    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
1005    at this time.
1006 
1007    Not Collective
1008 
1009    Input Parameter:
1010 .  snes - SNES context
1011 
1012    Output Parameter:
1013 .  iter - iteration number
1014 
1015    Notes:
1016    For example, during the computation of iteration 2 this would return 1.
1017 
1018    This is useful for using lagged Jacobians (where one does not recompute the
1019    Jacobian at each SNES iteration). For example, the code
1020 .vb
1021       ierr = SNESGetIterationNumber(snes,&it);
1022       if (!(it % 2)) {
1023         [compute Jacobian here]
1024       }
1025 .ve
1026    can be used in your ComputeJacobian() function to cause the Jacobian to be
1027    recomputed every second SNES iteration.
1028 
1029    Level: intermediate
1030 
1031 .keywords: SNES, nonlinear, get, iteration, number,
1032 
1033 .seealso:   SNESGetLinearSolveIterations()
1034 @*/
1035 PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
1036 {
1037   PetscFunctionBegin;
1038   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1039   PetscValidIntPointer(iter,2);
1040   *iter = snes->iter;
1041   PetscFunctionReturn(0);
1042 }
1043 
1044 #undef __FUNCT__
1045 #define __FUNCT__ "SNESSetIterationNumber"
1046 /*@
1047    SNESSetIterationNumber - Sets the current iteration number.
1048 
1049    Not Collective
1050 
1051    Input Parameter:
1052 .  snes - SNES context
1053 .  iter - iteration number
1054 
1055    Level: developer
1056 
1057 .keywords: SNES, nonlinear, set, iteration, number,
1058 
1059 .seealso:   SNESGetLinearSolveIterations()
1060 @*/
1061 PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
1062 {
1063   PetscErrorCode ierr;
1064 
1065   PetscFunctionBegin;
1066   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1067   ierr       = PetscObjectSAWsTakeAccess((PetscObject)snes);CHKERRQ(ierr);
1068   snes->iter = iter;
1069   ierr       = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr);
1070   PetscFunctionReturn(0);
1071 }
1072 
1073 #undef __FUNCT__
1074 #define __FUNCT__ "SNESGetNonlinearStepFailures"
1075 /*@
1076    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1077    attempted by the nonlinear solver.
1078 
1079    Not Collective
1080 
1081    Input Parameter:
1082 .  snes - SNES context
1083 
1084    Output Parameter:
1085 .  nfails - number of unsuccessful steps attempted
1086 
1087    Notes:
1088    This counter is reset to zero for each successive call to SNESSolve().
1089 
1090    Level: intermediate
1091 
1092 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1093 
1094 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1095           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
1096 @*/
1097 PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
1098 {
1099   PetscFunctionBegin;
1100   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1101   PetscValidIntPointer(nfails,2);
1102   *nfails = snes->numFailures;
1103   PetscFunctionReturn(0);
1104 }
1105 
1106 #undef __FUNCT__
1107 #define __FUNCT__ "SNESSetMaxNonlinearStepFailures"
1108 /*@
1109    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1110    attempted by the nonlinear solver before it gives up.
1111 
1112    Not Collective
1113 
1114    Input Parameters:
1115 +  snes     - SNES context
1116 -  maxFails - maximum of unsuccessful steps
1117 
1118    Level: intermediate
1119 
1120 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1121 
1122 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1123           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1124 @*/
1125 PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1126 {
1127   PetscFunctionBegin;
1128   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1129   snes->maxFailures = maxFails;
1130   PetscFunctionReturn(0);
1131 }
1132 
1133 #undef __FUNCT__
1134 #define __FUNCT__ "SNESGetMaxNonlinearStepFailures"
1135 /*@
1136    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1137    attempted by the nonlinear solver before it gives up.
1138 
1139    Not Collective
1140 
1141    Input Parameter:
1142 .  snes     - SNES context
1143 
1144    Output Parameter:
1145 .  maxFails - maximum of unsuccessful steps
1146 
1147    Level: intermediate
1148 
1149 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1150 
1151 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1152           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1153 
1154 @*/
1155 PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1156 {
1157   PetscFunctionBegin;
1158   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1159   PetscValidIntPointer(maxFails,2);
1160   *maxFails = snes->maxFailures;
1161   PetscFunctionReturn(0);
1162 }
1163 
1164 #undef __FUNCT__
1165 #define __FUNCT__ "SNESGetNumberFunctionEvals"
1166 /*@
1167    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1168      done by SNES.
1169 
1170    Not Collective
1171 
1172    Input Parameter:
1173 .  snes     - SNES context
1174 
1175    Output Parameter:
1176 .  nfuncs - number of evaluations
1177 
1178    Level: intermediate
1179 
1180    Notes: Reset every time SNESSolve is called unless SNESSetCountersReset() is used.
1181 
1182 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1183 
1184 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(), SNESSetCountersReset()
1185 @*/
1186 PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1187 {
1188   PetscFunctionBegin;
1189   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1190   PetscValidIntPointer(nfuncs,2);
1191   *nfuncs = snes->nfuncs;
1192   PetscFunctionReturn(0);
1193 }
1194 
1195 #undef __FUNCT__
1196 #define __FUNCT__ "SNESGetLinearSolveFailures"
1197 /*@
1198    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1199    linear solvers.
1200 
1201    Not Collective
1202 
1203    Input Parameter:
1204 .  snes - SNES context
1205 
1206    Output Parameter:
1207 .  nfails - number of failed solves
1208 
1209    Notes:
1210    This counter is reset to zero for each successive call to SNESSolve().
1211 
1212    Level: intermediate
1213 
1214 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1215 
1216 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1217 @*/
1218 PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
1219 {
1220   PetscFunctionBegin;
1221   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1222   PetscValidIntPointer(nfails,2);
1223   *nfails = snes->numLinearSolveFailures;
1224   PetscFunctionReturn(0);
1225 }
1226 
1227 #undef __FUNCT__
1228 #define __FUNCT__ "SNESSetMaxLinearSolveFailures"
1229 /*@
1230    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1231    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE
1232 
1233    Logically Collective on SNES
1234 
1235    Input Parameters:
1236 +  snes     - SNES context
1237 -  maxFails - maximum allowed linear solve failures
1238 
1239    Level: intermediate
1240 
1241    Notes: By default this is 0; that is SNES returns on the first failed linear solve
1242 
1243 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1244 
1245 .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1246 @*/
1247 PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1248 {
1249   PetscFunctionBegin;
1250   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1251   PetscValidLogicalCollectiveInt(snes,maxFails,2);
1252   snes->maxLinearSolveFailures = maxFails;
1253   PetscFunctionReturn(0);
1254 }
1255 
1256 #undef __FUNCT__
1257 #define __FUNCT__ "SNESGetMaxLinearSolveFailures"
1258 /*@
1259    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1260      are allowed before SNES terminates
1261 
1262    Not Collective
1263 
1264    Input Parameter:
1265 .  snes     - SNES context
1266 
1267    Output Parameter:
1268 .  maxFails - maximum of unsuccessful solves allowed
1269 
1270    Level: intermediate
1271 
1272    Notes: By default this is 1; that is SNES returns on the first failed linear solve
1273 
1274 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1275 
1276 .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1277 @*/
1278 PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1279 {
1280   PetscFunctionBegin;
1281   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1282   PetscValidIntPointer(maxFails,2);
1283   *maxFails = snes->maxLinearSolveFailures;
1284   PetscFunctionReturn(0);
1285 }
1286 
1287 #undef __FUNCT__
1288 #define __FUNCT__ "SNESGetLinearSolveIterations"
1289 /*@
1290    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1291    used by the nonlinear solver.
1292 
1293    Not Collective
1294 
1295    Input Parameter:
1296 .  snes - SNES context
1297 
1298    Output Parameter:
1299 .  lits - number of linear iterations
1300 
1301    Notes:
1302    This counter is reset to zero for each successive call to SNESSolve() unless SNESSetCountersReset() is used.
1303 
1304    Level: intermediate
1305 
1306 .keywords: SNES, nonlinear, get, number, linear, iterations
1307 
1308 .seealso:  SNESGetIterationNumber(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
1309 @*/
1310 PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
1311 {
1312   PetscFunctionBegin;
1313   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1314   PetscValidIntPointer(lits,2);
1315   *lits = snes->linear_its;
1316   PetscFunctionReturn(0);
1317 }
1318 
1319 #undef __FUNCT__
1320 #define __FUNCT__ "SNESSetCountersReset"
1321 /*@
1322    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1323    are reset every time SNESSolve() is called.
1324 
1325    Logically Collective on SNES
1326 
1327    Input Parameter:
1328 +  snes - SNES context
1329 -  reset - whether to reset the counters or not
1330 
1331    Notes:
1332    This is automatically called with FALSE
1333 
1334    Level: developer
1335 
1336 .keywords: SNES, nonlinear, set, reset, number, linear, iterations
1337 
1338 .seealso:  SNESGetNumberFunctionEvals(), SNESGetNumberLinearSolveIterations(), SNESGetNPC()
1339 @*/
1340 PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
1341 {
1342   PetscFunctionBegin;
1343   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1344   PetscValidLogicalCollectiveBool(snes,reset,2);
1345   snes->counters_reset = reset;
1346   PetscFunctionReturn(0);
1347 }
1348 
1349 
1350 #undef __FUNCT__
1351 #define __FUNCT__ "SNESSetKSP"
1352 /*@
1353    SNESSetKSP - Sets a KSP context for the SNES object to use
1354 
1355    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm
1356 
1357    Input Parameters:
1358 +  snes - the SNES context
1359 -  ksp - the KSP context
1360 
1361    Notes:
1362    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1363    so this routine is rarely needed.
1364 
1365    The KSP object that is already in the SNES object has its reference count
1366    decreased by one.
1367 
1368    Level: developer
1369 
1370 .keywords: SNES, nonlinear, get, KSP, context
1371 
1372 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1373 @*/
1374 PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1375 {
1376   PetscErrorCode ierr;
1377 
1378   PetscFunctionBegin;
1379   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1380   PetscValidHeaderSpecific(ksp,KSP_CLASSID,2);
1381   PetscCheckSameComm(snes,1,ksp,2);
1382   ierr = PetscObjectReference((PetscObject)ksp);CHKERRQ(ierr);
1383   if (snes->ksp) {ierr = PetscObjectDereference((PetscObject)snes->ksp);CHKERRQ(ierr);}
1384   snes->ksp = ksp;
1385   PetscFunctionReturn(0);
1386 }
1387 
1388 /* -----------------------------------------------------------*/
1389 #undef __FUNCT__
1390 #define __FUNCT__ "SNESCreate"
1391 /*@
1392    SNESCreate - Creates a nonlinear solver context.
1393 
1394    Collective on MPI_Comm
1395 
1396    Input Parameters:
1397 .  comm - MPI communicator
1398 
1399    Output Parameter:
1400 .  outsnes - the new SNES context
1401 
1402    Options Database Keys:
1403 +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1404                and no preconditioning matrix
1405 .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1406                products, and a user-provided preconditioning matrix
1407                as set by SNESSetJacobian()
1408 -   -snes_fd - Uses (slow!) finite differences to compute Jacobian
1409 
1410    Level: beginner
1411 
1412 .keywords: SNES, nonlinear, create, context
1413 
1414 .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()
1415 
1416 @*/
1417 PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1418 {
1419   PetscErrorCode ierr;
1420   SNES           snes;
1421   SNESKSPEW      *kctx;
1422 
1423   PetscFunctionBegin;
1424   PetscValidPointer(outsnes,2);
1425   *outsnes = NULL;
1426   ierr = SNESInitializePackage();CHKERRQ(ierr);
1427 
1428   ierr = PetscHeaderCreate(snes,_p_SNES,struct _SNESOps,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);CHKERRQ(ierr);
1429 
1430   snes->ops->converged    = SNESConvergedDefault;
1431   snes->usesksp           = PETSC_TRUE;
1432   snes->tolerancesset     = PETSC_FALSE;
1433   snes->max_its           = 50;
1434   snes->max_funcs         = 10000;
1435   snes->norm              = 0.0;
1436   snes->normschedule      = SNES_NORM_ALWAYS;
1437   snes->functype          = SNES_FUNCTION_DEFAULT;
1438 #if defined(PETSC_USE_REAL_SINGLE)
1439   snes->rtol              = 1.e-5;
1440 #else
1441   snes->rtol              = 1.e-8;
1442 #endif
1443   snes->ttol              = 0.0;
1444 #if defined(PETSC_USE_REAL_SINGLE)
1445   snes->abstol            = 1.e-25;
1446 #else
1447   snes->abstol            = 1.e-50;
1448 #endif
1449   snes->stol              = 1.e-8;
1450 #if defined(PETSC_USE_REAL_SINGLE)
1451   snes->deltatol          = 1.e-6;
1452 #else
1453   snes->deltatol          = 1.e-12;
1454 #endif
1455   snes->nfuncs            = 0;
1456   snes->numFailures       = 0;
1457   snes->maxFailures       = 1;
1458   snes->linear_its        = 0;
1459   snes->lagjacobian       = 1;
1460   snes->jac_iter          = 0;
1461   snes->lagjac_persist    = PETSC_FALSE;
1462   snes->lagpreconditioner = 1;
1463   snes->pre_iter          = 0;
1464   snes->lagpre_persist    = PETSC_FALSE;
1465   snes->numbermonitors    = 0;
1466   snes->data              = 0;
1467   snes->setupcalled       = PETSC_FALSE;
1468   snes->ksp_ewconv        = PETSC_FALSE;
1469   snes->nwork             = 0;
1470   snes->work              = 0;
1471   snes->nvwork            = 0;
1472   snes->vwork             = 0;
1473   snes->conv_hist_len     = 0;
1474   snes->conv_hist_max     = 0;
1475   snes->conv_hist         = NULL;
1476   snes->conv_hist_its     = NULL;
1477   snes->conv_hist_reset   = PETSC_TRUE;
1478   snes->counters_reset    = PETSC_TRUE;
1479   snes->vec_func_init_set = PETSC_FALSE;
1480   snes->reason            = SNES_CONVERGED_ITERATING;
1481   snes->pcside            = PC_RIGHT;
1482 
1483   snes->mf          = PETSC_FALSE;
1484   snes->mf_operator = PETSC_FALSE;
1485   snes->mf_version  = 1;
1486 
1487   snes->numLinearSolveFailures = 0;
1488   snes->maxLinearSolveFailures = 1;
1489 
1490   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1491   ierr = PetscNewLog(snes,&kctx);CHKERRQ(ierr);
1492 
1493   snes->kspconvctx  = (void*)kctx;
1494   kctx->version     = 2;
1495   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1496                              this was too large for some test cases */
1497   kctx->rtol_last   = 0.0;
1498   kctx->rtol_max    = .9;
1499   kctx->gamma       = 1.0;
1500   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1501   kctx->alpha2      = kctx->alpha;
1502   kctx->threshold   = .1;
1503   kctx->lresid_last = 0.0;
1504   kctx->norm_last   = 0.0;
1505 
1506   *outsnes = snes;
1507   PetscFunctionReturn(0);
1508 }
1509 
1510 /*MC
1511     SNESFunction - functional form used to convey the nonlinear function to be solved by SNES
1512 
1513      Synopsis:
1514      #include <petscsnes.h>
1515      SNESFunction(SNES snes,Vec x,Vec f,void *ctx);
1516 
1517      Input Parameters:
1518 +     snes - the SNES context
1519 .     x    - state at which to evaluate residual
1520 -     ctx     - optional user-defined function context, passed in with SNESSetFunction()
1521 
1522      Output Parameter:
1523 .     f  - vector to put residual (function value)
1524 
1525    Level: intermediate
1526 
1527 .seealso:   SNESSetFunction(), SNESGetFunction()
1528 M*/
1529 
1530 #undef __FUNCT__
1531 #define __FUNCT__ "SNESSetFunction"
1532 /*@C
1533    SNESSetFunction - Sets the function evaluation routine and function
1534    vector for use by the SNES routines in solving systems of nonlinear
1535    equations.
1536 
1537    Logically Collective on SNES
1538 
1539    Input Parameters:
1540 +  snes - the SNES context
1541 .  r - vector to store function value
1542 .  f - function evaluation routine; see SNESFunction for calling sequence details
1543 -  ctx - [optional] user-defined context for private data for the
1544          function evaluation routine (may be NULL)
1545 
1546    Notes:
1547    The Newton-like methods typically solve linear systems of the form
1548 $      f'(x) x = -f(x),
1549    where f'(x) denotes the Jacobian matrix and f(x) is the function.
1550 
1551    Level: beginner
1552 
1553 .keywords: SNES, nonlinear, set, function
1554 
1555 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
1556 @*/
1557 PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1558 {
1559   PetscErrorCode ierr;
1560   DM             dm;
1561 
1562   PetscFunctionBegin;
1563   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1564   if (r) {
1565     PetscValidHeaderSpecific(r,VEC_CLASSID,2);
1566     PetscCheckSameComm(snes,1,r,2);
1567     ierr = PetscObjectReference((PetscObject)r);CHKERRQ(ierr);
1568     ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
1569 
1570     snes->vec_func = r;
1571   }
1572   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1573   ierr = DMSNESSetFunction(dm,f,ctx);CHKERRQ(ierr);
1574   PetscFunctionReturn(0);
1575 }
1576 
1577 
1578 #undef __FUNCT__
1579 #define __FUNCT__ "SNESSetInitialFunction"
1580 /*@C
1581    SNESSetInitialFunction - Sets the function vector to be used as the
1582    function norm at the initialization of the method.  In some
1583    instances, the user has precomputed the function before calling
1584    SNESSolve.  This function allows one to avoid a redundant call
1585    to SNESComputeFunction in that case.
1586 
1587    Logically Collective on SNES
1588 
1589    Input Parameters:
1590 +  snes - the SNES context
1591 -  f - vector to store function value
1592 
1593    Notes:
1594    This should not be modified during the solution procedure.
1595 
1596    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1597 
1598    Level: developer
1599 
1600 .keywords: SNES, nonlinear, set, function
1601 
1602 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1603 @*/
1604 PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1605 {
1606   PetscErrorCode ierr;
1607   Vec            vec_func;
1608 
1609   PetscFunctionBegin;
1610   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1611   PetscValidHeaderSpecific(f,VEC_CLASSID,2);
1612   PetscCheckSameComm(snes,1,f,2);
1613   if (snes->pcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
1614     snes->vec_func_init_set = PETSC_FALSE;
1615     PetscFunctionReturn(0);
1616   }
1617   ierr = SNESGetFunction(snes,&vec_func,NULL,NULL);CHKERRQ(ierr);
1618   ierr = VecCopy(f, vec_func);CHKERRQ(ierr);
1619 
1620   snes->vec_func_init_set = PETSC_TRUE;
1621   PetscFunctionReturn(0);
1622 }
1623 
1624 #undef __FUNCT__
1625 #define __FUNCT__ "SNESSetNormSchedule"
1626 /*@
1627    SNESSetNormSchedule - Sets the SNESNormSchedule used in covergence and monitoring
1628    of the SNES method.
1629 
1630    Logically Collective on SNES
1631 
1632    Input Parameters:
1633 +  snes - the SNES context
1634 -  normschedule - the frequency of norm computation
1635 
1636    Notes:
1637    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1638    of the nonlinear function and the taking of its norm at every iteration to
1639    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1640    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1641    may either be monitored for convergence or not.  As these are often used as nonlinear
1642    preconditioners, monitoring the norm of their error is not a useful enterprise within
1643    their solution.
1644 
1645    Level: developer
1646 
1647 .keywords: SNES, nonlinear, set, function, norm, type
1648 
1649 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1650 @*/
1651 PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
1652 {
1653   PetscFunctionBegin;
1654   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1655   snes->normschedule = normschedule;
1656   PetscFunctionReturn(0);
1657 }
1658 
1659 
1660 #undef __FUNCT__
1661 #define __FUNCT__ "SNESGetNormSchedule"
1662 /*@
1663    SNESGetNormSchedule - Gets the SNESNormSchedule used in covergence and monitoring
1664    of the SNES method.
1665 
1666    Logically Collective on SNES
1667 
1668    Input Parameters:
1669 +  snes - the SNES context
1670 -  normschedule - the type of the norm used
1671 
1672    Level: advanced
1673 
1674 .keywords: SNES, nonlinear, set, function, norm, type
1675 
1676 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1677 @*/
1678 PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
1679 {
1680   PetscFunctionBegin;
1681   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1682   *normschedule = snes->normschedule;
1683   PetscFunctionReturn(0);
1684 }
1685 
1686 
1687 #undef __FUNCT__
1688 #define __FUNCT__ "SNESSetFunctionType"
1689 /*@C
1690    SNESSetFunctionType - Sets the SNESNormSchedule used in covergence and monitoring
1691    of the SNES method.
1692 
1693    Logically Collective on SNES
1694 
1695    Input Parameters:
1696 +  snes - the SNES context
1697 -  normschedule - the frequency of norm computation
1698 
1699    Notes:
1700    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1701    of the nonlinear function and the taking of its norm at every iteration to
1702    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1703    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1704    may either be monitored for convergence or not.  As these are often used as nonlinear
1705    preconditioners, monitoring the norm of their error is not a useful enterprise within
1706    their solution.
1707 
1708    Level: developer
1709 
1710 .keywords: SNES, nonlinear, set, function, norm, type
1711 
1712 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1713 @*/
1714 PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
1715 {
1716   PetscFunctionBegin;
1717   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1718   snes->functype = type;
1719   PetscFunctionReturn(0);
1720 }
1721 
1722 
1723 #undef __FUNCT__
1724 #define __FUNCT__ "SNESGetFunctionType"
1725 /*@C
1726    SNESGetFunctionType - Gets the SNESNormSchedule used in covergence and monitoring
1727    of the SNES method.
1728 
1729    Logically Collective on SNES
1730 
1731    Input Parameters:
1732 +  snes - the SNES context
1733 -  normschedule - the type of the norm used
1734 
1735    Level: advanced
1736 
1737 .keywords: SNES, nonlinear, set, function, norm, type
1738 
1739 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1740 @*/
1741 PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
1742 {
1743   PetscFunctionBegin;
1744   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1745   *type = snes->functype;
1746   PetscFunctionReturn(0);
1747 }
1748 
1749 /*MC
1750     SNESNGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function
1751 
1752      Synopsis:
1753      #include <petscsnes.h>
1754 $    SNESNGSFunction(SNES snes,Vec x,Vec b,void *ctx);
1755 
1756 +  X   - solution vector
1757 .  B   - RHS vector
1758 -  ctx - optional user-defined Gauss-Seidel context
1759 
1760    Level: intermediate
1761 
1762 .seealso:   SNESSetNGS(), SNESGetNGS()
1763 M*/
1764 
1765 #undef __FUNCT__
1766 #define __FUNCT__ "SNESSetNGS"
1767 /*@C
1768    SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
1769    use with composed nonlinear solvers.
1770 
1771    Input Parameters:
1772 +  snes   - the SNES context
1773 .  f - function evaluation routine to apply Gauss-Seidel see SNESNGSFunction
1774 -  ctx    - [optional] user-defined context for private data for the
1775             smoother evaluation routine (may be NULL)
1776 
1777    Notes:
1778    The NGS routines are used by the composed nonlinear solver to generate
1779     a problem appropriate update to the solution, particularly FAS.
1780 
1781    Level: intermediate
1782 
1783 .keywords: SNES, nonlinear, set, Gauss-Seidel
1784 
1785 .seealso: SNESGetFunction(), SNESComputeNGS()
1786 @*/
1787 PetscErrorCode SNESSetNGS(SNES snes,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1788 {
1789   PetscErrorCode ierr;
1790   DM             dm;
1791 
1792   PetscFunctionBegin;
1793   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1794   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1795   ierr = DMSNESSetNGS(dm,f,ctx);CHKERRQ(ierr);
1796   PetscFunctionReturn(0);
1797 }
1798 
1799 #undef __FUNCT__
1800 #define __FUNCT__ "SNESPicardComputeFunction"
1801 PETSC_EXTERN PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
1802 {
1803   PetscErrorCode ierr;
1804   DM             dm;
1805   DMSNES         sdm;
1806 
1807   PetscFunctionBegin;
1808   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1809   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
1810   /*  A(x)*x - b(x) */
1811   if (sdm->ops->computepfunction) {
1812     ierr = (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);CHKERRQ(ierr);
1813   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");
1814 
1815   if (sdm->ops->computepjacobian) {
1816     ierr = (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);CHKERRQ(ierr);
1817   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard matrix.");
1818   ierr = VecScale(f,-1.0);CHKERRQ(ierr);
1819   ierr = MatMultAdd(snes->jacobian,x,f,f);CHKERRQ(ierr);
1820   PetscFunctionReturn(0);
1821 }
1822 
1823 #undef __FUNCT__
1824 #define __FUNCT__ "SNESPicardComputeJacobian"
1825 PETSC_EXTERN PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
1826 {
1827   PetscFunctionBegin;
1828   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
1829   PetscFunctionReturn(0);
1830 }
1831 
1832 #undef __FUNCT__
1833 #define __FUNCT__ "SNESSetPicard"
1834 /*@C
1835    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)
1836 
1837    Logically Collective on SNES
1838 
1839    Input Parameters:
1840 +  snes - the SNES context
1841 .  r - vector to store function value
1842 .  b - function evaluation routine
1843 .  Amat - matrix with which A(x) x - b(x) is to be computed
1844 .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
1845 .  J  - function to compute matrix value
1846 -  ctx - [optional] user-defined context for private data for the
1847          function evaluation routine (may be NULL)
1848 
1849    Notes:
1850     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
1851     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.
1852 
1853     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both
1854 
1855 $     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}
1856 $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.
1857 
1858      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.
1859 
1860    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
1861    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)
1862 
1863    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
1864    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
1865    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).
1866 
1867    Level: intermediate
1868 
1869 .keywords: SNES, nonlinear, set, function
1870 
1871 .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard()
1872 @*/
1873 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)
1874 {
1875   PetscErrorCode ierr;
1876   DM             dm;
1877 
1878   PetscFunctionBegin;
1879   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1880   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
1881   ierr = DMSNESSetPicard(dm,b,J,ctx);CHKERRQ(ierr);
1882   ierr = SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);CHKERRQ(ierr);
1883   ierr = SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);CHKERRQ(ierr);
1884   PetscFunctionReturn(0);
1885 }
1886 
1887 #undef __FUNCT__
1888 #define __FUNCT__ "SNESGetPicard"
1889 /*@C
1890    SNESGetPicard - Returns the context for the Picard iteration
1891 
1892    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
1893 
1894    Input Parameter:
1895 .  snes - the SNES context
1896 
1897    Output Parameter:
1898 +  r - the function (or NULL)
1899 .  f - the function (or NULL); see SNESFunction for calling sequence details
1900 .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
1901 .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
1902 .  J - the function for matrix evaluation (or NULL); see SNESJacobianFunction for calling sequence details
1903 -  ctx - the function context (or NULL)
1904 
1905    Level: advanced
1906 
1907 .keywords: SNES, nonlinear, get, function
1908 
1909 .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
1910 @*/
1911 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)
1912 {
1913   PetscErrorCode ierr;
1914   DM             dm;
1915 
1916   PetscFunctionBegin;
1917   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1918   ierr = SNESGetFunction(snes,r,NULL,NULL);CHKERRQ(ierr);
1919   ierr = SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);CHKERRQ(ierr);
1920   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1921   ierr = DMSNESGetPicard(dm,f,J,ctx);CHKERRQ(ierr);
1922   PetscFunctionReturn(0);
1923 }
1924 
1925 #undef __FUNCT__
1926 #define __FUNCT__ "SNESSetComputeInitialGuess"
1927 /*@C
1928    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem
1929 
1930    Logically Collective on SNES
1931 
1932    Input Parameters:
1933 +  snes - the SNES context
1934 .  func - function evaluation routine
1935 -  ctx - [optional] user-defined context for private data for the
1936          function evaluation routine (may be NULL)
1937 
1938    Calling sequence of func:
1939 $    func (SNES snes,Vec x,void *ctx);
1940 
1941 .  f - function vector
1942 -  ctx - optional user-defined function context
1943 
1944    Level: intermediate
1945 
1946 .keywords: SNES, nonlinear, set, function
1947 
1948 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
1949 @*/
1950 PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
1951 {
1952   PetscFunctionBegin;
1953   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1954   if (func) snes->ops->computeinitialguess = func;
1955   if (ctx)  snes->initialguessP            = ctx;
1956   PetscFunctionReturn(0);
1957 }
1958 
1959 /* --------------------------------------------------------------- */
1960 #undef __FUNCT__
1961 #define __FUNCT__ "SNESGetRhs"
1962 /*@C
1963    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
1964    it assumes a zero right hand side.
1965 
1966    Logically Collective on SNES
1967 
1968    Input Parameter:
1969 .  snes - the SNES context
1970 
1971    Output Parameter:
1972 .  rhs - the right hand side vector or NULL if the right hand side vector is null
1973 
1974    Level: intermediate
1975 
1976 .keywords: SNES, nonlinear, get, function, right hand side
1977 
1978 .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
1979 @*/
1980 PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
1981 {
1982   PetscFunctionBegin;
1983   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1984   PetscValidPointer(rhs,2);
1985   *rhs = snes->vec_rhs;
1986   PetscFunctionReturn(0);
1987 }
1988 
1989 #undef __FUNCT__
1990 #define __FUNCT__ "SNESComputeFunction"
1991 /*@
1992    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().
1993 
1994    Collective on SNES
1995 
1996    Input Parameters:
1997 +  snes - the SNES context
1998 -  x - input vector
1999 
2000    Output Parameter:
2001 .  y - function vector, as set by SNESSetFunction()
2002 
2003    Notes:
2004    SNESComputeFunction() is typically used within nonlinear solvers
2005    implementations, so most users would not generally call this routine
2006    themselves.
2007 
2008    Level: developer
2009 
2010 .keywords: SNES, nonlinear, compute, function
2011 
2012 .seealso: SNESSetFunction(), SNESGetFunction()
2013 @*/
2014 PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
2015 {
2016   PetscErrorCode ierr;
2017   DM             dm;
2018   DMSNES         sdm;
2019 
2020   PetscFunctionBegin;
2021   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2022   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2023   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
2024   PetscCheckSameComm(snes,1,x,2);
2025   PetscCheckSameComm(snes,1,y,3);
2026   ierr = VecValidValues(x,2,PETSC_TRUE);CHKERRQ(ierr);
2027 
2028   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2029   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2030   if (sdm->ops->computefunction) {
2031     ierr = PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2032     PetscStackPush("SNES user function");
2033     ierr = (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);CHKERRQ(ierr);
2034     PetscStackPop;
2035     ierr = PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2036   } else if (snes->vec_rhs) {
2037     ierr = MatMult(snes->jacobian, x, y);CHKERRQ(ierr);
2038   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2039   if (snes->vec_rhs) {
2040     ierr = VecAXPY(y,-1.0,snes->vec_rhs);CHKERRQ(ierr);
2041   }
2042   snes->nfuncs++;
2043   ierr = VecValidValues(y,3,PETSC_FALSE);CHKERRQ(ierr);
2044   PetscFunctionReturn(0);
2045 }
2046 
2047 #undef __FUNCT__
2048 #define __FUNCT__ "SNESComputeNGS"
2049 /*@
2050    SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  SNESSetNGS().
2051 
2052    Collective on SNES
2053 
2054    Input Parameters:
2055 +  snes - the SNES context
2056 .  x - input vector
2057 -  b - rhs vector
2058 
2059    Output Parameter:
2060 .  x - new solution vector
2061 
2062    Notes:
2063    SNESComputeNGS() is typically used within composed nonlinear solver
2064    implementations, so most users would not generally call this routine
2065    themselves.
2066 
2067    Level: developer
2068 
2069 .keywords: SNES, nonlinear, compute, function
2070 
2071 .seealso: SNESSetNGS(), SNESComputeFunction()
2072 @*/
2073 PetscErrorCode  SNESComputeNGS(SNES snes,Vec b,Vec x)
2074 {
2075   PetscErrorCode ierr;
2076   DM             dm;
2077   DMSNES         sdm;
2078 
2079   PetscFunctionBegin;
2080   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2081   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2082   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,3);
2083   PetscCheckSameComm(snes,1,x,2);
2084   if (b) PetscCheckSameComm(snes,1,b,3);
2085   if (b) {ierr = VecValidValues(b,2,PETSC_TRUE);CHKERRQ(ierr);}
2086   ierr = PetscLogEventBegin(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2087   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2088   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2089   if (sdm->ops->computegs) {
2090     PetscStackPush("SNES user NGS");
2091     ierr = (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);CHKERRQ(ierr);
2092     PetscStackPop;
2093   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
2094   ierr = PetscLogEventEnd(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2095   ierr = VecValidValues(x,3,PETSC_FALSE);CHKERRQ(ierr);
2096   PetscFunctionReturn(0);
2097 }
2098 
2099 #undef __FUNCT__
2100 #define __FUNCT__ "SNESComputeJacobian"
2101 /*@
2102    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().
2103 
2104    Collective on SNES and Mat
2105 
2106    Input Parameters:
2107 +  snes - the SNES context
2108 -  x - input vector
2109 
2110    Output Parameters:
2111 +  A - Jacobian matrix
2112 -  B - optional preconditioning matrix
2113 
2114   Options Database Keys:
2115 +    -snes_lag_preconditioner <lag>
2116 .    -snes_lag_jacobian <lag>
2117 .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2118 .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2119 .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2120 .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2121 .    -snes_compare_coloring - Compute the finite differece Jacobian using coloring and display norms of difference
2122 .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
2123 .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2124 .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2125 .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2126 .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
2127 -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences
2128 
2129 
2130    Notes:
2131    Most users should not need to explicitly call this routine, as it
2132    is used internally within the nonlinear solvers.
2133 
2134    See KSPSetOperators() for important information about setting the
2135    flag parameter.
2136 
2137    Level: developer
2138 
2139 .keywords: SNES, compute, Jacobian, matrix
2140 
2141 .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2142 @*/
2143 PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat A,Mat B)
2144 {
2145   PetscErrorCode ierr;
2146   PetscBool      flag;
2147   DM             dm;
2148   DMSNES         sdm;
2149 
2150   PetscFunctionBegin;
2151   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2152   PetscValidHeaderSpecific(X,VEC_CLASSID,2);
2153   PetscCheckSameComm(snes,1,X,2);
2154   ierr = VecValidValues(X,2,PETSC_TRUE);CHKERRQ(ierr);
2155   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2156   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2157 
2158   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");
2159 
2160   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */
2161 
2162   if (snes->lagjacobian == -2) {
2163     snes->lagjacobian = -1;
2164 
2165     ierr = PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");CHKERRQ(ierr);
2166   } else if (snes->lagjacobian == -1) {
2167     ierr = PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");CHKERRQ(ierr);
2168     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2169     if (flag) {
2170       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2171       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2172     }
2173     PetscFunctionReturn(0);
2174   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2175     ierr = PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);CHKERRQ(ierr);
2176     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2177     if (flag) {
2178       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2179       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2180     }
2181     PetscFunctionReturn(0);
2182   }
2183   if (snes->pc && snes->pcside == PC_LEFT) {
2184       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2185       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2186       PetscFunctionReturn(0);
2187   }
2188 
2189   ierr = PetscLogEventBegin(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2190 
2191   PetscStackPush("SNES user Jacobian function");
2192   ierr = (*sdm->ops->computejacobian)(snes,X,A,B,sdm->jacobianctx);CHKERRQ(ierr);
2193   PetscStackPop;
2194 
2195   ierr = PetscLogEventEnd(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2196 
2197   if (snes->lagpreconditioner == -2) {
2198     ierr = PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");CHKERRQ(ierr);
2199     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2200     snes->lagpreconditioner = -1;
2201   } else if (snes->lagpreconditioner == -1) {
2202     ierr = PetscInfo(snes,"Reusing preconditioner because lag is -1\n");CHKERRQ(ierr);
2203     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2204   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2205     ierr = PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);CHKERRQ(ierr);
2206     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2207   } else {
2208     ierr = PetscInfo(snes,"Rebuilding preconditioner\n");CHKERRQ(ierr);
2209     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2210   }
2211 
2212   /* make sure user returned a correct Jacobian and preconditioner */
2213   /* PetscValidHeaderSpecific(A,MAT_CLASSID,3);
2214     PetscValidHeaderSpecific(B,MAT_CLASSID,4);   */
2215   {
2216     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2217     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit",&flag,NULL);CHKERRQ(ierr);
2218     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",&flag_draw,NULL);CHKERRQ(ierr);
2219     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2220     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_operator",&flag_operator,NULL);CHKERRQ(ierr);
2221     if (flag || flag_draw || flag_contour) {
2222       Mat          Bexp_mine = NULL,Bexp,FDexp;
2223       PetscViewer  vdraw,vstdout;
2224       PetscBool    flg;
2225       if (flag_operator) {
2226         ierr = MatComputeExplicitOperator(A,&Bexp_mine);CHKERRQ(ierr);
2227         Bexp = Bexp_mine;
2228       } else {
2229         /* See if the preconditioning matrix can be viewed and added directly */
2230         ierr = PetscObjectTypeCompareAny((PetscObject)B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");CHKERRQ(ierr);
2231         if (flg) Bexp = B;
2232         else {
2233           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2234           ierr = MatComputeExplicitOperator(B,&Bexp_mine);CHKERRQ(ierr);
2235           Bexp = Bexp_mine;
2236         }
2237       }
2238       ierr = MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);CHKERRQ(ierr);
2239       ierr = SNESComputeJacobianDefault(snes,X,FDexp,FDexp,NULL);CHKERRQ(ierr);
2240       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2241       if (flag_draw || flag_contour) {
2242         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2243         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2244       } else vdraw = NULL;
2245       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");CHKERRQ(ierr);
2246       if (flag) {ierr = MatView(Bexp,vstdout);CHKERRQ(ierr);}
2247       if (vdraw) {ierr = MatView(Bexp,vdraw);CHKERRQ(ierr);}
2248       ierr = PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");CHKERRQ(ierr);
2249       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2250       if (vdraw) {ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);}
2251       ierr = MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2252       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");CHKERRQ(ierr);
2253       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2254       if (vdraw) {              /* Always use contour for the difference */
2255         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2256         ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);
2257         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2258       }
2259       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2260       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2261       ierr = MatDestroy(&Bexp_mine);CHKERRQ(ierr);
2262       ierr = MatDestroy(&FDexp);CHKERRQ(ierr);
2263     }
2264   }
2265   {
2266     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2267     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2268     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring",&flag,NULL);CHKERRQ(ierr);
2269     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_display",&flag_display,NULL);CHKERRQ(ierr);
2270     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",&flag_draw,NULL);CHKERRQ(ierr);
2271     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2272     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",&flag_threshold,NULL);CHKERRQ(ierr);
2273     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);CHKERRQ(ierr);
2274     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);CHKERRQ(ierr);
2275     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2276       Mat            Bfd;
2277       PetscViewer    vdraw,vstdout;
2278       MatColoring    coloring;
2279       ISColoring     iscoloring;
2280       MatFDColoring  matfdcoloring;
2281       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2282       void           *funcctx;
2283       PetscReal      norm1,norm2,normmax;
2284 
2285       ierr = MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);CHKERRQ(ierr);
2286       ierr = MatColoringCreate(Bfd,&coloring);CHKERRQ(ierr);
2287       ierr = MatColoringSetType(coloring,MATCOLORINGSL);CHKERRQ(ierr);
2288       ierr = MatColoringSetFromOptions(coloring);CHKERRQ(ierr);
2289       ierr = MatColoringApply(coloring,&iscoloring);CHKERRQ(ierr);
2290       ierr = MatColoringDestroy(&coloring);CHKERRQ(ierr);
2291       ierr = MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);CHKERRQ(ierr);
2292       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2293       ierr = MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);CHKERRQ(ierr);
2294       ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr);
2295 
2296       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2297       ierr = SNESGetFunction(snes,NULL,&func,&funcctx);CHKERRQ(ierr);
2298       ierr = MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);CHKERRQ(ierr);
2299       ierr = PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);CHKERRQ(ierr);
2300       ierr = PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");CHKERRQ(ierr);
2301       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2302       ierr = MatFDColoringApply(Bfd,matfdcoloring,X,snes);CHKERRQ(ierr);
2303       ierr = MatFDColoringDestroy(&matfdcoloring);CHKERRQ(ierr);
2304 
2305       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2306       if (flag_draw || flag_contour) {
2307         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2308         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2309       } else vdraw = NULL;
2310       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");CHKERRQ(ierr);
2311       if (flag_display) {ierr = MatView(B,vstdout);CHKERRQ(ierr);}
2312       if (vdraw) {ierr = MatView(B,vdraw);CHKERRQ(ierr);}
2313       ierr = PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");CHKERRQ(ierr);
2314       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2315       if (vdraw) {ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);}
2316       ierr = MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2317       ierr = MatNorm(Bfd,NORM_1,&norm1);CHKERRQ(ierr);
2318       ierr = MatNorm(Bfd,NORM_FROBENIUS,&norm2);CHKERRQ(ierr);
2319       ierr = MatNorm(Bfd,NORM_MAX,&normmax);CHKERRQ(ierr);
2320       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);
2321       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2322       if (vdraw) {              /* Always use contour for the difference */
2323         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2324         ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);
2325         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2326       }
2327       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2328 
2329       if (flag_threshold) {
2330         PetscInt bs,rstart,rend,i;
2331         ierr = MatGetBlockSize(B,&bs);CHKERRQ(ierr);
2332         ierr = MatGetOwnershipRange(B,&rstart,&rend);CHKERRQ(ierr);
2333         for (i=rstart; i<rend; i++) {
2334           const PetscScalar *ba,*ca;
2335           const PetscInt    *bj,*cj;
2336           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2337           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2338           ierr = MatGetRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2339           ierr = MatGetRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2340           if (bn != cn) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2341           for (j=0; j<bn; j++) {
2342             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2343             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2344               maxentrycol = bj[j];
2345               maxentry    = PetscRealPart(ba[j]);
2346             }
2347             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2348               maxdiffcol = bj[j];
2349               maxdiff    = PetscRealPart(ca[j]);
2350             }
2351             if (rdiff > maxrdiff) {
2352               maxrdiffcol = bj[j];
2353               maxrdiff    = rdiff;
2354             }
2355           }
2356           if (maxrdiff > 1) {
2357             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);
2358             for (j=0; j<bn; j++) {
2359               PetscReal rdiff;
2360               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2361               if (rdiff > 1) {
2362                 ierr = PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));CHKERRQ(ierr);
2363               }
2364             }
2365             ierr = PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);CHKERRQ(ierr);
2366           }
2367           ierr = MatRestoreRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2368           ierr = MatRestoreRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2369         }
2370       }
2371       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2372       ierr = MatDestroy(&Bfd);CHKERRQ(ierr);
2373     }
2374   }
2375   PetscFunctionReturn(0);
2376 }
2377 
2378 /*MC
2379     SNESJacobianFunction - function used to convey the nonlinear Jacobian of the function to be solved by SNES
2380 
2381      Synopsis:
2382      #include <petscsnes.h>
2383 $     SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);
2384 
2385 +  x - input vector
2386 .  Amat - the matrix that defines the (approximate) Jacobian
2387 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2388 -  ctx - [optional] user-defined Jacobian context
2389 
2390    Level: intermediate
2391 
2392 .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2393 M*/
2394 
2395 #undef __FUNCT__
2396 #define __FUNCT__ "SNESSetJacobian"
2397 /*@C
2398    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2399    location to store the matrix.
2400 
2401    Logically Collective on SNES and Mat
2402 
2403    Input Parameters:
2404 +  snes - the SNES context
2405 .  Amat - the matrix that defines the (approximate) Jacobian
2406 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2407 .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value)
2408 -  ctx - [optional] user-defined context for private data for the
2409          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)
2410 
2411    Notes:
2412    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
2413    each matrix.
2414 
2415    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
2416    must be a MatFDColoring.
2417 
2418    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2419    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.
2420 
2421    Level: beginner
2422 
2423 .keywords: SNES, nonlinear, set, Jacobian, matrix
2424 
2425 .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J, SNESSetPicard()
2426 @*/
2427 PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2428 {
2429   PetscErrorCode ierr;
2430   DM             dm;
2431 
2432   PetscFunctionBegin;
2433   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2434   if (Amat) PetscValidHeaderSpecific(Amat,MAT_CLASSID,2);
2435   if (Pmat) PetscValidHeaderSpecific(Pmat,MAT_CLASSID,3);
2436   if (Amat) PetscCheckSameComm(snes,1,Amat,2);
2437   if (Pmat) PetscCheckSameComm(snes,1,Pmat,3);
2438   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2439   ierr = DMSNESSetJacobian(dm,J,ctx);CHKERRQ(ierr);
2440   if (Amat) {
2441     ierr = PetscObjectReference((PetscObject)Amat);CHKERRQ(ierr);
2442     ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2443 
2444     snes->jacobian = Amat;
2445   }
2446   if (Pmat) {
2447     ierr = PetscObjectReference((PetscObject)Pmat);CHKERRQ(ierr);
2448     ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2449 
2450     snes->jacobian_pre = Pmat;
2451   }
2452   PetscFunctionReturn(0);
2453 }
2454 
2455 #undef __FUNCT__
2456 #define __FUNCT__ "SNESGetJacobian"
2457 /*@C
2458    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2459    provided context for evaluating the Jacobian.
2460 
2461    Not Collective, but Mat object will be parallel if SNES object is
2462 
2463    Input Parameter:
2464 .  snes - the nonlinear solver context
2465 
2466    Output Parameters:
2467 +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
2468 .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
2469 .  J - location to put Jacobian function (or NULL)
2470 -  ctx - location to stash Jacobian ctx (or NULL)
2471 
2472    Level: advanced
2473 
2474 .seealso: SNESSetJacobian(), SNESComputeJacobian()
2475 @*/
2476 PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
2477 {
2478   PetscErrorCode ierr;
2479   DM             dm;
2480   DMSNES         sdm;
2481 
2482   PetscFunctionBegin;
2483   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2484   if (Amat) *Amat = snes->jacobian;
2485   if (Pmat) *Pmat = snes->jacobian_pre;
2486   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2487   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2488   if (J) *J = sdm->ops->computejacobian;
2489   if (ctx) *ctx = sdm->jacobianctx;
2490   PetscFunctionReturn(0);
2491 }
2492 
2493 #undef __FUNCT__
2494 #define __FUNCT__ "SNESSetUp"
2495 /*@
2496    SNESSetUp - Sets up the internal data structures for the later use
2497    of a nonlinear solver.
2498 
2499    Collective on SNES
2500 
2501    Input Parameters:
2502 .  snes - the SNES context
2503 
2504    Notes:
2505    For basic use of the SNES solvers the user need not explicitly call
2506    SNESSetUp(), since these actions will automatically occur during
2507    the call to SNESSolve().  However, if one wishes to control this
2508    phase separately, SNESSetUp() should be called after SNESCreate()
2509    and optional routines of the form SNESSetXXX(), but before SNESSolve().
2510 
2511    Level: advanced
2512 
2513 .keywords: SNES, nonlinear, setup
2514 
2515 .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
2516 @*/
2517 PetscErrorCode  SNESSetUp(SNES snes)
2518 {
2519   PetscErrorCode ierr;
2520   DM             dm;
2521   DMSNES         sdm;
2522   SNESLineSearch linesearch, pclinesearch;
2523   void           *lsprectx,*lspostctx;
2524   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
2525   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
2526   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2527   Vec            f,fpc;
2528   void           *funcctx;
2529   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
2530   void           *jacctx,*appctx;
2531 
2532   PetscFunctionBegin;
2533   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2534   if (snes->setupcalled) PetscFunctionReturn(0);
2535 
2536   if (!((PetscObject)snes)->type_name) {
2537     ierr = SNESSetType(snes,SNESNEWTONLS);CHKERRQ(ierr);
2538   }
2539 
2540   ierr = SNESGetFunction(snes,&snes->vec_func,NULL,NULL);CHKERRQ(ierr);
2541 
2542   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2543   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2544   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
2545   if (!sdm->ops->computejacobian) {
2546     ierr = DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);CHKERRQ(ierr);
2547   }
2548   if (!snes->vec_func) {
2549     ierr = DMCreateGlobalVector(dm,&snes->vec_func);CHKERRQ(ierr);
2550   }
2551 
2552   if (!snes->ksp) {
2553     ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);
2554   }
2555 
2556   if (!snes->linesearch) {
2557     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
2558   }
2559   ierr = SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);CHKERRQ(ierr);
2560 
2561   if (snes->pc && (snes->pcside == PC_LEFT)) {
2562     snes->mf          = PETSC_TRUE;
2563     snes->mf_operator = PETSC_FALSE;
2564   }
2565 
2566   if (snes->mf) {
2567     ierr = SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);CHKERRQ(ierr);
2568   }
2569 
2570   if (snes->ops->usercompute && !snes->user) {
2571     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2572   }
2573 
2574   if (snes->pc) {
2575     /* copy the DM over */
2576     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2577     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
2578 
2579     ierr = SNESGetFunction(snes,&f,&func,&funcctx);CHKERRQ(ierr);
2580     ierr = VecDuplicate(f,&fpc);CHKERRQ(ierr);
2581     ierr = SNESSetFunction(snes->pc,fpc,func,funcctx);CHKERRQ(ierr);
2582     ierr = SNESGetJacobian(snes,NULL,NULL,&jac,&jacctx);CHKERRQ(ierr);
2583     ierr = SNESSetJacobian(snes->pc,snes->jacobian,snes->jacobian_pre,jac,jacctx);CHKERRQ(ierr);
2584     ierr = SNESGetApplicationContext(snes,&appctx);CHKERRQ(ierr);
2585     ierr = SNESSetApplicationContext(snes->pc,appctx);CHKERRQ(ierr);
2586     ierr = VecDestroy(&fpc);CHKERRQ(ierr);
2587 
2588     /* copy the function pointers over */
2589     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
2590 
2591     /* default to 1 iteration */
2592     ierr = SNESSetTolerances(snes->pc,0.0,0.0,0.0,1,snes->pc->max_funcs);CHKERRQ(ierr);
2593     if (snes->pcside==PC_RIGHT) {
2594       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
2595     } else {
2596       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_NONE);CHKERRQ(ierr);
2597     }
2598     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
2599 
2600     /* copy the line search context over */
2601     ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2602     ierr = SNESGetLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
2603     ierr = SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);CHKERRQ(ierr);
2604     ierr = SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);CHKERRQ(ierr);
2605     ierr = SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);CHKERRQ(ierr);
2606     ierr = SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);CHKERRQ(ierr);
2607     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);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,void *ctx)
3128 {
3129   PetscErrorCode ierr;
3130 
3131   PetscFunctionBegin;
3132   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3133   ierr = KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);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,PetscDrawLG *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(PetscDrawLG *draw)
3151 {
3152   PetscErrorCode ierr;
3153 
3154   PetscFunctionBegin;
3155   ierr = KSPMonitorLGResidualNormDestroy(draw);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__ "SNESSolve"
3663 /*@C
3664    SNESSolve - Solves a nonlinear system F(x) = b.
3665    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3666 
3667    Collective on SNES
3668 
3669    Input Parameters:
3670 +  snes - the SNES context
3671 .  b - the constant part of the equation F(x) = b, or NULL to use zero.
3672 -  x - the solution vector.
3673 
3674    Notes:
3675    The user should initialize the vector,x, with the initial guess
3676    for the nonlinear solve prior to calling SNESSolve.  In particular,
3677    to employ an initial guess of zero, the user should explicitly set
3678    this vector to zero by calling VecSet().
3679 
3680    Level: beginner
3681 
3682 .keywords: SNES, nonlinear, solve
3683 
3684 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3685 @*/
3686 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3687 {
3688   PetscErrorCode    ierr;
3689   PetscBool         flg;
3690   PetscInt          grid;
3691   Vec               xcreated = NULL;
3692   DM                dm;
3693 
3694   PetscFunctionBegin;
3695   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3696   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3697   if (x) PetscCheckSameComm(snes,1,x,3);
3698   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3699   if (b) PetscCheckSameComm(snes,1,b,2);
3700 
3701   if (!x) {
3702     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3703     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3704     x    = xcreated;
3705   }
3706   ierr = SNESViewFromOptions(snes,NULL,"-snes_view_pre");CHKERRQ(ierr);
3707 
3708   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);}
3709   for (grid=0; grid<snes->gridsequence+1; grid++) {
3710 
3711     /* set solution vector */
3712     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3713     ierr          = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3714     snes->vec_sol = x;
3715     ierr          = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3716 
3717     /* set affine vector if provided */
3718     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3719     ierr          = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3720     snes->vec_rhs = b;
3721 
3722     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
3723     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
3724     if (!snes->vec_sol_update /* && snes->vec_sol */) {
3725       ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
3726       ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);CHKERRQ(ierr);
3727     }
3728     ierr = DMShellSetGlobalVector(dm,snes->vec_sol);CHKERRQ(ierr);
3729     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3730 
3731     if (!grid) {
3732       if (snes->ops->computeinitialguess) {
3733         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3734       }
3735     }
3736 
3737     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3738     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}
3739 
3740     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3741     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3742     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3743     if (snes->domainerror) {
3744       snes->reason      = SNES_DIVERGED_FUNCTION_DOMAIN;
3745       snes->domainerror = PETSC_FALSE;
3746     }
3747     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3748 
3749     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
3750     if (snes->lagpre_persist) snes->pre_iter += snes->iter;
3751 
3752     flg  = PETSC_FALSE;
3753     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,NULL);CHKERRQ(ierr);
3754     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
3755     if (snes->printreason) {
3756       ierr = PetscViewerASCIIAddTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3757       if (snes->reason > 0) {
3758         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3759       } else {
3760         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3761       }
3762       ierr = PetscViewerASCIISubtractTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3763     }
3764 
3765     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
3766     if (grid <  snes->gridsequence) {
3767       DM  fine;
3768       Vec xnew;
3769       Mat interp;
3770 
3771       ierr = DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);CHKERRQ(ierr);
3772       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
3773       ierr = DMCreateInterpolation(snes->dm,fine,&interp,NULL);CHKERRQ(ierr);
3774       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
3775       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
3776       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
3777       ierr = MatDestroy(&interp);CHKERRQ(ierr);
3778       x    = xnew;
3779 
3780       ierr = SNESReset(snes);CHKERRQ(ierr);
3781       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
3782       ierr = DMDestroy(&fine);CHKERRQ(ierr);
3783       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);
3784     }
3785   }
3786   ierr = SNESViewFromOptions(snes,NULL,"-snes_view");CHKERRQ(ierr);
3787   ierr = VecViewFromOptions(snes->vec_sol,((PetscObject)snes)->prefix,"-snes_view_solution");CHKERRQ(ierr);
3788 
3789   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
3790   ierr = PetscObjectSAWsBlock((PetscObject)snes);CHKERRQ(ierr);
3791   PetscFunctionReturn(0);
3792 }
3793 
3794 /* --------- Internal routines for SNES Package --------- */
3795 
3796 #undef __FUNCT__
3797 #define __FUNCT__ "SNESSetType"
3798 /*@C
3799    SNESSetType - Sets the method for the nonlinear solver.
3800 
3801    Collective on SNES
3802 
3803    Input Parameters:
3804 +  snes - the SNES context
3805 -  type - a known method
3806 
3807    Options Database Key:
3808 .  -snes_type <type> - Sets the method; use -help for a list
3809    of available methods (for instance, newtonls or newtontr)
3810 
3811    Notes:
3812    See "petsc/include/petscsnes.h" for available methods (for instance)
3813 +    SNESNEWTONLS - Newton's method with line search
3814      (systems of nonlinear equations)
3815 .    SNESNEWTONTR - Newton's method with trust region
3816      (systems of nonlinear equations)
3817 
3818   Normally, it is best to use the SNESSetFromOptions() command and then
3819   set the SNES solver type from the options database rather than by using
3820   this routine.  Using the options database provides the user with
3821   maximum flexibility in evaluating the many nonlinear solvers.
3822   The SNESSetType() routine is provided for those situations where it
3823   is necessary to set the nonlinear solver independently of the command
3824   line or options database.  This might be the case, for example, when
3825   the choice of solver changes during the execution of the program,
3826   and the user's application is taking responsibility for choosing the
3827   appropriate method.
3828 
3829     Developer Notes: SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
3830     the constructor in that list and calls it to create the spexific object.
3831 
3832   Level: intermediate
3833 
3834 .keywords: SNES, set, type
3835 
3836 .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()
3837 
3838 @*/
3839 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
3840 {
3841   PetscErrorCode ierr,(*r)(SNES);
3842   PetscBool      match;
3843 
3844   PetscFunctionBegin;
3845   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3846   PetscValidCharPointer(type,2);
3847 
3848   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
3849   if (match) PetscFunctionReturn(0);
3850 
3851   ierr =  PetscFunctionListFind(SNESList,type,&r);CHKERRQ(ierr);
3852   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
3853   /* Destroy the previous private SNES context */
3854   if (snes->ops->destroy) {
3855     ierr               = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
3856     snes->ops->destroy = NULL;
3857   }
3858   /* Reinitialize function pointers in SNESOps structure */
3859   snes->ops->setup          = 0;
3860   snes->ops->solve          = 0;
3861   snes->ops->view           = 0;
3862   snes->ops->setfromoptions = 0;
3863   snes->ops->destroy        = 0;
3864   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
3865   snes->setupcalled = PETSC_FALSE;
3866 
3867   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
3868   ierr = (*r)(snes);CHKERRQ(ierr);
3869   PetscFunctionReturn(0);
3870 }
3871 
3872 #undef __FUNCT__
3873 #define __FUNCT__ "SNESGetType"
3874 /*@C
3875    SNESGetType - Gets the SNES method type and name (as a string).
3876 
3877    Not Collective
3878 
3879    Input Parameter:
3880 .  snes - nonlinear solver context
3881 
3882    Output Parameter:
3883 .  type - SNES method (a character string)
3884 
3885    Level: intermediate
3886 
3887 .keywords: SNES, nonlinear, get, type, name
3888 @*/
3889 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
3890 {
3891   PetscFunctionBegin;
3892   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3893   PetscValidPointer(type,2);
3894   *type = ((PetscObject)snes)->type_name;
3895   PetscFunctionReturn(0);
3896 }
3897 
3898 #undef __FUNCT__
3899 #define __FUNCT__ "SNESGetSolution"
3900 /*@
3901    SNESGetSolution - Returns the vector where the approximate solution is
3902    stored. This is the fine grid solution when using SNESSetGridSequence().
3903 
3904    Not Collective, but Vec is parallel if SNES is parallel
3905 
3906    Input Parameter:
3907 .  snes - the SNES context
3908 
3909    Output Parameter:
3910 .  x - the solution
3911 
3912    Level: intermediate
3913 
3914 .keywords: SNES, nonlinear, get, solution
3915 
3916 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
3917 @*/
3918 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
3919 {
3920   PetscFunctionBegin;
3921   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3922   PetscValidPointer(x,2);
3923   *x = snes->vec_sol;
3924   PetscFunctionReturn(0);
3925 }
3926 
3927 #undef __FUNCT__
3928 #define __FUNCT__ "SNESGetSolutionUpdate"
3929 /*@
3930    SNESGetSolutionUpdate - Returns the vector where the solution update is
3931    stored.
3932 
3933    Not Collective, but Vec is parallel if SNES is parallel
3934 
3935    Input Parameter:
3936 .  snes - the SNES context
3937 
3938    Output Parameter:
3939 .  x - the solution update
3940 
3941    Level: advanced
3942 
3943 .keywords: SNES, nonlinear, get, solution, update
3944 
3945 .seealso: SNESGetSolution(), SNESGetFunction()
3946 @*/
3947 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
3948 {
3949   PetscFunctionBegin;
3950   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3951   PetscValidPointer(x,2);
3952   *x = snes->vec_sol_update;
3953   PetscFunctionReturn(0);
3954 }
3955 
3956 #undef __FUNCT__
3957 #define __FUNCT__ "SNESGetFunction"
3958 /*@C
3959    SNESGetFunction - Returns the vector where the function is stored.
3960 
3961    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
3962 
3963    Input Parameter:
3964 .  snes - the SNES context
3965 
3966    Output Parameter:
3967 +  r - the vector that is used to store residuals (or NULL if you don't want it)
3968 .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
3969 -  ctx - the function context (or NULL if you don't want it)
3970 
3971    Level: advanced
3972 
3973 .keywords: SNES, nonlinear, get, function
3974 
3975 .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
3976 @*/
3977 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
3978 {
3979   PetscErrorCode ierr;
3980   DM             dm;
3981 
3982   PetscFunctionBegin;
3983   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3984   if (r) {
3985     if (!snes->vec_func) {
3986       if (snes->vec_rhs) {
3987         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
3988       } else if (snes->vec_sol) {
3989         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
3990       } else if (snes->dm) {
3991         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
3992       }
3993     }
3994     *r = snes->vec_func;
3995   }
3996   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3997   ierr = DMSNESGetFunction(dm,f,ctx);CHKERRQ(ierr);
3998   PetscFunctionReturn(0);
3999 }
4000 
4001 /*@C
4002    SNESGetNGS - Returns the NGS function and context.
4003 
4004    Input Parameter:
4005 .  snes - the SNES context
4006 
4007    Output Parameter:
4008 +  f - the function (or NULL) see SNESNGSFunction for details
4009 -  ctx    - the function context (or NULL)
4010 
4011    Level: advanced
4012 
4013 .keywords: SNES, nonlinear, get, function
4014 
4015 .seealso: SNESSetNGS(), SNESGetFunction()
4016 @*/
4017 
4018 #undef __FUNCT__
4019 #define __FUNCT__ "SNESGetNGS"
4020 PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
4021 {
4022   PetscErrorCode ierr;
4023   DM             dm;
4024 
4025   PetscFunctionBegin;
4026   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4027   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4028   ierr = DMSNESGetNGS(dm,f,ctx);CHKERRQ(ierr);
4029   PetscFunctionReturn(0);
4030 }
4031 
4032 #undef __FUNCT__
4033 #define __FUNCT__ "SNESSetOptionsPrefix"
4034 /*@C
4035    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4036    SNES options in the database.
4037 
4038    Logically Collective on SNES
4039 
4040    Input Parameter:
4041 +  snes - the SNES context
4042 -  prefix - the prefix to prepend to all option names
4043 
4044    Notes:
4045    A hyphen (-) must NOT be given at the beginning of the prefix name.
4046    The first character of all runtime options is AUTOMATICALLY the hyphen.
4047 
4048    Level: advanced
4049 
4050 .keywords: SNES, set, options, prefix, database
4051 
4052 .seealso: SNESSetFromOptions()
4053 @*/
4054 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4055 {
4056   PetscErrorCode ierr;
4057 
4058   PetscFunctionBegin;
4059   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4060   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4061   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4062   if (snes->linesearch) {
4063     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4064     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4065   }
4066   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4067   PetscFunctionReturn(0);
4068 }
4069 
4070 #undef __FUNCT__
4071 #define __FUNCT__ "SNESAppendOptionsPrefix"
4072 /*@C
4073    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4074    SNES options in the database.
4075 
4076    Logically Collective on SNES
4077 
4078    Input Parameters:
4079 +  snes - the SNES context
4080 -  prefix - the prefix to prepend to all option names
4081 
4082    Notes:
4083    A hyphen (-) must NOT be given at the beginning of the prefix name.
4084    The first character of all runtime options is AUTOMATICALLY the hyphen.
4085 
4086    Level: advanced
4087 
4088 .keywords: SNES, append, options, prefix, database
4089 
4090 .seealso: SNESGetOptionsPrefix()
4091 @*/
4092 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4093 {
4094   PetscErrorCode ierr;
4095 
4096   PetscFunctionBegin;
4097   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4098   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4099   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4100   if (snes->linesearch) {
4101     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4102     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4103   }
4104   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4105   PetscFunctionReturn(0);
4106 }
4107 
4108 #undef __FUNCT__
4109 #define __FUNCT__ "SNESGetOptionsPrefix"
4110 /*@C
4111    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4112    SNES options in the database.
4113 
4114    Not Collective
4115 
4116    Input Parameter:
4117 .  snes - the SNES context
4118 
4119    Output Parameter:
4120 .  prefix - pointer to the prefix string used
4121 
4122    Notes: On the fortran side, the user should pass in a string 'prefix' of
4123    sufficient length to hold the prefix.
4124 
4125    Level: advanced
4126 
4127 .keywords: SNES, get, options, prefix, database
4128 
4129 .seealso: SNESAppendOptionsPrefix()
4130 @*/
4131 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4132 {
4133   PetscErrorCode ierr;
4134 
4135   PetscFunctionBegin;
4136   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4137   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4138   PetscFunctionReturn(0);
4139 }
4140 
4141 
4142 #undef __FUNCT__
4143 #define __FUNCT__ "SNESRegister"
4144 /*@C
4145   SNESRegister - Adds a method to the nonlinear solver package.
4146 
4147    Not collective
4148 
4149    Input Parameters:
4150 +  name_solver - name of a new user-defined solver
4151 -  routine_create - routine to create method context
4152 
4153    Notes:
4154    SNESRegister() may be called multiple times to add several user-defined solvers.
4155 
4156    Sample usage:
4157 .vb
4158    SNESRegister("my_solver",MySolverCreate);
4159 .ve
4160 
4161    Then, your solver can be chosen with the procedural interface via
4162 $     SNESSetType(snes,"my_solver")
4163    or at runtime via the option
4164 $     -snes_type my_solver
4165 
4166    Level: advanced
4167 
4168     Note: If your function is not being put into a shared library then use SNESRegister() instead
4169 
4170 .keywords: SNES, nonlinear, register
4171 
4172 .seealso: SNESRegisterAll(), SNESRegisterDestroy()
4173 
4174   Level: advanced
4175 @*/
4176 PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
4177 {
4178   PetscErrorCode ierr;
4179 
4180   PetscFunctionBegin;
4181   ierr = PetscFunctionListAdd(&SNESList,sname,function);CHKERRQ(ierr);
4182   PetscFunctionReturn(0);
4183 }
4184 
4185 #undef __FUNCT__
4186 #define __FUNCT__ "SNESTestLocalMin"
4187 PetscErrorCode  SNESTestLocalMin(SNES snes)
4188 {
4189   PetscErrorCode ierr;
4190   PetscInt       N,i,j;
4191   Vec            u,uh,fh;
4192   PetscScalar    value;
4193   PetscReal      norm;
4194 
4195   PetscFunctionBegin;
4196   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4197   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4198   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4199 
4200   /* currently only works for sequential */
4201   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");CHKERRQ(ierr);
4202   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4203   for (i=0; i<N; i++) {
4204     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4205     ierr = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4206     for (j=-10; j<11; j++) {
4207       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
4208       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4209       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4210       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4211       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4212       value = -value;
4213       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4214     }
4215   }
4216   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4217   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4218   PetscFunctionReturn(0);
4219 }
4220 
4221 #undef __FUNCT__
4222 #define __FUNCT__ "SNESKSPSetUseEW"
4223 /*@
4224    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4225    computing relative tolerance for linear solvers within an inexact
4226    Newton method.
4227 
4228    Logically Collective on SNES
4229 
4230    Input Parameters:
4231 +  snes - SNES context
4232 -  flag - PETSC_TRUE or PETSC_FALSE
4233 
4234     Options Database:
4235 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4236 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4237 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4238 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4239 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4240 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4241 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4242 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4243 
4244    Notes:
4245    Currently, the default is to use a constant relative tolerance for
4246    the inner linear solvers.  Alternatively, one can use the
4247    Eisenstat-Walker method, where the relative convergence tolerance
4248    is reset at each Newton iteration according progress of the nonlinear
4249    solver.
4250 
4251    Level: advanced
4252 
4253    Reference:
4254    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4255    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4256 
4257 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4258 
4259 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4260 @*/
4261 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
4262 {
4263   PetscFunctionBegin;
4264   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4265   PetscValidLogicalCollectiveBool(snes,flag,2);
4266   snes->ksp_ewconv = flag;
4267   PetscFunctionReturn(0);
4268 }
4269 
4270 #undef __FUNCT__
4271 #define __FUNCT__ "SNESKSPGetUseEW"
4272 /*@
4273    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4274    for computing relative tolerance for linear solvers within an
4275    inexact Newton method.
4276 
4277    Not Collective
4278 
4279    Input Parameter:
4280 .  snes - SNES context
4281 
4282    Output Parameter:
4283 .  flag - PETSC_TRUE or PETSC_FALSE
4284 
4285    Notes:
4286    Currently, the default is to use a constant relative tolerance for
4287    the inner linear solvers.  Alternatively, one can use the
4288    Eisenstat-Walker method, where the relative convergence tolerance
4289    is reset at each Newton iteration according progress of the nonlinear
4290    solver.
4291 
4292    Level: advanced
4293 
4294    Reference:
4295    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4296    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4297 
4298 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4299 
4300 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4301 @*/
4302 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4303 {
4304   PetscFunctionBegin;
4305   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4306   PetscValidPointer(flag,2);
4307   *flag = snes->ksp_ewconv;
4308   PetscFunctionReturn(0);
4309 }
4310 
4311 #undef __FUNCT__
4312 #define __FUNCT__ "SNESKSPSetParametersEW"
4313 /*@
4314    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4315    convergence criteria for the linear solvers within an inexact
4316    Newton method.
4317 
4318    Logically Collective on SNES
4319 
4320    Input Parameters:
4321 +    snes - SNES context
4322 .    version - version 1, 2 (default is 2) or 3
4323 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4324 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4325 .    gamma - multiplicative factor for version 2 rtol computation
4326              (0 <= gamma2 <= 1)
4327 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4328 .    alpha2 - power for safeguard
4329 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4330 
4331    Note:
4332    Version 3 was contributed by Luis Chacon, June 2006.
4333 
4334    Use PETSC_DEFAULT to retain the default for any of the parameters.
4335 
4336    Level: advanced
4337 
4338    Reference:
4339    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4340    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4341    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4342 
4343 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4344 
4345 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4346 @*/
4347 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4348 {
4349   SNESKSPEW *kctx;
4350 
4351   PetscFunctionBegin;
4352   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4353   kctx = (SNESKSPEW*)snes->kspconvctx;
4354   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4355   PetscValidLogicalCollectiveInt(snes,version,2);
4356   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4357   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4358   PetscValidLogicalCollectiveReal(snes,gamma,5);
4359   PetscValidLogicalCollectiveReal(snes,alpha,6);
4360   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4361   PetscValidLogicalCollectiveReal(snes,threshold,8);
4362 
4363   if (version != PETSC_DEFAULT)   kctx->version   = version;
4364   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4365   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4366   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4367   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4368   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4369   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4370 
4371   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);
4372   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);
4373   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);
4374   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);
4375   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);
4376   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);
4377   PetscFunctionReturn(0);
4378 }
4379 
4380 #undef __FUNCT__
4381 #define __FUNCT__ "SNESKSPGetParametersEW"
4382 /*@
4383    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4384    convergence criteria for the linear solvers within an inexact
4385    Newton method.
4386 
4387    Not Collective
4388 
4389    Input Parameters:
4390      snes - SNES context
4391 
4392    Output Parameters:
4393 +    version - version 1, 2 (default is 2) or 3
4394 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4395 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4396 .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
4397 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4398 .    alpha2 - power for safeguard
4399 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4400 
4401    Level: advanced
4402 
4403 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4404 
4405 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4406 @*/
4407 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4408 {
4409   SNESKSPEW *kctx;
4410 
4411   PetscFunctionBegin;
4412   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4413   kctx = (SNESKSPEW*)snes->kspconvctx;
4414   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4415   if (version)   *version   = kctx->version;
4416   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4417   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4418   if (gamma)     *gamma     = kctx->gamma;
4419   if (alpha)     *alpha     = kctx->alpha;
4420   if (alpha2)    *alpha2    = kctx->alpha2;
4421   if (threshold) *threshold = kctx->threshold;
4422   PetscFunctionReturn(0);
4423 }
4424 
4425 #undef __FUNCT__
4426 #define __FUNCT__ "KSPPreSolve_SNESEW"
4427  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4428 {
4429   PetscErrorCode ierr;
4430   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4431   PetscReal      rtol  = PETSC_DEFAULT,stol;
4432 
4433   PetscFunctionBegin;
4434   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4435   if (!snes->iter) {
4436     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
4437     ierr = VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);CHKERRQ(ierr);
4438   }
4439   else {
4440     if (kctx->version == 1) {
4441       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4442       if (rtol < 0.0) rtol = -rtol;
4443       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
4444       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4445     } else if (kctx->version == 2) {
4446       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4447       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
4448       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4449     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
4450       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4451       /* safeguard: avoid sharp decrease of rtol */
4452       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
4453       stol = PetscMax(rtol,stol);
4454       rtol = PetscMin(kctx->rtol_0,stol);
4455       /* safeguard: avoid oversolving */
4456       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
4457       stol = PetscMax(rtol,stol);
4458       rtol = PetscMin(kctx->rtol_0,stol);
4459     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4460   }
4461   /* safeguard: avoid rtol greater than one */
4462   rtol = PetscMin(rtol,kctx->rtol_max);
4463   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4464   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);CHKERRQ(ierr);
4465   PetscFunctionReturn(0);
4466 }
4467 
4468 #undef __FUNCT__
4469 #define __FUNCT__ "KSPPostSolve_SNESEW"
4470 PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4471 {
4472   PetscErrorCode ierr;
4473   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4474   PCSide         pcside;
4475   Vec            lres;
4476 
4477   PetscFunctionBegin;
4478   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4479   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4480   kctx->norm_last = snes->norm;
4481   if (kctx->version == 1) {
4482     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4483     if (pcside == PC_RIGHT) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4484       /* KSP residual is true linear residual */
4485       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4486     } else {
4487       /* KSP residual is preconditioned residual */
4488       /* compute true linear residual norm */
4489       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4490       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4491       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4492       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4493       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4494     }
4495   }
4496   PetscFunctionReturn(0);
4497 }
4498 
4499 #undef __FUNCT__
4500 #define __FUNCT__ "SNESGetKSP"
4501 /*@
4502    SNESGetKSP - Returns the KSP context for a SNES solver.
4503 
4504    Not Collective, but if SNES object is parallel, then KSP object is parallel
4505 
4506    Input Parameter:
4507 .  snes - the SNES context
4508 
4509    Output Parameter:
4510 .  ksp - the KSP context
4511 
4512    Notes:
4513    The user can then directly manipulate the KSP context to set various
4514    options, etc.  Likewise, the user can then extract and manipulate the
4515    PC contexts as well.
4516 
4517    Level: beginner
4518 
4519 .keywords: SNES, nonlinear, get, KSP, context
4520 
4521 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
4522 @*/
4523 PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
4524 {
4525   PetscErrorCode ierr;
4526 
4527   PetscFunctionBegin;
4528   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4529   PetscValidPointer(ksp,2);
4530 
4531   if (!snes->ksp) {
4532     ierr = KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);CHKERRQ(ierr);
4533     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);CHKERRQ(ierr);
4534     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);CHKERRQ(ierr);
4535 
4536     ierr = KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);CHKERRQ(ierr);
4537     ierr = KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);CHKERRQ(ierr);
4538   }
4539   *ksp = snes->ksp;
4540   PetscFunctionReturn(0);
4541 }
4542 
4543 
4544 #include <petsc-private/dmimpl.h>
4545 #undef __FUNCT__
4546 #define __FUNCT__ "SNESSetDM"
4547 /*@
4548    SNESSetDM - Sets the DM that may be used by some preconditioners
4549 
4550    Logically Collective on SNES
4551 
4552    Input Parameters:
4553 +  snes - the preconditioner context
4554 -  dm - the dm
4555 
4556    Level: intermediate
4557 
4558 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4559 @*/
4560 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4561 {
4562   PetscErrorCode ierr;
4563   KSP            ksp;
4564   DMSNES         sdm;
4565 
4566   PetscFunctionBegin;
4567   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4568   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4569   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4570     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4571       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4572       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4573       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
4574     }
4575     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4576   }
4577   snes->dm     = dm;
4578   snes->dmAuto = PETSC_FALSE;
4579 
4580   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4581   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4582   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4583   if (snes->pc) {
4584     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4585     ierr = SNESSetNPCSide(snes,snes->pcside);CHKERRQ(ierr);
4586   }
4587   PetscFunctionReturn(0);
4588 }
4589 
4590 #undef __FUNCT__
4591 #define __FUNCT__ "SNESGetDM"
4592 /*@
4593    SNESGetDM - Gets the DM that may be used by some preconditioners
4594 
4595    Not Collective but DM obtained is parallel on SNES
4596 
4597    Input Parameter:
4598 . snes - the preconditioner context
4599 
4600    Output Parameter:
4601 .  dm - the dm
4602 
4603    Level: intermediate
4604 
4605 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4606 @*/
4607 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4608 {
4609   PetscErrorCode ierr;
4610 
4611   PetscFunctionBegin;
4612   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4613   if (!snes->dm) {
4614     ierr         = DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);CHKERRQ(ierr);
4615     snes->dmAuto = PETSC_TRUE;
4616   }
4617   *dm = snes->dm;
4618   PetscFunctionReturn(0);
4619 }
4620 
4621 #undef __FUNCT__
4622 #define __FUNCT__ "SNESSetNPC"
4623 /*@
4624   SNESSetNPC - Sets the nonlinear preconditioner to be used.
4625 
4626   Collective on SNES
4627 
4628   Input Parameters:
4629 + snes - iterative context obtained from SNESCreate()
4630 - pc   - the preconditioner object
4631 
4632   Notes:
4633   Use SNESGetNPC() to retrieve the preconditioner context (for example,
4634   to configure it using the API).
4635 
4636   Level: developer
4637 
4638 .keywords: SNES, set, precondition
4639 .seealso: SNESGetNPC()
4640 @*/
4641 PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
4642 {
4643   PetscErrorCode ierr;
4644 
4645   PetscFunctionBegin;
4646   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4647   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4648   PetscCheckSameComm(snes, 1, pc, 2);
4649   ierr     = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4650   ierr     = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4651   snes->pc = pc;
4652   ierr     = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->pc);CHKERRQ(ierr);
4653   PetscFunctionReturn(0);
4654 }
4655 
4656 #undef __FUNCT__
4657 #define __FUNCT__ "SNESGetNPC"
4658 /*@
4659   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.
4660 
4661   Not Collective
4662 
4663   Input Parameter:
4664 . snes - iterative context obtained from SNESCreate()
4665 
4666   Output Parameter:
4667 . pc - preconditioner context
4668 
4669   Notes: If a SNES was previously set with SNESSetNPC() then that SNES is returned.
4670 
4671   Level: developer
4672 
4673 .keywords: SNES, get, preconditioner
4674 .seealso: SNESSetNPC()
4675 @*/
4676 PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
4677 {
4678   PetscErrorCode ierr;
4679   const char     *optionsprefix;
4680 
4681   PetscFunctionBegin;
4682   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4683   PetscValidPointer(pc, 2);
4684   if (!snes->pc) {
4685     ierr = SNESCreate(PetscObjectComm((PetscObject)snes),&snes->pc);CHKERRQ(ierr);
4686     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4687     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
4688     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4689     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4690     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4691     ierr = SNESSetCountersReset(snes->pc,PETSC_FALSE);CHKERRQ(ierr);
4692   }
4693   *pc = snes->pc;
4694   PetscFunctionReturn(0);
4695 }
4696 
4697 #undef __FUNCT__
4698 #define __FUNCT__ "SNESSetNPCSide"
4699 /*@
4700     SNESSetNPCSide - Sets the preconditioning side.
4701 
4702     Logically Collective on SNES
4703 
4704     Input Parameter:
4705 .   snes - iterative context obtained from SNESCreate()
4706 
4707     Output Parameter:
4708 .   side - the preconditioning side, where side is one of
4709 .vb
4710       PC_LEFT - left preconditioning (default)
4711       PC_RIGHT - right preconditioning
4712 .ve
4713 
4714     Options Database Keys:
4715 .   -snes_pc_side <right,left>
4716 
4717     Level: intermediate
4718 
4719 .keywords: SNES, set, right, left, side, preconditioner, flag
4720 
4721 .seealso: SNESGetNPCSide(), KSPSetPCSide()
4722 @*/
4723 PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
4724 {
4725   PetscFunctionBegin;
4726   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4727   PetscValidLogicalCollectiveEnum(snes,side,2);
4728   snes->pcside = side;
4729   PetscFunctionReturn(0);
4730 }
4731 
4732 #undef __FUNCT__
4733 #define __FUNCT__ "SNESGetNPCSide"
4734 /*@
4735     SNESGetNPCSide - Gets the preconditioning side.
4736 
4737     Not Collective
4738 
4739     Input Parameter:
4740 .   snes - iterative context obtained from SNESCreate()
4741 
4742     Output Parameter:
4743 .   side - the preconditioning side, where side is one of
4744 .vb
4745       PC_LEFT - left preconditioning (default)
4746       PC_RIGHT - right preconditioning
4747 .ve
4748 
4749     Level: intermediate
4750 
4751 .keywords: SNES, get, right, left, side, preconditioner, flag
4752 
4753 .seealso: SNESSetNPCSide(), KSPGetPCSide()
4754 @*/
4755 PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
4756 {
4757   PetscFunctionBegin;
4758   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4759   PetscValidPointer(side,2);
4760   *side = snes->pcside;
4761   PetscFunctionReturn(0);
4762 }
4763 
4764 #undef __FUNCT__
4765 #define __FUNCT__ "SNESSetLineSearch"
4766 /*@
4767   SNESSetLineSearch - Sets the linesearch on the SNES instance.
4768 
4769   Collective on SNES
4770 
4771   Input Parameters:
4772 + snes - iterative context obtained from SNESCreate()
4773 - linesearch   - the linesearch object
4774 
4775   Notes:
4776   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
4777   to configure it using the API).
4778 
4779   Level: developer
4780 
4781 .keywords: SNES, set, linesearch
4782 .seealso: SNESGetLineSearch()
4783 @*/
4784 PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
4785 {
4786   PetscErrorCode ierr;
4787 
4788   PetscFunctionBegin;
4789   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4790   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
4791   PetscCheckSameComm(snes, 1, linesearch, 2);
4792   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
4793   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
4794 
4795   snes->linesearch = linesearch;
4796 
4797   ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
4798   PetscFunctionReturn(0);
4799 }
4800 
4801 #undef __FUNCT__
4802 #define __FUNCT__ "SNESGetLineSearch"
4803 /*@
4804   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
4805   or creates a default line search instance associated with the SNES and returns it.
4806 
4807   Not Collective
4808 
4809   Input Parameter:
4810 . snes - iterative context obtained from SNESCreate()
4811 
4812   Output Parameter:
4813 . linesearch - linesearch context
4814 
4815   Level: beginner
4816 
4817 .keywords: SNES, get, linesearch
4818 .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
4819 @*/
4820 PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
4821 {
4822   PetscErrorCode ierr;
4823   const char     *optionsprefix;
4824 
4825   PetscFunctionBegin;
4826   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4827   PetscValidPointer(linesearch, 2);
4828   if (!snes->linesearch) {
4829     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
4830     ierr = SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);CHKERRQ(ierr);
4831     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
4832     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
4833     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
4834     ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
4835   }
4836   *linesearch = snes->linesearch;
4837   PetscFunctionReturn(0);
4838 }
4839 
4840 #if defined(PETSC_HAVE_MATLAB_ENGINE)
4841 #include <mex.h>
4842 
4843 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
4844 
4845 #undef __FUNCT__
4846 #define __FUNCT__ "SNESComputeFunction_Matlab"
4847 /*
4848    SNESComputeFunction_Matlab - Calls the function that has been set with SNESSetFunctionMatlab().
4849 
4850    Collective on SNES
4851 
4852    Input Parameters:
4853 +  snes - the SNES context
4854 -  x - input vector
4855 
4856    Output Parameter:
4857 .  y - function vector, as set by SNESSetFunction()
4858 
4859    Notes:
4860    SNESComputeFunction() is typically used within nonlinear solvers
4861    implementations, so most users would not generally call this routine
4862    themselves.
4863 
4864    Level: developer
4865 
4866 .keywords: SNES, nonlinear, compute, function
4867 
4868 .seealso: SNESSetFunction(), SNESGetFunction()
4869 */
4870 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
4871 {
4872   PetscErrorCode    ierr;
4873   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
4874   int               nlhs  = 1,nrhs = 5;
4875   mxArray           *plhs[1],*prhs[5];
4876   long long int     lx = 0,ly = 0,ls = 0;
4877 
4878   PetscFunctionBegin;
4879   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4880   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4881   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
4882   PetscCheckSameComm(snes,1,x,2);
4883   PetscCheckSameComm(snes,1,y,3);
4884 
4885   /* call Matlab function in ctx with arguments x and y */
4886 
4887   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4888   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4889   ierr    = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
4890   prhs[0] = mxCreateDoubleScalar((double)ls);
4891   prhs[1] = mxCreateDoubleScalar((double)lx);
4892   prhs[2] = mxCreateDoubleScalar((double)ly);
4893   prhs[3] = mxCreateString(sctx->funcname);
4894   prhs[4] = sctx->ctx;
4895   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
4896   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
4897   mxDestroyArray(prhs[0]);
4898   mxDestroyArray(prhs[1]);
4899   mxDestroyArray(prhs[2]);
4900   mxDestroyArray(prhs[3]);
4901   mxDestroyArray(plhs[0]);
4902   PetscFunctionReturn(0);
4903 }
4904 
4905 #undef __FUNCT__
4906 #define __FUNCT__ "SNESSetFunctionMatlab"
4907 /*
4908    SNESSetFunctionMatlab - Sets the function evaluation routine and function
4909    vector for use by the SNES routines in solving systems of nonlinear
4910    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4911 
4912    Logically Collective on SNES
4913 
4914    Input Parameters:
4915 +  snes - the SNES context
4916 .  r - vector to store function value
4917 -  f - function evaluation routine
4918 
4919    Notes:
4920    The Newton-like methods typically solve linear systems of the form
4921 $      f'(x) x = -f(x),
4922    where f'(x) denotes the Jacobian matrix and f(x) is the function.
4923 
4924    Level: beginner
4925 
4926    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
4927 
4928 .keywords: SNES, nonlinear, set, function
4929 
4930 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4931 */
4932 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *f,mxArray *ctx)
4933 {
4934   PetscErrorCode    ierr;
4935   SNESMatlabContext *sctx;
4936 
4937   PetscFunctionBegin;
4938   /* currently sctx is memory bleed */
4939   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4940   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
4941   /*
4942      This should work, but it doesn't
4943   sctx->ctx = ctx;
4944   mexMakeArrayPersistent(sctx->ctx);
4945   */
4946   sctx->ctx = mxDuplicateArray(ctx);
4947   ierr      = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
4948   PetscFunctionReturn(0);
4949 }
4950 
4951 #undef __FUNCT__
4952 #define __FUNCT__ "SNESComputeJacobian_Matlab"
4953 /*
4954    SNESComputeJacobian_Matlab - Calls the function that has been set with SNESSetJacobianMatlab().
4955 
4956    Collective on SNES
4957 
4958    Input Parameters:
4959 +  snes - the SNES context
4960 .  x - input vector
4961 .  A, B - the matrices
4962 -  ctx - user context
4963 
4964    Output Parameter:
4965 .  flag - structure of the matrix
4966 
4967    Level: developer
4968 
4969 .keywords: SNES, nonlinear, compute, function
4970 
4971 .seealso: SNESSetFunction(), SNESGetFunction()
4972 @*/
4973 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat A,Mat B,MatStructure *flag, void *ctx)
4974 {
4975   PetscErrorCode    ierr;
4976   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
4977   int               nlhs  = 2,nrhs = 6;
4978   mxArray           *plhs[2],*prhs[6];
4979   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
4980 
4981   PetscFunctionBegin;
4982   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4983   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4984 
4985   /* call Matlab function in ctx with arguments x and y */
4986 
4987   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4988   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4989   ierr    = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
4990   ierr    = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
4991   prhs[0] = mxCreateDoubleScalar((double)ls);
4992   prhs[1] = mxCreateDoubleScalar((double)lx);
4993   prhs[2] = mxCreateDoubleScalar((double)lA);
4994   prhs[3] = mxCreateDoubleScalar((double)lB);
4995   prhs[4] = mxCreateString(sctx->funcname);
4996   prhs[5] = sctx->ctx;
4997   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
4998   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
4999   *flag   = (MatStructure) mxGetScalar(plhs[1]);CHKERRQ(ierr);
5000   mxDestroyArray(prhs[0]);
5001   mxDestroyArray(prhs[1]);
5002   mxDestroyArray(prhs[2]);
5003   mxDestroyArray(prhs[3]);
5004   mxDestroyArray(prhs[4]);
5005   mxDestroyArray(plhs[0]);
5006   mxDestroyArray(plhs[1]);
5007   PetscFunctionReturn(0);
5008 }
5009 
5010 #undef __FUNCT__
5011 #define __FUNCT__ "SNESSetJacobianMatlab"
5012 /*
5013    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
5014    vector for use by the SNES routines in solving systems of nonlinear
5015    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5016 
5017    Logically Collective on SNES
5018 
5019    Input Parameters:
5020 +  snes - the SNES context
5021 .  A,B - Jacobian matrices
5022 .  J - function evaluation routine
5023 -  ctx - user context
5024 
5025    Level: developer
5026 
5027    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5028 
5029 .keywords: SNES, nonlinear, set, function
5030 
5031 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction(), J
5032 */
5033 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *J,mxArray *ctx)
5034 {
5035   PetscErrorCode    ierr;
5036   SNESMatlabContext *sctx;
5037 
5038   PetscFunctionBegin;
5039   /* currently sctx is memory bleed */
5040   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
5041   ierr = PetscStrallocpy(J,&sctx->funcname);CHKERRQ(ierr);
5042   /*
5043      This should work, but it doesn't
5044   sctx->ctx = ctx;
5045   mexMakeArrayPersistent(sctx->ctx);
5046   */
5047   sctx->ctx = mxDuplicateArray(ctx);
5048   ierr      = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
5049   PetscFunctionReturn(0);
5050 }
5051 
5052 #undef __FUNCT__
5053 #define __FUNCT__ "SNESMonitor_Matlab"
5054 /*
5055    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
5056 
5057    Collective on SNES
5058 
5059 .seealso: SNESSetFunction(), SNESGetFunction()
5060 @*/
5061 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
5062 {
5063   PetscErrorCode    ierr;
5064   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5065   int               nlhs  = 1,nrhs = 6;
5066   mxArray           *plhs[1],*prhs[6];
5067   long long int     lx = 0,ls = 0;
5068   Vec               x  = snes->vec_sol;
5069 
5070   PetscFunctionBegin;
5071   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5072 
5073   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5074   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5075   prhs[0] = mxCreateDoubleScalar((double)ls);
5076   prhs[1] = mxCreateDoubleScalar((double)it);
5077   prhs[2] = mxCreateDoubleScalar((double)fnorm);
5078   prhs[3] = mxCreateDoubleScalar((double)lx);
5079   prhs[4] = mxCreateString(sctx->funcname);
5080   prhs[5] = sctx->ctx;
5081   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
5082   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5083   mxDestroyArray(prhs[0]);
5084   mxDestroyArray(prhs[1]);
5085   mxDestroyArray(prhs[2]);
5086   mxDestroyArray(prhs[3]);
5087   mxDestroyArray(prhs[4]);
5088   mxDestroyArray(plhs[0]);
5089   PetscFunctionReturn(0);
5090 }
5091 
5092 #undef __FUNCT__
5093 #define __FUNCT__ "SNESMonitorSetMatlab"
5094 /*
5095    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
5096 
5097    Level: developer
5098 
5099    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5100 
5101 .keywords: SNES, nonlinear, set, function
5102 
5103 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5104 */
5105 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *f,mxArray *ctx)
5106 {
5107   PetscErrorCode    ierr;
5108   SNESMatlabContext *sctx;
5109 
5110   PetscFunctionBegin;
5111   /* currently sctx is memory bleed */
5112   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
5113   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5114   /*
5115      This should work, but it doesn't
5116   sctx->ctx = ctx;
5117   mexMakeArrayPersistent(sctx->ctx);
5118   */
5119   sctx->ctx = mxDuplicateArray(ctx);
5120   ierr      = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,NULL);CHKERRQ(ierr);
5121   PetscFunctionReturn(0);
5122 }
5123 
5124 #endif
5125