xref: /petsc/src/snes/interface/snes.c (revision f6291634e93a0403f42e7a416abc639b040e23c6)
1 
2 #include <petsc-private/snesimpl.h>      /*I "petscsnes.h"  I*/
3 #include <petscdmshell.h>                /*I "petscdmshell.h" I*/
4 #include <petscsys.h>                    /*I "petscsys.h" I*/
5 
6 PetscBool  SNESRegisterAllCalled = PETSC_FALSE;
7 PetscFList SNESList              = PETSC_NULL;
8 
9 /* Logging support */
10 PetscClassId  SNES_CLASSID, DMSNES_CLASSID;
11 PetscLogEvent  SNES_Solve, SNES_FunctionEval, SNES_JacobianEval, SNES_GSEval;
12 
13 #undef __FUNCT__
14 #define __FUNCT__ "SNESSetErrorIfNotConverged"
15 /*@
16    SNESSetErrorIfNotConverged - Causes SNESSolve() to generate an error if the solver has not converged.
17 
18    Logically Collective on SNES
19 
20    Input Parameters:
21 +  snes - iterative context obtained from SNESCreate()
22 -  flg - PETSC_TRUE indicates you want the error generated
23 
24    Options database keys:
25 .  -snes_error_if_not_converged : this takes an optional truth value (0/1/no/yes/true/false)
26 
27    Level: intermediate
28 
29    Notes:
30     Normally PETSc continues if a linear solver fails to converge, you can call SNESGetConvergedReason() after a SNESSolve()
31     to determine if it has converged.
32 
33 .keywords: SNES, set, initial guess, nonzero
34 
35 .seealso: SNESGetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
36 @*/
37 PetscErrorCode  SNESSetErrorIfNotConverged(SNES snes,PetscBool  flg)
38 {
39   PetscFunctionBegin;
40   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
41   PetscValidLogicalCollectiveBool(snes,flg,2);
42   snes->errorifnotconverged = flg;
43 
44   PetscFunctionReturn(0);
45 }
46 
47 #undef __FUNCT__
48 #define __FUNCT__ "SNESGetErrorIfNotConverged"
49 /*@
50    SNESGetErrorIfNotConverged - Will SNESSolve() generate an error if the solver does not converge?
51 
52    Not Collective
53 
54    Input Parameter:
55 .  snes - iterative context obtained from SNESCreate()
56 
57    Output Parameter:
58 .  flag - PETSC_TRUE if it will generate an error, else PETSC_FALSE
59 
60    Level: intermediate
61 
62 .keywords: SNES, set, initial guess, nonzero
63 
64 .seealso:  SNESSetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
65 @*/
66 PetscErrorCode  SNESGetErrorIfNotConverged(SNES snes,PetscBool  *flag)
67 {
68   PetscFunctionBegin;
69   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
70   PetscValidPointer(flag,2);
71   *flag = snes->errorifnotconverged;
72   PetscFunctionReturn(0);
73 }
74 
75 #undef __FUNCT__
76 #define __FUNCT__ "SNESSetFunctionDomainError"
77 /*@
78    SNESSetFunctionDomainError - tells SNES that the input vector to your FormFunction is not
79      in the functions domain. For example, negative pressure.
80 
81    Logically Collective on SNES
82 
83    Input Parameters:
84 .  snes - the SNES context
85 
86    Level: advanced
87 
88 .keywords: SNES, view
89 
90 .seealso: SNESCreate(), SNESSetFunction()
91 @*/
92 PetscErrorCode  SNESSetFunctionDomainError(SNES snes)
93 {
94   PetscFunctionBegin;
95   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
96   snes->domainerror = PETSC_TRUE;
97   PetscFunctionReturn(0);
98 }
99 
100 
101 #undef __FUNCT__
102 #define __FUNCT__ "SNESGetFunctionDomainError"
103 /*@
104    SNESGetFunctionDomainError - Gets the status of the domain error after a call to SNESComputeFunction;
105 
106    Logically Collective on SNES
107 
108    Input Parameters:
109 .  snes - the SNES context
110 
111    Output Parameters:
112 .  domainerror Set to PETSC_TRUE if there's a domain error; PETSC_FALSE otherwise.
113 
114    Level: advanced
115 
116 .keywords: SNES, view
117 
118 .seealso: SNESSetFunctionDomainError, SNESComputeFunction()
119 @*/
120 PetscErrorCode  SNESGetFunctionDomainError(SNES snes, PetscBool *domainerror)
121 {
122   PetscFunctionBegin;
123   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
124   PetscValidPointer(domainerror, 2);
125   *domainerror = snes->domainerror;
126   PetscFunctionReturn(0);
127 }
128 
129 #undef __FUNCT__
130 #define __FUNCT__ "SNESLoad"
131 /*@C
132   SNESLoad - Loads a SNES that has been stored in binary  with SNESView().
133 
134   Collective on PetscViewer
135 
136   Input Parameters:
137 + newdm - the newly loaded SNES, this needs to have been created with SNESCreate() or
138            some related function before a call to SNESLoad().
139 - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()
140 
141    Level: intermediate
142 
143   Notes:
144    The type is determined by the data in the file, any type set into the SNES before this call is ignored.
145 
146   Notes for advanced users:
147   Most users should not need to know the details of the binary storage
148   format, since SNESLoad() and TSView() completely hide these details.
149   But for anyone who's interested, the standard binary matrix storage
150   format is
151 .vb
152      has not yet been determined
153 .ve
154 
155 .seealso: PetscViewerBinaryOpen(), SNESView(), MatLoad(), VecLoad()
156 @*/
157 PetscErrorCode  SNESLoad(SNES snes, PetscViewer viewer)
158 {
159   PetscErrorCode ierr;
160   PetscBool      isbinary;
161   PetscInt       classid;
162   char           type[256];
163   KSP            ksp;
164   DM             dm;
165   DMSNES         dmsnes;
166 
167   PetscFunctionBegin;
168   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
169   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
170   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
171   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");
172 
173   ierr = PetscViewerBinaryRead(viewer,&classid,1,PETSC_INT);CHKERRQ(ierr);
174   if (classid != SNES_FILE_CLASSID) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONG,"Not SNES next in file");
175   ierr = PetscViewerBinaryRead(viewer,type,256,PETSC_CHAR);CHKERRQ(ierr);
176   ierr = SNESSetType(snes, type);CHKERRQ(ierr);
177   if (snes->ops->load) {
178     ierr = (*snes->ops->load)(snes,viewer);CHKERRQ(ierr);
179   }
180   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
181   ierr = DMGetDMSNES(dm,&dmsnes);CHKERRQ(ierr);
182   ierr = DMSNESLoad(dmsnes,viewer);CHKERRQ(ierr);
183   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
184   ierr = KSPLoad(ksp,viewer);CHKERRQ(ierr);
185   PetscFunctionReturn(0);
186 }
187 
188 #undef __FUNCT__
189 #define __FUNCT__ "SNESView"
190 /*@C
191    SNESView - Prints the SNES data structure.
192 
193    Collective on SNES
194 
195    Input Parameters:
196 +  SNES - the SNES context
197 -  viewer - visualization context
198 
199    Options Database Key:
200 .  -snes_view - Calls SNESView() at end of SNESSolve()
201 
202    Notes:
203    The available visualization contexts include
204 +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
205 -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
206          output where only the first processor opens
207          the file.  All other processors send their
208          data to the first processor to print.
209 
210    The user can open an alternative visualization context with
211    PetscViewerASCIIOpen() - output to a specified file.
212 
213    Level: beginner
214 
215 .keywords: SNES, view
216 
217 .seealso: PetscViewerASCIIOpen()
218 @*/
219 PetscErrorCode  SNESView(SNES snes,PetscViewer viewer)
220 {
221   SNESKSPEW           *kctx;
222   PetscErrorCode      ierr;
223   KSP                 ksp;
224   SNESLineSearch      linesearch;
225   PetscBool           iascii,isstring,isbinary,isdraw;
226   DMSNES              dmsnes;
227 
228   PetscFunctionBegin;
229   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
230   if (!viewer) {
231     ierr = PetscViewerASCIIGetStdout(((PetscObject)snes)->comm,&viewer);CHKERRQ(ierr);
232   }
233   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
234   PetscCheckSameComm(snes,1,viewer,2);
235 
236   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
237   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
238   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
239   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);CHKERRQ(ierr);
240   if (iascii) {
241     ierr = PetscObjectPrintClassNamePrefixType((PetscObject)snes,viewer,"SNES Object");CHKERRQ(ierr);
242     if (snes->ops->view) {
243       ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
244       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
245       ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
246     }
247     ierr = PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, maximum function evaluations=%D\n",snes->max_its,snes->max_funcs);CHKERRQ(ierr);
248     ierr = PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%G, absolute=%G, solution=%G\n",
249                  snes->rtol,snes->abstol,snes->stol);CHKERRQ(ierr);
250     ierr = PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",snes->linear_its);CHKERRQ(ierr);
251     ierr = PetscViewerASCIIPrintf(viewer,"  total number of function evaluations=%D\n",snes->nfuncs);CHKERRQ(ierr);
252     if (snes->gridsequence) {
253       ierr = PetscViewerASCIIPrintf(viewer,"  total number of grid sequence refinements=%D\n",snes->gridsequence);CHKERRQ(ierr);
254     }
255     if (snes->ksp_ewconv) {
256       kctx = (SNESKSPEW *)snes->kspconvctx;
257       if (kctx) {
258         ierr = PetscViewerASCIIPrintf(viewer,"  Eisenstat-Walker computation of KSP relative tolerance (version %D)\n",kctx->version);CHKERRQ(ierr);
259         ierr = PetscViewerASCIIPrintf(viewer,"    rtol_0=%G, rtol_max=%G, threshold=%G\n",kctx->rtol_0,kctx->rtol_max,kctx->threshold);CHKERRQ(ierr);
260         ierr = PetscViewerASCIIPrintf(viewer,"    gamma=%G, alpha=%G, alpha2=%G\n",kctx->gamma,kctx->alpha,kctx->alpha2);CHKERRQ(ierr);
261       }
262     }
263     if (snes->lagpreconditioner == -1) {
264       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is never rebuilt\n");CHKERRQ(ierr);
265     } else if (snes->lagpreconditioner > 1) {
266       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is rebuilt every %D new Jacobians\n",snes->lagpreconditioner);CHKERRQ(ierr);
267     }
268     if (snes->lagjacobian == -1) {
269       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is never rebuilt\n");CHKERRQ(ierr);
270     } else if (snes->lagjacobian > 1) {
271       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is rebuilt every %D SNES iterations\n",snes->lagjacobian);CHKERRQ(ierr);
272     }
273   } else if (isstring) {
274     const char *type;
275     ierr = SNESGetType(snes,&type);CHKERRQ(ierr);
276     ierr = PetscViewerStringSPrintf(viewer," %-3.3s",type);CHKERRQ(ierr);
277   } else if (isbinary) {
278     PetscInt         classid = SNES_FILE_CLASSID;
279     MPI_Comm         comm;
280     PetscMPIInt      rank;
281     char             type[256];
282 
283     ierr = PetscObjectGetComm((PetscObject)snes,&comm);CHKERRQ(ierr);
284     ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
285     if (!rank) {
286       ierr = PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);CHKERRQ(ierr);
287       ierr = PetscStrncpy(type,((PetscObject)snes)->type_name,256);CHKERRQ(ierr);
288       ierr = PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR,PETSC_FALSE);CHKERRQ(ierr);
289     }
290     if (snes->ops->view) {
291       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
292     }
293   } else if (isdraw) {
294     PetscDraw draw;
295     char      str[36];
296     PetscReal x,y,bottom,h;
297 
298     ierr = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
299     ierr = PetscDrawGetCurrentPoint(draw,&x,&y);CHKERRQ(ierr);
300     ierr = PetscStrcpy(str,"SNES: ");CHKERRQ(ierr);
301     ierr = PetscStrcat(str,((PetscObject)snes)->type_name);CHKERRQ(ierr);
302     ierr = PetscDrawBoxedString(draw,x,y,PETSC_DRAW_BLUE,PETSC_DRAW_BLACK,str,PETSC_NULL,&h);CHKERRQ(ierr);
303     bottom = y - h;
304     ierr = PetscDrawPushCurrentPoint(draw,x,bottom);CHKERRQ(ierr);
305     if (snes->ops->view) {
306       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
307     }
308   }
309   if (snes->linesearch) {
310     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
311     ierr = SNESGetSNESLineSearch(snes, &linesearch);CHKERRQ(ierr);
312     ierr = SNESLineSearchView(linesearch, viewer);CHKERRQ(ierr);
313     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
314   }
315   if (snes->pc && snes->usespc) {
316     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
317     ierr = SNESView(snes->pc, viewer);CHKERRQ(ierr);
318     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
319   }
320   ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
321   ierr = DMGetDMSNES(snes->dm,&dmsnes);CHKERRQ(ierr);
322   ierr = DMSNESView(dmsnes, viewer);CHKERRQ(ierr);
323   ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
324   if (snes->usesksp) {
325     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
326     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
327     ierr = KSPView(ksp,viewer);CHKERRQ(ierr);
328     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
329   }
330   if (isdraw) {
331     PetscDraw draw;
332     ierr = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
333     ierr = PetscDrawPopCurrentPoint(draw);CHKERRQ(ierr);
334   }
335   PetscFunctionReturn(0);
336 }
337 
338 /*
339   We retain a list of functions that also take SNES command
340   line options. These are called at the end SNESSetFromOptions()
341 */
342 #define MAXSETFROMOPTIONS 5
343 static PetscInt numberofsetfromoptions;
344 static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);
345 
346 #undef __FUNCT__
347 #define __FUNCT__ "SNESAddOptionsChecker"
348 /*@C
349   SNESAddOptionsChecker - Adds an additional function to check for SNES options.
350 
351   Not Collective
352 
353   Input Parameter:
354 . snescheck - function that checks for options
355 
356   Level: developer
357 
358 .seealso: SNESSetFromOptions()
359 @*/
360 PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
361 {
362   PetscFunctionBegin;
363   if (numberofsetfromoptions >= MAXSETFROMOPTIONS) {
364     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %D allowed", MAXSETFROMOPTIONS);
365   }
366   othersetfromoptions[numberofsetfromoptions++] = snescheck;
367   PetscFunctionReturn(0);
368 }
369 
370 extern PetscErrorCode  SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);
371 
372 #undef __FUNCT__
373 #define __FUNCT__ "SNESSetUpMatrixFree_Private"
374 static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool  hasOperator, PetscInt version)
375 {
376   Mat            J;
377   KSP            ksp;
378   PC             pc;
379   PetscBool      match;
380   PetscErrorCode ierr;
381 
382   PetscFunctionBegin;
383   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
384 
385   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
386     Mat A = snes->jacobian, B = snes->jacobian_pre;
387     ierr = MatGetVecs(A ? A : B, PETSC_NULL,&snes->vec_func);CHKERRQ(ierr);
388   }
389 
390   if (version == 1) {
391     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
392     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
393     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
394   } else if (version == 2) {
395     if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
396 #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128)
397     ierr = SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);CHKERRQ(ierr);
398 #else
399     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator rutines (version 2)");
400 #endif
401   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator rutines, only version 1 and 2");
402 
403   ierr = PetscInfo1(snes,"Setting default matrix-free operator routines (version %D)\n", version);CHKERRQ(ierr);
404   if (hasOperator) {
405 
406     /* This version replaces the user provided Jacobian matrix with a
407        matrix-free version but still employs the user-provided preconditioner matrix. */
408     ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);
409   } else {
410     /* This version replaces both the user-provided Jacobian and the user-
411      provided preconditioner Jacobian with the default matrix free version. */
412     if ((snes->pcside == PC_LEFT) && snes->pc) {
413       ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);
414     } else {
415       ierr = SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,0);CHKERRQ(ierr);
416     }
417     /* Force no preconditioner */
418     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
419     ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
420     ierr = PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);CHKERRQ(ierr);
421     if (!match) {
422       ierr = PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");CHKERRQ(ierr);
423       ierr = PCSetType(pc,PCNONE);CHKERRQ(ierr);
424     }
425   }
426   ierr = MatDestroy(&J);CHKERRQ(ierr);
427   PetscFunctionReturn(0);
428 }
429 
430 #undef __FUNCT__
431 #define __FUNCT__ "DMRestrictHook_SNESVecSol"
432 static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
433 {
434   SNES snes = (SNES)ctx;
435   PetscErrorCode ierr;
436   Vec Xfine,Xfine_named = PETSC_NULL,Xcoarse;
437 
438   PetscFunctionBegin;
439   if (PetscLogPrintInfo) {
440     PetscInt finelevel,coarselevel,fineclevel,coarseclevel;
441     ierr = DMGetRefineLevel(dmfine,&finelevel);CHKERRQ(ierr);
442     ierr = DMGetCoarsenLevel(dmfine,&fineclevel);CHKERRQ(ierr);
443     ierr = DMGetRefineLevel(dmcoarse,&coarselevel);CHKERRQ(ierr);
444     ierr = DMGetCoarsenLevel(dmcoarse,&coarseclevel);CHKERRQ(ierr);
445     ierr = PetscInfo4(dmfine,"Restricting SNES solution vector from level %D-%D to level %D-%D\n",finelevel,fineclevel,coarselevel,coarseclevel);CHKERRQ(ierr);
446   }
447   if (dmfine == snes->dm) Xfine = snes->vec_sol;
448   else {
449     ierr = DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);
450     Xfine = Xfine_named;
451   }
452   ierr = DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
453   ierr = MatRestrict(Restrict,Xfine,Xcoarse);CHKERRQ(ierr);
454   ierr = VecPointwiseMult(Xcoarse,Xcoarse,Rscale);CHKERRQ(ierr);
455   ierr = DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
456   if (Xfine_named) {ierr = DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);}
457   PetscFunctionReturn(0);
458 }
459 
460 #undef __FUNCT__
461 #define __FUNCT__ "DMCoarsenHook_SNESVecSol"
462 static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm,DM dmc,void *ctx)
463 {
464   PetscErrorCode ierr;
465 
466   PetscFunctionBegin;
467   ierr = DMCoarsenHookAdd(dmc,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,ctx);CHKERRQ(ierr);
468   PetscFunctionReturn(0);
469 }
470 
471 #undef __FUNCT__
472 #define __FUNCT__ "KSPComputeOperators_SNES"
473 /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
474  * safely call SNESGetDM() in their residual evaluation routine. */
475 static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,MatStructure *mstruct,void *ctx)
476 {
477   SNES                        snes = (SNES)ctx;
478   PetscErrorCode              ierr;
479   Mat                         Asave = A,Bsave = B;
480   Vec                         X,Xnamed = PETSC_NULL;
481   DM                          dmsave;
482   void                        *ctxsave;
483   PetscErrorCode              (*jac)(SNES,Vec,Mat*,Mat*,MatStructure*,void*);
484 
485   PetscFunctionBegin;
486   dmsave = snes->dm;
487   ierr = KSPGetDM(ksp,&snes->dm);CHKERRQ(ierr);
488   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
489   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
490     ierr = DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
491     X = Xnamed;
492     ierr = SNESGetJacobian(snes,PETSC_NULL,PETSC_NULL,&jac,&ctxsave);CHKERRQ(ierr);
493     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
494     if (jac == SNESDefaultComputeJacobianColor) {
495       ierr = SNESSetJacobian(snes,PETSC_NULL,PETSC_NULL,SNESDefaultComputeJacobianColor,0);CHKERRQ(ierr);
496     }
497   }
498   /* put the previous context back */
499 
500   ierr = SNESComputeJacobian(snes,X,&A,&B,mstruct);CHKERRQ(ierr);
501   if (snes->dm != dmsave && jac == SNESDefaultComputeJacobianColor) {
502     ierr = SNESSetJacobian(snes,PETSC_NULL,PETSC_NULL,jac,ctxsave);CHKERRQ(ierr);
503   }
504 
505   if (A != Asave || B != Bsave) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_SUP,"No support for changing matrices at this time");
506   if (Xnamed) {
507     ierr = DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
508   }
509   snes->dm = dmsave;
510   PetscFunctionReturn(0);
511 }
512 
513 #undef __FUNCT__
514 #define __FUNCT__ "SNESSetUpMatrices"
515 /*@
516    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()
517 
518    Collective
519 
520    Input Arguments:
521 .  snes - snes to configure
522 
523    Level: developer
524 
525 .seealso: SNESSetUp()
526 @*/
527 PetscErrorCode SNESSetUpMatrices(SNES snes)
528 {
529   PetscErrorCode ierr;
530   DM             dm;
531   DMSNES         sdm;
532 
533   PetscFunctionBegin;
534   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
535   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
536   if (!sdm->ops->computejacobian) {
537     SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_PLIB,"DMSNES not properly configured");
538   } else if (!snes->jacobian && snes->mf) {
539     Mat J;
540     void *functx;
541     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
542     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
543     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
544     ierr = SNESGetFunction(snes,PETSC_NULL,PETSC_NULL,&functx);CHKERRQ(ierr);
545     ierr = SNESSetJacobian(snes,J,J,0,0);CHKERRQ(ierr);
546     ierr = MatDestroy(&J);CHKERRQ(ierr);
547   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
548     Mat J,B;
549     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
550     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
551     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
552     ierr = DMCreateMatrix(snes->dm,MATAIJ,&B);CHKERRQ(ierr);
553     /* sdm->computejacobian was already set to reach here */
554     ierr = SNESSetJacobian(snes,J,B,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
555     ierr = MatDestroy(&J);CHKERRQ(ierr);
556     ierr = MatDestroy(&B);CHKERRQ(ierr);
557   } else if (!snes->jacobian_pre) {
558     Mat J,B;
559     J = snes->jacobian;
560     ierr = DMCreateMatrix(snes->dm,MATAIJ,&B);CHKERRQ(ierr);
561     ierr = SNESSetJacobian(snes,J?J:B,B,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
562     ierr = MatDestroy(&B);CHKERRQ(ierr);
563   }
564   {
565     KSP ksp;
566     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
567     ierr = KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);CHKERRQ(ierr);
568     ierr = DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);CHKERRQ(ierr);
569   }
570   PetscFunctionReturn(0);
571 }
572 
573 #undef __FUNCT__
574 #define __FUNCT__ "SNESSetFromOptions"
575 /*@
576    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.
577 
578    Collective on SNES
579 
580    Input Parameter:
581 .  snes - the SNES context
582 
583    Options Database Keys:
584 +  -snes_type <type> - ls, tr, ngmres, ncg, richardson, qn, vi, fas
585 .  -snes_stol - convergence tolerance in terms of the norm
586                 of the change in the solution between steps
587 .  -snes_atol <abstol> - absolute tolerance of residual norm
588 .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
589 .  -snes_max_it <max_it> - maximum number of iterations
590 .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
591 .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
592 .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
593 .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
594 .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
595 .  -snes_trtol <trtol> - trust region tolerance
596 .  -snes_no_convergence_test - skip convergence test in nonlinear
597                                solver; hence iterations will continue until max_it
598                                or some other criterion is reached. Saves expense
599                                of convergence test
600 .  -snes_monitor <optional filename> - prints residual norm at each iteration. if no
601                                        filename given prints to stdout
602 .  -snes_monitor_solution - plots solution at each iteration
603 .  -snes_monitor_residual - plots residual (not its norm) at each iteration
604 .  -snes_monitor_solution_update - plots update to solution at each iteration
605 .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
606 .  -snes_monitor_lg_range - plots residual norm at each iteration
607 .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
608 .  -snes_fd_color - use finite differences with coloring to compute Jacobian
609 .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
610 -  -snes_converged_reason - print the reason for convergence/divergence after each solve
611 
612     Options Database for Eisenstat-Walker method:
613 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
614 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
615 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
616 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
617 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
618 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
619 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
620 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
621 
622    Notes:
623    To see all options, run your program with the -help option or consult
624    the <A href="../../docs/manual.pdf#nameddest=ch_snes">SNES chapter of the users manual</A>.
625 
626    Level: beginner
627 
628 .keywords: SNES, nonlinear, set, options, database
629 
630 .seealso: SNESSetOptionsPrefix()
631 @*/
632 PetscErrorCode  SNESSetFromOptions(SNES snes)
633 {
634   PetscBool               flg,pcset;
635   PetscInt                i,indx,lag,grids;
636   MatStructure            matflag;
637   const char              *deft = SNESNEWTONLS;
638   const char              *convtests[] = {"default","skip"};
639   SNESKSPEW               *kctx = NULL;
640   char                    type[256], monfilename[PETSC_MAX_PATH_LEN];
641   PetscViewer             monviewer;
642   PetscErrorCode          ierr;
643   PCSide                  pcside;
644   const char              *optionsprefix;
645 
646   PetscFunctionBegin;
647   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
648 
649   if (!SNESRegisterAllCalled) {ierr = SNESRegisterAll(PETSC_NULL);CHKERRQ(ierr);}
650   ierr = PetscObjectOptionsBegin((PetscObject)snes);CHKERRQ(ierr);
651     if (((PetscObject)snes)->type_name) { deft = ((PetscObject)snes)->type_name; }
652     ierr = PetscOptionsList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);CHKERRQ(ierr);
653     if (flg) {
654       ierr = SNESSetType(snes,type);CHKERRQ(ierr);
655     } else if (!((PetscObject)snes)->type_name) {
656       ierr = SNESSetType(snes,deft);CHKERRQ(ierr);
657     }
658     /* not used here, but called so will go into help messaage */
659     ierr = PetscOptionsName("-snes_view","Print detailed information on solver used","SNESView",0);CHKERRQ(ierr);
660 
661     ierr = PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,0);CHKERRQ(ierr);
662     ierr = PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,0);CHKERRQ(ierr);
663 
664     ierr = PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,0);CHKERRQ(ierr);
665     ierr = PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,PETSC_NULL);CHKERRQ(ierr);
666     ierr = PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,PETSC_NULL);CHKERRQ(ierr);
667     ierr = PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,PETSC_NULL);CHKERRQ(ierr);
668     ierr = PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,PETSC_NULL);CHKERRQ(ierr);
669     ierr = PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,PETSC_NULL);CHKERRQ(ierr);
670 
671     ierr = PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);CHKERRQ(ierr);
672     if (flg) {
673       ierr = SNESSetLagPreconditioner(snes,lag);CHKERRQ(ierr);
674     }
675     ierr = PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);CHKERRQ(ierr);
676     if (flg) {
677       ierr = SNESSetLagJacobian(snes,lag);CHKERRQ(ierr);
678     }
679     ierr = PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);CHKERRQ(ierr);
680     if (flg) {
681       ierr = SNESSetGridSequence(snes,grids);CHKERRQ(ierr);
682     }
683 
684     ierr = PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);CHKERRQ(ierr);
685     if (flg) {
686       switch (indx) {
687       case 0: ierr = SNESSetConvergenceTest(snes,SNESDefaultConverged,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr); break;
688       case 1: ierr = SNESSetConvergenceTest(snes,SNESSkipConverged,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);    break;
689       }
690     }
691 
692     ierr = PetscOptionsBool("-snes_converged_reason","Print reason for converged or diverged","SNESSolve",snes->printreason,&snes->printreason,PETSC_NULL);CHKERRQ(ierr);
693 
694     ierr = PetscOptionsEList("-snes_norm_type","SNES Norm type","SNESSetNormType",SNESNormTypes,5,"function",&indx,&flg);CHKERRQ(ierr);
695     if (flg) { ierr = SNESSetNormType(snes,(SNESNormType)indx);CHKERRQ(ierr); }
696 
697     kctx = (SNESKSPEW *)snes->kspconvctx;
698 
699     ierr = PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,PETSC_NULL);CHKERRQ(ierr);
700 
701     ierr = PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,0);CHKERRQ(ierr);
702     ierr = PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,0);CHKERRQ(ierr);
703     ierr = PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,0);CHKERRQ(ierr);
704     ierr = PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,0);CHKERRQ(ierr);
705     ierr = PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,0);CHKERRQ(ierr);
706     ierr = PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,0);CHKERRQ(ierr);
707     ierr = PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,0);CHKERRQ(ierr);
708 
709     flg  = PETSC_FALSE;
710     ierr = PetscOptionsBool("-snes_check_jacobian","Check each Jacobian with a differenced one","SNESUpdateCheckJacobian",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
711     if (flg) {
712       ierr = SNESSetUpdate(snes,SNESUpdateCheckJacobian);CHKERRQ(ierr);
713     }
714 
715     flg  = PETSC_FALSE;
716     ierr = PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
717     if (flg) {ierr = SNESMonitorCancel(snes);CHKERRQ(ierr);}
718 
719     ierr = PetscOptionsString("-snes_monitor","Monitor norm of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
720     if (flg) {
721       ierr = PetscViewerASCIIOpen(((PetscObject)snes)->comm,monfilename,&monviewer);CHKERRQ(ierr);
722       ierr = SNESMonitorSet(snes,SNESMonitorDefault,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
723     }
724 
725     ierr = PetscOptionsString("-snes_monitor_range","Monitor range of elements of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
726     if (flg) {
727       ierr = SNESMonitorSet(snes,SNESMonitorRange,0,0);CHKERRQ(ierr);
728     }
729 
730     ierr = PetscOptionsString("-snes_ratiomonitor","Monitor ratios of norms of function","SNESMonitorSetRatio","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
731     if (flg) {
732       ierr = PetscViewerASCIIOpen(((PetscObject)snes)->comm,monfilename,&monviewer);CHKERRQ(ierr);
733       ierr = SNESMonitorSetRatio(snes,monviewer);CHKERRQ(ierr);
734     }
735 
736     ierr = PetscOptionsString("-snes_monitor_short","Monitor norm of function (fewer digits)","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
737     if (flg) {
738       ierr = PetscViewerASCIIOpen(((PetscObject)snes)->comm,monfilename,&monviewer);CHKERRQ(ierr);
739       ierr = SNESMonitorSet(snes,SNESMonitorDefaultShort,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
740     }
741 
742     ierr = PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
743     if (flg) {ierr = PetscPythonMonitorSet((PetscObject)snes,monfilename);CHKERRQ(ierr);}
744 
745     flg  = PETSC_FALSE;
746     ierr = PetscOptionsBool("-snes_monitor_solution","Plot solution at each iteration","SNESMonitorSolution",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
747     if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolution,0,0);CHKERRQ(ierr);}
748     flg  = PETSC_FALSE;
749     ierr = PetscOptionsBool("-snes_monitor_solution_update","Plot correction at each iteration","SNESMonitorSolutionUpdate",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
750     if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolutionUpdate,0,0);CHKERRQ(ierr);}
751     flg  = PETSC_FALSE;
752     ierr = PetscOptionsBool("-snes_monitor_residual","Plot residual at each iteration","SNESMonitorResidual",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
753     if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorResidual,0,0);CHKERRQ(ierr);}
754     flg  = PETSC_FALSE;
755     ierr = PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
756     if (flg) {
757       PetscDrawLG ctx;
758 
759       ierr = SNESMonitorLGCreate(0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
760       ierr = SNESMonitorSet(snes,SNESMonitorLGResidualNorm,ctx,(PetscErrorCode (*)(void**))SNESMonitorLGDestroy);CHKERRQ(ierr);
761     }
762     flg  = PETSC_FALSE;
763     ierr = PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
764     if (flg) {
765       PetscViewer ctx;
766 
767       ierr = PetscViewerDrawOpen(((PetscObject)snes)->comm,0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
768       ierr = SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
769     }
770 
771     flg  = PETSC_FALSE;
772     ierr = PetscOptionsBool("-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
773     if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorJacUpdateSpectrum,0,0);CHKERRQ(ierr);}
774 
775     flg  = PETSC_FALSE;
776     ierr = PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESDefaultComputeJacobian",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
777     if (flg) {
778       void *functx;
779       ierr = SNESGetFunction(snes,PETSC_NULL,PETSC_NULL,&functx);CHKERRQ(ierr);
780       ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESDefaultComputeJacobian,functx);CHKERRQ(ierr);
781       ierr = PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");CHKERRQ(ierr);
782     }
783 
784     flg  = PETSC_FALSE;
785     ierr = PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESDefaultObjectiveComputeFunctionFD",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
786     if (flg) {
787       ierr = SNESSetFunction(snes,PETSC_NULL,SNESDefaultObjectiveComputeFunctionFD,PETSC_NULL);CHKERRQ(ierr);
788     }
789 
790     flg  = PETSC_FALSE;
791     ierr = PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESDefaultComputeJacobianColor",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
792     if (flg) {
793       void *functx;
794       ierr = SNESGetFunction(snes,PETSC_NULL,PETSC_NULL,&functx);CHKERRQ(ierr);
795       ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESDefaultComputeJacobianColor,0);CHKERRQ(ierr);
796       ierr = PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");CHKERRQ(ierr);
797     }
798 
799     flg = PETSC_FALSE;
800     ierr = PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf_operator,&flg);CHKERRQ(ierr);
801     if (flg && snes->mf_operator) {
802       snes->mf_operator = PETSC_TRUE;
803       snes->mf = PETSC_TRUE;
804     }
805     flg = PETSC_FALSE;
806     ierr = PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf,&flg);CHKERRQ(ierr);
807     if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
808     ierr = PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,0);CHKERRQ(ierr);
809 
810     flg = PETSC_FALSE;
811     ierr = SNESGetPCSide(snes,&pcside);CHKERRQ(ierr);
812     ierr = PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);CHKERRQ(ierr);
813     if (flg) {ierr = SNESSetPCSide(snes,pcside);CHKERRQ(ierr);}
814 
815     /* GS Options */
816     ierr = PetscOptionsInt("-snes_gs_sweeps","Number of sweeps of GS to apply","SNESComputeGS",snes->gssweeps,&snes->gssweeps,PETSC_NULL);CHKERRQ(ierr);
817 
818     for (i = 0; i < numberofsetfromoptions; i++) {
819       ierr = (*othersetfromoptions[i])(snes);CHKERRQ(ierr);
820     }
821 
822     if (snes->ops->setfromoptions) {
823       ierr = (*snes->ops->setfromoptions)(snes);CHKERRQ(ierr);
824     }
825 
826     /* process any options handlers added with PetscObjectAddOptionsHandler() */
827     ierr = PetscObjectProcessOptionsHandlers((PetscObject)snes);CHKERRQ(ierr);
828   ierr = PetscOptionsEnd();CHKERRQ(ierr);
829 
830   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
831   ierr = KSPGetOperators(snes->ksp,PETSC_NULL,PETSC_NULL,&matflag);CHKERRQ(ierr);
832   ierr = KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre,matflag);CHKERRQ(ierr);
833   ierr = KSPSetFromOptions(snes->ksp);CHKERRQ(ierr);
834 
835   if (!snes->linesearch) {
836     ierr = SNESGetSNESLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
837   }
838   ierr = SNESLineSearchSetFromOptions(snes->linesearch);CHKERRQ(ierr);
839 
840   /* if someone has set the SNES PC type, create it. */
841   ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
842   ierr = PetscOptionsHasName(optionsprefix, "-npc_snes_type", &pcset);CHKERRQ(ierr);
843   if (pcset && (!snes->pc)) {
844     ierr = SNESGetPC(snes, &snes->pc);CHKERRQ(ierr);
845   }
846   PetscFunctionReturn(0);
847 }
848 
849 #undef __FUNCT__
850 #define __FUNCT__ "SNESSetComputeApplicationContext"
851 /*@
852    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
853    the nonlinear solvers.
854 
855    Logically Collective on SNES
856 
857    Input Parameters:
858 +  snes - the SNES context
859 .  compute - function to compute the context
860 -  destroy - function to destroy the context
861 
862    Level: intermediate
863 
864 .keywords: SNES, nonlinear, set, application, context
865 
866 .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
867 @*/
868 PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
869 {
870   PetscFunctionBegin;
871   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
872   snes->ops->usercompute = compute;
873   snes->ops->userdestroy = destroy;
874   PetscFunctionReturn(0);
875 }
876 
877 #undef __FUNCT__
878 #define __FUNCT__ "SNESSetApplicationContext"
879 /*@
880    SNESSetApplicationContext - Sets the optional user-defined context for
881    the nonlinear solvers.
882 
883    Logically Collective on SNES
884 
885    Input Parameters:
886 +  snes - the SNES context
887 -  usrP - optional user context
888 
889    Level: intermediate
890 
891 .keywords: SNES, nonlinear, set, application, context
892 
893 .seealso: SNESGetApplicationContext()
894 @*/
895 PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
896 {
897   PetscErrorCode ierr;
898   KSP            ksp;
899 
900   PetscFunctionBegin;
901   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
902   ierr       = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
903   ierr       = KSPSetApplicationContext(ksp,usrP);CHKERRQ(ierr);
904   snes->user = usrP;
905   PetscFunctionReturn(0);
906 }
907 
908 #undef __FUNCT__
909 #define __FUNCT__ "SNESGetApplicationContext"
910 /*@
911    SNESGetApplicationContext - Gets the user-defined context for the
912    nonlinear solvers.
913 
914    Not Collective
915 
916    Input Parameter:
917 .  snes - SNES context
918 
919    Output Parameter:
920 .  usrP - user context
921 
922    Level: intermediate
923 
924 .keywords: SNES, nonlinear, get, application, context
925 
926 .seealso: SNESSetApplicationContext()
927 @*/
928 PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
929 {
930   PetscFunctionBegin;
931   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
932   *(void**)usrP = snes->user;
933   PetscFunctionReturn(0);
934 }
935 
936 #undef __FUNCT__
937 #define __FUNCT__ "SNESGetIterationNumber"
938 /*@
939    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
940    at this time.
941 
942    Not Collective
943 
944    Input Parameter:
945 .  snes - SNES context
946 
947    Output Parameter:
948 .  iter - iteration number
949 
950    Notes:
951    For example, during the computation of iteration 2 this would return 1.
952 
953    This is useful for using lagged Jacobians (where one does not recompute the
954    Jacobian at each SNES iteration). For example, the code
955 .vb
956       ierr = SNESGetIterationNumber(snes,&it);
957       if (!(it % 2)) {
958         [compute Jacobian here]
959       }
960 .ve
961    can be used in your ComputeJacobian() function to cause the Jacobian to be
962    recomputed every second SNES iteration.
963 
964    Level: intermediate
965 
966 .keywords: SNES, nonlinear, get, iteration, number,
967 
968 .seealso:   SNESGetFunctionNorm(), SNESGetLinearSolveIterations()
969 @*/
970 PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt* iter)
971 {
972   PetscFunctionBegin;
973   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
974   PetscValidIntPointer(iter,2);
975   *iter = snes->iter;
976   PetscFunctionReturn(0);
977 }
978 
979 #undef __FUNCT__
980 #define __FUNCT__ "SNESSetIterationNumber"
981 /*@
982    SNESSetIterationNumber - Sets the current iteration number.
983 
984    Not Collective
985 
986    Input Parameter:
987 .  snes - SNES context
988 .  iter - iteration number
989 
990    Level: developer
991 
992 .keywords: SNES, nonlinear, set, iteration, number,
993 
994 .seealso:   SNESGetFunctionNorm(), SNESGetLinearSolveIterations()
995 @*/
996 PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
997 {
998   PetscErrorCode ierr;
999 
1000   PetscFunctionBegin;
1001   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1002   ierr = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
1003   snes->iter = iter;
1004   ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
1005   PetscFunctionReturn(0);
1006 }
1007 
1008 #undef __FUNCT__
1009 #define __FUNCT__ "SNESGetFunctionNorm"
1010 /*@
1011    SNESGetFunctionNorm - Gets the norm of the current function that was set
1012    with SNESSSetFunction().
1013 
1014    Collective on SNES
1015 
1016    Input Parameter:
1017 .  snes - SNES context
1018 
1019    Output Parameter:
1020 .  fnorm - 2-norm of function
1021 
1022    Level: intermediate
1023 
1024 .keywords: SNES, nonlinear, get, function, norm
1025 
1026 .seealso: SNESGetFunction(), SNESGetIterationNumber(), SNESGetLinearSolveIterations()
1027 @*/
1028 PetscErrorCode  SNESGetFunctionNorm(SNES snes,PetscReal *fnorm)
1029 {
1030   PetscFunctionBegin;
1031   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1032   PetscValidScalarPointer(fnorm,2);
1033   *fnorm = snes->norm;
1034   PetscFunctionReturn(0);
1035 }
1036 
1037 
1038 #undef __FUNCT__
1039 #define __FUNCT__ "SNESSetFunctionNorm"
1040 /*@
1041    SNESSetFunctionNorm - Sets the 2-norm of the current function computed using VecNorm().
1042 
1043    Collective on SNES
1044 
1045    Input Parameter:
1046 .  snes - SNES context
1047 .  fnorm - 2-norm of function
1048 
1049    Level: developer
1050 
1051 .keywords: SNES, nonlinear, set, function, norm
1052 
1053 .seealso: SNESSetFunction(), SNESSetIterationNumber(), VecNorm().
1054 @*/
1055 PetscErrorCode  SNESSetFunctionNorm(SNES snes,PetscReal fnorm)
1056 {
1057 
1058   PetscErrorCode ierr;
1059 
1060   PetscFunctionBegin;
1061   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1062   ierr = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
1063   snes->norm = fnorm;
1064   ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
1065   PetscFunctionReturn(0);
1066 }
1067 
1068 #undef __FUNCT__
1069 #define __FUNCT__ "SNESGetNonlinearStepFailures"
1070 /*@
1071    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1072    attempted by the nonlinear solver.
1073 
1074    Not Collective
1075 
1076    Input Parameter:
1077 .  snes - SNES context
1078 
1079    Output Parameter:
1080 .  nfails - number of unsuccessful steps attempted
1081 
1082    Notes:
1083    This counter is reset to zero for each successive call to SNESSolve().
1084 
1085    Level: intermediate
1086 
1087 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1088 
1089 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1090           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
1091 @*/
1092 PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt* nfails)
1093 {
1094   PetscFunctionBegin;
1095   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1096   PetscValidIntPointer(nfails,2);
1097   *nfails = snes->numFailures;
1098   PetscFunctionReturn(0);
1099 }
1100 
1101 #undef __FUNCT__
1102 #define __FUNCT__ "SNESSetMaxNonlinearStepFailures"
1103 /*@
1104    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1105    attempted by the nonlinear solver before it gives up.
1106 
1107    Not Collective
1108 
1109    Input Parameters:
1110 +  snes     - SNES context
1111 -  maxFails - maximum of unsuccessful steps
1112 
1113    Level: intermediate
1114 
1115 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1116 
1117 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1118           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1119 @*/
1120 PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1121 {
1122   PetscFunctionBegin;
1123   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1124   snes->maxFailures = maxFails;
1125   PetscFunctionReturn(0);
1126 }
1127 
1128 #undef __FUNCT__
1129 #define __FUNCT__ "SNESGetMaxNonlinearStepFailures"
1130 /*@
1131    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1132    attempted by the nonlinear solver before it gives up.
1133 
1134    Not Collective
1135 
1136    Input Parameter:
1137 .  snes     - SNES context
1138 
1139    Output Parameter:
1140 .  maxFails - maximum of unsuccessful steps
1141 
1142    Level: intermediate
1143 
1144 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1145 
1146 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1147           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1148 
1149 @*/
1150 PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1151 {
1152   PetscFunctionBegin;
1153   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1154   PetscValidIntPointer(maxFails,2);
1155   *maxFails = snes->maxFailures;
1156   PetscFunctionReturn(0);
1157 }
1158 
1159 #undef __FUNCT__
1160 #define __FUNCT__ "SNESGetNumberFunctionEvals"
1161 /*@
1162    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1163      done by SNES.
1164 
1165    Not Collective
1166 
1167    Input Parameter:
1168 .  snes     - SNES context
1169 
1170    Output Parameter:
1171 .  nfuncs - number of evaluations
1172 
1173    Level: intermediate
1174 
1175 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1176 
1177 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures()
1178 @*/
1179 PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1180 {
1181   PetscFunctionBegin;
1182   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1183   PetscValidIntPointer(nfuncs,2);
1184   *nfuncs = snes->nfuncs;
1185   PetscFunctionReturn(0);
1186 }
1187 
1188 #undef __FUNCT__
1189 #define __FUNCT__ "SNESGetLinearSolveFailures"
1190 /*@
1191    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1192    linear solvers.
1193 
1194    Not Collective
1195 
1196    Input Parameter:
1197 .  snes - SNES context
1198 
1199    Output Parameter:
1200 .  nfails - number of failed solves
1201 
1202    Notes:
1203    This counter is reset to zero for each successive call to SNESSolve().
1204 
1205    Level: intermediate
1206 
1207 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1208 
1209 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1210 @*/
1211 PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt* nfails)
1212 {
1213   PetscFunctionBegin;
1214   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1215   PetscValidIntPointer(nfails,2);
1216   *nfails = snes->numLinearSolveFailures;
1217   PetscFunctionReturn(0);
1218 }
1219 
1220 #undef __FUNCT__
1221 #define __FUNCT__ "SNESSetMaxLinearSolveFailures"
1222 /*@
1223    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1224    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE
1225 
1226    Logically Collective on SNES
1227 
1228    Input Parameters:
1229 +  snes     - SNES context
1230 -  maxFails - maximum allowed linear solve failures
1231 
1232    Level: intermediate
1233 
1234    Notes: By default this is 0; that is SNES returns on the first failed linear solve
1235 
1236 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1237 
1238 .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1239 @*/
1240 PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1241 {
1242   PetscFunctionBegin;
1243   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1244   PetscValidLogicalCollectiveInt(snes,maxFails,2);
1245   snes->maxLinearSolveFailures = maxFails;
1246   PetscFunctionReturn(0);
1247 }
1248 
1249 #undef __FUNCT__
1250 #define __FUNCT__ "SNESGetMaxLinearSolveFailures"
1251 /*@
1252    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1253      are allowed before SNES terminates
1254 
1255    Not Collective
1256 
1257    Input Parameter:
1258 .  snes     - SNES context
1259 
1260    Output Parameter:
1261 .  maxFails - maximum of unsuccessful solves allowed
1262 
1263    Level: intermediate
1264 
1265    Notes: By default this is 1; that is SNES returns on the first failed linear solve
1266 
1267 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1268 
1269 .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1270 @*/
1271 PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1272 {
1273   PetscFunctionBegin;
1274   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1275   PetscValidIntPointer(maxFails,2);
1276   *maxFails = snes->maxLinearSolveFailures;
1277   PetscFunctionReturn(0);
1278 }
1279 
1280 #undef __FUNCT__
1281 #define __FUNCT__ "SNESGetLinearSolveIterations"
1282 /*@
1283    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1284    used by the nonlinear solver.
1285 
1286    Not Collective
1287 
1288    Input Parameter:
1289 .  snes - SNES context
1290 
1291    Output Parameter:
1292 .  lits - number of linear iterations
1293 
1294    Notes:
1295    This counter is reset to zero for each successive call to SNESSolve().
1296 
1297    Level: intermediate
1298 
1299 .keywords: SNES, nonlinear, get, number, linear, iterations
1300 
1301 .seealso:  SNESGetIterationNumber(), SNESGetFunctionNorm(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures()
1302 @*/
1303 PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt* lits)
1304 {
1305   PetscFunctionBegin;
1306   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1307   PetscValidIntPointer(lits,2);
1308   *lits = snes->linear_its;
1309   PetscFunctionReturn(0);
1310 }
1311 
1312 #undef __FUNCT__
1313 #define __FUNCT__ "SNESGetKSP"
1314 /*@
1315    SNESGetKSP - Returns the KSP context for a SNES solver.
1316 
1317    Not Collective, but if SNES object is parallel, then KSP object is parallel
1318 
1319    Input Parameter:
1320 .  snes - the SNES context
1321 
1322    Output Parameter:
1323 .  ksp - the KSP context
1324 
1325    Notes:
1326    The user can then directly manipulate the KSP context to set various
1327    options, etc.  Likewise, the user can then extract and manipulate the
1328    PC contexts as well.
1329 
1330    Level: beginner
1331 
1332 .keywords: SNES, nonlinear, get, KSP, context
1333 
1334 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1335 @*/
1336 PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
1337 {
1338   PetscErrorCode ierr;
1339 
1340   PetscFunctionBegin;
1341   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1342   PetscValidPointer(ksp,2);
1343 
1344   if (!snes->ksp) {
1345     ierr = KSPCreate(((PetscObject)snes)->comm,&snes->ksp);CHKERRQ(ierr);
1346     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);CHKERRQ(ierr);
1347     ierr = PetscLogObjectParent(snes,snes->ksp);CHKERRQ(ierr);
1348   }
1349   *ksp = snes->ksp;
1350   PetscFunctionReturn(0);
1351 }
1352 
1353 #undef __FUNCT__
1354 #define __FUNCT__ "SNESSetKSP"
1355 /*@
1356    SNESSetKSP - Sets a KSP context for the SNES object to use
1357 
1358    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm
1359 
1360    Input Parameters:
1361 +  snes - the SNES context
1362 -  ksp - the KSP context
1363 
1364    Notes:
1365    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1366    so this routine is rarely needed.
1367 
1368    The KSP object that is already in the SNES object has its reference count
1369    decreased by one.
1370 
1371    Level: developer
1372 
1373 .keywords: SNES, nonlinear, get, KSP, context
1374 
1375 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1376 @*/
1377 PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1378 {
1379   PetscErrorCode ierr;
1380 
1381   PetscFunctionBegin;
1382   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1383   PetscValidHeaderSpecific(ksp,KSP_CLASSID,2);
1384   PetscCheckSameComm(snes,1,ksp,2);
1385   ierr = PetscObjectReference((PetscObject)ksp);CHKERRQ(ierr);
1386   if (snes->ksp) {ierr = PetscObjectDereference((PetscObject)snes->ksp);CHKERRQ(ierr);}
1387   snes->ksp = ksp;
1388   PetscFunctionReturn(0);
1389 }
1390 
1391 #if 0
1392 #undef __FUNCT__
1393 #define __FUNCT__ "SNESPublish_Petsc"
1394 static PetscErrorCode SNESPublish_Petsc(PetscObject obj)
1395 {
1396   PetscFunctionBegin;
1397   PetscFunctionReturn(0);
1398 }
1399 #endif
1400 
1401 /* -----------------------------------------------------------*/
1402 #undef __FUNCT__
1403 #define __FUNCT__ "SNESCreate"
1404 /*@
1405    SNESCreate - Creates a nonlinear solver context.
1406 
1407    Collective on MPI_Comm
1408 
1409    Input Parameters:
1410 .  comm - MPI communicator
1411 
1412    Output Parameter:
1413 .  outsnes - the new SNES context
1414 
1415    Options Database Keys:
1416 +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1417                and no preconditioning matrix
1418 .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1419                products, and a user-provided preconditioning matrix
1420                as set by SNESSetJacobian()
1421 -   -snes_fd - Uses (slow!) finite differences to compute Jacobian
1422 
1423    Level: beginner
1424 
1425 .keywords: SNES, nonlinear, create, context
1426 
1427 .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()
1428 
1429 @*/
1430 PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1431 {
1432   PetscErrorCode      ierr;
1433   SNES                snes;
1434   SNESKSPEW           *kctx;
1435 
1436   PetscFunctionBegin;
1437   PetscValidPointer(outsnes,2);
1438   *outsnes = PETSC_NULL;
1439 #ifndef PETSC_USE_DYNAMIC_LIBRARIES
1440   ierr = SNESInitializePackage(PETSC_NULL);CHKERRQ(ierr);
1441 #endif
1442 
1443   ierr = PetscHeaderCreate(snes,_p_SNES,struct _SNESOps,SNES_CLASSID,0,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);CHKERRQ(ierr);
1444 
1445   snes->ops->converged    = SNESDefaultConverged;
1446   snes->usesksp           = PETSC_TRUE;
1447   snes->tolerancesset     = PETSC_FALSE;
1448   snes->max_its           = 50;
1449   snes->max_funcs         = 10000;
1450   snes->norm              = 0.0;
1451   snes->normtype          = SNES_NORM_FUNCTION;
1452   snes->rtol              = 1.e-8;
1453   snes->ttol              = 0.0;
1454   snes->abstol            = 1.e-50;
1455   snes->stol              = 1.e-8;
1456   snes->deltatol          = 1.e-12;
1457   snes->nfuncs            = 0;
1458   snes->numFailures       = 0;
1459   snes->maxFailures       = 1;
1460   snes->linear_its        = 0;
1461   snes->lagjacobian       = 1;
1462   snes->lagpreconditioner = 1;
1463   snes->numbermonitors    = 0;
1464   snes->data              = 0;
1465   snes->setupcalled       = PETSC_FALSE;
1466   snes->ksp_ewconv        = PETSC_FALSE;
1467   snes->nwork             = 0;
1468   snes->work              = 0;
1469   snes->nvwork            = 0;
1470   snes->vwork             = 0;
1471   snes->conv_hist_len     = 0;
1472   snes->conv_hist_max     = 0;
1473   snes->conv_hist         = PETSC_NULL;
1474   snes->conv_hist_its     = PETSC_NULL;
1475   snes->conv_hist_reset   = PETSC_TRUE;
1476   snes->vec_func_init_set = PETSC_FALSE;
1477   snes->norm_init         = 0.;
1478   snes->norm_init_set     = PETSC_FALSE;
1479   snes->reason            = SNES_CONVERGED_ITERATING;
1480   snes->gssweeps          = 1;
1481 
1482   snes->pcside            = PC_RIGHT;
1483 
1484   snes->mf                = PETSC_FALSE;
1485   snes->mf_operator       = PETSC_FALSE;
1486   snes->mf_version        = 1;
1487 
1488   snes->numLinearSolveFailures = 0;
1489   snes->maxLinearSolveFailures = 1;
1490 
1491   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1492   ierr = PetscNewLog(snes,SNESKSPEW,&kctx);CHKERRQ(ierr);
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 #undef __FUNCT__
1511 #define __FUNCT__ "SNESSetFunction"
1512 /*@C
1513    SNESSetFunction - Sets the function evaluation routine and function
1514    vector for use by the SNES routines in solving systems of nonlinear
1515    equations.
1516 
1517    Logically Collective on SNES
1518 
1519    Input Parameters:
1520 +  snes - the SNES context
1521 .  r - vector to store function value
1522 .  func - function evaluation routine
1523 -  ctx - [optional] user-defined context for private data for the
1524          function evaluation routine (may be PETSC_NULL)
1525 
1526    Calling sequence of func:
1527 $    func (SNES snes,Vec x,Vec f,void *ctx);
1528 
1529 +  snes - the SNES context
1530 .  x - state at which to evaluate residual
1531 .  f - vector to put residual
1532 -  ctx - optional user-defined function context
1533 
1534    Notes:
1535    The Newton-like methods typically solve linear systems of the form
1536 $      f'(x) x = -f(x),
1537    where f'(x) denotes the Jacobian matrix and f(x) is the function.
1538 
1539    Level: beginner
1540 
1541 .keywords: SNES, nonlinear, set, function
1542 
1543 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard()
1544 @*/
1545 PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*func)(SNES,Vec,Vec,void*),void *ctx)
1546 {
1547   PetscErrorCode ierr;
1548   DM             dm;
1549 
1550   PetscFunctionBegin;
1551   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1552   if (r) {
1553     PetscValidHeaderSpecific(r,VEC_CLASSID,2);
1554     PetscCheckSameComm(snes,1,r,2);
1555     ierr = PetscObjectReference((PetscObject)r);CHKERRQ(ierr);
1556     ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
1557     snes->vec_func = r;
1558   }
1559   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1560   ierr = DMSNESSetFunction(dm,func,ctx);CHKERRQ(ierr);
1561   PetscFunctionReturn(0);
1562 }
1563 
1564 
1565 #undef __FUNCT__
1566 #define __FUNCT__ "SNESSetInitialFunction"
1567 /*@C
1568    SNESSetInitialFunction - Sets the function vector to be used as the
1569    function norm at the initialization of the method.  In some
1570    instances, the user has precomputed the function before calling
1571    SNESSolve.  This function allows one to avoid a redundant call
1572    to SNESComputeFunction in that case.
1573 
1574    Logically Collective on SNES
1575 
1576    Input Parameters:
1577 +  snes - the SNES context
1578 -  f - vector to store function value
1579 
1580    Notes:
1581    This should not be modified during the solution procedure.
1582 
1583    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1584 
1585    Level: developer
1586 
1587 .keywords: SNES, nonlinear, set, function
1588 
1589 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1590 @*/
1591 PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1592 {
1593   PetscErrorCode ierr;
1594   Vec            vec_func;
1595 
1596   PetscFunctionBegin;
1597   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1598   PetscValidHeaderSpecific(f,VEC_CLASSID,2);
1599   PetscCheckSameComm(snes,1,f,2);
1600   ierr = SNESGetFunction(snes,&vec_func,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
1601   ierr = VecCopy(f, vec_func);CHKERRQ(ierr);
1602   snes->vec_func_init_set = PETSC_TRUE;
1603   PetscFunctionReturn(0);
1604 }
1605 
1606 
1607 #undef __FUNCT__
1608 #define __FUNCT__ "SNESSetInitialFunctionNorm"
1609 /*@C
1610    SNESSetInitialFunctionNorm - Sets the function norm to be used as the function norm
1611    at the initialization of the  method.  In some instances, the user has precomputed
1612    the function and its norm before calling SNESSolve.  This function allows one to
1613    avoid a redundant call to SNESComputeFunction() and VecNorm() in that case.
1614 
1615    Logically Collective on SNES
1616 
1617    Input Parameters:
1618 +  snes - the SNES context
1619 -  fnorm - the norm of F as set by SNESSetInitialFunction()
1620 
1621    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1622 
1623    Level: developer
1624 
1625 .keywords: SNES, nonlinear, set, function, norm
1626 
1627 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunction()
1628 @*/
1629 PetscErrorCode  SNESSetInitialFunctionNorm(SNES snes, PetscReal fnorm)
1630 {
1631   PetscFunctionBegin;
1632   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1633   snes->norm_init = fnorm;
1634   snes->norm_init_set = PETSC_TRUE;
1635   PetscFunctionReturn(0);
1636 }
1637 
1638 #undef __FUNCT__
1639 #define __FUNCT__ "SNESSetNormType"
1640 /*@
1641    SNESSetNormType - Sets the SNESNormType used in covergence and monitoring
1642    of the SNES method.
1643 
1644    Logically Collective on SNES
1645 
1646    Input Parameters:
1647 +  snes - the SNES context
1648 -  normtype - the type of the norm used
1649 
1650    Notes:
1651    Only certain SNES methods support certain SNESNormTypes.  Most require evaluation
1652    of the nonlinear function and the taking of its norm at every iteration to
1653    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1654    (SNESGS) and the like do not require the norm of the function to be computed, and therfore
1655    may either be monitored for convergence or not.  As these are often used as nonlinear
1656    preconditioners, monitoring the norm of their error is not a useful enterprise within
1657    their solution.
1658 
1659    Level: developer
1660 
1661 .keywords: SNES, nonlinear, set, function, norm, type
1662 
1663 .seealso: SNESGetNormType(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormType
1664 @*/
1665 PetscErrorCode  SNESSetNormType(SNES snes, SNESNormType normtype)
1666 {
1667   PetscFunctionBegin;
1668   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1669   snes->normtype = normtype;
1670   PetscFunctionReturn(0);
1671 }
1672 
1673 
1674 #undef __FUNCT__
1675 #define __FUNCT__ "SNESGetNormType"
1676 /*@
1677    SNESGetNormType - Gets the SNESNormType used in covergence and monitoring
1678    of the SNES method.
1679 
1680    Logically Collective on SNES
1681 
1682    Input Parameters:
1683 +  snes - the SNES context
1684 -  normtype - the type of the norm used
1685 
1686    Level: advanced
1687 
1688 .keywords: SNES, nonlinear, set, function, norm, type
1689 
1690 .seealso: SNESSetNormType(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormType
1691 @*/
1692 PetscErrorCode  SNESGetNormType(SNES snes, SNESNormType *normtype)
1693 {
1694   PetscFunctionBegin;
1695   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1696   *normtype = snes->normtype;
1697   PetscFunctionReturn(0);
1698 }
1699 
1700 #undef __FUNCT__
1701 #define __FUNCT__ "SNESSetGS"
1702 /*@C
1703    SNESSetGS - Sets the user nonlinear Gauss-Seidel routine for
1704    use with composed nonlinear solvers.
1705 
1706    Input Parameters:
1707 +  snes   - the SNES context
1708 .  gsfunc - function evaluation routine
1709 -  ctx    - [optional] user-defined context for private data for the
1710             smoother evaluation routine (may be PETSC_NULL)
1711 
1712    Calling sequence of func:
1713 $    func (SNES snes,Vec x,Vec b,void *ctx);
1714 
1715 +  X   - solution vector
1716 .  B   - RHS vector
1717 -  ctx - optional user-defined Gauss-Seidel context
1718 
1719    Notes:
1720    The GS routines are used by the composed nonlinear solver to generate
1721     a problem appropriate update to the solution, particularly FAS.
1722 
1723    Level: intermediate
1724 
1725 .keywords: SNES, nonlinear, set, Gauss-Seidel
1726 
1727 .seealso: SNESGetFunction(), SNESComputeGS()
1728 @*/
1729 PetscErrorCode SNESSetGS(SNES snes,PetscErrorCode (*gsfunc)(SNES,Vec,Vec,void*),void *ctx)
1730 {
1731   PetscErrorCode ierr;
1732   DM             dm;
1733 
1734   PetscFunctionBegin;
1735   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1736   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1737   ierr = DMSNESSetGS(dm,gsfunc,ctx);CHKERRQ(ierr);
1738   PetscFunctionReturn(0);
1739 }
1740 
1741 #undef __FUNCT__
1742 #define __FUNCT__ "SNESSetGSSweeps"
1743 /*@
1744    SNESSetGSSweeps - Sets the number of sweeps of GS to use.
1745 
1746    Input Parameters:
1747 +  snes   - the SNES context
1748 -  sweeps  - the number of sweeps of GS to perform.
1749 
1750    Level: intermediate
1751 
1752 .keywords: SNES, nonlinear, set, Gauss-Siedel
1753 
1754 .seealso: SNESSetGS(), SNESGetGS(), SNESSetPC(), SNESGetGSSweeps()
1755 @*/
1756 
1757 PetscErrorCode SNESSetGSSweeps(SNES snes, PetscInt sweeps)
1758 {
1759   PetscFunctionBegin;
1760   snes->gssweeps = sweeps;
1761   PetscFunctionReturn(0);
1762 }
1763 
1764 
1765 #undef __FUNCT__
1766 #define __FUNCT__ "SNESGetGSSweeps"
1767 /*@
1768    SNESGetGSSweeps - Gets the number of sweeps GS will use.
1769 
1770    Input Parameters:
1771 .  snes   - the SNES context
1772 
1773    Output Parameters:
1774 .  sweeps  - the number of sweeps of GS to perform.
1775 
1776    Level: intermediate
1777 
1778 .keywords: SNES, nonlinear, set, Gauss-Siedel
1779 
1780 .seealso: SNESSetGS(), SNESGetGS(), SNESSetPC(), SNESSetGSSweeps()
1781 @*/
1782 PetscErrorCode SNESGetGSSweeps(SNES snes, PetscInt * sweeps)
1783 {
1784   PetscFunctionBegin;
1785   *sweeps = snes->gssweeps;
1786   PetscFunctionReturn(0);
1787 }
1788 
1789 #undef __FUNCT__
1790 #define __FUNCT__ "SNESPicardComputeFunction"
1791 PetscErrorCode  SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
1792 {
1793   PetscErrorCode ierr;
1794   DM             dm;
1795   DMSNES         sdm;
1796 
1797   PetscFunctionBegin;
1798   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1799   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
1800   /*  A(x)*x - b(x) */
1801   if (sdm->ops->computepfunction) {
1802     ierr = (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);CHKERRQ(ierr);
1803   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");
1804 
1805   if (sdm->ops->computepjacobian) {
1806     ierr = (*sdm->ops->computepjacobian)(snes,x,&snes->jacobian,&snes->jacobian_pre,&snes->matstruct,sdm->pctx);CHKERRQ(ierr);
1807   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard matrix.");
1808   ierr = VecScale(f,-1.0);CHKERRQ(ierr);
1809   ierr = MatMultAdd(snes->jacobian,x,f,f);CHKERRQ(ierr);
1810   PetscFunctionReturn(0);
1811 }
1812 
1813 #undef __FUNCT__
1814 #define __FUNCT__ "SNESPicardComputeJacobian"
1815 PetscErrorCode  SNESPicardComputeJacobian(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx)
1816 {
1817   PetscFunctionBegin;
1818   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
1819   *flag = snes->matstruct;
1820   PetscFunctionReturn(0);
1821 }
1822 
1823 #undef __FUNCT__
1824 #define __FUNCT__ "SNESSetPicard"
1825 /*@C
1826    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)
1827 
1828    Logically Collective on SNES
1829 
1830    Input Parameters:
1831 +  snes - the SNES context
1832 .  r - vector to store function value
1833 .  func - function evaluation routine
1834 .  jmat - normally the same as mat but you can pass another matrix for which you compute A(x) x - b(x) (see jmat below)
1835 .  mat - matrix to store A
1836 .  mfunc  - function to compute matrix value
1837 -  ctx - [optional] user-defined context for private data for the
1838          function evaluation routine (may be PETSC_NULL)
1839 
1840    Calling sequence of func:
1841 $    func (SNES snes,Vec x,Vec f,void *ctx);
1842 
1843 +  f - function vector
1844 -  ctx - optional user-defined function context
1845 
1846    Calling sequence of mfunc:
1847 $     mfunc (SNES snes,Vec x,Mat *jmat,Mat *mat,int *flag,void *ctx);
1848 
1849 +  x - input vector
1850 .  jmat - Form  matrix of A(x) x - b(x) if available, not there is really no reason to use it in this way since then you can just use SNESSetJacobian(),
1851           normally just pass mat in this location
1852 .  mat - form A(x) matrix
1853 .  flag - flag indicating information about the preconditioner matrix
1854    structure (same as flag in KSPSetOperators()), one of SAME_NONZERO_PATTERN,DIFFERENT_NONZERO_PATTERN,SAME_PRECONDITIONER
1855 -  ctx - [optional] user-defined Jacobian context
1856 
1857    Notes:
1858     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
1859     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.
1860 
1861     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both
1862 
1863 $     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}
1864 $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.
1865 
1866      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.
1867 
1868    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
1869    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)
1870 
1871    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
1872    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
1873    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).
1874 
1875    Level: intermediate
1876 
1877 .keywords: SNES, nonlinear, set, function
1878 
1879 .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard()
1880 @*/
1881 PetscErrorCode  SNESSetPicard(SNES snes,Vec r,PetscErrorCode (*func)(SNES,Vec,Vec,void*),Mat jmat, Mat mat, PetscErrorCode (*mfunc)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void *ctx)
1882 {
1883   PetscErrorCode ierr;
1884   DM             dm;
1885 
1886   PetscFunctionBegin;
1887   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1888   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
1889   ierr = DMSNESSetPicard(dm,func,mfunc,ctx);CHKERRQ(ierr);
1890   ierr = SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);CHKERRQ(ierr);
1891   ierr = SNESSetJacobian(snes,jmat,mat,SNESPicardComputeJacobian,ctx);CHKERRQ(ierr);
1892   PetscFunctionReturn(0);
1893 }
1894 
1895 
1896 #undef __FUNCT__
1897 #define __FUNCT__ "SNESGetPicard"
1898 /*@C
1899    SNESGetPicard - Returns the context for the Picard iteration
1900 
1901    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
1902 
1903    Input Parameter:
1904 .  snes - the SNES context
1905 
1906    Output Parameter:
1907 +  r - the function (or PETSC_NULL)
1908 .  func - the function (or PETSC_NULL)
1909 .  jmat - the picard matrix (or PETSC_NULL)
1910 .  mat  - the picard preconditioner matrix (or PETSC_NULL)
1911 .  mfunc - the function for matrix evaluation (or PETSC_NULL)
1912 -  ctx - the function context (or PETSC_NULL)
1913 
1914    Level: advanced
1915 
1916 .keywords: SNES, nonlinear, get, function
1917 
1918 .seealso: SNESSetPicard, SNESGetFunction, SNESGetJacobian, SNESGetDM
1919 @*/
1920 PetscErrorCode  SNESGetPicard(SNES snes,Vec *r,PetscErrorCode (**func)(SNES,Vec,Vec,void*),Mat *jmat, Mat *mat, PetscErrorCode (**mfunc)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void **ctx)
1921 {
1922   PetscErrorCode ierr;
1923   DM             dm;
1924 
1925   PetscFunctionBegin;
1926   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1927   ierr = SNESGetFunction(snes,r,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
1928   ierr = SNESGetJacobian(snes,jmat,mat,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
1929   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1930   ierr = DMSNESGetPicard(dm,func,mfunc,ctx);CHKERRQ(ierr);
1931   PetscFunctionReturn(0);
1932 }
1933 
1934 #undef __FUNCT__
1935 #define __FUNCT__ "SNESSetComputeInitialGuess"
1936 /*@C
1937    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem
1938 
1939    Logically Collective on SNES
1940 
1941    Input Parameters:
1942 +  snes - the SNES context
1943 .  func - function evaluation routine
1944 -  ctx - [optional] user-defined context for private data for the
1945          function evaluation routine (may be PETSC_NULL)
1946 
1947    Calling sequence of func:
1948 $    func (SNES snes,Vec x,void *ctx);
1949 
1950 .  f - function vector
1951 -  ctx - optional user-defined function context
1952 
1953    Level: intermediate
1954 
1955 .keywords: SNES, nonlinear, set, function
1956 
1957 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
1958 @*/
1959 PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
1960 {
1961   PetscFunctionBegin;
1962   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1963   if (func) snes->ops->computeinitialguess = func;
1964   if (ctx)  snes->initialguessP            = ctx;
1965   PetscFunctionReturn(0);
1966 }
1967 
1968 /* --------------------------------------------------------------- */
1969 #undef __FUNCT__
1970 #define __FUNCT__ "SNESGetRhs"
1971 /*@C
1972    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
1973    it assumes a zero right hand side.
1974 
1975    Logically Collective on SNES
1976 
1977    Input Parameter:
1978 .  snes - the SNES context
1979 
1980    Output Parameter:
1981 .  rhs - the right hand side vector or PETSC_NULL if the right hand side vector is null
1982 
1983    Level: intermediate
1984 
1985 .keywords: SNES, nonlinear, get, function, right hand side
1986 
1987 .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
1988 @*/
1989 PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
1990 {
1991   PetscFunctionBegin;
1992   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1993   PetscValidPointer(rhs,2);
1994   *rhs = snes->vec_rhs;
1995   PetscFunctionReturn(0);
1996 }
1997 
1998 #undef __FUNCT__
1999 #define __FUNCT__ "SNESComputeFunction"
2000 /*@
2001    SNESComputeFunction - Calls the function that has been set with
2002                          SNESSetFunction().
2003 
2004    Collective on SNES
2005 
2006    Input Parameters:
2007 +  snes - the SNES context
2008 -  x - input vector
2009 
2010    Output Parameter:
2011 .  y - function vector, as set by SNESSetFunction()
2012 
2013    Notes:
2014    SNESComputeFunction() is typically used within nonlinear solvers
2015    implementations, so most users would not generally call this routine
2016    themselves.
2017 
2018    Level: developer
2019 
2020 .keywords: SNES, nonlinear, compute, function
2021 
2022 .seealso: SNESSetFunction(), SNESGetFunction()
2023 @*/
2024 PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
2025 {
2026   PetscErrorCode ierr;
2027   DM             dm;
2028   DMSNES         sdm;
2029 
2030   PetscFunctionBegin;
2031   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2032   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2033   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
2034   PetscCheckSameComm(snes,1,x,2);
2035   PetscCheckSameComm(snes,1,y,3);
2036   VecValidValues(x,2,PETSC_TRUE);
2037 
2038   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2039   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2040   ierr = PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2041   if (snes->pc && snes->pcside == PC_LEFT) {
2042     ierr = VecCopy(x,y);CHKERRQ(ierr);
2043     ierr = SNESSolve(snes->pc,snes->vec_rhs,y);CHKERRQ(ierr);
2044     ierr = VecAYPX(y,-1.0,x);CHKERRQ(ierr);
2045   } else if (sdm->ops->computefunction) {
2046     PetscStackPush("SNES user function");
2047     ierr = (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);CHKERRQ(ierr);
2048     PetscStackPop;
2049   } else if (snes->vec_rhs) {
2050     ierr = MatMult(snes->jacobian, x, y);CHKERRQ(ierr);
2051   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2052   if (snes->vec_rhs) {
2053     ierr = VecAXPY(y,-1.0,snes->vec_rhs);CHKERRQ(ierr);
2054   }
2055   snes->nfuncs++;
2056   ierr = PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2057   VecValidValues(y,3,PETSC_FALSE);
2058   PetscFunctionReturn(0);
2059 }
2060 
2061 #undef __FUNCT__
2062 #define __FUNCT__ "SNESComputeGS"
2063 /*@
2064    SNESComputeGS - Calls the Gauss-Seidel function that has been set with
2065                    SNESSetGS().
2066 
2067    Collective on SNES
2068 
2069    Input Parameters:
2070 +  snes - the SNES context
2071 .  x - input vector
2072 -  b - rhs vector
2073 
2074    Output Parameter:
2075 .  x - new solution vector
2076 
2077    Notes:
2078    SNESComputeGS() is typically used within composed nonlinear solver
2079    implementations, so most users would not generally call this routine
2080    themselves.
2081 
2082    Level: developer
2083 
2084 .keywords: SNES, nonlinear, compute, function
2085 
2086 .seealso: SNESSetGS(), SNESComputeFunction()
2087 @*/
2088 PetscErrorCode  SNESComputeGS(SNES snes,Vec b,Vec x)
2089 {
2090   PetscErrorCode ierr;
2091   PetscInt       i;
2092   DM             dm;
2093   DMSNES         sdm;
2094 
2095   PetscFunctionBegin;
2096   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2097   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2098   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,3);
2099   PetscCheckSameComm(snes,1,x,2);
2100   if (b) PetscCheckSameComm(snes,1,b,3);
2101   if (b) VecValidValues(b,2,PETSC_TRUE);
2102   ierr = PetscLogEventBegin(SNES_GSEval,snes,x,b,0);CHKERRQ(ierr);
2103   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2104   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2105   if (sdm->ops->computegs) {
2106     for (i = 0; i < snes->gssweeps; i++) {
2107       PetscStackPush("SNES user GS");
2108       ierr = (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);CHKERRQ(ierr);
2109       PetscStackPop;
2110     }
2111   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetGS() before SNESComputeGS(), likely called from SNESSolve().");
2112   ierr = PetscLogEventEnd(SNES_GSEval,snes,x,b,0);CHKERRQ(ierr);
2113   VecValidValues(x,3,PETSC_FALSE);
2114   PetscFunctionReturn(0);
2115 }
2116 
2117 
2118 #undef __FUNCT__
2119 #define __FUNCT__ "SNESComputeJacobian"
2120 /*@
2121    SNESComputeJacobian - Computes the Jacobian matrix that has been
2122    set with SNESSetJacobian().
2123 
2124    Collective on SNES and Mat
2125 
2126    Input Parameters:
2127 +  snes - the SNES context
2128 -  x - input vector
2129 
2130    Output Parameters:
2131 +  A - Jacobian matrix
2132 .  B - optional preconditioning matrix
2133 -  flag - flag indicating matrix structure (one of, SAME_NONZERO_PATTERN,DIFFERENT_NONZERO_PATTERN,SAME_PRECONDITIONER)
2134 
2135   Options Database Keys:
2136 +    -snes_lag_preconditioner <lag>
2137 .    -snes_lag_jacobian <lag>
2138 .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2139 .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2140 .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2141 .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2142 .    -snes_compare_coloring - Compute the finite differece Jacobian using coloring and display norms of difference
2143 .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
2144 .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2145 .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2146 .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2147 .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
2148 -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences
2149 
2150 
2151    Notes:
2152    Most users should not need to explicitly call this routine, as it
2153    is used internally within the nonlinear solvers.
2154 
2155    See KSPSetOperators() for important information about setting the
2156    flag parameter.
2157 
2158    Level: developer
2159 
2160 .keywords: SNES, compute, Jacobian, matrix
2161 
2162 .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2163 @*/
2164 PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat *A,Mat *B,MatStructure *flg)
2165 {
2166   PetscErrorCode ierr;
2167   PetscBool      flag;
2168   DM             dm;
2169   DMSNES         sdm;
2170 
2171   PetscFunctionBegin;
2172   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2173   PetscValidHeaderSpecific(X,VEC_CLASSID,2);
2174   PetscValidPointer(flg,5);
2175   PetscCheckSameComm(snes,1,X,2);
2176   VecValidValues(X,2,PETSC_TRUE);
2177   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2178   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2179 
2180   if (!sdm->ops->computejacobian) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");
2181 
2182   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */
2183 
2184   if (snes->lagjacobian == -2) {
2185     snes->lagjacobian = -1;
2186     ierr = PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");CHKERRQ(ierr);
2187   } else if (snes->lagjacobian == -1) {
2188     *flg = SAME_PRECONDITIONER;
2189     ierr = PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");CHKERRQ(ierr);
2190     ierr = PetscObjectTypeCompare((PetscObject)*A,MATMFFD,&flag);CHKERRQ(ierr);
2191     if (flag) {
2192       ierr = MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2193       ierr = MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2194     }
2195     PetscFunctionReturn(0);
2196   } else if (snes->lagjacobian > 1 && snes->iter % snes->lagjacobian) {
2197     *flg = SAME_PRECONDITIONER;
2198     ierr = PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);CHKERRQ(ierr);
2199     ierr = PetscObjectTypeCompare((PetscObject)*A,MATMFFD,&flag);CHKERRQ(ierr);
2200     if (flag) {
2201       ierr = MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2202       ierr = MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2203     }
2204     PetscFunctionReturn(0);
2205   }
2206 
2207   *flg = DIFFERENT_NONZERO_PATTERN;
2208   ierr = PetscLogEventBegin(SNES_JacobianEval,snes,X,*A,*B);CHKERRQ(ierr);
2209 
2210   PetscStackPush("SNES user Jacobian function");
2211   ierr = (*sdm->ops->computejacobian)(snes,X,A,B,flg,sdm->jacobianctx);CHKERRQ(ierr);
2212   PetscStackPop;
2213 
2214   ierr = PetscLogEventEnd(SNES_JacobianEval,snes,X,*A,*B);CHKERRQ(ierr);
2215 
2216   if (snes->lagpreconditioner == -2) {
2217     ierr = PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");CHKERRQ(ierr);
2218     snes->lagpreconditioner = -1;
2219   } else if (snes->lagpreconditioner == -1) {
2220     *flg = SAME_PRECONDITIONER;
2221     ierr = PetscInfo(snes,"Reusing preconditioner because lag is -1\n");CHKERRQ(ierr);
2222   } else if (snes->lagpreconditioner > 1 && snes->iter % snes->lagpreconditioner) {
2223     *flg = SAME_PRECONDITIONER;
2224     ierr = PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);CHKERRQ(ierr);
2225   }
2226 
2227   /* make sure user returned a correct Jacobian and preconditioner */
2228   /* PetscValidHeaderSpecific(*A,MAT_CLASSID,3);
2229     PetscValidHeaderSpecific(*B,MAT_CLASSID,4);   */
2230   {
2231     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2232     ierr  = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit",&flag,PETSC_NULL);CHKERRQ(ierr);
2233     ierr  = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",&flag_draw,PETSC_NULL);CHKERRQ(ierr);
2234     ierr  = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",&flag_contour,PETSC_NULL);CHKERRQ(ierr);
2235     ierr  = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_operator",&flag_operator,PETSC_NULL);CHKERRQ(ierr);
2236     if (flag || flag_draw || flag_contour) {
2237       Mat Bexp_mine = PETSC_NULL,Bexp,FDexp;
2238       MatStructure mstruct;
2239       PetscViewer vdraw,vstdout;
2240       PetscBool flg;
2241       if (flag_operator) {
2242         ierr = MatComputeExplicitOperator(*A,&Bexp_mine);CHKERRQ(ierr);
2243         Bexp = Bexp_mine;
2244       } else {
2245         /* See if the preconditioning matrix can be viewed and added directly */
2246         ierr = PetscObjectTypeCompareAny((PetscObject)*B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");CHKERRQ(ierr);
2247         if (flg) Bexp = *B;
2248         else {
2249           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2250           ierr = MatComputeExplicitOperator(*B,&Bexp_mine);CHKERRQ(ierr);
2251           Bexp = Bexp_mine;
2252         }
2253       }
2254       ierr = MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);CHKERRQ(ierr);
2255       ierr = SNESDefaultComputeJacobian(snes,X,&FDexp,&FDexp,&mstruct,NULL);CHKERRQ(ierr);
2256       ierr = PetscViewerASCIIGetStdout(((PetscObject)snes)->comm,&vstdout);CHKERRQ(ierr);
2257       if (flag_draw || flag_contour) {
2258         ierr = PetscViewerDrawOpen(((PetscObject)snes)->comm,0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2259         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2260       } else vdraw = PETSC_NULL;
2261       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator?"Jacobian":"preconditioning Jacobian");CHKERRQ(ierr);
2262       if (flag) {ierr = MatView(Bexp,vstdout);CHKERRQ(ierr);}
2263       if (vdraw) {ierr = MatView(Bexp,vdraw);CHKERRQ(ierr);}
2264       ierr = PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");CHKERRQ(ierr);
2265       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2266       if (vdraw) {ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);}
2267       ierr = MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2268       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");CHKERRQ(ierr);
2269       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2270       if (vdraw) {              /* Always use contour for the difference */
2271         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2272         ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);
2273         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2274       }
2275       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2276       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2277       ierr = MatDestroy(&Bexp_mine);CHKERRQ(ierr);
2278       ierr = MatDestroy(&FDexp);CHKERRQ(ierr);
2279     }
2280   }
2281   {
2282     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2283     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2284     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring",&flag,PETSC_NULL);CHKERRQ(ierr);
2285     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_display",&flag_display,PETSC_NULL);CHKERRQ(ierr);
2286     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",&flag_draw,PETSC_NULL);CHKERRQ(ierr);
2287     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",&flag_contour,PETSC_NULL);CHKERRQ(ierr);
2288     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",&flag_threshold,PETSC_NULL);CHKERRQ(ierr);
2289     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,PETSC_NULL);CHKERRQ(ierr);
2290     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,PETSC_NULL);CHKERRQ(ierr);
2291     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2292       Mat            Bfd;
2293       MatStructure   mstruct;
2294       PetscViewer    vdraw,vstdout;
2295       ISColoring     iscoloring;
2296       MatFDColoring  matfdcoloring;
2297       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2298       void           *funcctx;
2299       PetscReal      norm1,norm2,normmax;
2300 
2301       ierr = MatDuplicate(*B,MAT_DO_NOT_COPY_VALUES,&Bfd);CHKERRQ(ierr);
2302       ierr = MatGetColoring(Bfd,MATCOLORINGSL,&iscoloring);CHKERRQ(ierr);
2303       ierr = MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);CHKERRQ(ierr);
2304       ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr);
2305 
2306       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2307       ierr = SNESGetFunction(snes,PETSC_NULL,&func,&funcctx);CHKERRQ(ierr);
2308         ierr = MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode(*)(void))func,funcctx);CHKERRQ(ierr);
2309         ierr = PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);CHKERRQ(ierr);
2310         ierr = PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");CHKERRQ(ierr);
2311         ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2312         ierr = MatFDColoringApply(Bfd,matfdcoloring,X,&mstruct,snes);CHKERRQ(ierr);
2313         ierr = MatFDColoringDestroy(&matfdcoloring);CHKERRQ(ierr);
2314 
2315       ierr = PetscViewerASCIIGetStdout(((PetscObject)snes)->comm,&vstdout);CHKERRQ(ierr);
2316       if (flag_draw || flag_contour) {
2317         ierr = PetscViewerDrawOpen(((PetscObject)snes)->comm,0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2318         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2319       } else vdraw = PETSC_NULL;
2320       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");CHKERRQ(ierr);
2321       if (flag_display) {ierr = MatView(*B,vstdout);CHKERRQ(ierr);}
2322       if (vdraw) {ierr = MatView(*B,vdraw);CHKERRQ(ierr);}
2323       ierr = PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");CHKERRQ(ierr);
2324       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2325       if (vdraw) {ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);}
2326       ierr = MatAYPX(Bfd,-1.0,*B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2327       ierr = MatNorm(Bfd,NORM_1,&norm1);CHKERRQ(ierr);
2328       ierr = MatNorm(Bfd,NORM_FROBENIUS,&norm2);CHKERRQ(ierr);
2329       ierr = MatNorm(Bfd,NORM_MAX,&normmax);CHKERRQ(ierr);
2330       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%G normFrob=%G normmax=%G\n",norm1,norm2,normmax);CHKERRQ(ierr);
2331       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2332       if (vdraw) {              /* Always use contour for the difference */
2333         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2334         ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);
2335         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2336       }
2337       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2338 
2339       if (flag_threshold) {
2340         PetscInt bs,rstart,rend,i;
2341         ierr = MatGetBlockSize(*B,&bs);CHKERRQ(ierr);
2342         ierr = MatGetOwnershipRange(*B,&rstart,&rend);CHKERRQ(ierr);
2343         for (i=rstart; i<rend; i++) {
2344           const PetscScalar *ba,*ca;
2345           const PetscInt    *bj,*cj;
2346           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2347           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2348           ierr = MatGetRow(*B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2349           ierr = MatGetRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2350           if (bn != cn) SETERRQ(((PetscObject)*A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2351           for (j=0; j<bn; j++) {
2352             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2353             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2354               maxentrycol = bj[j];
2355               maxentry = PetscRealPart(ba[j]);
2356             }
2357             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2358               maxdiffcol = bj[j];
2359               maxdiff = PetscRealPart(ca[j]);
2360             }
2361             if (rdiff > maxrdiff) {
2362               maxrdiffcol = bj[j];
2363               maxrdiff = rdiff;
2364             }
2365           }
2366           if (maxrdiff > 1) {
2367             ierr = PetscViewerASCIIPrintf(vstdout,"row %D (maxentry=%G at %D, maxdiff=%G at %D, maxrdiff=%G at %D):",i,maxentry,maxentrycol,maxdiff,maxdiffcol,maxrdiff,maxrdiffcol);CHKERRQ(ierr);
2368             for (j=0; j<bn; j++) {
2369               PetscReal rdiff;
2370               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2371               if (rdiff > 1) {
2372                 ierr = PetscViewerASCIIPrintf(vstdout," (%D,%G:%G)",bj[j],PetscRealPart(ba[j]),PetscRealPart(ca[j]));CHKERRQ(ierr);
2373               }
2374             }
2375             ierr = PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);CHKERRQ(ierr);
2376           }
2377           ierr = MatRestoreRow(*B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2378           ierr = MatRestoreRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2379         }
2380       }
2381       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2382       ierr = MatDestroy(&Bfd);CHKERRQ(ierr);
2383     }
2384   }
2385   PetscFunctionReturn(0);
2386 }
2387 
2388 #undef __FUNCT__
2389 #define __FUNCT__ "SNESSetJacobian"
2390 /*@C
2391    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2392    location to store the matrix.
2393 
2394    Logically Collective on SNES and Mat
2395 
2396    Input Parameters:
2397 +  snes - the SNES context
2398 .  A - Jacobian matrix
2399 .  B - preconditioner matrix (usually same as the Jacobian)
2400 .  func - Jacobian evaluation routine (if PETSC_NULL then SNES retains any previously set value)
2401 -  ctx - [optional] user-defined context for private data for the
2402          Jacobian evaluation routine (may be PETSC_NULL) (if PETSC_NULL then SNES retains any previously set value)
2403 
2404    Calling sequence of func:
2405 $     func (SNES snes,Vec x,Mat *A,Mat *B,int *flag,void *ctx);
2406 
2407 +  x - input vector
2408 .  A - Jacobian matrix
2409 .  B - preconditioner matrix, usually the same as A
2410 .  flag - flag indicating information about the preconditioner matrix
2411    structure (same as flag in KSPSetOperators()), one of SAME_NONZERO_PATTERN,DIFFERENT_NONZERO_PATTERN,SAME_PRECONDITIONER
2412 -  ctx - [optional] user-defined Jacobian context
2413 
2414    Notes:
2415    See KSPSetOperators() for important information about setting the flag
2416    output parameter in the routine func().  Be sure to read this information!
2417 
2418    The routine func() takes Mat * as the matrix arguments rather than Mat.
2419    This allows the Jacobian evaluation routine to replace A and/or B with a
2420    completely new new matrix structure (not just different matrix elements)
2421    when appropriate, for instance, if the nonzero structure is changing
2422    throughout the global iterations.
2423 
2424    If the A matrix and B matrix are different you must call MatAssemblyBegin/End() on
2425    each matrix.
2426 
2427    If using SNESDefaultComputeJacobianColor() to assemble a Jacobian, the ctx argument
2428    must be a MatFDColoring.
2429 
2430    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2431    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.
2432 
2433    Level: beginner
2434 
2435 .keywords: SNES, nonlinear, set, Jacobian, matrix
2436 
2437 .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESDefaultComputeJacobianColor(), MatStructure
2438 @*/
2439 PetscErrorCode  SNESSetJacobian(SNES snes,Mat A,Mat B,PetscErrorCode (*func)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void *ctx)
2440 {
2441   PetscErrorCode ierr;
2442   DM             dm;
2443 
2444   PetscFunctionBegin;
2445   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2446   if (A) PetscValidHeaderSpecific(A,MAT_CLASSID,2);
2447   if (B) PetscValidHeaderSpecific(B,MAT_CLASSID,3);
2448   if (A) PetscCheckSameComm(snes,1,A,2);
2449   if (B) PetscCheckSameComm(snes,1,B,3);
2450   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2451   ierr = DMSNESSetJacobian(dm,func,ctx);CHKERRQ(ierr);
2452   if (A) {
2453     ierr = PetscObjectReference((PetscObject)A);CHKERRQ(ierr);
2454     ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2455     snes->jacobian = A;
2456   }
2457   if (B) {
2458     ierr = PetscObjectReference((PetscObject)B);CHKERRQ(ierr);
2459     ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2460     snes->jacobian_pre = B;
2461   }
2462   PetscFunctionReturn(0);
2463 }
2464 
2465 #undef __FUNCT__
2466 #define __FUNCT__ "SNESGetJacobian"
2467 /*@C
2468    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2469    provided context for evaluating the Jacobian.
2470 
2471    Not Collective, but Mat object will be parallel if SNES object is
2472 
2473    Input Parameter:
2474 .  snes - the nonlinear solver context
2475 
2476    Output Parameters:
2477 +  A - location to stash Jacobian matrix (or PETSC_NULL)
2478 .  B - location to stash preconditioner matrix (or PETSC_NULL)
2479 .  func - location to put Jacobian function (or PETSC_NULL)
2480 -  ctx - location to stash Jacobian ctx (or PETSC_NULL)
2481 
2482    Level: advanced
2483 
2484 .seealso: SNESSetJacobian(), SNESComputeJacobian()
2485 @*/
2486 PetscErrorCode SNESGetJacobian(SNES snes,Mat *A,Mat *B,PetscErrorCode (**func)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void **ctx)
2487 {
2488   PetscErrorCode ierr;
2489   DM             dm;
2490   DMSNES         sdm;
2491 
2492   PetscFunctionBegin;
2493   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2494   if (A)    *A    = snes->jacobian;
2495   if (B)    *B    = snes->jacobian_pre;
2496   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2497   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2498   if (func) *func = sdm->ops->computejacobian;
2499   if (ctx)  *ctx  = sdm->jacobianctx;
2500   PetscFunctionReturn(0);
2501 }
2502 
2503 /* ----- Routines to initialize and destroy a nonlinear solver ---- */
2504 
2505 #undef __FUNCT__
2506 #define __FUNCT__ "SNESSetUp"
2507 /*@
2508    SNESSetUp - Sets up the internal data structures for the later use
2509    of a nonlinear solver.
2510 
2511    Collective on SNES
2512 
2513    Input Parameters:
2514 .  snes - the SNES context
2515 
2516    Notes:
2517    For basic use of the SNES solvers the user need not explicitly call
2518    SNESSetUp(), since these actions will automatically occur during
2519    the call to SNESSolve().  However, if one wishes to control this
2520    phase separately, SNESSetUp() should be called after SNESCreate()
2521    and optional routines of the form SNESSetXXX(), but before SNESSolve().
2522 
2523    Level: advanced
2524 
2525 .keywords: SNES, nonlinear, setup
2526 
2527 .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
2528 @*/
2529 PetscErrorCode  SNESSetUp(SNES snes)
2530 {
2531   PetscErrorCode              ierr;
2532   DM                          dm;
2533   DMSNES                      sdm;
2534   SNESLineSearch              linesearch, pclinesearch;
2535   void                        *lsprectx,*lspostctx;
2536   SNESLineSearchPreCheckFunc  lsprefunc;
2537   SNESLineSearchPostCheckFunc lspostfunc;
2538   PetscErrorCode              (*func)(SNES,Vec,Vec,void*);
2539   Vec                         f,fpc;
2540   void                        *funcctx;
2541   PetscErrorCode              (*jac)(SNES,Vec,Mat*,Mat*,MatStructure*,void*);
2542   void                        *jacctx,*appctx;
2543   Mat                         A,B;
2544 
2545   PetscFunctionBegin;
2546   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2547   if (snes->setupcalled) PetscFunctionReturn(0);
2548 
2549   if (!((PetscObject)snes)->type_name) {
2550     ierr = SNESSetType(snes,SNESNEWTONLS);CHKERRQ(ierr);
2551   }
2552 
2553   ierr = SNESGetFunction(snes,&snes->vec_func,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
2554   if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
2555   if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
2556 
2557   if (!snes->vec_sol_update /* && snes->vec_sol */) {
2558     ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
2559     ierr = PetscLogObjectParent(snes,snes->vec_sol_update);CHKERRQ(ierr);
2560   }
2561 
2562   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2563   ierr = DMShellSetGlobalVector(snes->dm,snes->vec_sol);CHKERRQ(ierr);
2564   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2565   if (!sdm->ops->computefunction) SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
2566   if (!sdm->ops->computejacobian) {
2567     ierr = DMSNESSetJacobian(dm,SNESDefaultComputeJacobianColor,PETSC_NULL);CHKERRQ(ierr);
2568   }
2569   if (!snes->vec_func) {
2570     ierr = DMCreateGlobalVector(dm,&snes->vec_func);CHKERRQ(ierr);
2571   }
2572 
2573   if (!snes->ksp) {
2574     ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);
2575   }
2576 
2577   if (!snes->linesearch) {
2578     ierr = SNESGetSNESLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
2579   }
2580 
2581   if (snes->pc && (snes->pcside == PC_LEFT)) {
2582     snes->mf = PETSC_TRUE;
2583     snes->mf_operator = PETSC_FALSE;
2584   }
2585 
2586   if (snes->mf) {
2587     ierr = SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);CHKERRQ(ierr);
2588   }
2589 
2590   if (snes->ops->usercompute && !snes->user) {
2591     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2592   }
2593 
2594   if (snes->pc) {
2595     /* copy the DM over */
2596     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2597     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
2598 
2599     ierr = SNESGetFunction(snes,&f,&func,&funcctx);CHKERRQ(ierr);
2600     ierr = VecDuplicate(f,&fpc);CHKERRQ(ierr);
2601     ierr = SNESSetFunction(snes->pc,fpc,func,funcctx);CHKERRQ(ierr);
2602     ierr = SNESGetJacobian(snes,&A,&B,&jac,&jacctx);CHKERRQ(ierr);
2603     ierr = SNESSetJacobian(snes->pc,A,B,jac,jacctx);CHKERRQ(ierr);
2604     ierr = SNESGetApplicationContext(snes,&appctx);CHKERRQ(ierr);
2605     ierr = SNESSetApplicationContext(snes->pc,appctx);CHKERRQ(ierr);
2606     ierr = VecDestroy(&fpc);CHKERRQ(ierr);
2607 
2608     /* copy the function pointers over */
2609     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
2610 
2611      /* default to 1 iteration */
2612     ierr = SNESSetTolerances(snes->pc, 0.0, 0.0, 0.0, 1, snes->pc->max_funcs);CHKERRQ(ierr);
2613     ierr = SNESSetNormType(snes->pc, SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
2614     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
2615 
2616     /* copy the line search context over */
2617     ierr = SNESGetSNESLineSearch(snes,&linesearch);CHKERRQ(ierr);
2618     ierr = SNESGetSNESLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
2619     ierr = SNESLineSearchGetPreCheck(linesearch,&lsprefunc,&lsprectx);CHKERRQ(ierr);
2620     ierr = SNESLineSearchGetPostCheck(linesearch,&lspostfunc,&lspostctx);CHKERRQ(ierr);
2621     ierr = SNESLineSearchSetPreCheck(pclinesearch,lsprefunc,lsprectx);CHKERRQ(ierr);
2622     ierr = SNESLineSearchSetPostCheck(pclinesearch,lspostfunc,lspostctx);CHKERRQ(ierr);
2623     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);CHKERRQ(ierr);
2624   }
2625 
2626   if (snes->ops->setup) {
2627     ierr = (*snes->ops->setup)(snes);CHKERRQ(ierr);
2628   }
2629 
2630   snes->setupcalled = PETSC_TRUE;
2631   PetscFunctionReturn(0);
2632 }
2633 
2634 #undef __FUNCT__
2635 #define __FUNCT__ "SNESReset"
2636 /*@
2637    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats
2638 
2639    Collective on SNES
2640 
2641    Input Parameter:
2642 .  snes - iterative context obtained from SNESCreate()
2643 
2644    Level: intermediate
2645 
2646    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()
2647 
2648 .keywords: SNES, destroy
2649 
2650 .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
2651 @*/
2652 PetscErrorCode  SNESReset(SNES snes)
2653 {
2654   PetscErrorCode ierr;
2655 
2656   PetscFunctionBegin;
2657   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2658   if (snes->ops->userdestroy && snes->user) {
2659     ierr       = (*snes->ops->userdestroy)((void**)&snes->user);CHKERRQ(ierr);
2660     snes->user = PETSC_NULL;
2661   }
2662   if (snes->pc) {
2663     ierr = SNESReset(snes->pc);CHKERRQ(ierr);
2664   }
2665 
2666   if (snes->ops->reset) {
2667     ierr = (*snes->ops->reset)(snes);CHKERRQ(ierr);
2668   }
2669   if (snes->ksp) {
2670     ierr = KSPReset(snes->ksp);CHKERRQ(ierr);
2671   }
2672 
2673   if (snes->linesearch) {
2674     ierr = SNESLineSearchReset(snes->linesearch);CHKERRQ(ierr);
2675   }
2676 
2677   ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
2678   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
2679   ierr = VecDestroy(&snes->vec_sol_update);CHKERRQ(ierr);
2680   ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
2681   ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2682   ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2683   ierr = VecDestroyVecs(snes->nwork,&snes->work);CHKERRQ(ierr);
2684   ierr = VecDestroyVecs(snes->nvwork,&snes->vwork);CHKERRQ(ierr);
2685   snes->nwork = snes->nvwork = 0;
2686   snes->setupcalled = PETSC_FALSE;
2687   PetscFunctionReturn(0);
2688 }
2689 
2690 #undef __FUNCT__
2691 #define __FUNCT__ "SNESDestroy"
2692 /*@
2693    SNESDestroy - Destroys the nonlinear solver context that was created
2694    with SNESCreate().
2695 
2696    Collective on SNES
2697 
2698    Input Parameter:
2699 .  snes - the SNES context
2700 
2701    Level: beginner
2702 
2703 .keywords: SNES, nonlinear, destroy
2704 
2705 .seealso: SNESCreate(), SNESSolve()
2706 @*/
2707 PetscErrorCode  SNESDestroy(SNES *snes)
2708 {
2709   PetscErrorCode ierr;
2710 
2711   PetscFunctionBegin;
2712   if (!*snes) PetscFunctionReturn(0);
2713   PetscValidHeaderSpecific((*snes),SNES_CLASSID,1);
2714   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; PetscFunctionReturn(0);}
2715 
2716   ierr = SNESReset((*snes));CHKERRQ(ierr);
2717   ierr = SNESDestroy(&(*snes)->pc);CHKERRQ(ierr);
2718 
2719   /* if memory was published with AMS then destroy it */
2720   ierr = PetscObjectDepublish((*snes));CHKERRQ(ierr);
2721   if ((*snes)->ops->destroy) {ierr = (*((*snes))->ops->destroy)((*snes));CHKERRQ(ierr);}
2722 
2723   ierr = DMDestroy(&(*snes)->dm);CHKERRQ(ierr);
2724   ierr = KSPDestroy(&(*snes)->ksp);CHKERRQ(ierr);
2725   ierr = SNESLineSearchDestroy(&(*snes)->linesearch);CHKERRQ(ierr);
2726 
2727   ierr = PetscFree((*snes)->kspconvctx);CHKERRQ(ierr);
2728   if ((*snes)->ops->convergeddestroy) {
2729     ierr = (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);CHKERRQ(ierr);
2730   }
2731   if ((*snes)->conv_malloc) {
2732     ierr = PetscFree((*snes)->conv_hist);CHKERRQ(ierr);
2733     ierr = PetscFree((*snes)->conv_hist_its);CHKERRQ(ierr);
2734   }
2735   ierr = SNESMonitorCancel((*snes));CHKERRQ(ierr);
2736   ierr = PetscHeaderDestroy(snes);CHKERRQ(ierr);
2737  PetscFunctionReturn(0);
2738 }
2739 
2740 /* ----------- Routines to set solver parameters ---------- */
2741 
2742 #undef __FUNCT__
2743 #define __FUNCT__ "SNESSetLagPreconditioner"
2744 /*@
2745    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.
2746 
2747    Logically Collective on SNES
2748 
2749    Input Parameters:
2750 +  snes - the SNES context
2751 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2752          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2753 
2754    Options Database Keys:
2755 .    -snes_lag_preconditioner <lag>
2756 
2757    Notes:
2758    The default is 1
2759    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2760    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use
2761 
2762    Level: intermediate
2763 
2764 .keywords: SNES, nonlinear, set, convergence, tolerances
2765 
2766 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2767 
2768 @*/
2769 PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
2770 {
2771   PetscFunctionBegin;
2772   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2773   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2774   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2775   PetscValidLogicalCollectiveInt(snes,lag,2);
2776   snes->lagpreconditioner = lag;
2777   PetscFunctionReturn(0);
2778 }
2779 
2780 #undef __FUNCT__
2781 #define __FUNCT__ "SNESSetGridSequence"
2782 /*@
2783    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does
2784 
2785    Logically Collective on SNES
2786 
2787    Input Parameters:
2788 +  snes - the SNES context
2789 -  steps - the number of refinements to do, defaults to 0
2790 
2791    Options Database Keys:
2792 .    -snes_grid_sequence <steps>
2793 
2794    Level: intermediate
2795 
2796    Notes:
2797    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2798 
2799 .keywords: SNES, nonlinear, set, convergence, tolerances
2800 
2801 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2802 
2803 @*/
2804 PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
2805 {
2806   PetscFunctionBegin;
2807   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2808   PetscValidLogicalCollectiveInt(snes,steps,2);
2809   snes->gridsequence = steps;
2810   PetscFunctionReturn(0);
2811 }
2812 
2813 #undef __FUNCT__
2814 #define __FUNCT__ "SNESGetLagPreconditioner"
2815 /*@
2816    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt
2817 
2818    Not Collective
2819 
2820    Input Parameter:
2821 .  snes - the SNES context
2822 
2823    Output Parameter:
2824 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2825          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2826 
2827    Options Database Keys:
2828 .    -snes_lag_preconditioner <lag>
2829 
2830    Notes:
2831    The default is 1
2832    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2833 
2834    Level: intermediate
2835 
2836 .keywords: SNES, nonlinear, set, convergence, tolerances
2837 
2838 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()
2839 
2840 @*/
2841 PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
2842 {
2843   PetscFunctionBegin;
2844   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2845   *lag = snes->lagpreconditioner;
2846   PetscFunctionReturn(0);
2847 }
2848 
2849 #undef __FUNCT__
2850 #define __FUNCT__ "SNESSetLagJacobian"
2851 /*@
2852    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
2853      often the preconditioner is rebuilt.
2854 
2855    Logically Collective on SNES
2856 
2857    Input Parameters:
2858 +  snes - the SNES context
2859 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2860          the Jacobian is built etc. -2 means rebuild at next chance but then never again
2861 
2862    Options Database Keys:
2863 .    -snes_lag_jacobian <lag>
2864 
2865    Notes:
2866    The default is 1
2867    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2868    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
2869    at the next Newton step but never again (unless it is reset to another value)
2870 
2871    Level: intermediate
2872 
2873 .keywords: SNES, nonlinear, set, convergence, tolerances
2874 
2875 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()
2876 
2877 @*/
2878 PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
2879 {
2880   PetscFunctionBegin;
2881   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2882   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2883   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2884   PetscValidLogicalCollectiveInt(snes,lag,2);
2885   snes->lagjacobian = lag;
2886   PetscFunctionReturn(0);
2887 }
2888 
2889 #undef __FUNCT__
2890 #define __FUNCT__ "SNESGetLagJacobian"
2891 /*@
2892    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt
2893 
2894    Not Collective
2895 
2896    Input Parameter:
2897 .  snes - the SNES context
2898 
2899    Output Parameter:
2900 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2901          the Jacobian is built etc.
2902 
2903    Options Database Keys:
2904 .    -snes_lag_jacobian <lag>
2905 
2906    Notes:
2907    The default is 1
2908    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2909 
2910    Level: intermediate
2911 
2912 .keywords: SNES, nonlinear, set, convergence, tolerances
2913 
2914 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()
2915 
2916 @*/
2917 PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
2918 {
2919   PetscFunctionBegin;
2920   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2921   *lag = snes->lagjacobian;
2922   PetscFunctionReturn(0);
2923 }
2924 
2925 #undef __FUNCT__
2926 #define __FUNCT__ "SNESSetTolerances"
2927 /*@
2928    SNESSetTolerances - Sets various parameters used in convergence tests.
2929 
2930    Logically Collective on SNES
2931 
2932    Input Parameters:
2933 +  snes - the SNES context
2934 .  abstol - absolute convergence tolerance
2935 .  rtol - relative convergence tolerance
2936 .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
2937 .  maxit - maximum number of iterations
2938 -  maxf - maximum number of function evaluations
2939 
2940    Options Database Keys:
2941 +    -snes_atol <abstol> - Sets abstol
2942 .    -snes_rtol <rtol> - Sets rtol
2943 .    -snes_stol <stol> - Sets stol
2944 .    -snes_max_it <maxit> - Sets maxit
2945 -    -snes_max_funcs <maxf> - Sets maxf
2946 
2947    Notes:
2948    The default maximum number of iterations is 50.
2949    The default maximum number of function evaluations is 1000.
2950 
2951    Level: intermediate
2952 
2953 .keywords: SNES, nonlinear, set, convergence, tolerances
2954 
2955 .seealso: SNESSetTrustRegionTolerance()
2956 @*/
2957 PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
2958 {
2959   PetscFunctionBegin;
2960   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2961   PetscValidLogicalCollectiveReal(snes,abstol,2);
2962   PetscValidLogicalCollectiveReal(snes,rtol,3);
2963   PetscValidLogicalCollectiveReal(snes,stol,4);
2964   PetscValidLogicalCollectiveInt(snes,maxit,5);
2965   PetscValidLogicalCollectiveInt(snes,maxf,6);
2966 
2967   if (abstol != PETSC_DEFAULT) {
2968     if (abstol < 0.0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %G must be non-negative",abstol);
2969     snes->abstol = abstol;
2970   }
2971   if (rtol != PETSC_DEFAULT) {
2972     if (rtol < 0.0 || 1.0 <= rtol) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Relative tolerance %G must be non-negative and less than 1.0",rtol);
2973     snes->rtol = rtol;
2974   }
2975   if (stol != PETSC_DEFAULT) {
2976     if (stol < 0.0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %G must be non-negative",stol);
2977     snes->stol = stol;
2978   }
2979   if (maxit != PETSC_DEFAULT) {
2980     if (maxit < 0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
2981     snes->max_its = maxit;
2982   }
2983   if (maxf != PETSC_DEFAULT) {
2984     if (maxf < 0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
2985     snes->max_funcs = maxf;
2986   }
2987   snes->tolerancesset = PETSC_TRUE;
2988   PetscFunctionReturn(0);
2989 }
2990 
2991 #undef __FUNCT__
2992 #define __FUNCT__ "SNESGetTolerances"
2993 /*@
2994    SNESGetTolerances - Gets various parameters used in convergence tests.
2995 
2996    Not Collective
2997 
2998    Input Parameters:
2999 +  snes - the SNES context
3000 .  atol - absolute convergence tolerance
3001 .  rtol - relative convergence tolerance
3002 .  stol -  convergence tolerance in terms of the norm
3003            of the change in the solution between steps
3004 .  maxit - maximum number of iterations
3005 -  maxf - maximum number of function evaluations
3006 
3007    Notes:
3008    The user can specify PETSC_NULL for any parameter that is not needed.
3009 
3010    Level: intermediate
3011 
3012 .keywords: SNES, nonlinear, get, convergence, tolerances
3013 
3014 .seealso: SNESSetTolerances()
3015 @*/
3016 PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3017 {
3018   PetscFunctionBegin;
3019   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3020   if (atol)  *atol  = snes->abstol;
3021   if (rtol)  *rtol  = snes->rtol;
3022   if (stol)  *stol  = snes->stol;
3023   if (maxit) *maxit = snes->max_its;
3024   if (maxf)  *maxf  = snes->max_funcs;
3025   PetscFunctionReturn(0);
3026 }
3027 
3028 #undef __FUNCT__
3029 #define __FUNCT__ "SNESSetTrustRegionTolerance"
3030 /*@
3031    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.
3032 
3033    Logically Collective on SNES
3034 
3035    Input Parameters:
3036 +  snes - the SNES context
3037 -  tol - tolerance
3038 
3039    Options Database Key:
3040 .  -snes_trtol <tol> - Sets tol
3041 
3042    Level: intermediate
3043 
3044 .keywords: SNES, nonlinear, set, trust region, tolerance
3045 
3046 .seealso: SNESSetTolerances()
3047 @*/
3048 PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3049 {
3050   PetscFunctionBegin;
3051   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3052   PetscValidLogicalCollectiveReal(snes,tol,2);
3053   snes->deltatol = tol;
3054   PetscFunctionReturn(0);
3055 }
3056 
3057 /*
3058    Duplicate the lg monitors for SNES from KSP; for some reason with
3059    dynamic libraries things don't work under Sun4 if we just use
3060    macros instead of functions
3061 */
3062 #undef __FUNCT__
3063 #define __FUNCT__ "SNESMonitorLGResidualNorm"
3064 PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,void *ctx)
3065 {
3066   PetscErrorCode ierr;
3067 
3068   PetscFunctionBegin;
3069   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3070   ierr = KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);CHKERRQ(ierr);
3071   PetscFunctionReturn(0);
3072 }
3073 
3074 #undef __FUNCT__
3075 #define __FUNCT__ "SNESMonitorLGCreate"
3076 PetscErrorCode  SNESMonitorLGCreate(const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *draw)
3077 {
3078   PetscErrorCode ierr;
3079 
3080   PetscFunctionBegin;
3081   ierr = KSPMonitorLGResidualNormCreate(host,label,x,y,m,n,draw);CHKERRQ(ierr);
3082   PetscFunctionReturn(0);
3083 }
3084 
3085 #undef __FUNCT__
3086 #define __FUNCT__ "SNESMonitorLGDestroy"
3087 PetscErrorCode  SNESMonitorLGDestroy(PetscDrawLG *draw)
3088 {
3089   PetscErrorCode ierr;
3090 
3091   PetscFunctionBegin;
3092   ierr = KSPMonitorLGResidualNormDestroy(draw);CHKERRQ(ierr);
3093   PetscFunctionReturn(0);
3094 }
3095 
3096 extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
3097 #undef __FUNCT__
3098 #define __FUNCT__ "SNESMonitorLGRange"
3099 PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3100 {
3101   PetscDrawLG      lg;
3102   PetscErrorCode   ierr;
3103   PetscReal        x,y,per;
3104   PetscViewer      v = (PetscViewer)monctx;
3105   static PetscReal prev; /* should be in the context */
3106   PetscDraw        draw;
3107 
3108   PetscFunctionBegin;
3109   ierr   = PetscViewerDrawGetDrawLG(v,0,&lg);CHKERRQ(ierr);
3110   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3111   ierr   = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3112   ierr   = PetscDrawSetTitle(draw,"Residual norm");CHKERRQ(ierr);
3113   x = (PetscReal) n;
3114   if (rnorm > 0.0) y = log10(rnorm); else y = -15.0;
3115   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3116   if (n < 20 || !(n % 5)) {
3117     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3118   }
3119 
3120   ierr = PetscViewerDrawGetDrawLG(v,1,&lg);CHKERRQ(ierr);
3121   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3122   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3123   ierr = PetscDrawSetTitle(draw,"% elemts > .2*max elemt");CHKERRQ(ierr);
3124   ierr =  SNESMonitorRange_Private(snes,n,&per);CHKERRQ(ierr);
3125   x = (PetscReal) n;
3126   y = 100.0*per;
3127   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3128   if (n < 20 || !(n % 5)) {
3129     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3130   }
3131 
3132   ierr = PetscViewerDrawGetDrawLG(v,2,&lg);CHKERRQ(ierr);
3133   if (!n) {prev = rnorm;ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3134   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3135   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");CHKERRQ(ierr);
3136   x = (PetscReal) n;
3137   y = (prev - rnorm)/prev;
3138   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3139   if (n < 20 || !(n % 5)) {
3140     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3141   }
3142 
3143   ierr = PetscViewerDrawGetDrawLG(v,3,&lg);CHKERRQ(ierr);
3144   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3145   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3146   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");CHKERRQ(ierr);
3147   x = (PetscReal) n;
3148   y = (prev - rnorm)/(prev*per);
3149   if (n > 2) { /*skip initial crazy value */
3150     ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3151   }
3152   if (n < 20 || !(n % 5)) {
3153     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3154   }
3155   prev = rnorm;
3156   PetscFunctionReturn(0);
3157 }
3158 
3159 #undef __FUNCT__
3160 #define __FUNCT__ "SNESMonitor"
3161 /*@
3162    SNESMonitor - runs the user provided monitor routines, if they exist
3163 
3164    Collective on SNES
3165 
3166    Input Parameters:
3167 +  snes - nonlinear solver context obtained from SNESCreate()
3168 .  iter - iteration number
3169 -  rnorm - relative norm of the residual
3170 
3171    Notes:
3172    This routine is called by the SNES implementations.
3173    It does not typically need to be called by the user.
3174 
3175    Level: developer
3176 
3177 .seealso: SNESMonitorSet()
3178 @*/
3179 PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3180 {
3181   PetscErrorCode ierr;
3182   PetscInt       i,n = snes->numbermonitors;
3183 
3184   PetscFunctionBegin;
3185   for (i=0; i<n; i++) {
3186     ierr = (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);CHKERRQ(ierr);
3187   }
3188   PetscFunctionReturn(0);
3189 }
3190 
3191 /* ------------ Routines to set performance monitoring options ----------- */
3192 
3193 #undef __FUNCT__
3194 #define __FUNCT__ "SNESMonitorSet"
3195 /*@C
3196    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3197    iteration of the nonlinear solver to display the iteration's
3198    progress.
3199 
3200    Logically Collective on SNES
3201 
3202    Input Parameters:
3203 +  snes - the SNES context
3204 .  func - monitoring routine
3205 .  mctx - [optional] user-defined context for private data for the
3206           monitor routine (use PETSC_NULL if no context is desired)
3207 -  monitordestroy - [optional] routine that frees monitor context
3208           (may be PETSC_NULL)
3209 
3210    Calling sequence of func:
3211 $     int func(SNES snes,PetscInt its, PetscReal norm,void *mctx)
3212 
3213 +    snes - the SNES context
3214 .    its - iteration number
3215 .    norm - 2-norm function value (may be estimated)
3216 -    mctx - [optional] monitoring context
3217 
3218    Options Database Keys:
3219 +    -snes_monitor        - sets SNESMonitorDefault()
3220 .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3221                             uses SNESMonitorLGCreate()
3222 -    -snes_monitor_cancel - cancels all monitors that have
3223                             been hardwired into a code by
3224                             calls to SNESMonitorSet(), but
3225                             does not cancel those set via
3226                             the options database.
3227 
3228    Notes:
3229    Several different monitoring routines may be set by calling
3230    SNESMonitorSet() multiple times; all will be called in the
3231    order in which they were set.
3232 
3233    Fortran notes: Only a single monitor function can be set for each SNES object
3234 
3235    Level: intermediate
3236 
3237 .keywords: SNES, nonlinear, set, monitor
3238 
3239 .seealso: SNESMonitorDefault(), SNESMonitorCancel()
3240 @*/
3241 PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*monitor)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3242 {
3243   PetscInt       i;
3244   PetscErrorCode ierr;
3245 
3246   PetscFunctionBegin;
3247   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3248   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3249   for (i=0; i<snes->numbermonitors;i++) {
3250     if (monitor == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
3251       if (monitordestroy) {
3252         ierr = (*monitordestroy)(&mctx);CHKERRQ(ierr);
3253       }
3254       PetscFunctionReturn(0);
3255     }
3256   }
3257   snes->monitor[snes->numbermonitors]           = monitor;
3258   snes->monitordestroy[snes->numbermonitors]    = monitordestroy;
3259   snes->monitorcontext[snes->numbermonitors++]  = (void*)mctx;
3260   PetscFunctionReturn(0);
3261 }
3262 
3263 #undef __FUNCT__
3264 #define __FUNCT__ "SNESMonitorCancel"
3265 /*@C
3266    SNESMonitorCancel - Clears all the monitor functions for a SNES object.
3267 
3268    Logically Collective on SNES
3269 
3270    Input Parameters:
3271 .  snes - the SNES context
3272 
3273    Options Database Key:
3274 .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3275     into a code by calls to SNESMonitorSet(), but does not cancel those
3276     set via the options database
3277 
3278    Notes:
3279    There is no way to clear one specific monitor from a SNES object.
3280 
3281    Level: intermediate
3282 
3283 .keywords: SNES, nonlinear, set, monitor
3284 
3285 .seealso: SNESMonitorDefault(), SNESMonitorSet()
3286 @*/
3287 PetscErrorCode  SNESMonitorCancel(SNES snes)
3288 {
3289   PetscErrorCode ierr;
3290   PetscInt       i;
3291 
3292   PetscFunctionBegin;
3293   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3294   for (i=0; i<snes->numbermonitors; i++) {
3295     if (snes->monitordestroy[i]) {
3296       ierr = (*snes->monitordestroy[i])(&snes->monitorcontext[i]);CHKERRQ(ierr);
3297     }
3298   }
3299   snes->numbermonitors = 0;
3300   PetscFunctionReturn(0);
3301 }
3302 
3303 #undef __FUNCT__
3304 #define __FUNCT__ "SNESSetConvergenceTest"
3305 /*@C
3306    SNESSetConvergenceTest - Sets the function that is to be used
3307    to test for convergence of the nonlinear iterative solution.
3308 
3309    Logically Collective on SNES
3310 
3311    Input Parameters:
3312 +  snes - the SNES context
3313 .  func - routine to test for convergence
3314 .  cctx - [optional] context for private data for the convergence routine  (may be PETSC_NULL)
3315 -  destroy - [optional] destructor for the context (may be PETSC_NULL; PETSC_NULL_FUNCTION in Fortran)
3316 
3317    Calling sequence of func:
3318 $     PetscErrorCode func (SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)
3319 
3320 +    snes - the SNES context
3321 .    it - current iteration (0 is the first and is before any Newton step)
3322 .    cctx - [optional] convergence context
3323 .    reason - reason for convergence/divergence
3324 .    xnorm - 2-norm of current iterate
3325 .    gnorm - 2-norm of current step
3326 -    f - 2-norm of function
3327 
3328    Level: advanced
3329 
3330 .keywords: SNES, nonlinear, set, convergence, test
3331 
3332 .seealso: SNESDefaultConverged(), SNESSkipConverged()
3333 @*/
3334 PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*func)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
3335 {
3336   PetscErrorCode ierr;
3337 
3338   PetscFunctionBegin;
3339   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3340   if (!func) func = SNESSkipConverged;
3341   if (snes->ops->convergeddestroy) {
3342     ierr = (*snes->ops->convergeddestroy)(snes->cnvP);CHKERRQ(ierr);
3343   }
3344   snes->ops->converged        = func;
3345   snes->ops->convergeddestroy = destroy;
3346   snes->cnvP                  = cctx;
3347   PetscFunctionReturn(0);
3348 }
3349 
3350 #undef __FUNCT__
3351 #define __FUNCT__ "SNESGetConvergedReason"
3352 /*@
3353    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.
3354 
3355    Not Collective
3356 
3357    Input Parameter:
3358 .  snes - the SNES context
3359 
3360    Output Parameter:
3361 .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3362             manual pages for the individual convergence tests for complete lists
3363 
3364    Level: intermediate
3365 
3366    Notes: Can only be called after the call the SNESSolve() is complete.
3367 
3368 .keywords: SNES, nonlinear, set, convergence, test
3369 
3370 .seealso: SNESSetConvergenceTest(), SNESConvergedReason
3371 @*/
3372 PetscErrorCode  SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
3373 {
3374   PetscFunctionBegin;
3375   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3376   PetscValidPointer(reason,2);
3377   *reason = snes->reason;
3378   PetscFunctionReturn(0);
3379 }
3380 
3381 #undef __FUNCT__
3382 #define __FUNCT__ "SNESSetConvergenceHistory"
3383 /*@
3384    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.
3385 
3386    Logically Collective on SNES
3387 
3388    Input Parameters:
3389 +  snes - iterative context obtained from SNESCreate()
3390 .  a   - array to hold history, this array will contain the function norms computed at each step
3391 .  its - integer array holds the number of linear iterations for each solve.
3392 .  na  - size of a and its
3393 -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
3394            else it continues storing new values for new nonlinear solves after the old ones
3395 
3396    Notes:
3397    If 'a' and 'its' are PETSC_NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
3398    default array of length 10000 is allocated.
3399 
3400    This routine is useful, e.g., when running a code for purposes
3401    of accurate performance monitoring, when no I/O should be done
3402    during the section of code that is being timed.
3403 
3404    Level: intermediate
3405 
3406 .keywords: SNES, set, convergence, history
3407 
3408 .seealso: SNESGetConvergenceHistory()
3409 
3410 @*/
3411 PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool  reset)
3412 {
3413   PetscErrorCode ierr;
3414 
3415   PetscFunctionBegin;
3416   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3417   if (na)  PetscValidScalarPointer(a,2);
3418   if (its) PetscValidIntPointer(its,3);
3419   if (na == PETSC_DECIDE || na == PETSC_DEFAULT || !a) {
3420     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
3421     ierr = PetscMalloc(na*sizeof(PetscReal),&a);CHKERRQ(ierr);
3422     ierr = PetscMalloc(na*sizeof(PetscInt),&its);CHKERRQ(ierr);
3423     snes->conv_malloc   = PETSC_TRUE;
3424   }
3425   snes->conv_hist       = a;
3426   snes->conv_hist_its   = its;
3427   snes->conv_hist_max   = na;
3428   snes->conv_hist_len   = 0;
3429   snes->conv_hist_reset = reset;
3430   PetscFunctionReturn(0);
3431 }
3432 
3433 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3434 #include <engine.h>   /* MATLAB include file */
3435 #include <mex.h>      /* MATLAB include file */
3436 EXTERN_C_BEGIN
3437 #undef __FUNCT__
3438 #define __FUNCT__ "SNESGetConvergenceHistoryMatlab"
3439 mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
3440 {
3441   mxArray   *mat;
3442   PetscInt  i;
3443   PetscReal *ar;
3444 
3445   PetscFunctionBegin;
3446   mat  = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
3447   ar   = (PetscReal*) mxGetData(mat);
3448   for (i=0; i<snes->conv_hist_len; i++) {
3449     ar[i] = snes->conv_hist[i];
3450   }
3451   PetscFunctionReturn(mat);
3452 }
3453 EXTERN_C_END
3454 #endif
3455 
3456 
3457 #undef __FUNCT__
3458 #define __FUNCT__ "SNESGetConvergenceHistory"
3459 /*@C
3460    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.
3461 
3462    Not Collective
3463 
3464    Input Parameter:
3465 .  snes - iterative context obtained from SNESCreate()
3466 
3467    Output Parameters:
3468 .  a   - array to hold history
3469 .  its - integer array holds the number of linear iterations (or
3470          negative if not converged) for each solve.
3471 -  na  - size of a and its
3472 
3473    Notes:
3474     The calling sequence for this routine in Fortran is
3475 $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
3476 
3477    This routine is useful, e.g., when running a code for purposes
3478    of accurate performance monitoring, when no I/O should be done
3479    during the section of code that is being timed.
3480 
3481    Level: intermediate
3482 
3483 .keywords: SNES, get, convergence, history
3484 
3485 .seealso: SNESSetConvergencHistory()
3486 
3487 @*/
3488 PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
3489 {
3490   PetscFunctionBegin;
3491   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3492   if (a)   *a   = snes->conv_hist;
3493   if (its) *its = snes->conv_hist_its;
3494   if (na)  *na  = snes->conv_hist_len;
3495   PetscFunctionReturn(0);
3496 }
3497 
3498 #undef __FUNCT__
3499 #define __FUNCT__ "SNESSetUpdate"
3500 /*@C
3501   SNESSetUpdate - Sets the general-purpose update function called
3502   at the beginning of every iteration of the nonlinear solve. Specifically
3503   it is called just before the Jacobian is "evaluated".
3504 
3505   Logically Collective on SNES
3506 
3507   Input Parameters:
3508 . snes - The nonlinear solver context
3509 . func - The function
3510 
3511   Calling sequence of func:
3512 . func (SNES snes, PetscInt step);
3513 
3514 . step - The current step of the iteration
3515 
3516   Level: advanced
3517 
3518   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()
3519         This is not used by most users.
3520 
3521 .keywords: SNES, update
3522 
3523 .seealso SNESDefaultUpdate(), SNESSetJacobian(), SNESSolve()
3524 @*/
3525 PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
3526 {
3527   PetscFunctionBegin;
3528   PetscValidHeaderSpecific(snes, SNES_CLASSID,1);
3529   snes->ops->update = func;
3530   PetscFunctionReturn(0);
3531 }
3532 
3533 #undef __FUNCT__
3534 #define __FUNCT__ "SNESDefaultUpdate"
3535 /*@
3536   SNESDefaultUpdate - The default update function which does nothing.
3537 
3538   Not collective
3539 
3540   Input Parameters:
3541 . snes - The nonlinear solver context
3542 . step - The current step of the iteration
3543 
3544   Level: intermediate
3545 
3546 .keywords: SNES, update
3547 .seealso SNESSetUpdate(), SNESDefaultRhsBC(), SNESDefaultShortolutionBC()
3548 @*/
3549 PetscErrorCode  SNESDefaultUpdate(SNES snes, PetscInt step)
3550 {
3551   PetscFunctionBegin;
3552   PetscFunctionReturn(0);
3553 }
3554 
3555 #undef __FUNCT__
3556 #define __FUNCT__ "SNESScaleStep_Private"
3557 /*
3558    SNESScaleStep_Private - Scales a step so that its length is less than the
3559    positive parameter delta.
3560 
3561     Input Parameters:
3562 +   snes - the SNES context
3563 .   y - approximate solution of linear system
3564 .   fnorm - 2-norm of current function
3565 -   delta - trust region size
3566 
3567     Output Parameters:
3568 +   gpnorm - predicted function norm at the new point, assuming local
3569     linearization.  The value is zero if the step lies within the trust
3570     region, and exceeds zero otherwise.
3571 -   ynorm - 2-norm of the step
3572 
3573     Note:
3574     For non-trust region methods such as SNESNEWTONLS, the parameter delta
3575     is set to be the maximum allowable step size.
3576 
3577 .keywords: SNES, nonlinear, scale, step
3578 */
3579 PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
3580 {
3581   PetscReal      nrm;
3582   PetscScalar    cnorm;
3583   PetscErrorCode ierr;
3584 
3585   PetscFunctionBegin;
3586   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3587   PetscValidHeaderSpecific(y,VEC_CLASSID,2);
3588   PetscCheckSameComm(snes,1,y,2);
3589 
3590   ierr = VecNorm(y,NORM_2,&nrm);CHKERRQ(ierr);
3591   if (nrm > *delta) {
3592      nrm = *delta/nrm;
3593      *gpnorm = (1.0 - nrm)*(*fnorm);
3594      cnorm = nrm;
3595      ierr = VecScale(y,cnorm);CHKERRQ(ierr);
3596      *ynorm = *delta;
3597   } else {
3598      *gpnorm = 0.0;
3599      *ynorm = nrm;
3600   }
3601   PetscFunctionReturn(0);
3602 }
3603 
3604 #undef __FUNCT__
3605 #define __FUNCT__ "SNESSolve"
3606 /*@C
3607    SNESSolve - Solves a nonlinear system F(x) = b.
3608    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3609 
3610    Collective on SNES
3611 
3612    Input Parameters:
3613 +  snes - the SNES context
3614 .  b - the constant part of the equation F(x) = b, or PETSC_NULL to use zero.
3615 -  x - the solution vector.
3616 
3617    Notes:
3618    The user should initialize the vector,x, with the initial guess
3619    for the nonlinear solve prior to calling SNESSolve.  In particular,
3620    to employ an initial guess of zero, the user should explicitly set
3621    this vector to zero by calling VecSet().
3622 
3623    Level: beginner
3624 
3625 .keywords: SNES, nonlinear, solve
3626 
3627 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3628 @*/
3629 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3630 {
3631   PetscErrorCode    ierr;
3632   PetscBool         flg;
3633   PetscViewer       viewer;
3634   PetscInt          grid;
3635   Vec               xcreated = PETSC_NULL;
3636   DM                dm;
3637   PetscViewerFormat format;
3638 
3639   PetscFunctionBegin;
3640   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3641   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3642   if (x) PetscCheckSameComm(snes,1,x,3);
3643   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3644   if (b) PetscCheckSameComm(snes,1,b,2);
3645 
3646   if (!x) {
3647     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3648     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3649     x    = xcreated;
3650   }
3651 
3652   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm));CHKERRQ(ierr);}
3653   for (grid=0; grid<snes->gridsequence+1; grid++) {
3654 
3655     /* set solution vector */
3656     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3657     ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3658     snes->vec_sol = x;
3659     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3660 
3661     /* set affine vector if provided */
3662     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3663     ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3664     snes->vec_rhs = b;
3665 
3666     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3667 
3668     if (!grid) {
3669       if (snes->ops->computeinitialguess) {
3670         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3671       }
3672     }
3673 
3674     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3675     snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;
3676 
3677     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3678     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3679     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3680     if (snes->domainerror){
3681       snes->reason      = SNES_DIVERGED_FUNCTION_DOMAIN;
3682       snes->domainerror = PETSC_FALSE;
3683     }
3684     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3685 
3686     flg  = PETSC_FALSE;
3687     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,PETSC_NULL);CHKERRQ(ierr);
3688     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
3689     if (snes->printreason) {
3690       ierr = PetscViewerASCIIAddTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3691       if (snes->reason > 0) {
3692         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3693       } else {
3694         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3695       }
3696       ierr = PetscViewerASCIISubtractTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3697     }
3698 
3699     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
3700     if (grid <  snes->gridsequence) {
3701       DM  fine;
3702       Vec xnew;
3703       Mat interp;
3704 
3705       ierr = DMRefine(snes->dm,((PetscObject)snes)->comm,&fine);CHKERRQ(ierr);
3706       if (!fine) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
3707       ierr = DMCreateInterpolation(snes->dm,fine,&interp,PETSC_NULL);CHKERRQ(ierr);
3708       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
3709       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
3710       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
3711       ierr = MatDestroy(&interp);CHKERRQ(ierr);
3712       x    = xnew;
3713 
3714       ierr = SNESReset(snes);CHKERRQ(ierr);
3715       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
3716       ierr = DMDestroy(&fine);CHKERRQ(ierr);
3717       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm));CHKERRQ(ierr);
3718     }
3719   }
3720   /* monitoring and viewing */
3721   ierr = PetscOptionsGetViewer(((PetscObject)snes)->comm,((PetscObject)snes)->prefix,"-snes_view",&viewer,&format,&flg);CHKERRQ(ierr);
3722   if (flg && !PetscPreLoadingOn) {
3723     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
3724     ierr = SNESView(snes,viewer);CHKERRQ(ierr);
3725     ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
3726     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3727   }
3728   ierr = VecViewFromOptions(snes->vec_sol,"-snes_view_solution");CHKERRQ(ierr);
3729 
3730   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
3731   PetscFunctionReturn(0);
3732 }
3733 
3734 /* --------- Internal routines for SNES Package --------- */
3735 
3736 #undef __FUNCT__
3737 #define __FUNCT__ "SNESSetType"
3738 /*@C
3739    SNESSetType - Sets the method for the nonlinear solver.
3740 
3741    Collective on SNES
3742 
3743    Input Parameters:
3744 +  snes - the SNES context
3745 -  type - a known method
3746 
3747    Options Database Key:
3748 .  -snes_type <type> - Sets the method; use -help for a list
3749    of available methods (for instance, newtonls or newtontr)
3750 
3751    Notes:
3752    See "petsc/include/petscsnes.h" for available methods (for instance)
3753 +    SNESNEWTONLS - Newton's method with line search
3754      (systems of nonlinear equations)
3755 .    SNESNEWTONTR - Newton's method with trust region
3756      (systems of nonlinear equations)
3757 
3758   Normally, it is best to use the SNESSetFromOptions() command and then
3759   set the SNES solver type from the options database rather than by using
3760   this routine.  Using the options database provides the user with
3761   maximum flexibility in evaluating the many nonlinear solvers.
3762   The SNESSetType() routine is provided for those situations where it
3763   is necessary to set the nonlinear solver independently of the command
3764   line or options database.  This might be the case, for example, when
3765   the choice of solver changes during the execution of the program,
3766   and the user's application is taking responsibility for choosing the
3767   appropriate method.
3768 
3769   Level: intermediate
3770 
3771 .keywords: SNES, set, type
3772 
3773 .seealso: SNESType, SNESCreate()
3774 
3775 @*/
3776 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
3777 {
3778   PetscErrorCode ierr,(*r)(SNES);
3779   PetscBool      match;
3780 
3781   PetscFunctionBegin;
3782   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3783   PetscValidCharPointer(type,2);
3784 
3785   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
3786   if (match) PetscFunctionReturn(0);
3787 
3788   ierr =  PetscFListFind(SNESList,((PetscObject)snes)->comm,type,PETSC_TRUE,(void (**)(void)) &r);CHKERRQ(ierr);
3789   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
3790   /* Destroy the previous private SNES context */
3791   if (snes->ops->destroy) {
3792     ierr = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
3793     snes->ops->destroy = PETSC_NULL;
3794   }
3795   /* Reinitialize function pointers in SNESOps structure */
3796   snes->ops->setup          = 0;
3797   snes->ops->solve          = 0;
3798   snes->ops->view           = 0;
3799   snes->ops->setfromoptions = 0;
3800   snes->ops->destroy        = 0;
3801   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
3802   snes->setupcalled = PETSC_FALSE;
3803   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
3804   ierr = (*r)(snes);CHKERRQ(ierr);
3805 #if defined(PETSC_HAVE_AMS)
3806   if (PetscAMSPublishAll) {
3807     ierr = PetscObjectAMSPublish((PetscObject)snes);CHKERRQ(ierr);
3808   }
3809 #endif
3810   PetscFunctionReturn(0);
3811 }
3812 
3813 
3814 /* --------------------------------------------------------------------- */
3815 #undef __FUNCT__
3816 #define __FUNCT__ "SNESRegisterDestroy"
3817 /*@
3818    SNESRegisterDestroy - Frees the list of nonlinear solvers that were
3819    registered by SNESRegisterDynamic().
3820 
3821    Not Collective
3822 
3823    Level: advanced
3824 
3825 .keywords: SNES, nonlinear, register, destroy
3826 
3827 .seealso: SNESRegisterAll()
3828 @*/
3829 PetscErrorCode  SNESRegisterDestroy(void)
3830 {
3831   PetscErrorCode ierr;
3832 
3833   PetscFunctionBegin;
3834   ierr = PetscFListDestroy(&SNESList);CHKERRQ(ierr);
3835   SNESRegisterAllCalled = PETSC_FALSE;
3836   PetscFunctionReturn(0);
3837 }
3838 
3839 #undef __FUNCT__
3840 #define __FUNCT__ "SNESGetType"
3841 /*@C
3842    SNESGetType - Gets the SNES method type and name (as a string).
3843 
3844    Not Collective
3845 
3846    Input Parameter:
3847 .  snes - nonlinear solver context
3848 
3849    Output Parameter:
3850 .  type - SNES method (a character string)
3851 
3852    Level: intermediate
3853 
3854 .keywords: SNES, nonlinear, get, type, name
3855 @*/
3856 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
3857 {
3858   PetscFunctionBegin;
3859   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3860   PetscValidPointer(type,2);
3861   *type = ((PetscObject)snes)->type_name;
3862   PetscFunctionReturn(0);
3863 }
3864 
3865 #undef __FUNCT__
3866 #define __FUNCT__ "SNESGetSolution"
3867 /*@
3868    SNESGetSolution - Returns the vector where the approximate solution is
3869    stored. This is the fine grid solution when using SNESSetGridSequence().
3870 
3871    Not Collective, but Vec is parallel if SNES is parallel
3872 
3873    Input Parameter:
3874 .  snes - the SNES context
3875 
3876    Output Parameter:
3877 .  x - the solution
3878 
3879    Level: intermediate
3880 
3881 .keywords: SNES, nonlinear, get, solution
3882 
3883 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
3884 @*/
3885 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
3886 {
3887   PetscFunctionBegin;
3888   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3889   PetscValidPointer(x,2);
3890   *x = snes->vec_sol;
3891   PetscFunctionReturn(0);
3892 }
3893 
3894 #undef __FUNCT__
3895 #define __FUNCT__ "SNESGetSolutionUpdate"
3896 /*@
3897    SNESGetSolutionUpdate - Returns the vector where the solution update is
3898    stored.
3899 
3900    Not Collective, but Vec is parallel if SNES is parallel
3901 
3902    Input Parameter:
3903 .  snes - the SNES context
3904 
3905    Output Parameter:
3906 .  x - the solution update
3907 
3908    Level: advanced
3909 
3910 .keywords: SNES, nonlinear, get, solution, update
3911 
3912 .seealso: SNESGetSolution(), SNESGetFunction()
3913 @*/
3914 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
3915 {
3916   PetscFunctionBegin;
3917   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3918   PetscValidPointer(x,2);
3919   *x = snes->vec_sol_update;
3920   PetscFunctionReturn(0);
3921 }
3922 
3923 #undef __FUNCT__
3924 #define __FUNCT__ "SNESGetFunction"
3925 /*@C
3926    SNESGetFunction - Returns the vector where the function is stored.
3927 
3928    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
3929 
3930    Input Parameter:
3931 .  snes - the SNES context
3932 
3933    Output Parameter:
3934 +  r - the function (or PETSC_NULL)
3935 .  func - the function (or PETSC_NULL)
3936 -  ctx - the function context (or PETSC_NULL)
3937 
3938    Level: advanced
3939 
3940 .keywords: SNES, nonlinear, get, function
3941 
3942 .seealso: SNESSetFunction(), SNESGetSolution()
3943 @*/
3944 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**func)(SNES,Vec,Vec,void*),void **ctx)
3945 {
3946   PetscErrorCode ierr;
3947   DM             dm;
3948 
3949   PetscFunctionBegin;
3950   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3951   if (r) {
3952     if (!snes->vec_func) {
3953       if (snes->vec_rhs) {
3954         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
3955       } else if (snes->vec_sol) {
3956         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
3957       } else if (snes->dm) {
3958         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
3959       }
3960     }
3961     *r = snes->vec_func;
3962   }
3963   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3964   ierr = DMSNESGetFunction(dm,func,ctx);CHKERRQ(ierr);
3965   PetscFunctionReturn(0);
3966 }
3967 
3968 /*@C
3969    SNESGetGS - Returns the GS function and context.
3970 
3971    Input Parameter:
3972 .  snes - the SNES context
3973 
3974    Output Parameter:
3975 +  gsfunc - the function (or PETSC_NULL)
3976 -  ctx    - the function context (or PETSC_NULL)
3977 
3978    Level: advanced
3979 
3980 .keywords: SNES, nonlinear, get, function
3981 
3982 .seealso: SNESSetGS(), SNESGetFunction()
3983 @*/
3984 
3985 #undef __FUNCT__
3986 #define __FUNCT__ "SNESGetGS"
3987 PetscErrorCode SNESGetGS (SNES snes, PetscErrorCode(**func)(SNES, Vec, Vec, void*), void ** ctx)
3988 {
3989   PetscErrorCode ierr;
3990   DM             dm;
3991 
3992   PetscFunctionBegin;
3993   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3994   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3995   ierr = DMSNESGetGS(dm,func,ctx);CHKERRQ(ierr);
3996   PetscFunctionReturn(0);
3997 }
3998 
3999 #undef __FUNCT__
4000 #define __FUNCT__ "SNESSetOptionsPrefix"
4001 /*@C
4002    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4003    SNES options in the database.
4004 
4005    Logically Collective on SNES
4006 
4007    Input Parameter:
4008 +  snes - the SNES context
4009 -  prefix - the prefix to prepend to all option names
4010 
4011    Notes:
4012    A hyphen (-) must NOT be given at the beginning of the prefix name.
4013    The first character of all runtime options is AUTOMATICALLY the hyphen.
4014 
4015    Level: advanced
4016 
4017 .keywords: SNES, set, options, prefix, database
4018 
4019 .seealso: SNESSetFromOptions()
4020 @*/
4021 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4022 {
4023   PetscErrorCode ierr;
4024 
4025   PetscFunctionBegin;
4026   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4027   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4028   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4029   if (snes->linesearch) {
4030     ierr = SNESGetSNESLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4031     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4032   }
4033   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4034   PetscFunctionReturn(0);
4035 }
4036 
4037 #undef __FUNCT__
4038 #define __FUNCT__ "SNESAppendOptionsPrefix"
4039 /*@C
4040    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4041    SNES options in the database.
4042 
4043    Logically Collective on SNES
4044 
4045    Input Parameters:
4046 +  snes - the SNES context
4047 -  prefix - the prefix to prepend to all option names
4048 
4049    Notes:
4050    A hyphen (-) must NOT be given at the beginning of the prefix name.
4051    The first character of all runtime options is AUTOMATICALLY the hyphen.
4052 
4053    Level: advanced
4054 
4055 .keywords: SNES, append, options, prefix, database
4056 
4057 .seealso: SNESGetOptionsPrefix()
4058 @*/
4059 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4060 {
4061   PetscErrorCode ierr;
4062 
4063   PetscFunctionBegin;
4064   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4065   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4066   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4067   if (snes->linesearch) {
4068     ierr = SNESGetSNESLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4069     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4070   }
4071   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4072   PetscFunctionReturn(0);
4073 }
4074 
4075 #undef __FUNCT__
4076 #define __FUNCT__ "SNESGetOptionsPrefix"
4077 /*@C
4078    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4079    SNES options in the database.
4080 
4081    Not Collective
4082 
4083    Input Parameter:
4084 .  snes - the SNES context
4085 
4086    Output Parameter:
4087 .  prefix - pointer to the prefix string used
4088 
4089    Notes: On the fortran side, the user should pass in a string 'prefix' of
4090    sufficient length to hold the prefix.
4091 
4092    Level: advanced
4093 
4094 .keywords: SNES, get, options, prefix, database
4095 
4096 .seealso: SNESAppendOptionsPrefix()
4097 @*/
4098 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4099 {
4100   PetscErrorCode ierr;
4101 
4102   PetscFunctionBegin;
4103   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4104   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4105   PetscFunctionReturn(0);
4106 }
4107 
4108 
4109 #undef __FUNCT__
4110 #define __FUNCT__ "SNESRegister"
4111 /*@C
4112   SNESRegister - See SNESRegisterDynamic()
4113 
4114   Level: advanced
4115 @*/
4116 PetscErrorCode  SNESRegister(const char sname[],const char path[],const char name[],PetscErrorCode (*function)(SNES))
4117 {
4118   char           fullname[PETSC_MAX_PATH_LEN];
4119   PetscErrorCode ierr;
4120 
4121   PetscFunctionBegin;
4122   ierr = PetscFListConcat(path,name,fullname);CHKERRQ(ierr);
4123   ierr = PetscFListAdd(&SNESList,sname,fullname,(void (*)(void))function);CHKERRQ(ierr);
4124   PetscFunctionReturn(0);
4125 }
4126 
4127 #undef __FUNCT__
4128 #define __FUNCT__ "SNESTestLocalMin"
4129 PetscErrorCode  SNESTestLocalMin(SNES snes)
4130 {
4131   PetscErrorCode ierr;
4132   PetscInt       N,i,j;
4133   Vec            u,uh,fh;
4134   PetscScalar    value;
4135   PetscReal      norm;
4136 
4137   PetscFunctionBegin;
4138   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4139   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4140   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4141 
4142   /* currently only works for sequential */
4143   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");CHKERRQ(ierr);
4144   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4145   for (i=0; i<N; i++) {
4146     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4147     ierr  = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4148     for (j=-10; j<11; j++) {
4149       value = PetscSign(j)*exp(PetscAbs(j)-10.0);
4150       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4151       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4152       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4153       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4154       value = -value;
4155       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4156     }
4157   }
4158   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4159   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4160   PetscFunctionReturn(0);
4161 }
4162 
4163 #undef __FUNCT__
4164 #define __FUNCT__ "SNESKSPSetUseEW"
4165 /*@
4166    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4167    computing relative tolerance for linear solvers within an inexact
4168    Newton method.
4169 
4170    Logically Collective on SNES
4171 
4172    Input Parameters:
4173 +  snes - SNES context
4174 -  flag - PETSC_TRUE or PETSC_FALSE
4175 
4176     Options Database:
4177 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4178 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4179 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4180 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4181 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4182 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4183 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4184 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4185 
4186    Notes:
4187    Currently, the default is to use a constant relative tolerance for
4188    the inner linear solvers.  Alternatively, one can use the
4189    Eisenstat-Walker method, where the relative convergence tolerance
4190    is reset at each Newton iteration according progress of the nonlinear
4191    solver.
4192 
4193    Level: advanced
4194 
4195    Reference:
4196    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4197    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4198 
4199 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4200 
4201 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4202 @*/
4203 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool  flag)
4204 {
4205   PetscFunctionBegin;
4206   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4207   PetscValidLogicalCollectiveBool(snes,flag,2);
4208   snes->ksp_ewconv = flag;
4209   PetscFunctionReturn(0);
4210 }
4211 
4212 #undef __FUNCT__
4213 #define __FUNCT__ "SNESKSPGetUseEW"
4214 /*@
4215    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4216    for computing relative tolerance for linear solvers within an
4217    inexact Newton method.
4218 
4219    Not Collective
4220 
4221    Input Parameter:
4222 .  snes - SNES context
4223 
4224    Output Parameter:
4225 .  flag - PETSC_TRUE or PETSC_FALSE
4226 
4227    Notes:
4228    Currently, the default is to use a constant relative tolerance for
4229    the inner linear solvers.  Alternatively, one can use the
4230    Eisenstat-Walker method, where the relative convergence tolerance
4231    is reset at each Newton iteration according progress of the nonlinear
4232    solver.
4233 
4234    Level: advanced
4235 
4236    Reference:
4237    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4238    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4239 
4240 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4241 
4242 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4243 @*/
4244 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4245 {
4246   PetscFunctionBegin;
4247   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4248   PetscValidPointer(flag,2);
4249   *flag = snes->ksp_ewconv;
4250   PetscFunctionReturn(0);
4251 }
4252 
4253 #undef __FUNCT__
4254 #define __FUNCT__ "SNESKSPSetParametersEW"
4255 /*@
4256    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4257    convergence criteria for the linear solvers within an inexact
4258    Newton method.
4259 
4260    Logically Collective on SNES
4261 
4262    Input Parameters:
4263 +    snes - SNES context
4264 .    version - version 1, 2 (default is 2) or 3
4265 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4266 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4267 .    gamma - multiplicative factor for version 2 rtol computation
4268              (0 <= gamma2 <= 1)
4269 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4270 .    alpha2 - power for safeguard
4271 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4272 
4273    Note:
4274    Version 3 was contributed by Luis Chacon, June 2006.
4275 
4276    Use PETSC_DEFAULT to retain the default for any of the parameters.
4277 
4278    Level: advanced
4279 
4280    Reference:
4281    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4282    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4283    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4284 
4285 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4286 
4287 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4288 @*/
4289 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,
4290 							    PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4291 {
4292   SNESKSPEW *kctx;
4293   PetscFunctionBegin;
4294   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4295   kctx = (SNESKSPEW*)snes->kspconvctx;
4296   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4297   PetscValidLogicalCollectiveInt(snes,version,2);
4298   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4299   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4300   PetscValidLogicalCollectiveReal(snes,gamma,5);
4301   PetscValidLogicalCollectiveReal(snes,alpha,6);
4302   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4303   PetscValidLogicalCollectiveReal(snes,threshold,8);
4304 
4305   if (version != PETSC_DEFAULT)   kctx->version   = version;
4306   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4307   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4308   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4309   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4310   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4311   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4312 
4313   if (kctx->version < 1 || kctx->version > 3) {
4314     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 and 3 are supported: %D",kctx->version);
4315   }
4316   if (kctx->rtol_0 < 0.0 || kctx->rtol_0 >= 1.0) {
4317     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_0 < 1.0: %G",kctx->rtol_0);
4318   }
4319   if (kctx->rtol_max < 0.0 || kctx->rtol_max >= 1.0) {
4320     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_max (%G) < 1.0\n",kctx->rtol_max);
4321   }
4322   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) {
4323     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%G) <= 1.0\n",kctx->gamma);
4324   }
4325   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) {
4326     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%G) <= 2.0\n",kctx->alpha);
4327   }
4328   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) {
4329     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%G) < 1.0\n",kctx->threshold);
4330   }
4331   PetscFunctionReturn(0);
4332 }
4333 
4334 #undef __FUNCT__
4335 #define __FUNCT__ "SNESKSPGetParametersEW"
4336 /*@
4337    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4338    convergence criteria for the linear solvers within an inexact
4339    Newton method.
4340 
4341    Not Collective
4342 
4343    Input Parameters:
4344      snes - SNES context
4345 
4346    Output Parameters:
4347 +    version - version 1, 2 (default is 2) or 3
4348 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4349 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4350 .    gamma - multiplicative factor for version 2 rtol computation
4351              (0 <= gamma2 <= 1)
4352 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4353 .    alpha2 - power for safeguard
4354 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4355 
4356    Level: advanced
4357 
4358 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4359 
4360 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4361 @*/
4362 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,
4363 							    PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4364 {
4365   SNESKSPEW *kctx;
4366   PetscFunctionBegin;
4367   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4368   kctx = (SNESKSPEW*)snes->kspconvctx;
4369   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4370   if (version)   *version   = kctx->version;
4371   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4372   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4373   if (gamma)     *gamma     = kctx->gamma;
4374   if (alpha)     *alpha     = kctx->alpha;
4375   if (alpha2)    *alpha2    = kctx->alpha2;
4376   if (threshold) *threshold = kctx->threshold;
4377   PetscFunctionReturn(0);
4378 }
4379 
4380 #undef __FUNCT__
4381 #define __FUNCT__ "SNESKSPEW_PreSolve"
4382 static PetscErrorCode SNESKSPEW_PreSolve(SNES snes, KSP ksp, Vec b, Vec x)
4383 {
4384   PetscErrorCode ierr;
4385   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4386   PetscReal      rtol=PETSC_DEFAULT,stol;
4387 
4388   PetscFunctionBegin;
4389   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context exists");
4390   if (!snes->iter) { /* first time in, so use the original user rtol */
4391     rtol = kctx->rtol_0;
4392   } else {
4393     if (kctx->version == 1) {
4394       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4395       if (rtol < 0.0) rtol = -rtol;
4396       stol = pow(kctx->rtol_last,kctx->alpha2);
4397       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4398     } else if (kctx->version == 2) {
4399       rtol = kctx->gamma * pow(snes->norm/kctx->norm_last,kctx->alpha);
4400       stol = kctx->gamma * pow(kctx->rtol_last,kctx->alpha);
4401       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4402     } else if (kctx->version == 3) {/* contributed by Luis Chacon, June 2006. */
4403       rtol = kctx->gamma * pow(snes->norm/kctx->norm_last,kctx->alpha);
4404       /* safeguard: avoid sharp decrease of rtol */
4405       stol = kctx->gamma*pow(kctx->rtol_last,kctx->alpha);
4406       stol = PetscMax(rtol,stol);
4407       rtol = PetscMin(kctx->rtol_0,stol);
4408       /* safeguard: avoid oversolving */
4409       stol = kctx->gamma*(snes->ttol)/snes->norm;
4410       stol = PetscMax(rtol,stol);
4411       rtol = PetscMin(kctx->rtol_0,stol);
4412     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4413   }
4414   /* safeguard: avoid rtol greater than one */
4415   rtol = PetscMin(rtol,kctx->rtol_max);
4416   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4417   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%G\n",snes->iter,kctx->version,rtol);CHKERRQ(ierr);
4418   PetscFunctionReturn(0);
4419 }
4420 
4421 #undef __FUNCT__
4422 #define __FUNCT__ "SNESKSPEW_PostSolve"
4423 static PetscErrorCode SNESKSPEW_PostSolve(SNES snes, KSP ksp, Vec b, Vec x)
4424 {
4425   PetscErrorCode ierr;
4426   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4427   PCSide         pcside;
4428   Vec            lres;
4429 
4430   PetscFunctionBegin;
4431   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context exists");
4432   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4433   ierr = SNESGetFunctionNorm(snes,&kctx->norm_last);CHKERRQ(ierr);
4434   if (kctx->version == 1) {
4435     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4436     if (pcside == PC_RIGHT) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4437       /* KSP residual is true linear residual */
4438       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4439     } else {
4440       /* KSP residual is preconditioned residual */
4441       /* compute true linear residual norm */
4442       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4443       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4444       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4445       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4446       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4447     }
4448   }
4449   PetscFunctionReturn(0);
4450 }
4451 
4452 #undef __FUNCT__
4453 #define __FUNCT__ "SNES_KSPSolve"
4454 PetscErrorCode SNES_KSPSolve(SNES snes, KSP ksp, Vec b, Vec x)
4455 {
4456   PetscErrorCode ierr;
4457 
4458   PetscFunctionBegin;
4459   if (snes->ksp_ewconv) { ierr = SNESKSPEW_PreSolve(snes,ksp,b,x);CHKERRQ(ierr);  }
4460   ierr = KSPSolve(ksp,b,x);CHKERRQ(ierr);
4461   if (snes->ksp_ewconv) { ierr = SNESKSPEW_PostSolve(snes,ksp,b,x);CHKERRQ(ierr); }
4462   PetscFunctionReturn(0);
4463 }
4464 
4465 #include <petsc-private/dmimpl.h>
4466 #undef __FUNCT__
4467 #define __FUNCT__ "SNESSetDM"
4468 /*@
4469    SNESSetDM - Sets the DM that may be used by some preconditioners
4470 
4471    Logically Collective on SNES
4472 
4473    Input Parameters:
4474 +  snes - the preconditioner context
4475 -  dm - the dm
4476 
4477    Level: intermediate
4478 
4479 
4480 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4481 @*/
4482 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4483 {
4484   PetscErrorCode ierr;
4485   KSP            ksp;
4486   DMSNES         sdm;
4487 
4488   PetscFunctionBegin;
4489   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4490   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4491   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4492     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4493       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4494       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4495       if (sdm->originaldm == snes->dm) { /* Grant write privileges to the replacement DM */
4496         sdm->originaldm = dm;
4497       }
4498     }
4499     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4500   }
4501   snes->dm = dm;
4502   snes->dmAuto = PETSC_FALSE;
4503   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4504   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4505   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4506   if (snes->pc) {
4507     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4508     ierr = SNESSetPCSide(snes,snes->pcside);CHKERRQ(ierr);
4509   }
4510   PetscFunctionReturn(0);
4511 }
4512 
4513 #undef __FUNCT__
4514 #define __FUNCT__ "SNESGetDM"
4515 /*@
4516    SNESGetDM - Gets the DM that may be used by some preconditioners
4517 
4518    Not Collective but DM obtained is parallel on SNES
4519 
4520    Input Parameter:
4521 . snes - the preconditioner context
4522 
4523    Output Parameter:
4524 .  dm - the dm
4525 
4526    Level: intermediate
4527 
4528 
4529 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4530 @*/
4531 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4532 {
4533   PetscErrorCode ierr;
4534 
4535   PetscFunctionBegin;
4536   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4537   if (!snes->dm) {
4538     ierr = DMShellCreate(((PetscObject)snes)->comm,&snes->dm);CHKERRQ(ierr);
4539     snes->dmAuto = PETSC_TRUE;
4540   }
4541   *dm = snes->dm;
4542   PetscFunctionReturn(0);
4543 }
4544 
4545 #undef __FUNCT__
4546 #define __FUNCT__ "SNESSetPC"
4547 /*@
4548   SNESSetPC - Sets the nonlinear preconditioner to be used.
4549 
4550   Collective on SNES
4551 
4552   Input Parameters:
4553 + snes - iterative context obtained from SNESCreate()
4554 - pc   - the preconditioner object
4555 
4556   Notes:
4557   Use SNESGetPC() to retrieve the preconditioner context (for example,
4558   to configure it using the API).
4559 
4560   Level: developer
4561 
4562 .keywords: SNES, set, precondition
4563 .seealso: SNESGetPC()
4564 @*/
4565 PetscErrorCode SNESSetPC(SNES snes, SNES pc)
4566 {
4567   PetscErrorCode ierr;
4568 
4569   PetscFunctionBegin;
4570   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4571   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4572   PetscCheckSameComm(snes, 1, pc, 2);
4573   ierr = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4574   ierr = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4575   snes->pc = pc;
4576   ierr = PetscLogObjectParent(snes, snes->pc);CHKERRQ(ierr);
4577   PetscFunctionReturn(0);
4578 }
4579 
4580 #undef __FUNCT__
4581 #define __FUNCT__ "SNESGetPC"
4582 /*@
4583   SNESGetPC - Returns a pointer to the nonlinear preconditioning context set with SNESSetPC().
4584 
4585   Not Collective
4586 
4587   Input Parameter:
4588 . snes - iterative context obtained from SNESCreate()
4589 
4590   Output Parameter:
4591 . pc - preconditioner context
4592 
4593   Level: developer
4594 
4595 .keywords: SNES, get, preconditioner
4596 .seealso: SNESSetPC()
4597 @*/
4598 PetscErrorCode SNESGetPC(SNES snes, SNES *pc)
4599 {
4600   PetscErrorCode              ierr;
4601   const char                  *optionsprefix;
4602 
4603   PetscFunctionBegin;
4604   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4605   PetscValidPointer(pc, 2);
4606   if (!snes->pc) {
4607     ierr = SNESCreate(((PetscObject) snes)->comm,&snes->pc);CHKERRQ(ierr);
4608     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4609     ierr = PetscLogObjectParent(snes,snes->pc);CHKERRQ(ierr);
4610     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4611     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4612     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4613   }
4614   *pc = snes->pc;
4615   PetscFunctionReturn(0);
4616 }
4617 
4618 
4619 #undef __FUNCT__
4620 #define __FUNCT__ "SNESSetPCSide"
4621 /*@
4622     SNESSetPCSide - Sets the preconditioning side.
4623 
4624     Logically Collective on SNES
4625 
4626     Input Parameter:
4627 .   snes - iterative context obtained from SNESCreate()
4628 
4629     Output Parameter:
4630 .   side - the preconditioning side, where side is one of
4631 .vb
4632       PC_LEFT - left preconditioning (default)
4633       PC_RIGHT - right preconditioning
4634 .ve
4635 
4636     Options Database Keys:
4637 .   -snes_pc_side <right,left>
4638 
4639     Level: intermediate
4640 
4641 .keywords: SNES, set, right, left, side, preconditioner, flag
4642 
4643 .seealso: SNESGetPCSide(), KSPSetPCSide()
4644 @*/
4645 PetscErrorCode  SNESSetPCSide(SNES snes,PCSide side)
4646 {
4647   PetscFunctionBegin;
4648   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4649   PetscValidLogicalCollectiveEnum(snes,side,2);
4650   snes->pcside = side;
4651   PetscFunctionReturn(0);
4652 }
4653 
4654 #undef __FUNCT__
4655 #define __FUNCT__ "SNESGetPCSide"
4656 /*@
4657     SNESGetPCSide - Gets the preconditioning side.
4658 
4659     Not Collective
4660 
4661     Input Parameter:
4662 .   snes - iterative context obtained from SNESCreate()
4663 
4664     Output Parameter:
4665 .   side - the preconditioning side, where side is one of
4666 .vb
4667       PC_LEFT - left preconditioning (default)
4668       PC_RIGHT - right preconditioning
4669 .ve
4670 
4671     Level: intermediate
4672 
4673 .keywords: SNES, get, right, left, side, preconditioner, flag
4674 
4675 .seealso: SNESSetPCSide(), KSPGetPCSide()
4676 @*/
4677 PetscErrorCode  SNESGetPCSide(SNES snes,PCSide *side)
4678 {
4679   PetscFunctionBegin;
4680   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4681   PetscValidPointer(side,2);
4682   *side = snes->pcside;
4683   PetscFunctionReturn(0);
4684 }
4685 
4686 #undef __FUNCT__
4687 #define __FUNCT__ "SNESSetSNESLineSearch"
4688 /*@
4689   SNESSetSNESLineSearch - Sets the linesearch on the SNES instance.
4690 
4691   Collective on SNES
4692 
4693   Input Parameters:
4694 + snes - iterative context obtained from SNESCreate()
4695 - linesearch   - the linesearch object
4696 
4697   Notes:
4698   Use SNESGetSNESLineSearch() to retrieve the preconditioner context (for example,
4699   to configure it using the API).
4700 
4701   Level: developer
4702 
4703 .keywords: SNES, set, linesearch
4704 .seealso: SNESGetSNESLineSearch()
4705 @*/
4706 PetscErrorCode SNESSetSNESLineSearch(SNES snes, SNESLineSearch linesearch)
4707 {
4708   PetscErrorCode ierr;
4709 
4710   PetscFunctionBegin;
4711   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4712   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
4713   PetscCheckSameComm(snes, 1, linesearch, 2);
4714   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
4715   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
4716   snes->linesearch = linesearch;
4717   ierr = PetscLogObjectParent(snes, snes->linesearch);CHKERRQ(ierr);
4718   PetscFunctionReturn(0);
4719 }
4720 
4721 #undef __FUNCT__
4722 #define __FUNCT__ "SNESGetSNESLineSearch"
4723 /*@C
4724   SNESGetSNESLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
4725   or creates a default line search instance associated with the SNES and returns it.
4726 
4727   Not Collective
4728 
4729   Input Parameter:
4730 . snes - iterative context obtained from SNESCreate()
4731 
4732   Output Parameter:
4733 . linesearch - linesearch context
4734 
4735   Level: developer
4736 
4737 .keywords: SNES, get, linesearch
4738 .seealso: SNESSetSNESLineSearch()
4739 @*/
4740 PetscErrorCode SNESGetSNESLineSearch(SNES snes, SNESLineSearch *linesearch)
4741 {
4742   PetscErrorCode ierr;
4743   const char     *optionsprefix;
4744 
4745   PetscFunctionBegin;
4746   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4747   PetscValidPointer(linesearch, 2);
4748   if (!snes->linesearch) {
4749     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
4750     ierr = SNESLineSearchCreate(((PetscObject) snes)->comm, &snes->linesearch);CHKERRQ(ierr);
4751     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
4752     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
4753     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
4754     ierr = PetscLogObjectParent(snes, snes->linesearch);CHKERRQ(ierr);
4755   }
4756   *linesearch = snes->linesearch;
4757   PetscFunctionReturn(0);
4758 }
4759 
4760 #if defined(PETSC_HAVE_MATLAB_ENGINE)
4761 #include <mex.h>
4762 
4763 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
4764 
4765 #undef __FUNCT__
4766 #define __FUNCT__ "SNESComputeFunction_Matlab"
4767 /*
4768    SNESComputeFunction_Matlab - Calls the function that has been set with
4769                          SNESSetFunctionMatlab().
4770 
4771    Collective on SNES
4772 
4773    Input Parameters:
4774 +  snes - the SNES context
4775 -  x - input vector
4776 
4777    Output Parameter:
4778 .  y - function vector, as set by SNESSetFunction()
4779 
4780    Notes:
4781    SNESComputeFunction() is typically used within nonlinear solvers
4782    implementations, so most users would not generally call this routine
4783    themselves.
4784 
4785    Level: developer
4786 
4787 .keywords: SNES, nonlinear, compute, function
4788 
4789 .seealso: SNESSetFunction(), SNESGetFunction()
4790 */
4791 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
4792 {
4793   PetscErrorCode    ierr;
4794   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4795   int               nlhs = 1,nrhs = 5;
4796   mxArray	    *plhs[1],*prhs[5];
4797   long long int     lx = 0,ly = 0,ls = 0;
4798 
4799   PetscFunctionBegin;
4800   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4801   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4802   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
4803   PetscCheckSameComm(snes,1,x,2);
4804   PetscCheckSameComm(snes,1,y,3);
4805 
4806   /* call Matlab function in ctx with arguments x and y */
4807 
4808   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4809   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4810   ierr = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
4811   prhs[0] =  mxCreateDoubleScalar((double)ls);
4812   prhs[1] =  mxCreateDoubleScalar((double)lx);
4813   prhs[2] =  mxCreateDoubleScalar((double)ly);
4814   prhs[3] =  mxCreateString(sctx->funcname);
4815   prhs[4] =  sctx->ctx;
4816   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
4817   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
4818   mxDestroyArray(prhs[0]);
4819   mxDestroyArray(prhs[1]);
4820   mxDestroyArray(prhs[2]);
4821   mxDestroyArray(prhs[3]);
4822   mxDestroyArray(plhs[0]);
4823   PetscFunctionReturn(0);
4824 }
4825 
4826 
4827 #undef __FUNCT__
4828 #define __FUNCT__ "SNESSetFunctionMatlab"
4829 /*
4830    SNESSetFunctionMatlab - Sets the function evaluation routine and function
4831    vector for use by the SNES routines in solving systems of nonlinear
4832    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4833 
4834    Logically Collective on SNES
4835 
4836    Input Parameters:
4837 +  snes - the SNES context
4838 .  r - vector to store function value
4839 -  func - function evaluation routine
4840 
4841    Calling sequence of func:
4842 $    func (SNES snes,Vec x,Vec f,void *ctx);
4843 
4844 
4845    Notes:
4846    The Newton-like methods typically solve linear systems of the form
4847 $      f'(x) x = -f(x),
4848    where f'(x) denotes the Jacobian matrix and f(x) is the function.
4849 
4850    Level: beginner
4851 
4852 .keywords: SNES, nonlinear, set, function
4853 
4854 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4855 */
4856 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *func,mxArray *ctx)
4857 {
4858   PetscErrorCode    ierr;
4859   SNESMatlabContext *sctx;
4860 
4861   PetscFunctionBegin;
4862   /* currently sctx is memory bleed */
4863   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4864   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4865   /*
4866      This should work, but it doesn't
4867   sctx->ctx = ctx;
4868   mexMakeArrayPersistent(sctx->ctx);
4869   */
4870   sctx->ctx = mxDuplicateArray(ctx);
4871   ierr = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
4872   PetscFunctionReturn(0);
4873 }
4874 
4875 #undef __FUNCT__
4876 #define __FUNCT__ "SNESComputeJacobian_Matlab"
4877 /*
4878    SNESComputeJacobian_Matlab - Calls the function that has been set with
4879                          SNESSetJacobianMatlab().
4880 
4881    Collective on SNES
4882 
4883    Input Parameters:
4884 +  snes - the SNES context
4885 .  x - input vector
4886 .  A, B - the matrices
4887 -  ctx - user context
4888 
4889    Output Parameter:
4890 .  flag - structure of the matrix
4891 
4892    Level: developer
4893 
4894 .keywords: SNES, nonlinear, compute, function
4895 
4896 .seealso: SNESSetFunction(), SNESGetFunction()
4897 @*/
4898 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat *A,Mat *B,MatStructure *flag, void *ctx)
4899 {
4900   PetscErrorCode    ierr;
4901   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4902   int               nlhs = 2,nrhs = 6;
4903   mxArray	    *plhs[2],*prhs[6];
4904   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
4905 
4906   PetscFunctionBegin;
4907   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4908   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4909 
4910   /* call Matlab function in ctx with arguments x and y */
4911 
4912   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4913   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4914   ierr = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
4915   ierr = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
4916   prhs[0] =  mxCreateDoubleScalar((double)ls);
4917   prhs[1] =  mxCreateDoubleScalar((double)lx);
4918   prhs[2] =  mxCreateDoubleScalar((double)lA);
4919   prhs[3] =  mxCreateDoubleScalar((double)lB);
4920   prhs[4] =  mxCreateString(sctx->funcname);
4921   prhs[5] =  sctx->ctx;
4922   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
4923   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
4924   *flag   =  (MatStructure) mxGetScalar(plhs[1]);CHKERRQ(ierr);
4925   mxDestroyArray(prhs[0]);
4926   mxDestroyArray(prhs[1]);
4927   mxDestroyArray(prhs[2]);
4928   mxDestroyArray(prhs[3]);
4929   mxDestroyArray(prhs[4]);
4930   mxDestroyArray(plhs[0]);
4931   mxDestroyArray(plhs[1]);
4932   PetscFunctionReturn(0);
4933 }
4934 
4935 
4936 #undef __FUNCT__
4937 #define __FUNCT__ "SNESSetJacobianMatlab"
4938 /*
4939    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
4940    vector for use by the SNES routines in solving systems of nonlinear
4941    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4942 
4943    Logically Collective on SNES
4944 
4945    Input Parameters:
4946 +  snes - the SNES context
4947 .  A,B - Jacobian matrices
4948 .  func - function evaluation routine
4949 -  ctx - user context
4950 
4951    Calling sequence of func:
4952 $    flag = func (SNES snes,Vec x,Mat A,Mat B,void *ctx);
4953 
4954 
4955    Level: developer
4956 
4957 .keywords: SNES, nonlinear, set, function
4958 
4959 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4960 */
4961 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *func,mxArray *ctx)
4962 {
4963   PetscErrorCode    ierr;
4964   SNESMatlabContext *sctx;
4965 
4966   PetscFunctionBegin;
4967   /* currently sctx is memory bleed */
4968   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4969   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4970   /*
4971      This should work, but it doesn't
4972   sctx->ctx = ctx;
4973   mexMakeArrayPersistent(sctx->ctx);
4974   */
4975   sctx->ctx = mxDuplicateArray(ctx);
4976   ierr = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
4977   PetscFunctionReturn(0);
4978 }
4979 
4980 #undef __FUNCT__
4981 #define __FUNCT__ "SNESMonitor_Matlab"
4982 /*
4983    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
4984 
4985    Collective on SNES
4986 
4987 .seealso: SNESSetFunction(), SNESGetFunction()
4988 @*/
4989 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
4990 {
4991   PetscErrorCode  ierr;
4992   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4993   int             nlhs = 1,nrhs = 6;
4994   mxArray	  *plhs[1],*prhs[6];
4995   long long int   lx = 0,ls = 0;
4996   Vec             x=snes->vec_sol;
4997 
4998   PetscFunctionBegin;
4999   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5000 
5001   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5002   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5003   prhs[0] =  mxCreateDoubleScalar((double)ls);
5004   prhs[1] =  mxCreateDoubleScalar((double)it);
5005   prhs[2] =  mxCreateDoubleScalar((double)fnorm);
5006   prhs[3] =  mxCreateDoubleScalar((double)lx);
5007   prhs[4] =  mxCreateString(sctx->funcname);
5008   prhs[5] =  sctx->ctx;
5009   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
5010   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
5011   mxDestroyArray(prhs[0]);
5012   mxDestroyArray(prhs[1]);
5013   mxDestroyArray(prhs[2]);
5014   mxDestroyArray(prhs[3]);
5015   mxDestroyArray(prhs[4]);
5016   mxDestroyArray(plhs[0]);
5017   PetscFunctionReturn(0);
5018 }
5019 
5020 
5021 #undef __FUNCT__
5022 #define __FUNCT__ "SNESMonitorSetMatlab"
5023 /*
5024    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
5025 
5026    Level: developer
5027 
5028 .keywords: SNES, nonlinear, set, function
5029 
5030 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5031 */
5032 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *func,mxArray *ctx)
5033 {
5034   PetscErrorCode    ierr;
5035   SNESMatlabContext *sctx;
5036 
5037   PetscFunctionBegin;
5038   /* currently sctx is memory bleed */
5039   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
5040   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
5041   /*
5042      This should work, but it doesn't
5043   sctx->ctx = ctx;
5044   mexMakeArrayPersistent(sctx->ctx);
5045   */
5046   sctx->ctx = mxDuplicateArray(ctx);
5047   ierr = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,PETSC_NULL);CHKERRQ(ierr);
5048   PetscFunctionReturn(0);
5049 }
5050 
5051 #endif
5052