xref: /petsc/src/snes/interface/snes.c (revision 6d187b9135d66ac23f29b4e7e5d4e626b6954b97)
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);
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);
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) {ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);}
2574 
2575   if (!snes->linesearch) {ierr = SNESGetSNESLineSearch(snes, &snes->linesearch);}
2576 
2577   if (snes->pc && (snes->pcside == PC_LEFT)) {
2578     snes->mf = PETSC_TRUE;
2579     snes->mf_operator = PETSC_FALSE;
2580   }
2581 
2582   if (snes->mf) {
2583     ierr = SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);CHKERRQ(ierr);
2584   }
2585 
2586   if (snes->ops->usercompute && !snes->user) {
2587     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2588   }
2589 
2590   if (snes->pc) {
2591     /* copy the DM over */
2592     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2593     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
2594 
2595     ierr = SNESGetFunction(snes,&f,&func,&funcctx);CHKERRQ(ierr);
2596     ierr = VecDuplicate(f,&fpc);CHKERRQ(ierr);
2597     ierr = SNESSetFunction(snes->pc,fpc,func,funcctx);CHKERRQ(ierr);
2598     ierr = SNESGetJacobian(snes,&A,&B,&jac,&jacctx);CHKERRQ(ierr);
2599     ierr = SNESSetJacobian(snes->pc,A,B,jac,jacctx);CHKERRQ(ierr);
2600     ierr = SNESGetApplicationContext(snes,&appctx);CHKERRQ(ierr);
2601     ierr = SNESSetApplicationContext(snes->pc,appctx);CHKERRQ(ierr);
2602     ierr = VecDestroy(&fpc);CHKERRQ(ierr);
2603 
2604     /* copy the function pointers over */
2605     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
2606 
2607      /* default to 1 iteration */
2608     ierr = SNESSetTolerances(snes->pc, 0.0, 0.0, 0.0, 1, snes->pc->max_funcs);CHKERRQ(ierr);
2609     ierr = SNESSetNormType(snes->pc, SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
2610     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
2611 
2612     /* copy the line search context over */
2613     ierr = SNESGetSNESLineSearch(snes,&linesearch);CHKERRQ(ierr);
2614     ierr = SNESGetSNESLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
2615     ierr = SNESLineSearchGetPreCheck(linesearch,&lsprefunc,&lsprectx);CHKERRQ(ierr);
2616     ierr = SNESLineSearchGetPostCheck(linesearch,&lspostfunc,&lspostctx);CHKERRQ(ierr);
2617     ierr = SNESLineSearchSetPreCheck(pclinesearch,lsprefunc,lsprectx);CHKERRQ(ierr);
2618     ierr = SNESLineSearchSetPostCheck(pclinesearch,lspostfunc,lspostctx);CHKERRQ(ierr);
2619     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);CHKERRQ(ierr);
2620   }
2621 
2622   if (snes->ops->setup) {
2623     ierr = (*snes->ops->setup)(snes);CHKERRQ(ierr);
2624   }
2625 
2626   snes->setupcalled = PETSC_TRUE;
2627   PetscFunctionReturn(0);
2628 }
2629 
2630 #undef __FUNCT__
2631 #define __FUNCT__ "SNESReset"
2632 /*@
2633    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats
2634 
2635    Collective on SNES
2636 
2637    Input Parameter:
2638 .  snes - iterative context obtained from SNESCreate()
2639 
2640    Level: intermediate
2641 
2642    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()
2643 
2644 .keywords: SNES, destroy
2645 
2646 .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
2647 @*/
2648 PetscErrorCode  SNESReset(SNES snes)
2649 {
2650   PetscErrorCode ierr;
2651 
2652   PetscFunctionBegin;
2653   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2654   if (snes->ops->userdestroy && snes->user) {
2655     ierr       = (*snes->ops->userdestroy)((void**)&snes->user);CHKERRQ(ierr);
2656     snes->user = PETSC_NULL;
2657   }
2658   if (snes->pc) {
2659     ierr = SNESReset(snes->pc);CHKERRQ(ierr);
2660   }
2661 
2662   if (snes->ops->reset) {
2663     ierr = (*snes->ops->reset)(snes);CHKERRQ(ierr);
2664   }
2665   if (snes->ksp) {
2666     ierr = KSPReset(snes->ksp);CHKERRQ(ierr);
2667   }
2668 
2669   if (snes->linesearch) {
2670     ierr = SNESLineSearchReset(snes->linesearch);CHKERRQ(ierr);
2671   }
2672 
2673   ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
2674   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
2675   ierr = VecDestroy(&snes->vec_sol_update);CHKERRQ(ierr);
2676   ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
2677   ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2678   ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2679   ierr = VecDestroyVecs(snes->nwork,&snes->work);CHKERRQ(ierr);
2680   ierr = VecDestroyVecs(snes->nvwork,&snes->vwork);CHKERRQ(ierr);
2681   snes->nwork = snes->nvwork = 0;
2682   snes->setupcalled = PETSC_FALSE;
2683   PetscFunctionReturn(0);
2684 }
2685 
2686 #undef __FUNCT__
2687 #define __FUNCT__ "SNESDestroy"
2688 /*@
2689    SNESDestroy - Destroys the nonlinear solver context that was created
2690    with SNESCreate().
2691 
2692    Collective on SNES
2693 
2694    Input Parameter:
2695 .  snes - the SNES context
2696 
2697    Level: beginner
2698 
2699 .keywords: SNES, nonlinear, destroy
2700 
2701 .seealso: SNESCreate(), SNESSolve()
2702 @*/
2703 PetscErrorCode  SNESDestroy(SNES *snes)
2704 {
2705   PetscErrorCode ierr;
2706 
2707   PetscFunctionBegin;
2708   if (!*snes) PetscFunctionReturn(0);
2709   PetscValidHeaderSpecific((*snes),SNES_CLASSID,1);
2710   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; PetscFunctionReturn(0);}
2711 
2712   ierr = SNESReset((*snes));CHKERRQ(ierr);
2713   ierr = SNESDestroy(&(*snes)->pc);CHKERRQ(ierr);
2714 
2715   /* if memory was published with AMS then destroy it */
2716   ierr = PetscObjectDepublish((*snes));CHKERRQ(ierr);
2717   if ((*snes)->ops->destroy) {ierr = (*((*snes))->ops->destroy)((*snes));CHKERRQ(ierr);}
2718 
2719   ierr = DMDestroy(&(*snes)->dm);CHKERRQ(ierr);
2720   ierr = KSPDestroy(&(*snes)->ksp);CHKERRQ(ierr);
2721   ierr = SNESLineSearchDestroy(&(*snes)->linesearch);CHKERRQ(ierr);
2722 
2723   ierr = PetscFree((*snes)->kspconvctx);CHKERRQ(ierr);
2724   if ((*snes)->ops->convergeddestroy) {
2725     ierr = (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);CHKERRQ(ierr);
2726   }
2727   if ((*snes)->conv_malloc) {
2728     ierr = PetscFree((*snes)->conv_hist);CHKERRQ(ierr);
2729     ierr = PetscFree((*snes)->conv_hist_its);CHKERRQ(ierr);
2730   }
2731   ierr = SNESMonitorCancel((*snes));CHKERRQ(ierr);
2732   ierr = PetscHeaderDestroy(snes);CHKERRQ(ierr);
2733  PetscFunctionReturn(0);
2734 }
2735 
2736 /* ----------- Routines to set solver parameters ---------- */
2737 
2738 #undef __FUNCT__
2739 #define __FUNCT__ "SNESSetLagPreconditioner"
2740 /*@
2741    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.
2742 
2743    Logically Collective on SNES
2744 
2745    Input Parameters:
2746 +  snes - the SNES context
2747 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2748          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2749 
2750    Options Database Keys:
2751 .    -snes_lag_preconditioner <lag>
2752 
2753    Notes:
2754    The default is 1
2755    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2756    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use
2757 
2758    Level: intermediate
2759 
2760 .keywords: SNES, nonlinear, set, convergence, tolerances
2761 
2762 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2763 
2764 @*/
2765 PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
2766 {
2767   PetscFunctionBegin;
2768   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2769   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2770   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2771   PetscValidLogicalCollectiveInt(snes,lag,2);
2772   snes->lagpreconditioner = lag;
2773   PetscFunctionReturn(0);
2774 }
2775 
2776 #undef __FUNCT__
2777 #define __FUNCT__ "SNESSetGridSequence"
2778 /*@
2779    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does
2780 
2781    Logically Collective on SNES
2782 
2783    Input Parameters:
2784 +  snes - the SNES context
2785 -  steps - the number of refinements to do, defaults to 0
2786 
2787    Options Database Keys:
2788 .    -snes_grid_sequence <steps>
2789 
2790    Level: intermediate
2791 
2792    Notes:
2793    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2794 
2795 .keywords: SNES, nonlinear, set, convergence, tolerances
2796 
2797 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2798 
2799 @*/
2800 PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
2801 {
2802   PetscFunctionBegin;
2803   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2804   PetscValidLogicalCollectiveInt(snes,steps,2);
2805   snes->gridsequence = steps;
2806   PetscFunctionReturn(0);
2807 }
2808 
2809 #undef __FUNCT__
2810 #define __FUNCT__ "SNESGetLagPreconditioner"
2811 /*@
2812    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt
2813 
2814    Not Collective
2815 
2816    Input Parameter:
2817 .  snes - the SNES context
2818 
2819    Output Parameter:
2820 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2821          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2822 
2823    Options Database Keys:
2824 .    -snes_lag_preconditioner <lag>
2825 
2826    Notes:
2827    The default is 1
2828    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2829 
2830    Level: intermediate
2831 
2832 .keywords: SNES, nonlinear, set, convergence, tolerances
2833 
2834 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()
2835 
2836 @*/
2837 PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
2838 {
2839   PetscFunctionBegin;
2840   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2841   *lag = snes->lagpreconditioner;
2842   PetscFunctionReturn(0);
2843 }
2844 
2845 #undef __FUNCT__
2846 #define __FUNCT__ "SNESSetLagJacobian"
2847 /*@
2848    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
2849      often the preconditioner is rebuilt.
2850 
2851    Logically Collective on SNES
2852 
2853    Input Parameters:
2854 +  snes - the SNES context
2855 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2856          the Jacobian is built etc. -2 means rebuild at next chance but then never again
2857 
2858    Options Database Keys:
2859 .    -snes_lag_jacobian <lag>
2860 
2861    Notes:
2862    The default is 1
2863    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2864    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
2865    at the next Newton step but never again (unless it is reset to another value)
2866 
2867    Level: intermediate
2868 
2869 .keywords: SNES, nonlinear, set, convergence, tolerances
2870 
2871 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()
2872 
2873 @*/
2874 PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
2875 {
2876   PetscFunctionBegin;
2877   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2878   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2879   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2880   PetscValidLogicalCollectiveInt(snes,lag,2);
2881   snes->lagjacobian = lag;
2882   PetscFunctionReturn(0);
2883 }
2884 
2885 #undef __FUNCT__
2886 #define __FUNCT__ "SNESGetLagJacobian"
2887 /*@
2888    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt
2889 
2890    Not Collective
2891 
2892    Input Parameter:
2893 .  snes - the SNES context
2894 
2895    Output Parameter:
2896 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2897          the Jacobian is built etc.
2898 
2899    Options Database Keys:
2900 .    -snes_lag_jacobian <lag>
2901 
2902    Notes:
2903    The default is 1
2904    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2905 
2906    Level: intermediate
2907 
2908 .keywords: SNES, nonlinear, set, convergence, tolerances
2909 
2910 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()
2911 
2912 @*/
2913 PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
2914 {
2915   PetscFunctionBegin;
2916   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2917   *lag = snes->lagjacobian;
2918   PetscFunctionReturn(0);
2919 }
2920 
2921 #undef __FUNCT__
2922 #define __FUNCT__ "SNESSetTolerances"
2923 /*@
2924    SNESSetTolerances - Sets various parameters used in convergence tests.
2925 
2926    Logically Collective on SNES
2927 
2928    Input Parameters:
2929 +  snes - the SNES context
2930 .  abstol - absolute convergence tolerance
2931 .  rtol - relative convergence tolerance
2932 .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
2933 .  maxit - maximum number of iterations
2934 -  maxf - maximum number of function evaluations
2935 
2936    Options Database Keys:
2937 +    -snes_atol <abstol> - Sets abstol
2938 .    -snes_rtol <rtol> - Sets rtol
2939 .    -snes_stol <stol> - Sets stol
2940 .    -snes_max_it <maxit> - Sets maxit
2941 -    -snes_max_funcs <maxf> - Sets maxf
2942 
2943    Notes:
2944    The default maximum number of iterations is 50.
2945    The default maximum number of function evaluations is 1000.
2946 
2947    Level: intermediate
2948 
2949 .keywords: SNES, nonlinear, set, convergence, tolerances
2950 
2951 .seealso: SNESSetTrustRegionTolerance()
2952 @*/
2953 PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
2954 {
2955   PetscFunctionBegin;
2956   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2957   PetscValidLogicalCollectiveReal(snes,abstol,2);
2958   PetscValidLogicalCollectiveReal(snes,rtol,3);
2959   PetscValidLogicalCollectiveReal(snes,stol,4);
2960   PetscValidLogicalCollectiveInt(snes,maxit,5);
2961   PetscValidLogicalCollectiveInt(snes,maxf,6);
2962 
2963   if (abstol != PETSC_DEFAULT) {
2964     if (abstol < 0.0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %G must be non-negative",abstol);
2965     snes->abstol = abstol;
2966   }
2967   if (rtol != PETSC_DEFAULT) {
2968     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);
2969     snes->rtol = rtol;
2970   }
2971   if (stol != PETSC_DEFAULT) {
2972     if (stol < 0.0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %G must be non-negative",stol);
2973     snes->stol = stol;
2974   }
2975   if (maxit != PETSC_DEFAULT) {
2976     if (maxit < 0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
2977     snes->max_its = maxit;
2978   }
2979   if (maxf != PETSC_DEFAULT) {
2980     if (maxf < 0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
2981     snes->max_funcs = maxf;
2982   }
2983   snes->tolerancesset = PETSC_TRUE;
2984   PetscFunctionReturn(0);
2985 }
2986 
2987 #undef __FUNCT__
2988 #define __FUNCT__ "SNESGetTolerances"
2989 /*@
2990    SNESGetTolerances - Gets various parameters used in convergence tests.
2991 
2992    Not Collective
2993 
2994    Input Parameters:
2995 +  snes - the SNES context
2996 .  atol - absolute convergence tolerance
2997 .  rtol - relative convergence tolerance
2998 .  stol -  convergence tolerance in terms of the norm
2999            of the change in the solution between steps
3000 .  maxit - maximum number of iterations
3001 -  maxf - maximum number of function evaluations
3002 
3003    Notes:
3004    The user can specify PETSC_NULL for any parameter that is not needed.
3005 
3006    Level: intermediate
3007 
3008 .keywords: SNES, nonlinear, get, convergence, tolerances
3009 
3010 .seealso: SNESSetTolerances()
3011 @*/
3012 PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3013 {
3014   PetscFunctionBegin;
3015   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3016   if (atol)  *atol  = snes->abstol;
3017   if (rtol)  *rtol  = snes->rtol;
3018   if (stol)  *stol  = snes->stol;
3019   if (maxit) *maxit = snes->max_its;
3020   if (maxf)  *maxf  = snes->max_funcs;
3021   PetscFunctionReturn(0);
3022 }
3023 
3024 #undef __FUNCT__
3025 #define __FUNCT__ "SNESSetTrustRegionTolerance"
3026 /*@
3027    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.
3028 
3029    Logically Collective on SNES
3030 
3031    Input Parameters:
3032 +  snes - the SNES context
3033 -  tol - tolerance
3034 
3035    Options Database Key:
3036 .  -snes_trtol <tol> - Sets tol
3037 
3038    Level: intermediate
3039 
3040 .keywords: SNES, nonlinear, set, trust region, tolerance
3041 
3042 .seealso: SNESSetTolerances()
3043 @*/
3044 PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3045 {
3046   PetscFunctionBegin;
3047   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3048   PetscValidLogicalCollectiveReal(snes,tol,2);
3049   snes->deltatol = tol;
3050   PetscFunctionReturn(0);
3051 }
3052 
3053 /*
3054    Duplicate the lg monitors for SNES from KSP; for some reason with
3055    dynamic libraries things don't work under Sun4 if we just use
3056    macros instead of functions
3057 */
3058 #undef __FUNCT__
3059 #define __FUNCT__ "SNESMonitorLGResidualNorm"
3060 PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,void *ctx)
3061 {
3062   PetscErrorCode ierr;
3063 
3064   PetscFunctionBegin;
3065   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3066   ierr = KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);CHKERRQ(ierr);
3067   PetscFunctionReturn(0);
3068 }
3069 
3070 #undef __FUNCT__
3071 #define __FUNCT__ "SNESMonitorLGCreate"
3072 PetscErrorCode  SNESMonitorLGCreate(const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *draw)
3073 {
3074   PetscErrorCode ierr;
3075 
3076   PetscFunctionBegin;
3077   ierr = KSPMonitorLGResidualNormCreate(host,label,x,y,m,n,draw);CHKERRQ(ierr);
3078   PetscFunctionReturn(0);
3079 }
3080 
3081 #undef __FUNCT__
3082 #define __FUNCT__ "SNESMonitorLGDestroy"
3083 PetscErrorCode  SNESMonitorLGDestroy(PetscDrawLG *draw)
3084 {
3085   PetscErrorCode ierr;
3086 
3087   PetscFunctionBegin;
3088   ierr = KSPMonitorLGResidualNormDestroy(draw);CHKERRQ(ierr);
3089   PetscFunctionReturn(0);
3090 }
3091 
3092 extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
3093 #undef __FUNCT__
3094 #define __FUNCT__ "SNESMonitorLGRange"
3095 PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3096 {
3097   PetscDrawLG      lg;
3098   PetscErrorCode   ierr;
3099   PetscReal        x,y,per;
3100   PetscViewer      v = (PetscViewer)monctx;
3101   static PetscReal prev; /* should be in the context */
3102   PetscDraw        draw;
3103 
3104   PetscFunctionBegin;
3105   ierr   = PetscViewerDrawGetDrawLG(v,0,&lg);CHKERRQ(ierr);
3106   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3107   ierr   = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3108   ierr   = PetscDrawSetTitle(draw,"Residual norm");CHKERRQ(ierr);
3109   x = (PetscReal) n;
3110   if (rnorm > 0.0) y = log10(rnorm); else y = -15.0;
3111   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3112   if (n < 20 || !(n % 5)) {
3113     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3114   }
3115 
3116   ierr = PetscViewerDrawGetDrawLG(v,1,&lg);CHKERRQ(ierr);
3117   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3118   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3119   ierr = PetscDrawSetTitle(draw,"% elemts > .2*max elemt");CHKERRQ(ierr);
3120   ierr =  SNESMonitorRange_Private(snes,n,&per);CHKERRQ(ierr);
3121   x = (PetscReal) n;
3122   y = 100.0*per;
3123   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3124   if (n < 20 || !(n % 5)) {
3125     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3126   }
3127 
3128   ierr = PetscViewerDrawGetDrawLG(v,2,&lg);CHKERRQ(ierr);
3129   if (!n) {prev = rnorm;ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3130   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3131   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");CHKERRQ(ierr);
3132   x = (PetscReal) n;
3133   y = (prev - rnorm)/prev;
3134   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3135   if (n < 20 || !(n % 5)) {
3136     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3137   }
3138 
3139   ierr = PetscViewerDrawGetDrawLG(v,3,&lg);CHKERRQ(ierr);
3140   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3141   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3142   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");CHKERRQ(ierr);
3143   x = (PetscReal) n;
3144   y = (prev - rnorm)/(prev*per);
3145   if (n > 2) { /*skip initial crazy value */
3146     ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3147   }
3148   if (n < 20 || !(n % 5)) {
3149     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3150   }
3151   prev = rnorm;
3152   PetscFunctionReturn(0);
3153 }
3154 
3155 #undef __FUNCT__
3156 #define __FUNCT__ "SNESMonitor"
3157 /*@
3158    SNESMonitor - runs the user provided monitor routines, if they exist
3159 
3160    Collective on SNES
3161 
3162    Input Parameters:
3163 +  snes - nonlinear solver context obtained from SNESCreate()
3164 .  iter - iteration number
3165 -  rnorm - relative norm of the residual
3166 
3167    Notes:
3168    This routine is called by the SNES implementations.
3169    It does not typically need to be called by the user.
3170 
3171    Level: developer
3172 
3173 .seealso: SNESMonitorSet()
3174 @*/
3175 PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3176 {
3177   PetscErrorCode ierr;
3178   PetscInt       i,n = snes->numbermonitors;
3179 
3180   PetscFunctionBegin;
3181   for (i=0; i<n; i++) {
3182     ierr = (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);CHKERRQ(ierr);
3183   }
3184   PetscFunctionReturn(0);
3185 }
3186 
3187 /* ------------ Routines to set performance monitoring options ----------- */
3188 
3189 #undef __FUNCT__
3190 #define __FUNCT__ "SNESMonitorSet"
3191 /*@C
3192    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3193    iteration of the nonlinear solver to display the iteration's
3194    progress.
3195 
3196    Logically Collective on SNES
3197 
3198    Input Parameters:
3199 +  snes - the SNES context
3200 .  func - monitoring routine
3201 .  mctx - [optional] user-defined context for private data for the
3202           monitor routine (use PETSC_NULL if no context is desired)
3203 -  monitordestroy - [optional] routine that frees monitor context
3204           (may be PETSC_NULL)
3205 
3206    Calling sequence of func:
3207 $     int func(SNES snes,PetscInt its, PetscReal norm,void *mctx)
3208 
3209 +    snes - the SNES context
3210 .    its - iteration number
3211 .    norm - 2-norm function value (may be estimated)
3212 -    mctx - [optional] monitoring context
3213 
3214    Options Database Keys:
3215 +    -snes_monitor        - sets SNESMonitorDefault()
3216 .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3217                             uses SNESMonitorLGCreate()
3218 -    -snes_monitor_cancel - cancels all monitors that have
3219                             been hardwired into a code by
3220                             calls to SNESMonitorSet(), but
3221                             does not cancel those set via
3222                             the options database.
3223 
3224    Notes:
3225    Several different monitoring routines may be set by calling
3226    SNESMonitorSet() multiple times; all will be called in the
3227    order in which they were set.
3228 
3229    Fortran notes: Only a single monitor function can be set for each SNES object
3230 
3231    Level: intermediate
3232 
3233 .keywords: SNES, nonlinear, set, monitor
3234 
3235 .seealso: SNESMonitorDefault(), SNESMonitorCancel()
3236 @*/
3237 PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*monitor)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3238 {
3239   PetscInt       i;
3240   PetscErrorCode ierr;
3241 
3242   PetscFunctionBegin;
3243   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3244   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3245   for (i=0; i<snes->numbermonitors;i++) {
3246     if (monitor == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
3247       if (monitordestroy) {
3248         ierr = (*monitordestroy)(&mctx);CHKERRQ(ierr);
3249       }
3250       PetscFunctionReturn(0);
3251     }
3252   }
3253   snes->monitor[snes->numbermonitors]           = monitor;
3254   snes->monitordestroy[snes->numbermonitors]    = monitordestroy;
3255   snes->monitorcontext[snes->numbermonitors++]  = (void*)mctx;
3256   PetscFunctionReturn(0);
3257 }
3258 
3259 #undef __FUNCT__
3260 #define __FUNCT__ "SNESMonitorCancel"
3261 /*@C
3262    SNESMonitorCancel - Clears all the monitor functions for a SNES object.
3263 
3264    Logically Collective on SNES
3265 
3266    Input Parameters:
3267 .  snes - the SNES context
3268 
3269    Options Database Key:
3270 .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3271     into a code by calls to SNESMonitorSet(), but does not cancel those
3272     set via the options database
3273 
3274    Notes:
3275    There is no way to clear one specific monitor from a SNES object.
3276 
3277    Level: intermediate
3278 
3279 .keywords: SNES, nonlinear, set, monitor
3280 
3281 .seealso: SNESMonitorDefault(), SNESMonitorSet()
3282 @*/
3283 PetscErrorCode  SNESMonitorCancel(SNES snes)
3284 {
3285   PetscErrorCode ierr;
3286   PetscInt       i;
3287 
3288   PetscFunctionBegin;
3289   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3290   for (i=0; i<snes->numbermonitors; i++) {
3291     if (snes->monitordestroy[i]) {
3292       ierr = (*snes->monitordestroy[i])(&snes->monitorcontext[i]);CHKERRQ(ierr);
3293     }
3294   }
3295   snes->numbermonitors = 0;
3296   PetscFunctionReturn(0);
3297 }
3298 
3299 #undef __FUNCT__
3300 #define __FUNCT__ "SNESSetConvergenceTest"
3301 /*@C
3302    SNESSetConvergenceTest - Sets the function that is to be used
3303    to test for convergence of the nonlinear iterative solution.
3304 
3305    Logically Collective on SNES
3306 
3307    Input Parameters:
3308 +  snes - the SNES context
3309 .  func - routine to test for convergence
3310 .  cctx - [optional] context for private data for the convergence routine  (may be PETSC_NULL)
3311 -  destroy - [optional] destructor for the context (may be PETSC_NULL; PETSC_NULL_FUNCTION in Fortran)
3312 
3313    Calling sequence of func:
3314 $     PetscErrorCode func (SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)
3315 
3316 +    snes - the SNES context
3317 .    it - current iteration (0 is the first and is before any Newton step)
3318 .    cctx - [optional] convergence context
3319 .    reason - reason for convergence/divergence
3320 .    xnorm - 2-norm of current iterate
3321 .    gnorm - 2-norm of current step
3322 -    f - 2-norm of function
3323 
3324    Level: advanced
3325 
3326 .keywords: SNES, nonlinear, set, convergence, test
3327 
3328 .seealso: SNESDefaultConverged(), SNESSkipConverged()
3329 @*/
3330 PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*func)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
3331 {
3332   PetscErrorCode ierr;
3333 
3334   PetscFunctionBegin;
3335   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3336   if (!func) func = SNESSkipConverged;
3337   if (snes->ops->convergeddestroy) {
3338     ierr = (*snes->ops->convergeddestroy)(snes->cnvP);CHKERRQ(ierr);
3339   }
3340   snes->ops->converged        = func;
3341   snes->ops->convergeddestroy = destroy;
3342   snes->cnvP                  = cctx;
3343   PetscFunctionReturn(0);
3344 }
3345 
3346 #undef __FUNCT__
3347 #define __FUNCT__ "SNESGetConvergedReason"
3348 /*@
3349    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.
3350 
3351    Not Collective
3352 
3353    Input Parameter:
3354 .  snes - the SNES context
3355 
3356    Output Parameter:
3357 .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3358             manual pages for the individual convergence tests for complete lists
3359 
3360    Level: intermediate
3361 
3362    Notes: Can only be called after the call the SNESSolve() is complete.
3363 
3364 .keywords: SNES, nonlinear, set, convergence, test
3365 
3366 .seealso: SNESSetConvergenceTest(), SNESConvergedReason
3367 @*/
3368 PetscErrorCode  SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
3369 {
3370   PetscFunctionBegin;
3371   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3372   PetscValidPointer(reason,2);
3373   *reason = snes->reason;
3374   PetscFunctionReturn(0);
3375 }
3376 
3377 #undef __FUNCT__
3378 #define __FUNCT__ "SNESSetConvergenceHistory"
3379 /*@
3380    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.
3381 
3382    Logically Collective on SNES
3383 
3384    Input Parameters:
3385 +  snes - iterative context obtained from SNESCreate()
3386 .  a   - array to hold history, this array will contain the function norms computed at each step
3387 .  its - integer array holds the number of linear iterations for each solve.
3388 .  na  - size of a and its
3389 -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
3390            else it continues storing new values for new nonlinear solves after the old ones
3391 
3392    Notes:
3393    If 'a' and 'its' are PETSC_NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
3394    default array of length 10000 is allocated.
3395 
3396    This routine is useful, e.g., when running a code for purposes
3397    of accurate performance monitoring, when no I/O should be done
3398    during the section of code that is being timed.
3399 
3400    Level: intermediate
3401 
3402 .keywords: SNES, set, convergence, history
3403 
3404 .seealso: SNESGetConvergenceHistory()
3405 
3406 @*/
3407 PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool  reset)
3408 {
3409   PetscErrorCode ierr;
3410 
3411   PetscFunctionBegin;
3412   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3413   if (na)  PetscValidScalarPointer(a,2);
3414   if (its) PetscValidIntPointer(its,3);
3415   if (na == PETSC_DECIDE || na == PETSC_DEFAULT || !a) {
3416     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
3417     ierr = PetscMalloc(na*sizeof(PetscReal),&a);CHKERRQ(ierr);
3418     ierr = PetscMalloc(na*sizeof(PetscInt),&its);CHKERRQ(ierr);
3419     snes->conv_malloc   = PETSC_TRUE;
3420   }
3421   snes->conv_hist       = a;
3422   snes->conv_hist_its   = its;
3423   snes->conv_hist_max   = na;
3424   snes->conv_hist_len   = 0;
3425   snes->conv_hist_reset = reset;
3426   PetscFunctionReturn(0);
3427 }
3428 
3429 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3430 #include <engine.h>   /* MATLAB include file */
3431 #include <mex.h>      /* MATLAB include file */
3432 EXTERN_C_BEGIN
3433 #undef __FUNCT__
3434 #define __FUNCT__ "SNESGetConvergenceHistoryMatlab"
3435 mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
3436 {
3437   mxArray   *mat;
3438   PetscInt  i;
3439   PetscReal *ar;
3440 
3441   PetscFunctionBegin;
3442   mat  = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
3443   ar   = (PetscReal*) mxGetData(mat);
3444   for (i=0; i<snes->conv_hist_len; i++) {
3445     ar[i] = snes->conv_hist[i];
3446   }
3447   PetscFunctionReturn(mat);
3448 }
3449 EXTERN_C_END
3450 #endif
3451 
3452 
3453 #undef __FUNCT__
3454 #define __FUNCT__ "SNESGetConvergenceHistory"
3455 /*@C
3456    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.
3457 
3458    Not Collective
3459 
3460    Input Parameter:
3461 .  snes - iterative context obtained from SNESCreate()
3462 
3463    Output Parameters:
3464 .  a   - array to hold history
3465 .  its - integer array holds the number of linear iterations (or
3466          negative if not converged) for each solve.
3467 -  na  - size of a and its
3468 
3469    Notes:
3470     The calling sequence for this routine in Fortran is
3471 $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
3472 
3473    This routine is useful, e.g., when running a code for purposes
3474    of accurate performance monitoring, when no I/O should be done
3475    during the section of code that is being timed.
3476 
3477    Level: intermediate
3478 
3479 .keywords: SNES, get, convergence, history
3480 
3481 .seealso: SNESSetConvergencHistory()
3482 
3483 @*/
3484 PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
3485 {
3486   PetscFunctionBegin;
3487   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3488   if (a)   *a   = snes->conv_hist;
3489   if (its) *its = snes->conv_hist_its;
3490   if (na)  *na  = snes->conv_hist_len;
3491   PetscFunctionReturn(0);
3492 }
3493 
3494 #undef __FUNCT__
3495 #define __FUNCT__ "SNESSetUpdate"
3496 /*@C
3497   SNESSetUpdate - Sets the general-purpose update function called
3498   at the beginning of every iteration of the nonlinear solve. Specifically
3499   it is called just before the Jacobian is "evaluated".
3500 
3501   Logically Collective on SNES
3502 
3503   Input Parameters:
3504 . snes - The nonlinear solver context
3505 . func - The function
3506 
3507   Calling sequence of func:
3508 . func (SNES snes, PetscInt step);
3509 
3510 . step - The current step of the iteration
3511 
3512   Level: advanced
3513 
3514   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()
3515         This is not used by most users.
3516 
3517 .keywords: SNES, update
3518 
3519 .seealso SNESDefaultUpdate(), SNESSetJacobian(), SNESSolve()
3520 @*/
3521 PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
3522 {
3523   PetscFunctionBegin;
3524   PetscValidHeaderSpecific(snes, SNES_CLASSID,1);
3525   snes->ops->update = func;
3526   PetscFunctionReturn(0);
3527 }
3528 
3529 #undef __FUNCT__
3530 #define __FUNCT__ "SNESDefaultUpdate"
3531 /*@
3532   SNESDefaultUpdate - The default update function which does nothing.
3533 
3534   Not collective
3535 
3536   Input Parameters:
3537 . snes - The nonlinear solver context
3538 . step - The current step of the iteration
3539 
3540   Level: intermediate
3541 
3542 .keywords: SNES, update
3543 .seealso SNESSetUpdate(), SNESDefaultRhsBC(), SNESDefaultShortolutionBC()
3544 @*/
3545 PetscErrorCode  SNESDefaultUpdate(SNES snes, PetscInt step)
3546 {
3547   PetscFunctionBegin;
3548   PetscFunctionReturn(0);
3549 }
3550 
3551 #undef __FUNCT__
3552 #define __FUNCT__ "SNESScaleStep_Private"
3553 /*
3554    SNESScaleStep_Private - Scales a step so that its length is less than the
3555    positive parameter delta.
3556 
3557     Input Parameters:
3558 +   snes - the SNES context
3559 .   y - approximate solution of linear system
3560 .   fnorm - 2-norm of current function
3561 -   delta - trust region size
3562 
3563     Output Parameters:
3564 +   gpnorm - predicted function norm at the new point, assuming local
3565     linearization.  The value is zero if the step lies within the trust
3566     region, and exceeds zero otherwise.
3567 -   ynorm - 2-norm of the step
3568 
3569     Note:
3570     For non-trust region methods such as SNESNEWTONLS, the parameter delta
3571     is set to be the maximum allowable step size.
3572 
3573 .keywords: SNES, nonlinear, scale, step
3574 */
3575 PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
3576 {
3577   PetscReal      nrm;
3578   PetscScalar    cnorm;
3579   PetscErrorCode ierr;
3580 
3581   PetscFunctionBegin;
3582   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3583   PetscValidHeaderSpecific(y,VEC_CLASSID,2);
3584   PetscCheckSameComm(snes,1,y,2);
3585 
3586   ierr = VecNorm(y,NORM_2,&nrm);CHKERRQ(ierr);
3587   if (nrm > *delta) {
3588      nrm = *delta/nrm;
3589      *gpnorm = (1.0 - nrm)*(*fnorm);
3590      cnorm = nrm;
3591      ierr = VecScale(y,cnorm);CHKERRQ(ierr);
3592      *ynorm = *delta;
3593   } else {
3594      *gpnorm = 0.0;
3595      *ynorm = nrm;
3596   }
3597   PetscFunctionReturn(0);
3598 }
3599 
3600 #undef __FUNCT__
3601 #define __FUNCT__ "SNESSolve"
3602 /*@C
3603    SNESSolve - Solves a nonlinear system F(x) = b.
3604    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3605 
3606    Collective on SNES
3607 
3608    Input Parameters:
3609 +  snes - the SNES context
3610 .  b - the constant part of the equation F(x) = b, or PETSC_NULL to use zero.
3611 -  x - the solution vector.
3612 
3613    Notes:
3614    The user should initialize the vector,x, with the initial guess
3615    for the nonlinear solve prior to calling SNESSolve.  In particular,
3616    to employ an initial guess of zero, the user should explicitly set
3617    this vector to zero by calling VecSet().
3618 
3619    Level: beginner
3620 
3621 .keywords: SNES, nonlinear, solve
3622 
3623 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3624 @*/
3625 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3626 {
3627   PetscErrorCode ierr;
3628   PetscBool      flg;
3629   PetscViewer    viewer;
3630   PetscInt       grid;
3631   Vec            xcreated = PETSC_NULL;
3632   DM             dm;
3633 
3634   PetscFunctionBegin;
3635   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3636   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3637   if (x) PetscCheckSameComm(snes,1,x,3);
3638   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3639   if (b) PetscCheckSameComm(snes,1,b,2);
3640 
3641   if (!x) {
3642     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3643     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3644     x    = xcreated;
3645   }
3646 
3647   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm));CHKERRQ(ierr);}
3648   for (grid=0; grid<snes->gridsequence+1; grid++) {
3649 
3650     /* set solution vector */
3651     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3652     ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3653     snes->vec_sol = x;
3654     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3655 
3656     /* set affine vector if provided */
3657     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3658     ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3659     snes->vec_rhs = b;
3660 
3661     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3662 
3663     if (!grid) {
3664       if (snes->ops->computeinitialguess) {
3665         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3666       }
3667     }
3668 
3669     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3670     snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;
3671 
3672     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3673     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3674     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3675     if (snes->domainerror){
3676       snes->reason      = SNES_DIVERGED_FUNCTION_DOMAIN;
3677       snes->domainerror = PETSC_FALSE;
3678     }
3679     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3680 
3681     flg  = PETSC_FALSE;
3682     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,PETSC_NULL);CHKERRQ(ierr);
3683     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
3684     if (snes->printreason) {
3685       ierr = PetscViewerASCIIAddTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3686       if (snes->reason > 0) {
3687         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3688       } else {
3689         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);
3690       }
3691       ierr = PetscViewerASCIISubtractTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3692     }
3693 
3694     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
3695     if (grid <  snes->gridsequence) {
3696       DM  fine;
3697       Vec xnew;
3698       Mat interp;
3699 
3700       ierr = DMRefine(snes->dm,((PetscObject)snes)->comm,&fine);CHKERRQ(ierr);
3701       if (!fine) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
3702       ierr = DMCreateInterpolation(snes->dm,fine,&interp,PETSC_NULL);CHKERRQ(ierr);
3703       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
3704       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
3705       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
3706       ierr = MatDestroy(&interp);CHKERRQ(ierr);
3707       x    = xnew;
3708 
3709       ierr = SNESReset(snes);CHKERRQ(ierr);
3710       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
3711       ierr = DMDestroy(&fine);CHKERRQ(ierr);
3712       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm));CHKERRQ(ierr);
3713     }
3714   }
3715   /* monitoring and viewing */
3716   ierr = PetscOptionsGetViewer(((PetscObject)snes)->comm,((PetscObject)snes)->prefix,"-snes_view",&viewer,&flg);CHKERRQ(ierr);
3717   if (flg && !PetscPreLoadingOn) {
3718     ierr = SNESView(snes,viewer);CHKERRQ(ierr);
3719     ierr = PetscOptionsRestoreViewer(viewer);CHKERRQ(ierr);
3720   }
3721   ierr = VecViewFromOptions(snes->vec_sol,"-snes_view_solution");CHKERRQ(ierr);
3722 
3723   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
3724   PetscFunctionReturn(0);
3725 }
3726 
3727 /* --------- Internal routines for SNES Package --------- */
3728 
3729 #undef __FUNCT__
3730 #define __FUNCT__ "SNESSetType"
3731 /*@C
3732    SNESSetType - Sets the method for the nonlinear solver.
3733 
3734    Collective on SNES
3735 
3736    Input Parameters:
3737 +  snes - the SNES context
3738 -  type - a known method
3739 
3740    Options Database Key:
3741 .  -snes_type <type> - Sets the method; use -help for a list
3742    of available methods (for instance, newtonls or newtontr)
3743 
3744    Notes:
3745    See "petsc/include/petscsnes.h" for available methods (for instance)
3746 +    SNESNEWTONLS - Newton's method with line search
3747      (systems of nonlinear equations)
3748 .    SNESNEWTONTR - Newton's method with trust region
3749      (systems of nonlinear equations)
3750 
3751   Normally, it is best to use the SNESSetFromOptions() command and then
3752   set the SNES solver type from the options database rather than by using
3753   this routine.  Using the options database provides the user with
3754   maximum flexibility in evaluating the many nonlinear solvers.
3755   The SNESSetType() routine is provided for those situations where it
3756   is necessary to set the nonlinear solver independently of the command
3757   line or options database.  This might be the case, for example, when
3758   the choice of solver changes during the execution of the program,
3759   and the user's application is taking responsibility for choosing the
3760   appropriate method.
3761 
3762   Level: intermediate
3763 
3764 .keywords: SNES, set, type
3765 
3766 .seealso: SNESType, SNESCreate()
3767 
3768 @*/
3769 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
3770 {
3771   PetscErrorCode ierr,(*r)(SNES);
3772   PetscBool      match;
3773 
3774   PetscFunctionBegin;
3775   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3776   PetscValidCharPointer(type,2);
3777 
3778   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
3779   if (match) PetscFunctionReturn(0);
3780 
3781   ierr =  PetscFListFind(SNESList,((PetscObject)snes)->comm,type,PETSC_TRUE,(void (**)(void)) &r);CHKERRQ(ierr);
3782   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
3783   /* Destroy the previous private SNES context */
3784   if (snes->ops->destroy) {
3785     ierr = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
3786     snes->ops->destroy = PETSC_NULL;
3787   }
3788   /* Reinitialize function pointers in SNESOps structure */
3789   snes->ops->setup          = 0;
3790   snes->ops->solve          = 0;
3791   snes->ops->view           = 0;
3792   snes->ops->setfromoptions = 0;
3793   snes->ops->destroy        = 0;
3794   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
3795   snes->setupcalled = PETSC_FALSE;
3796   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
3797   ierr = (*r)(snes);CHKERRQ(ierr);
3798 #if defined(PETSC_HAVE_AMS)
3799   if (PetscAMSPublishAll) {
3800     ierr = PetscObjectAMSPublish((PetscObject)snes);CHKERRQ(ierr);
3801   }
3802 #endif
3803   PetscFunctionReturn(0);
3804 }
3805 
3806 
3807 /* --------------------------------------------------------------------- */
3808 #undef __FUNCT__
3809 #define __FUNCT__ "SNESRegisterDestroy"
3810 /*@
3811    SNESRegisterDestroy - Frees the list of nonlinear solvers that were
3812    registered by SNESRegisterDynamic().
3813 
3814    Not Collective
3815 
3816    Level: advanced
3817 
3818 .keywords: SNES, nonlinear, register, destroy
3819 
3820 .seealso: SNESRegisterAll(), SNESRegisterAll()
3821 @*/
3822 PetscErrorCode  SNESRegisterDestroy(void)
3823 {
3824   PetscErrorCode ierr;
3825 
3826   PetscFunctionBegin;
3827   ierr = PetscFListDestroy(&SNESList);CHKERRQ(ierr);
3828   SNESRegisterAllCalled = PETSC_FALSE;
3829   PetscFunctionReturn(0);
3830 }
3831 
3832 #undef __FUNCT__
3833 #define __FUNCT__ "SNESGetType"
3834 /*@C
3835    SNESGetType - Gets the SNES method type and name (as a string).
3836 
3837    Not Collective
3838 
3839    Input Parameter:
3840 .  snes - nonlinear solver context
3841 
3842    Output Parameter:
3843 .  type - SNES method (a character string)
3844 
3845    Level: intermediate
3846 
3847 .keywords: SNES, nonlinear, get, type, name
3848 @*/
3849 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
3850 {
3851   PetscFunctionBegin;
3852   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3853   PetscValidPointer(type,2);
3854   *type = ((PetscObject)snes)->type_name;
3855   PetscFunctionReturn(0);
3856 }
3857 
3858 #undef __FUNCT__
3859 #define __FUNCT__ "SNESGetSolution"
3860 /*@
3861    SNESGetSolution - Returns the vector where the approximate solution is
3862    stored. This is the fine grid solution when using SNESSetGridSequence().
3863 
3864    Not Collective, but Vec is parallel if SNES is parallel
3865 
3866    Input Parameter:
3867 .  snes - the SNES context
3868 
3869    Output Parameter:
3870 .  x - the solution
3871 
3872    Level: intermediate
3873 
3874 .keywords: SNES, nonlinear, get, solution
3875 
3876 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
3877 @*/
3878 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
3879 {
3880   PetscFunctionBegin;
3881   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3882   PetscValidPointer(x,2);
3883   *x = snes->vec_sol;
3884   PetscFunctionReturn(0);
3885 }
3886 
3887 #undef __FUNCT__
3888 #define __FUNCT__ "SNESGetSolutionUpdate"
3889 /*@
3890    SNESGetSolutionUpdate - Returns the vector where the solution update is
3891    stored.
3892 
3893    Not Collective, but Vec is parallel if SNES is parallel
3894 
3895    Input Parameter:
3896 .  snes - the SNES context
3897 
3898    Output Parameter:
3899 .  x - the solution update
3900 
3901    Level: advanced
3902 
3903 .keywords: SNES, nonlinear, get, solution, update
3904 
3905 .seealso: SNESGetSolution(), SNESGetFunction()
3906 @*/
3907 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
3908 {
3909   PetscFunctionBegin;
3910   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3911   PetscValidPointer(x,2);
3912   *x = snes->vec_sol_update;
3913   PetscFunctionReturn(0);
3914 }
3915 
3916 #undef __FUNCT__
3917 #define __FUNCT__ "SNESGetFunction"
3918 /*@C
3919    SNESGetFunction - Returns the vector where the function is stored.
3920 
3921    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
3922 
3923    Input Parameter:
3924 .  snes - the SNES context
3925 
3926    Output Parameter:
3927 +  r - the function (or PETSC_NULL)
3928 .  func - the function (or PETSC_NULL)
3929 -  ctx - the function context (or PETSC_NULL)
3930 
3931    Level: advanced
3932 
3933 .keywords: SNES, nonlinear, get, function
3934 
3935 .seealso: SNESSetFunction(), SNESGetSolution()
3936 @*/
3937 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**func)(SNES,Vec,Vec,void*),void **ctx)
3938 {
3939   PetscErrorCode ierr;
3940   DM             dm;
3941 
3942   PetscFunctionBegin;
3943   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3944   if (r) {
3945     if (!snes->vec_func) {
3946       if (snes->vec_rhs) {
3947         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
3948       } else if (snes->vec_sol) {
3949         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
3950       } else if (snes->dm) {
3951         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
3952       }
3953     }
3954     *r = snes->vec_func;
3955   }
3956   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3957   ierr = DMSNESGetFunction(dm,func,ctx);CHKERRQ(ierr);
3958   PetscFunctionReturn(0);
3959 }
3960 
3961 /*@C
3962    SNESGetGS - Returns the GS function and context.
3963 
3964    Input Parameter:
3965 .  snes - the SNES context
3966 
3967    Output Parameter:
3968 +  gsfunc - the function (or PETSC_NULL)
3969 -  ctx    - the function context (or PETSC_NULL)
3970 
3971    Level: advanced
3972 
3973 .keywords: SNES, nonlinear, get, function
3974 
3975 .seealso: SNESSetGS(), SNESGetFunction()
3976 @*/
3977 
3978 #undef __FUNCT__
3979 #define __FUNCT__ "SNESGetGS"
3980 PetscErrorCode SNESGetGS (SNES snes, PetscErrorCode(**func)(SNES, Vec, Vec, void*), void ** ctx)
3981 {
3982   PetscErrorCode ierr;
3983   DM             dm;
3984 
3985   PetscFunctionBegin;
3986   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3987   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3988   ierr = DMSNESGetGS(dm,func,ctx);CHKERRQ(ierr);
3989   PetscFunctionReturn(0);
3990 }
3991 
3992 #undef __FUNCT__
3993 #define __FUNCT__ "SNESSetOptionsPrefix"
3994 /*@C
3995    SNESSetOptionsPrefix - Sets the prefix used for searching for all
3996    SNES options in the database.
3997 
3998    Logically Collective on SNES
3999 
4000    Input Parameter:
4001 +  snes - the SNES context
4002 -  prefix - the prefix to prepend to all option names
4003 
4004    Notes:
4005    A hyphen (-) must NOT be given at the beginning of the prefix name.
4006    The first character of all runtime options is AUTOMATICALLY the hyphen.
4007 
4008    Level: advanced
4009 
4010 .keywords: SNES, set, options, prefix, database
4011 
4012 .seealso: SNESSetFromOptions()
4013 @*/
4014 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4015 {
4016   PetscErrorCode ierr;
4017 
4018   PetscFunctionBegin;
4019   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4020   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4021   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4022   if (snes->linesearch) {
4023     ierr = SNESGetSNESLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4024     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4025   }
4026   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4027   PetscFunctionReturn(0);
4028 }
4029 
4030 #undef __FUNCT__
4031 #define __FUNCT__ "SNESAppendOptionsPrefix"
4032 /*@C
4033    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4034    SNES options in the database.
4035 
4036    Logically Collective on SNES
4037 
4038    Input Parameters:
4039 +  snes - the SNES context
4040 -  prefix - the prefix to prepend to all option names
4041 
4042    Notes:
4043    A hyphen (-) must NOT be given at the beginning of the prefix name.
4044    The first character of all runtime options is AUTOMATICALLY the hyphen.
4045 
4046    Level: advanced
4047 
4048 .keywords: SNES, append, options, prefix, database
4049 
4050 .seealso: SNESGetOptionsPrefix()
4051 @*/
4052 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4053 {
4054   PetscErrorCode ierr;
4055 
4056   PetscFunctionBegin;
4057   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4058   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4059   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4060   if (snes->linesearch) {
4061     ierr = SNESGetSNESLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4062     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4063   }
4064   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4065   PetscFunctionReturn(0);
4066 }
4067 
4068 #undef __FUNCT__
4069 #define __FUNCT__ "SNESGetOptionsPrefix"
4070 /*@C
4071    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4072    SNES options in the database.
4073 
4074    Not Collective
4075 
4076    Input Parameter:
4077 .  snes - the SNES context
4078 
4079    Output Parameter:
4080 .  prefix - pointer to the prefix string used
4081 
4082    Notes: On the fortran side, the user should pass in a string 'prefix' of
4083    sufficient length to hold the prefix.
4084 
4085    Level: advanced
4086 
4087 .keywords: SNES, get, options, prefix, database
4088 
4089 .seealso: SNESAppendOptionsPrefix()
4090 @*/
4091 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4092 {
4093   PetscErrorCode ierr;
4094 
4095   PetscFunctionBegin;
4096   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4097   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4098   PetscFunctionReturn(0);
4099 }
4100 
4101 
4102 #undef __FUNCT__
4103 #define __FUNCT__ "SNESRegister"
4104 /*@C
4105   SNESRegister - See SNESRegisterDynamic()
4106 
4107   Level: advanced
4108 @*/
4109 PetscErrorCode  SNESRegister(const char sname[],const char path[],const char name[],PetscErrorCode (*function)(SNES))
4110 {
4111   char           fullname[PETSC_MAX_PATH_LEN];
4112   PetscErrorCode ierr;
4113 
4114   PetscFunctionBegin;
4115   ierr = PetscFListConcat(path,name,fullname);CHKERRQ(ierr);
4116   ierr = PetscFListAdd(&SNESList,sname,fullname,(void (*)(void))function);CHKERRQ(ierr);
4117   PetscFunctionReturn(0);
4118 }
4119 
4120 #undef __FUNCT__
4121 #define __FUNCT__ "SNESTestLocalMin"
4122 PetscErrorCode  SNESTestLocalMin(SNES snes)
4123 {
4124   PetscErrorCode ierr;
4125   PetscInt       N,i,j;
4126   Vec            u,uh,fh;
4127   PetscScalar    value;
4128   PetscReal      norm;
4129 
4130   PetscFunctionBegin;
4131   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4132   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4133   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4134 
4135   /* currently only works for sequential */
4136   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");
4137   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4138   for (i=0; i<N; i++) {
4139     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4140     ierr  = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4141     for (j=-10; j<11; j++) {
4142       value = PetscSign(j)*exp(PetscAbs(j)-10.0);
4143       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4144       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4145       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4146       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4147       value = -value;
4148       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4149     }
4150   }
4151   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4152   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4153   PetscFunctionReturn(0);
4154 }
4155 
4156 #undef __FUNCT__
4157 #define __FUNCT__ "SNESKSPSetUseEW"
4158 /*@
4159    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4160    computing relative tolerance for linear solvers within an inexact
4161    Newton method.
4162 
4163    Logically Collective on SNES
4164 
4165    Input Parameters:
4166 +  snes - SNES context
4167 -  flag - PETSC_TRUE or PETSC_FALSE
4168 
4169     Options Database:
4170 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4171 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4172 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4173 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4174 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4175 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4176 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4177 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4178 
4179    Notes:
4180    Currently, the default is to use a constant relative tolerance for
4181    the inner linear solvers.  Alternatively, one can use the
4182    Eisenstat-Walker method, where the relative convergence tolerance
4183    is reset at each Newton iteration according progress of the nonlinear
4184    solver.
4185 
4186    Level: advanced
4187 
4188    Reference:
4189    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4190    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4191 
4192 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4193 
4194 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4195 @*/
4196 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool  flag)
4197 {
4198   PetscFunctionBegin;
4199   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4200   PetscValidLogicalCollectiveBool(snes,flag,2);
4201   snes->ksp_ewconv = flag;
4202   PetscFunctionReturn(0);
4203 }
4204 
4205 #undef __FUNCT__
4206 #define __FUNCT__ "SNESKSPGetUseEW"
4207 /*@
4208    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4209    for computing relative tolerance for linear solvers within an
4210    inexact Newton method.
4211 
4212    Not Collective
4213 
4214    Input Parameter:
4215 .  snes - SNES context
4216 
4217    Output Parameter:
4218 .  flag - PETSC_TRUE or PETSC_FALSE
4219 
4220    Notes:
4221    Currently, the default is to use a constant relative tolerance for
4222    the inner linear solvers.  Alternatively, one can use the
4223    Eisenstat-Walker method, where the relative convergence tolerance
4224    is reset at each Newton iteration according progress of the nonlinear
4225    solver.
4226 
4227    Level: advanced
4228 
4229    Reference:
4230    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4231    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4232 
4233 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4234 
4235 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4236 @*/
4237 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4238 {
4239   PetscFunctionBegin;
4240   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4241   PetscValidPointer(flag,2);
4242   *flag = snes->ksp_ewconv;
4243   PetscFunctionReturn(0);
4244 }
4245 
4246 #undef __FUNCT__
4247 #define __FUNCT__ "SNESKSPSetParametersEW"
4248 /*@
4249    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4250    convergence criteria for the linear solvers within an inexact
4251    Newton method.
4252 
4253    Logically Collective on SNES
4254 
4255    Input Parameters:
4256 +    snes - SNES context
4257 .    version - version 1, 2 (default is 2) or 3
4258 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4259 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4260 .    gamma - multiplicative factor for version 2 rtol computation
4261              (0 <= gamma2 <= 1)
4262 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4263 .    alpha2 - power for safeguard
4264 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4265 
4266    Note:
4267    Version 3 was contributed by Luis Chacon, June 2006.
4268 
4269    Use PETSC_DEFAULT to retain the default for any of the parameters.
4270 
4271    Level: advanced
4272 
4273    Reference:
4274    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4275    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4276    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4277 
4278 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4279 
4280 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4281 @*/
4282 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,
4283 							    PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4284 {
4285   SNESKSPEW *kctx;
4286   PetscFunctionBegin;
4287   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4288   kctx = (SNESKSPEW*)snes->kspconvctx;
4289   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4290   PetscValidLogicalCollectiveInt(snes,version,2);
4291   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4292   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4293   PetscValidLogicalCollectiveReal(snes,gamma,5);
4294   PetscValidLogicalCollectiveReal(snes,alpha,6);
4295   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4296   PetscValidLogicalCollectiveReal(snes,threshold,8);
4297 
4298   if (version != PETSC_DEFAULT)   kctx->version   = version;
4299   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4300   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4301   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4302   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4303   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4304   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4305 
4306   if (kctx->version < 1 || kctx->version > 3) {
4307     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 and 3 are supported: %D",kctx->version);
4308   }
4309   if (kctx->rtol_0 < 0.0 || kctx->rtol_0 >= 1.0) {
4310     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_0 < 1.0: %G",kctx->rtol_0);
4311   }
4312   if (kctx->rtol_max < 0.0 || kctx->rtol_max >= 1.0) {
4313     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_max (%G) < 1.0\n",kctx->rtol_max);
4314   }
4315   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) {
4316     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%G) <= 1.0\n",kctx->gamma);
4317   }
4318   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) {
4319     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%G) <= 2.0\n",kctx->alpha);
4320   }
4321   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) {
4322     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%G) < 1.0\n",kctx->threshold);
4323   }
4324   PetscFunctionReturn(0);
4325 }
4326 
4327 #undef __FUNCT__
4328 #define __FUNCT__ "SNESKSPGetParametersEW"
4329 /*@
4330    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4331    convergence criteria for the linear solvers within an inexact
4332    Newton method.
4333 
4334    Not Collective
4335 
4336    Input Parameters:
4337      snes - SNES context
4338 
4339    Output Parameters:
4340 +    version - version 1, 2 (default is 2) or 3
4341 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4342 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4343 .    gamma - multiplicative factor for version 2 rtol computation
4344              (0 <= gamma2 <= 1)
4345 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4346 .    alpha2 - power for safeguard
4347 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4348 
4349    Level: advanced
4350 
4351 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4352 
4353 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4354 @*/
4355 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,
4356 							    PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4357 {
4358   SNESKSPEW *kctx;
4359   PetscFunctionBegin;
4360   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4361   kctx = (SNESKSPEW*)snes->kspconvctx;
4362   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4363   if (version)   *version   = kctx->version;
4364   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4365   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4366   if (gamma)     *gamma     = kctx->gamma;
4367   if (alpha)     *alpha     = kctx->alpha;
4368   if (alpha2)    *alpha2    = kctx->alpha2;
4369   if (threshold) *threshold = kctx->threshold;
4370   PetscFunctionReturn(0);
4371 }
4372 
4373 #undef __FUNCT__
4374 #define __FUNCT__ "SNESKSPEW_PreSolve"
4375 static PetscErrorCode SNESKSPEW_PreSolve(SNES snes, KSP ksp, Vec b, Vec x)
4376 {
4377   PetscErrorCode ierr;
4378   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4379   PetscReal      rtol=PETSC_DEFAULT,stol;
4380 
4381   PetscFunctionBegin;
4382   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context exists");
4383   if (!snes->iter) { /* first time in, so use the original user rtol */
4384     rtol = kctx->rtol_0;
4385   } else {
4386     if (kctx->version == 1) {
4387       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4388       if (rtol < 0.0) rtol = -rtol;
4389       stol = pow(kctx->rtol_last,kctx->alpha2);
4390       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4391     } else if (kctx->version == 2) {
4392       rtol = kctx->gamma * pow(snes->norm/kctx->norm_last,kctx->alpha);
4393       stol = kctx->gamma * pow(kctx->rtol_last,kctx->alpha);
4394       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4395     } else if (kctx->version == 3) {/* contributed by Luis Chacon, June 2006. */
4396       rtol = kctx->gamma * pow(snes->norm/kctx->norm_last,kctx->alpha);
4397       /* safeguard: avoid sharp decrease of rtol */
4398       stol = kctx->gamma*pow(kctx->rtol_last,kctx->alpha);
4399       stol = PetscMax(rtol,stol);
4400       rtol = PetscMin(kctx->rtol_0,stol);
4401       /* safeguard: avoid oversolving */
4402       stol = kctx->gamma*(snes->ttol)/snes->norm;
4403       stol = PetscMax(rtol,stol);
4404       rtol = PetscMin(kctx->rtol_0,stol);
4405     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4406   }
4407   /* safeguard: avoid rtol greater than one */
4408   rtol = PetscMin(rtol,kctx->rtol_max);
4409   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4410   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%G\n",snes->iter,kctx->version,rtol);CHKERRQ(ierr);
4411   PetscFunctionReturn(0);
4412 }
4413 
4414 #undef __FUNCT__
4415 #define __FUNCT__ "SNESKSPEW_PostSolve"
4416 static PetscErrorCode SNESKSPEW_PostSolve(SNES snes, KSP ksp, Vec b, Vec x)
4417 {
4418   PetscErrorCode ierr;
4419   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4420   PCSide         pcside;
4421   Vec            lres;
4422 
4423   PetscFunctionBegin;
4424   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context exists");
4425   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4426   ierr = SNESGetFunctionNorm(snes,&kctx->norm_last);CHKERRQ(ierr);
4427   if (kctx->version == 1) {
4428     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4429     if (pcside == PC_RIGHT) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4430       /* KSP residual is true linear residual */
4431       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4432     } else {
4433       /* KSP residual is preconditioned residual */
4434       /* compute true linear residual norm */
4435       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4436       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4437       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4438       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4439       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4440     }
4441   }
4442   PetscFunctionReturn(0);
4443 }
4444 
4445 #undef __FUNCT__
4446 #define __FUNCT__ "SNES_KSPSolve"
4447 PetscErrorCode SNES_KSPSolve(SNES snes, KSP ksp, Vec b, Vec x)
4448 {
4449   PetscErrorCode ierr;
4450 
4451   PetscFunctionBegin;
4452   if (snes->ksp_ewconv) { ierr = SNESKSPEW_PreSolve(snes,ksp,b,x);CHKERRQ(ierr);  }
4453   ierr = KSPSolve(ksp,b,x);CHKERRQ(ierr);
4454   if (snes->ksp_ewconv) { ierr = SNESKSPEW_PostSolve(snes,ksp,b,x);CHKERRQ(ierr); }
4455   PetscFunctionReturn(0);
4456 }
4457 
4458 #include <petsc-private/dmimpl.h>
4459 #undef __FUNCT__
4460 #define __FUNCT__ "SNESSetDM"
4461 /*@
4462    SNESSetDM - Sets the DM that may be used by some preconditioners
4463 
4464    Logically Collective on SNES
4465 
4466    Input Parameters:
4467 +  snes - the preconditioner context
4468 -  dm - the dm
4469 
4470    Level: intermediate
4471 
4472 
4473 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4474 @*/
4475 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4476 {
4477   PetscErrorCode ierr;
4478   KSP            ksp;
4479   DMSNES         sdm;
4480 
4481   PetscFunctionBegin;
4482   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4483   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4484   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4485     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4486       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4487       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4488       if (sdm->originaldm == snes->dm) { /* Grant write privileges to the replacement DM */
4489         sdm->originaldm = dm;
4490       }
4491     }
4492     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4493   }
4494   snes->dm = dm;
4495   snes->dmAuto = PETSC_FALSE;
4496   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4497   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4498   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4499   if (snes->pc) {
4500     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4501     ierr = SNESSetPCSide(snes,snes->pcside);CHKERRQ(ierr);
4502   }
4503   PetscFunctionReturn(0);
4504 }
4505 
4506 #undef __FUNCT__
4507 #define __FUNCT__ "SNESGetDM"
4508 /*@
4509    SNESGetDM - Gets the DM that may be used by some preconditioners
4510 
4511    Not Collective but DM obtained is parallel on SNES
4512 
4513    Input Parameter:
4514 . snes - the preconditioner context
4515 
4516    Output Parameter:
4517 .  dm - the dm
4518 
4519    Level: intermediate
4520 
4521 
4522 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4523 @*/
4524 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4525 {
4526   PetscErrorCode ierr;
4527 
4528   PetscFunctionBegin;
4529   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4530   if (!snes->dm) {
4531     ierr = DMShellCreate(((PetscObject)snes)->comm,&snes->dm);CHKERRQ(ierr);
4532     snes->dmAuto = PETSC_TRUE;
4533   }
4534   *dm = snes->dm;
4535   PetscFunctionReturn(0);
4536 }
4537 
4538 #undef __FUNCT__
4539 #define __FUNCT__ "SNESSetPC"
4540 /*@
4541   SNESSetPC - Sets the nonlinear preconditioner to be used.
4542 
4543   Collective on SNES
4544 
4545   Input Parameters:
4546 + snes - iterative context obtained from SNESCreate()
4547 - pc   - the preconditioner object
4548 
4549   Notes:
4550   Use SNESGetPC() to retrieve the preconditioner context (for example,
4551   to configure it using the API).
4552 
4553   Level: developer
4554 
4555 .keywords: SNES, set, precondition
4556 .seealso: SNESGetPC()
4557 @*/
4558 PetscErrorCode SNESSetPC(SNES snes, SNES pc)
4559 {
4560   PetscErrorCode ierr;
4561 
4562   PetscFunctionBegin;
4563   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4564   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4565   PetscCheckSameComm(snes, 1, pc, 2);
4566   ierr = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4567   ierr = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4568   snes->pc = pc;
4569   ierr = PetscLogObjectParent(snes, snes->pc);CHKERRQ(ierr);
4570   PetscFunctionReturn(0);
4571 }
4572 
4573 #undef __FUNCT__
4574 #define __FUNCT__ "SNESGetPC"
4575 /*@
4576   SNESGetPC - Returns a pointer to the nonlinear preconditioning context set with SNESSetPC().
4577 
4578   Not Collective
4579 
4580   Input Parameter:
4581 . snes - iterative context obtained from SNESCreate()
4582 
4583   Output Parameter:
4584 . pc - preconditioner context
4585 
4586   Level: developer
4587 
4588 .keywords: SNES, get, preconditioner
4589 .seealso: SNESSetPC()
4590 @*/
4591 PetscErrorCode SNESGetPC(SNES snes, SNES *pc)
4592 {
4593   PetscErrorCode              ierr;
4594   const char                  *optionsprefix;
4595 
4596   PetscFunctionBegin;
4597   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4598   PetscValidPointer(pc, 2);
4599   if (!snes->pc) {
4600     ierr = SNESCreate(((PetscObject) snes)->comm,&snes->pc);CHKERRQ(ierr);
4601     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4602     ierr = PetscLogObjectParent(snes,snes->pc);CHKERRQ(ierr);
4603     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4604     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4605     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4606   }
4607   *pc = snes->pc;
4608   PetscFunctionReturn(0);
4609 }
4610 
4611 
4612 #undef __FUNCT__
4613 #define __FUNCT__ "SNESSetPCSide"
4614 /*@
4615     SNESSetPCSide - Sets the preconditioning side.
4616 
4617     Logically Collective on SNES
4618 
4619     Input Parameter:
4620 .   snes - iterative context obtained from SNESCreate()
4621 
4622     Output Parameter:
4623 .   side - the preconditioning side, where side is one of
4624 .vb
4625       PC_LEFT - left preconditioning (default)
4626       PC_RIGHT - right preconditioning
4627 .ve
4628 
4629     Options Database Keys:
4630 .   -snes_pc_side <right,left>
4631 
4632     Level: intermediate
4633 
4634 .keywords: SNES, set, right, left, side, preconditioner, flag
4635 
4636 .seealso: SNESGetPCSide(), KSPSetPCSide()
4637 @*/
4638 PetscErrorCode  SNESSetPCSide(SNES snes,PCSide side)
4639 {
4640   PetscFunctionBegin;
4641   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4642   PetscValidLogicalCollectiveEnum(snes,side,2);
4643   snes->pcside = side;
4644   PetscFunctionReturn(0);
4645 }
4646 
4647 #undef __FUNCT__
4648 #define __FUNCT__ "SNESGetPCSide"
4649 /*@
4650     SNESGetPCSide - Gets the preconditioning side.
4651 
4652     Not Collective
4653 
4654     Input Parameter:
4655 .   snes - iterative context obtained from SNESCreate()
4656 
4657     Output Parameter:
4658 .   side - the preconditioning side, where side is one of
4659 .vb
4660       PC_LEFT - left preconditioning (default)
4661       PC_RIGHT - right preconditioning
4662 .ve
4663 
4664     Level: intermediate
4665 
4666 .keywords: SNES, get, right, left, side, preconditioner, flag
4667 
4668 .seealso: SNESSetPCSide(), KSPGetPCSide()
4669 @*/
4670 PetscErrorCode  SNESGetPCSide(SNES snes,PCSide *side)
4671 {
4672   PetscFunctionBegin;
4673   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4674   PetscValidPointer(side,2);
4675   *side = snes->pcside;
4676   PetscFunctionReturn(0);
4677 }
4678 
4679 #undef __FUNCT__
4680 #define __FUNCT__ "SNESSetSNESLineSearch"
4681 /*@
4682   SNESSetSNESLineSearch - Sets the linesearch on the SNES instance.
4683 
4684   Collective on SNES
4685 
4686   Input Parameters:
4687 + snes - iterative context obtained from SNESCreate()
4688 - linesearch   - the linesearch object
4689 
4690   Notes:
4691   Use SNESGetSNESLineSearch() to retrieve the preconditioner context (for example,
4692   to configure it using the API).
4693 
4694   Level: developer
4695 
4696 .keywords: SNES, set, linesearch
4697 .seealso: SNESGetSNESLineSearch()
4698 @*/
4699 PetscErrorCode SNESSetSNESLineSearch(SNES snes, SNESLineSearch linesearch)
4700 {
4701   PetscErrorCode ierr;
4702 
4703   PetscFunctionBegin;
4704   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4705   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
4706   PetscCheckSameComm(snes, 1, linesearch, 2);
4707   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
4708   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
4709   snes->linesearch = linesearch;
4710   ierr = PetscLogObjectParent(snes, snes->linesearch);CHKERRQ(ierr);
4711   PetscFunctionReturn(0);
4712 }
4713 
4714 #undef __FUNCT__
4715 #define __FUNCT__ "SNESGetSNESLineSearch"
4716 /*@C
4717   SNESGetSNESLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
4718   or creates a default line search instance associated with the SNES and returns it.
4719 
4720   Not Collective
4721 
4722   Input Parameter:
4723 . snes - iterative context obtained from SNESCreate()
4724 
4725   Output Parameter:
4726 . linesearch - linesearch context
4727 
4728   Level: developer
4729 
4730 .keywords: SNES, get, linesearch
4731 .seealso: SNESSetSNESLineSearch()
4732 @*/
4733 PetscErrorCode SNESGetSNESLineSearch(SNES snes, SNESLineSearch *linesearch)
4734 {
4735   PetscErrorCode ierr;
4736   const char     *optionsprefix;
4737 
4738   PetscFunctionBegin;
4739   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4740   PetscValidPointer(linesearch, 2);
4741   if (!snes->linesearch) {
4742     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
4743     ierr = SNESLineSearchCreate(((PetscObject) snes)->comm, &snes->linesearch);CHKERRQ(ierr);
4744     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
4745     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
4746     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
4747     ierr = PetscLogObjectParent(snes, snes->linesearch);CHKERRQ(ierr);
4748   }
4749   *linesearch = snes->linesearch;
4750   PetscFunctionReturn(0);
4751 }
4752 
4753 #if defined(PETSC_HAVE_MATLAB_ENGINE)
4754 #include <mex.h>
4755 
4756 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
4757 
4758 #undef __FUNCT__
4759 #define __FUNCT__ "SNESComputeFunction_Matlab"
4760 /*
4761    SNESComputeFunction_Matlab - Calls the function that has been set with
4762                          SNESSetFunctionMatlab().
4763 
4764    Collective on SNES
4765 
4766    Input Parameters:
4767 +  snes - the SNES context
4768 -  x - input vector
4769 
4770    Output Parameter:
4771 .  y - function vector, as set by SNESSetFunction()
4772 
4773    Notes:
4774    SNESComputeFunction() is typically used within nonlinear solvers
4775    implementations, so most users would not generally call this routine
4776    themselves.
4777 
4778    Level: developer
4779 
4780 .keywords: SNES, nonlinear, compute, function
4781 
4782 .seealso: SNESSetFunction(), SNESGetFunction()
4783 */
4784 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
4785 {
4786   PetscErrorCode    ierr;
4787   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4788   int               nlhs = 1,nrhs = 5;
4789   mxArray	    *plhs[1],*prhs[5];
4790   long long int     lx = 0,ly = 0,ls = 0;
4791 
4792   PetscFunctionBegin;
4793   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4794   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4795   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
4796   PetscCheckSameComm(snes,1,x,2);
4797   PetscCheckSameComm(snes,1,y,3);
4798 
4799   /* call Matlab function in ctx with arguments x and y */
4800 
4801   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4802   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4803   ierr = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
4804   prhs[0] =  mxCreateDoubleScalar((double)ls);
4805   prhs[1] =  mxCreateDoubleScalar((double)lx);
4806   prhs[2] =  mxCreateDoubleScalar((double)ly);
4807   prhs[3] =  mxCreateString(sctx->funcname);
4808   prhs[4] =  sctx->ctx;
4809   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
4810   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
4811   mxDestroyArray(prhs[0]);
4812   mxDestroyArray(prhs[1]);
4813   mxDestroyArray(prhs[2]);
4814   mxDestroyArray(prhs[3]);
4815   mxDestroyArray(plhs[0]);
4816   PetscFunctionReturn(0);
4817 }
4818 
4819 
4820 #undef __FUNCT__
4821 #define __FUNCT__ "SNESSetFunctionMatlab"
4822 /*
4823    SNESSetFunctionMatlab - Sets the function evaluation routine and function
4824    vector for use by the SNES routines in solving systems of nonlinear
4825    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4826 
4827    Logically Collective on SNES
4828 
4829    Input Parameters:
4830 +  snes - the SNES context
4831 .  r - vector to store function value
4832 -  func - function evaluation routine
4833 
4834    Calling sequence of func:
4835 $    func (SNES snes,Vec x,Vec f,void *ctx);
4836 
4837 
4838    Notes:
4839    The Newton-like methods typically solve linear systems of the form
4840 $      f'(x) x = -f(x),
4841    where f'(x) denotes the Jacobian matrix and f(x) is the function.
4842 
4843    Level: beginner
4844 
4845 .keywords: SNES, nonlinear, set, function
4846 
4847 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4848 */
4849 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *func,mxArray *ctx)
4850 {
4851   PetscErrorCode    ierr;
4852   SNESMatlabContext *sctx;
4853 
4854   PetscFunctionBegin;
4855   /* currently sctx is memory bleed */
4856   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4857   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4858   /*
4859      This should work, but it doesn't
4860   sctx->ctx = ctx;
4861   mexMakeArrayPersistent(sctx->ctx);
4862   */
4863   sctx->ctx = mxDuplicateArray(ctx);
4864   ierr = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
4865   PetscFunctionReturn(0);
4866 }
4867 
4868 #undef __FUNCT__
4869 #define __FUNCT__ "SNESComputeJacobian_Matlab"
4870 /*
4871    SNESComputeJacobian_Matlab - Calls the function that has been set with
4872                          SNESSetJacobianMatlab().
4873 
4874    Collective on SNES
4875 
4876    Input Parameters:
4877 +  snes - the SNES context
4878 .  x - input vector
4879 .  A, B - the matrices
4880 -  ctx - user context
4881 
4882    Output Parameter:
4883 .  flag - structure of the matrix
4884 
4885    Level: developer
4886 
4887 .keywords: SNES, nonlinear, compute, function
4888 
4889 .seealso: SNESSetFunction(), SNESGetFunction()
4890 @*/
4891 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat *A,Mat *B,MatStructure *flag, void *ctx)
4892 {
4893   PetscErrorCode    ierr;
4894   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4895   int               nlhs = 2,nrhs = 6;
4896   mxArray	    *plhs[2],*prhs[6];
4897   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
4898 
4899   PetscFunctionBegin;
4900   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4901   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4902 
4903   /* call Matlab function in ctx with arguments x and y */
4904 
4905   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4906   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4907   ierr = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
4908   ierr = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
4909   prhs[0] =  mxCreateDoubleScalar((double)ls);
4910   prhs[1] =  mxCreateDoubleScalar((double)lx);
4911   prhs[2] =  mxCreateDoubleScalar((double)lA);
4912   prhs[3] =  mxCreateDoubleScalar((double)lB);
4913   prhs[4] =  mxCreateString(sctx->funcname);
4914   prhs[5] =  sctx->ctx;
4915   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
4916   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
4917   *flag   =  (MatStructure) mxGetScalar(plhs[1]);CHKERRQ(ierr);
4918   mxDestroyArray(prhs[0]);
4919   mxDestroyArray(prhs[1]);
4920   mxDestroyArray(prhs[2]);
4921   mxDestroyArray(prhs[3]);
4922   mxDestroyArray(prhs[4]);
4923   mxDestroyArray(plhs[0]);
4924   mxDestroyArray(plhs[1]);
4925   PetscFunctionReturn(0);
4926 }
4927 
4928 
4929 #undef __FUNCT__
4930 #define __FUNCT__ "SNESSetJacobianMatlab"
4931 /*
4932    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
4933    vector for use by the SNES routines in solving systems of nonlinear
4934    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4935 
4936    Logically Collective on SNES
4937 
4938    Input Parameters:
4939 +  snes - the SNES context
4940 .  A,B - Jacobian matrices
4941 .  func - function evaluation routine
4942 -  ctx - user context
4943 
4944    Calling sequence of func:
4945 $    flag = func (SNES snes,Vec x,Mat A,Mat B,void *ctx);
4946 
4947 
4948    Level: developer
4949 
4950 .keywords: SNES, nonlinear, set, function
4951 
4952 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4953 */
4954 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *func,mxArray *ctx)
4955 {
4956   PetscErrorCode    ierr;
4957   SNESMatlabContext *sctx;
4958 
4959   PetscFunctionBegin;
4960   /* currently sctx is memory bleed */
4961   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4962   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4963   /*
4964      This should work, but it doesn't
4965   sctx->ctx = ctx;
4966   mexMakeArrayPersistent(sctx->ctx);
4967   */
4968   sctx->ctx = mxDuplicateArray(ctx);
4969   ierr = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
4970   PetscFunctionReturn(0);
4971 }
4972 
4973 #undef __FUNCT__
4974 #define __FUNCT__ "SNESMonitor_Matlab"
4975 /*
4976    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
4977 
4978    Collective on SNES
4979 
4980 .seealso: SNESSetFunction(), SNESGetFunction()
4981 @*/
4982 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
4983 {
4984   PetscErrorCode  ierr;
4985   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4986   int             nlhs = 1,nrhs = 6;
4987   mxArray	  *plhs[1],*prhs[6];
4988   long long int   lx = 0,ls = 0;
4989   Vec             x=snes->vec_sol;
4990 
4991   PetscFunctionBegin;
4992   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4993 
4994   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4995   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4996   prhs[0] =  mxCreateDoubleScalar((double)ls);
4997   prhs[1] =  mxCreateDoubleScalar((double)it);
4998   prhs[2] =  mxCreateDoubleScalar((double)fnorm);
4999   prhs[3] =  mxCreateDoubleScalar((double)lx);
5000   prhs[4] =  mxCreateString(sctx->funcname);
5001   prhs[5] =  sctx->ctx;
5002   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
5003   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
5004   mxDestroyArray(prhs[0]);
5005   mxDestroyArray(prhs[1]);
5006   mxDestroyArray(prhs[2]);
5007   mxDestroyArray(prhs[3]);
5008   mxDestroyArray(prhs[4]);
5009   mxDestroyArray(plhs[0]);
5010   PetscFunctionReturn(0);
5011 }
5012 
5013 
5014 #undef __FUNCT__
5015 #define __FUNCT__ "SNESMonitorSetMatlab"
5016 /*
5017    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
5018 
5019    Level: developer
5020 
5021 .keywords: SNES, nonlinear, set, function
5022 
5023 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5024 */
5025 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *func,mxArray *ctx)
5026 {
5027   PetscErrorCode    ierr;
5028   SNESMatlabContext *sctx;
5029 
5030   PetscFunctionBegin;
5031   /* currently sctx is memory bleed */
5032   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
5033   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
5034   /*
5035      This should work, but it doesn't
5036   sctx->ctx = ctx;
5037   mexMakeArrayPersistent(sctx->ctx);
5038   */
5039   sctx->ctx = mxDuplicateArray(ctx);
5040   ierr = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,PETSC_NULL);CHKERRQ(ierr);
5041   PetscFunctionReturn(0);
5042 }
5043 
5044 #endif
5045