xref: /petsc/src/snes/interface/snes.c (revision cffb1e400d6c3ea2f6cb522ae2432dc42cf29e73)
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   PetscViewerFormat format;
3634 
3635   PetscFunctionBegin;
3636   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3637   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3638   if (x) PetscCheckSameComm(snes,1,x,3);
3639   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3640   if (b) PetscCheckSameComm(snes,1,b,2);
3641 
3642   if (!x) {
3643     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3644     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3645     x    = xcreated;
3646   }
3647 
3648   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm));CHKERRQ(ierr);}
3649   for (grid=0; grid<snes->gridsequence+1; grid++) {
3650 
3651     /* set solution vector */
3652     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3653     ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3654     snes->vec_sol = x;
3655     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3656 
3657     /* set affine vector if provided */
3658     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3659     ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3660     snes->vec_rhs = b;
3661 
3662     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3663 
3664     if (!grid) {
3665       if (snes->ops->computeinitialguess) {
3666         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3667       }
3668     }
3669 
3670     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3671     snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;
3672 
3673     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3674     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3675     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3676     if (snes->domainerror){
3677       snes->reason      = SNES_DIVERGED_FUNCTION_DOMAIN;
3678       snes->domainerror = PETSC_FALSE;
3679     }
3680     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3681 
3682     flg  = PETSC_FALSE;
3683     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,PETSC_NULL);CHKERRQ(ierr);
3684     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
3685     if (snes->printreason) {
3686       ierr = PetscViewerASCIIAddTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3687       if (snes->reason > 0) {
3688         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3689       } else {
3690         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);
3691       }
3692       ierr = PetscViewerASCIISubtractTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3693     }
3694 
3695     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
3696     if (grid <  snes->gridsequence) {
3697       DM  fine;
3698       Vec xnew;
3699       Mat interp;
3700 
3701       ierr = DMRefine(snes->dm,((PetscObject)snes)->comm,&fine);CHKERRQ(ierr);
3702       if (!fine) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
3703       ierr = DMCreateInterpolation(snes->dm,fine,&interp,PETSC_NULL);CHKERRQ(ierr);
3704       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
3705       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
3706       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
3707       ierr = MatDestroy(&interp);CHKERRQ(ierr);
3708       x    = xnew;
3709 
3710       ierr = SNESReset(snes);CHKERRQ(ierr);
3711       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
3712       ierr = DMDestroy(&fine);CHKERRQ(ierr);
3713       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm));CHKERRQ(ierr);
3714     }
3715   }
3716   /* monitoring and viewing */
3717   ierr = PetscOptionsGetViewer(((PetscObject)snes)->comm,((PetscObject)snes)->prefix,"-snes_view",&viewer,&format,&flg);CHKERRQ(ierr);
3718   if (flg && !PetscPreLoadingOn) {
3719     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
3720     ierr = SNESView(snes,viewer);CHKERRQ(ierr);
3721     ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
3722     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3723   }
3724   ierr = VecViewFromOptions(snes->vec_sol,"-snes_view_solution");CHKERRQ(ierr);
3725 
3726   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
3727   PetscFunctionReturn(0);
3728 }
3729 
3730 /* --------- Internal routines for SNES Package --------- */
3731 
3732 #undef __FUNCT__
3733 #define __FUNCT__ "SNESSetType"
3734 /*@C
3735    SNESSetType - Sets the method for the nonlinear solver.
3736 
3737    Collective on SNES
3738 
3739    Input Parameters:
3740 +  snes - the SNES context
3741 -  type - a known method
3742 
3743    Options Database Key:
3744 .  -snes_type <type> - Sets the method; use -help for a list
3745    of available methods (for instance, newtonls or newtontr)
3746 
3747    Notes:
3748    See "petsc/include/petscsnes.h" for available methods (for instance)
3749 +    SNESNEWTONLS - Newton's method with line search
3750      (systems of nonlinear equations)
3751 .    SNESNEWTONTR - Newton's method with trust region
3752      (systems of nonlinear equations)
3753 
3754   Normally, it is best to use the SNESSetFromOptions() command and then
3755   set the SNES solver type from the options database rather than by using
3756   this routine.  Using the options database provides the user with
3757   maximum flexibility in evaluating the many nonlinear solvers.
3758   The SNESSetType() routine is provided for those situations where it
3759   is necessary to set the nonlinear solver independently of the command
3760   line or options database.  This might be the case, for example, when
3761   the choice of solver changes during the execution of the program,
3762   and the user's application is taking responsibility for choosing the
3763   appropriate method.
3764 
3765   Level: intermediate
3766 
3767 .keywords: SNES, set, type
3768 
3769 .seealso: SNESType, SNESCreate()
3770 
3771 @*/
3772 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
3773 {
3774   PetscErrorCode ierr,(*r)(SNES);
3775   PetscBool      match;
3776 
3777   PetscFunctionBegin;
3778   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3779   PetscValidCharPointer(type,2);
3780 
3781   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
3782   if (match) PetscFunctionReturn(0);
3783 
3784   ierr =  PetscFListFind(SNESList,((PetscObject)snes)->comm,type,PETSC_TRUE,(void (**)(void)) &r);CHKERRQ(ierr);
3785   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
3786   /* Destroy the previous private SNES context */
3787   if (snes->ops->destroy) {
3788     ierr = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
3789     snes->ops->destroy = PETSC_NULL;
3790   }
3791   /* Reinitialize function pointers in SNESOps structure */
3792   snes->ops->setup          = 0;
3793   snes->ops->solve          = 0;
3794   snes->ops->view           = 0;
3795   snes->ops->setfromoptions = 0;
3796   snes->ops->destroy        = 0;
3797   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
3798   snes->setupcalled = PETSC_FALSE;
3799   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
3800   ierr = (*r)(snes);CHKERRQ(ierr);
3801 #if defined(PETSC_HAVE_AMS)
3802   if (PetscAMSPublishAll) {
3803     ierr = PetscObjectAMSPublish((PetscObject)snes);CHKERRQ(ierr);
3804   }
3805 #endif
3806   PetscFunctionReturn(0);
3807 }
3808 
3809 
3810 /* --------------------------------------------------------------------- */
3811 #undef __FUNCT__
3812 #define __FUNCT__ "SNESRegisterDestroy"
3813 /*@
3814    SNESRegisterDestroy - Frees the list of nonlinear solvers that were
3815    registered by SNESRegisterDynamic().
3816 
3817    Not Collective
3818 
3819    Level: advanced
3820 
3821 .keywords: SNES, nonlinear, register, destroy
3822 
3823 .seealso: SNESRegisterAll(), SNESRegisterAll()
3824 @*/
3825 PetscErrorCode  SNESRegisterDestroy(void)
3826 {
3827   PetscErrorCode ierr;
3828 
3829   PetscFunctionBegin;
3830   ierr = PetscFListDestroy(&SNESList);CHKERRQ(ierr);
3831   SNESRegisterAllCalled = PETSC_FALSE;
3832   PetscFunctionReturn(0);
3833 }
3834 
3835 #undef __FUNCT__
3836 #define __FUNCT__ "SNESGetType"
3837 /*@C
3838    SNESGetType - Gets the SNES method type and name (as a string).
3839 
3840    Not Collective
3841 
3842    Input Parameter:
3843 .  snes - nonlinear solver context
3844 
3845    Output Parameter:
3846 .  type - SNES method (a character string)
3847 
3848    Level: intermediate
3849 
3850 .keywords: SNES, nonlinear, get, type, name
3851 @*/
3852 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
3853 {
3854   PetscFunctionBegin;
3855   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3856   PetscValidPointer(type,2);
3857   *type = ((PetscObject)snes)->type_name;
3858   PetscFunctionReturn(0);
3859 }
3860 
3861 #undef __FUNCT__
3862 #define __FUNCT__ "SNESGetSolution"
3863 /*@
3864    SNESGetSolution - Returns the vector where the approximate solution is
3865    stored. This is the fine grid solution when using SNESSetGridSequence().
3866 
3867    Not Collective, but Vec is parallel if SNES is parallel
3868 
3869    Input Parameter:
3870 .  snes - the SNES context
3871 
3872    Output Parameter:
3873 .  x - the solution
3874 
3875    Level: intermediate
3876 
3877 .keywords: SNES, nonlinear, get, solution
3878 
3879 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
3880 @*/
3881 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
3882 {
3883   PetscFunctionBegin;
3884   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3885   PetscValidPointer(x,2);
3886   *x = snes->vec_sol;
3887   PetscFunctionReturn(0);
3888 }
3889 
3890 #undef __FUNCT__
3891 #define __FUNCT__ "SNESGetSolutionUpdate"
3892 /*@
3893    SNESGetSolutionUpdate - Returns the vector where the solution update is
3894    stored.
3895 
3896    Not Collective, but Vec is parallel if SNES is parallel
3897 
3898    Input Parameter:
3899 .  snes - the SNES context
3900 
3901    Output Parameter:
3902 .  x - the solution update
3903 
3904    Level: advanced
3905 
3906 .keywords: SNES, nonlinear, get, solution, update
3907 
3908 .seealso: SNESGetSolution(), SNESGetFunction()
3909 @*/
3910 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
3911 {
3912   PetscFunctionBegin;
3913   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3914   PetscValidPointer(x,2);
3915   *x = snes->vec_sol_update;
3916   PetscFunctionReturn(0);
3917 }
3918 
3919 #undef __FUNCT__
3920 #define __FUNCT__ "SNESGetFunction"
3921 /*@C
3922    SNESGetFunction - Returns the vector where the function is stored.
3923 
3924    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
3925 
3926    Input Parameter:
3927 .  snes - the SNES context
3928 
3929    Output Parameter:
3930 +  r - the function (or PETSC_NULL)
3931 .  func - the function (or PETSC_NULL)
3932 -  ctx - the function context (or PETSC_NULL)
3933 
3934    Level: advanced
3935 
3936 .keywords: SNES, nonlinear, get, function
3937 
3938 .seealso: SNESSetFunction(), SNESGetSolution()
3939 @*/
3940 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**func)(SNES,Vec,Vec,void*),void **ctx)
3941 {
3942   PetscErrorCode ierr;
3943   DM             dm;
3944 
3945   PetscFunctionBegin;
3946   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3947   if (r) {
3948     if (!snes->vec_func) {
3949       if (snes->vec_rhs) {
3950         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
3951       } else if (snes->vec_sol) {
3952         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
3953       } else if (snes->dm) {
3954         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
3955       }
3956     }
3957     *r = snes->vec_func;
3958   }
3959   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3960   ierr = DMSNESGetFunction(dm,func,ctx);CHKERRQ(ierr);
3961   PetscFunctionReturn(0);
3962 }
3963 
3964 /*@C
3965    SNESGetGS - Returns the GS function and context.
3966 
3967    Input Parameter:
3968 .  snes - the SNES context
3969 
3970    Output Parameter:
3971 +  gsfunc - the function (or PETSC_NULL)
3972 -  ctx    - the function context (or PETSC_NULL)
3973 
3974    Level: advanced
3975 
3976 .keywords: SNES, nonlinear, get, function
3977 
3978 .seealso: SNESSetGS(), SNESGetFunction()
3979 @*/
3980 
3981 #undef __FUNCT__
3982 #define __FUNCT__ "SNESGetGS"
3983 PetscErrorCode SNESGetGS (SNES snes, PetscErrorCode(**func)(SNES, Vec, Vec, void*), void ** ctx)
3984 {
3985   PetscErrorCode ierr;
3986   DM             dm;
3987 
3988   PetscFunctionBegin;
3989   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3990   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3991   ierr = DMSNESGetGS(dm,func,ctx);CHKERRQ(ierr);
3992   PetscFunctionReturn(0);
3993 }
3994 
3995 #undef __FUNCT__
3996 #define __FUNCT__ "SNESSetOptionsPrefix"
3997 /*@C
3998    SNESSetOptionsPrefix - Sets the prefix used for searching for all
3999    SNES options in the database.
4000 
4001    Logically Collective on SNES
4002 
4003    Input Parameter:
4004 +  snes - the SNES context
4005 -  prefix - the prefix to prepend to all option names
4006 
4007    Notes:
4008    A hyphen (-) must NOT be given at the beginning of the prefix name.
4009    The first character of all runtime options is AUTOMATICALLY the hyphen.
4010 
4011    Level: advanced
4012 
4013 .keywords: SNES, set, options, prefix, database
4014 
4015 .seealso: SNESSetFromOptions()
4016 @*/
4017 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4018 {
4019   PetscErrorCode ierr;
4020 
4021   PetscFunctionBegin;
4022   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4023   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4024   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4025   if (snes->linesearch) {
4026     ierr = SNESGetSNESLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4027     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4028   }
4029   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4030   PetscFunctionReturn(0);
4031 }
4032 
4033 #undef __FUNCT__
4034 #define __FUNCT__ "SNESAppendOptionsPrefix"
4035 /*@C
4036    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4037    SNES options in the database.
4038 
4039    Logically Collective on SNES
4040 
4041    Input Parameters:
4042 +  snes - the SNES context
4043 -  prefix - the prefix to prepend to all option names
4044 
4045    Notes:
4046    A hyphen (-) must NOT be given at the beginning of the prefix name.
4047    The first character of all runtime options is AUTOMATICALLY the hyphen.
4048 
4049    Level: advanced
4050 
4051 .keywords: SNES, append, options, prefix, database
4052 
4053 .seealso: SNESGetOptionsPrefix()
4054 @*/
4055 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4056 {
4057   PetscErrorCode ierr;
4058 
4059   PetscFunctionBegin;
4060   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4061   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4062   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4063   if (snes->linesearch) {
4064     ierr = SNESGetSNESLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4065     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4066   }
4067   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4068   PetscFunctionReturn(0);
4069 }
4070 
4071 #undef __FUNCT__
4072 #define __FUNCT__ "SNESGetOptionsPrefix"
4073 /*@C
4074    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4075    SNES options in the database.
4076 
4077    Not Collective
4078 
4079    Input Parameter:
4080 .  snes - the SNES context
4081 
4082    Output Parameter:
4083 .  prefix - pointer to the prefix string used
4084 
4085    Notes: On the fortran side, the user should pass in a string 'prefix' of
4086    sufficient length to hold the prefix.
4087 
4088    Level: advanced
4089 
4090 .keywords: SNES, get, options, prefix, database
4091 
4092 .seealso: SNESAppendOptionsPrefix()
4093 @*/
4094 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4095 {
4096   PetscErrorCode ierr;
4097 
4098   PetscFunctionBegin;
4099   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4100   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4101   PetscFunctionReturn(0);
4102 }
4103 
4104 
4105 #undef __FUNCT__
4106 #define __FUNCT__ "SNESRegister"
4107 /*@C
4108   SNESRegister - See SNESRegisterDynamic()
4109 
4110   Level: advanced
4111 @*/
4112 PetscErrorCode  SNESRegister(const char sname[],const char path[],const char name[],PetscErrorCode (*function)(SNES))
4113 {
4114   char           fullname[PETSC_MAX_PATH_LEN];
4115   PetscErrorCode ierr;
4116 
4117   PetscFunctionBegin;
4118   ierr = PetscFListConcat(path,name,fullname);CHKERRQ(ierr);
4119   ierr = PetscFListAdd(&SNESList,sname,fullname,(void (*)(void))function);CHKERRQ(ierr);
4120   PetscFunctionReturn(0);
4121 }
4122 
4123 #undef __FUNCT__
4124 #define __FUNCT__ "SNESTestLocalMin"
4125 PetscErrorCode  SNESTestLocalMin(SNES snes)
4126 {
4127   PetscErrorCode ierr;
4128   PetscInt       N,i,j;
4129   Vec            u,uh,fh;
4130   PetscScalar    value;
4131   PetscReal      norm;
4132 
4133   PetscFunctionBegin;
4134   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4135   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4136   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4137 
4138   /* currently only works for sequential */
4139   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");
4140   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4141   for (i=0; i<N; i++) {
4142     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4143     ierr  = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4144     for (j=-10; j<11; j++) {
4145       value = PetscSign(j)*exp(PetscAbs(j)-10.0);
4146       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4147       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4148       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4149       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4150       value = -value;
4151       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4152     }
4153   }
4154   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4155   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4156   PetscFunctionReturn(0);
4157 }
4158 
4159 #undef __FUNCT__
4160 #define __FUNCT__ "SNESKSPSetUseEW"
4161 /*@
4162    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4163    computing relative tolerance for linear solvers within an inexact
4164    Newton method.
4165 
4166    Logically Collective on SNES
4167 
4168    Input Parameters:
4169 +  snes - SNES context
4170 -  flag - PETSC_TRUE or PETSC_FALSE
4171 
4172     Options Database:
4173 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4174 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4175 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4176 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4177 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4178 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4179 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4180 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4181 
4182    Notes:
4183    Currently, the default is to use a constant relative tolerance for
4184    the inner linear solvers.  Alternatively, one can use the
4185    Eisenstat-Walker method, where the relative convergence tolerance
4186    is reset at each Newton iteration according progress of the nonlinear
4187    solver.
4188 
4189    Level: advanced
4190 
4191    Reference:
4192    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4193    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4194 
4195 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4196 
4197 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4198 @*/
4199 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool  flag)
4200 {
4201   PetscFunctionBegin;
4202   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4203   PetscValidLogicalCollectiveBool(snes,flag,2);
4204   snes->ksp_ewconv = flag;
4205   PetscFunctionReturn(0);
4206 }
4207 
4208 #undef __FUNCT__
4209 #define __FUNCT__ "SNESKSPGetUseEW"
4210 /*@
4211    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4212    for computing relative tolerance for linear solvers within an
4213    inexact Newton method.
4214 
4215    Not Collective
4216 
4217    Input Parameter:
4218 .  snes - SNES context
4219 
4220    Output Parameter:
4221 .  flag - PETSC_TRUE or PETSC_FALSE
4222 
4223    Notes:
4224    Currently, the default is to use a constant relative tolerance for
4225    the inner linear solvers.  Alternatively, one can use the
4226    Eisenstat-Walker method, where the relative convergence tolerance
4227    is reset at each Newton iteration according progress of the nonlinear
4228    solver.
4229 
4230    Level: advanced
4231 
4232    Reference:
4233    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4234    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4235 
4236 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4237 
4238 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4239 @*/
4240 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4241 {
4242   PetscFunctionBegin;
4243   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4244   PetscValidPointer(flag,2);
4245   *flag = snes->ksp_ewconv;
4246   PetscFunctionReturn(0);
4247 }
4248 
4249 #undef __FUNCT__
4250 #define __FUNCT__ "SNESKSPSetParametersEW"
4251 /*@
4252    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4253    convergence criteria for the linear solvers within an inexact
4254    Newton method.
4255 
4256    Logically Collective on SNES
4257 
4258    Input Parameters:
4259 +    snes - SNES context
4260 .    version - version 1, 2 (default is 2) or 3
4261 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4262 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4263 .    gamma - multiplicative factor for version 2 rtol computation
4264              (0 <= gamma2 <= 1)
4265 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4266 .    alpha2 - power for safeguard
4267 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4268 
4269    Note:
4270    Version 3 was contributed by Luis Chacon, June 2006.
4271 
4272    Use PETSC_DEFAULT to retain the default for any of the parameters.
4273 
4274    Level: advanced
4275 
4276    Reference:
4277    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4278    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4279    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4280 
4281 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4282 
4283 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4284 @*/
4285 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,
4286 							    PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4287 {
4288   SNESKSPEW *kctx;
4289   PetscFunctionBegin;
4290   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4291   kctx = (SNESKSPEW*)snes->kspconvctx;
4292   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4293   PetscValidLogicalCollectiveInt(snes,version,2);
4294   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4295   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4296   PetscValidLogicalCollectiveReal(snes,gamma,5);
4297   PetscValidLogicalCollectiveReal(snes,alpha,6);
4298   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4299   PetscValidLogicalCollectiveReal(snes,threshold,8);
4300 
4301   if (version != PETSC_DEFAULT)   kctx->version   = version;
4302   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4303   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4304   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4305   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4306   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4307   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4308 
4309   if (kctx->version < 1 || kctx->version > 3) {
4310     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 and 3 are supported: %D",kctx->version);
4311   }
4312   if (kctx->rtol_0 < 0.0 || kctx->rtol_0 >= 1.0) {
4313     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_0 < 1.0: %G",kctx->rtol_0);
4314   }
4315   if (kctx->rtol_max < 0.0 || kctx->rtol_max >= 1.0) {
4316     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_max (%G) < 1.0\n",kctx->rtol_max);
4317   }
4318   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) {
4319     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%G) <= 1.0\n",kctx->gamma);
4320   }
4321   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) {
4322     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%G) <= 2.0\n",kctx->alpha);
4323   }
4324   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) {
4325     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%G) < 1.0\n",kctx->threshold);
4326   }
4327   PetscFunctionReturn(0);
4328 }
4329 
4330 #undef __FUNCT__
4331 #define __FUNCT__ "SNESKSPGetParametersEW"
4332 /*@
4333    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4334    convergence criteria for the linear solvers within an inexact
4335    Newton method.
4336 
4337    Not Collective
4338 
4339    Input Parameters:
4340      snes - SNES context
4341 
4342    Output Parameters:
4343 +    version - version 1, 2 (default is 2) or 3
4344 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4345 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4346 .    gamma - multiplicative factor for version 2 rtol computation
4347              (0 <= gamma2 <= 1)
4348 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4349 .    alpha2 - power for safeguard
4350 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4351 
4352    Level: advanced
4353 
4354 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4355 
4356 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4357 @*/
4358 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,
4359 							    PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4360 {
4361   SNESKSPEW *kctx;
4362   PetscFunctionBegin;
4363   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4364   kctx = (SNESKSPEW*)snes->kspconvctx;
4365   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4366   if (version)   *version   = kctx->version;
4367   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4368   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4369   if (gamma)     *gamma     = kctx->gamma;
4370   if (alpha)     *alpha     = kctx->alpha;
4371   if (alpha2)    *alpha2    = kctx->alpha2;
4372   if (threshold) *threshold = kctx->threshold;
4373   PetscFunctionReturn(0);
4374 }
4375 
4376 #undef __FUNCT__
4377 #define __FUNCT__ "SNESKSPEW_PreSolve"
4378 static PetscErrorCode SNESKSPEW_PreSolve(SNES snes, KSP ksp, Vec b, Vec x)
4379 {
4380   PetscErrorCode ierr;
4381   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4382   PetscReal      rtol=PETSC_DEFAULT,stol;
4383 
4384   PetscFunctionBegin;
4385   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context exists");
4386   if (!snes->iter) { /* first time in, so use the original user rtol */
4387     rtol = kctx->rtol_0;
4388   } else {
4389     if (kctx->version == 1) {
4390       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4391       if (rtol < 0.0) rtol = -rtol;
4392       stol = pow(kctx->rtol_last,kctx->alpha2);
4393       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4394     } else if (kctx->version == 2) {
4395       rtol = kctx->gamma * pow(snes->norm/kctx->norm_last,kctx->alpha);
4396       stol = kctx->gamma * pow(kctx->rtol_last,kctx->alpha);
4397       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4398     } else if (kctx->version == 3) {/* contributed by Luis Chacon, June 2006. */
4399       rtol = kctx->gamma * pow(snes->norm/kctx->norm_last,kctx->alpha);
4400       /* safeguard: avoid sharp decrease of rtol */
4401       stol = kctx->gamma*pow(kctx->rtol_last,kctx->alpha);
4402       stol = PetscMax(rtol,stol);
4403       rtol = PetscMin(kctx->rtol_0,stol);
4404       /* safeguard: avoid oversolving */
4405       stol = kctx->gamma*(snes->ttol)/snes->norm;
4406       stol = PetscMax(rtol,stol);
4407       rtol = PetscMin(kctx->rtol_0,stol);
4408     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4409   }
4410   /* safeguard: avoid rtol greater than one */
4411   rtol = PetscMin(rtol,kctx->rtol_max);
4412   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4413   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%G\n",snes->iter,kctx->version,rtol);CHKERRQ(ierr);
4414   PetscFunctionReturn(0);
4415 }
4416 
4417 #undef __FUNCT__
4418 #define __FUNCT__ "SNESKSPEW_PostSolve"
4419 static PetscErrorCode SNESKSPEW_PostSolve(SNES snes, KSP ksp, Vec b, Vec x)
4420 {
4421   PetscErrorCode ierr;
4422   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4423   PCSide         pcside;
4424   Vec            lres;
4425 
4426   PetscFunctionBegin;
4427   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context exists");
4428   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4429   ierr = SNESGetFunctionNorm(snes,&kctx->norm_last);CHKERRQ(ierr);
4430   if (kctx->version == 1) {
4431     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4432     if (pcside == PC_RIGHT) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4433       /* KSP residual is true linear residual */
4434       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4435     } else {
4436       /* KSP residual is preconditioned residual */
4437       /* compute true linear residual norm */
4438       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4439       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4440       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4441       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4442       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4443     }
4444   }
4445   PetscFunctionReturn(0);
4446 }
4447 
4448 #undef __FUNCT__
4449 #define __FUNCT__ "SNES_KSPSolve"
4450 PetscErrorCode SNES_KSPSolve(SNES snes, KSP ksp, Vec b, Vec x)
4451 {
4452   PetscErrorCode ierr;
4453 
4454   PetscFunctionBegin;
4455   if (snes->ksp_ewconv) { ierr = SNESKSPEW_PreSolve(snes,ksp,b,x);CHKERRQ(ierr);  }
4456   ierr = KSPSolve(ksp,b,x);CHKERRQ(ierr);
4457   if (snes->ksp_ewconv) { ierr = SNESKSPEW_PostSolve(snes,ksp,b,x);CHKERRQ(ierr); }
4458   PetscFunctionReturn(0);
4459 }
4460 
4461 #include <petsc-private/dmimpl.h>
4462 #undef __FUNCT__
4463 #define __FUNCT__ "SNESSetDM"
4464 /*@
4465    SNESSetDM - Sets the DM that may be used by some preconditioners
4466 
4467    Logically Collective on SNES
4468 
4469    Input Parameters:
4470 +  snes - the preconditioner context
4471 -  dm - the dm
4472 
4473    Level: intermediate
4474 
4475 
4476 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4477 @*/
4478 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4479 {
4480   PetscErrorCode ierr;
4481   KSP            ksp;
4482   DMSNES         sdm;
4483 
4484   PetscFunctionBegin;
4485   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4486   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4487   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4488     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4489       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4490       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4491       if (sdm->originaldm == snes->dm) { /* Grant write privileges to the replacement DM */
4492         sdm->originaldm = dm;
4493       }
4494     }
4495     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4496   }
4497   snes->dm = dm;
4498   snes->dmAuto = PETSC_FALSE;
4499   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4500   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4501   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4502   if (snes->pc) {
4503     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4504     ierr = SNESSetPCSide(snes,snes->pcside);CHKERRQ(ierr);
4505   }
4506   PetscFunctionReturn(0);
4507 }
4508 
4509 #undef __FUNCT__
4510 #define __FUNCT__ "SNESGetDM"
4511 /*@
4512    SNESGetDM - Gets the DM that may be used by some preconditioners
4513 
4514    Not Collective but DM obtained is parallel on SNES
4515 
4516    Input Parameter:
4517 . snes - the preconditioner context
4518 
4519    Output Parameter:
4520 .  dm - the dm
4521 
4522    Level: intermediate
4523 
4524 
4525 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4526 @*/
4527 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4528 {
4529   PetscErrorCode ierr;
4530 
4531   PetscFunctionBegin;
4532   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4533   if (!snes->dm) {
4534     ierr = DMShellCreate(((PetscObject)snes)->comm,&snes->dm);CHKERRQ(ierr);
4535     snes->dmAuto = PETSC_TRUE;
4536   }
4537   *dm = snes->dm;
4538   PetscFunctionReturn(0);
4539 }
4540 
4541 #undef __FUNCT__
4542 #define __FUNCT__ "SNESSetPC"
4543 /*@
4544   SNESSetPC - Sets the nonlinear preconditioner to be used.
4545 
4546   Collective on SNES
4547 
4548   Input Parameters:
4549 + snes - iterative context obtained from SNESCreate()
4550 - pc   - the preconditioner object
4551 
4552   Notes:
4553   Use SNESGetPC() to retrieve the preconditioner context (for example,
4554   to configure it using the API).
4555 
4556   Level: developer
4557 
4558 .keywords: SNES, set, precondition
4559 .seealso: SNESGetPC()
4560 @*/
4561 PetscErrorCode SNESSetPC(SNES snes, SNES pc)
4562 {
4563   PetscErrorCode ierr;
4564 
4565   PetscFunctionBegin;
4566   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4567   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4568   PetscCheckSameComm(snes, 1, pc, 2);
4569   ierr = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4570   ierr = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4571   snes->pc = pc;
4572   ierr = PetscLogObjectParent(snes, snes->pc);CHKERRQ(ierr);
4573   PetscFunctionReturn(0);
4574 }
4575 
4576 #undef __FUNCT__
4577 #define __FUNCT__ "SNESGetPC"
4578 /*@
4579   SNESGetPC - Returns a pointer to the nonlinear preconditioning context set with SNESSetPC().
4580 
4581   Not Collective
4582 
4583   Input Parameter:
4584 . snes - iterative context obtained from SNESCreate()
4585 
4586   Output Parameter:
4587 . pc - preconditioner context
4588 
4589   Level: developer
4590 
4591 .keywords: SNES, get, preconditioner
4592 .seealso: SNESSetPC()
4593 @*/
4594 PetscErrorCode SNESGetPC(SNES snes, SNES *pc)
4595 {
4596   PetscErrorCode              ierr;
4597   const char                  *optionsprefix;
4598 
4599   PetscFunctionBegin;
4600   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4601   PetscValidPointer(pc, 2);
4602   if (!snes->pc) {
4603     ierr = SNESCreate(((PetscObject) snes)->comm,&snes->pc);CHKERRQ(ierr);
4604     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4605     ierr = PetscLogObjectParent(snes,snes->pc);CHKERRQ(ierr);
4606     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4607     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4608     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4609   }
4610   *pc = snes->pc;
4611   PetscFunctionReturn(0);
4612 }
4613 
4614 
4615 #undef __FUNCT__
4616 #define __FUNCT__ "SNESSetPCSide"
4617 /*@
4618     SNESSetPCSide - Sets the preconditioning side.
4619 
4620     Logically Collective on SNES
4621 
4622     Input Parameter:
4623 .   snes - iterative context obtained from SNESCreate()
4624 
4625     Output Parameter:
4626 .   side - the preconditioning side, where side is one of
4627 .vb
4628       PC_LEFT - left preconditioning (default)
4629       PC_RIGHT - right preconditioning
4630 .ve
4631 
4632     Options Database Keys:
4633 .   -snes_pc_side <right,left>
4634 
4635     Level: intermediate
4636 
4637 .keywords: SNES, set, right, left, side, preconditioner, flag
4638 
4639 .seealso: SNESGetPCSide(), KSPSetPCSide()
4640 @*/
4641 PetscErrorCode  SNESSetPCSide(SNES snes,PCSide side)
4642 {
4643   PetscFunctionBegin;
4644   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4645   PetscValidLogicalCollectiveEnum(snes,side,2);
4646   snes->pcside = side;
4647   PetscFunctionReturn(0);
4648 }
4649 
4650 #undef __FUNCT__
4651 #define __FUNCT__ "SNESGetPCSide"
4652 /*@
4653     SNESGetPCSide - Gets the preconditioning side.
4654 
4655     Not Collective
4656 
4657     Input Parameter:
4658 .   snes - iterative context obtained from SNESCreate()
4659 
4660     Output Parameter:
4661 .   side - the preconditioning side, where side is one of
4662 .vb
4663       PC_LEFT - left preconditioning (default)
4664       PC_RIGHT - right preconditioning
4665 .ve
4666 
4667     Level: intermediate
4668 
4669 .keywords: SNES, get, right, left, side, preconditioner, flag
4670 
4671 .seealso: SNESSetPCSide(), KSPGetPCSide()
4672 @*/
4673 PetscErrorCode  SNESGetPCSide(SNES snes,PCSide *side)
4674 {
4675   PetscFunctionBegin;
4676   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4677   PetscValidPointer(side,2);
4678   *side = snes->pcside;
4679   PetscFunctionReturn(0);
4680 }
4681 
4682 #undef __FUNCT__
4683 #define __FUNCT__ "SNESSetSNESLineSearch"
4684 /*@
4685   SNESSetSNESLineSearch - Sets the linesearch on the SNES instance.
4686 
4687   Collective on SNES
4688 
4689   Input Parameters:
4690 + snes - iterative context obtained from SNESCreate()
4691 - linesearch   - the linesearch object
4692 
4693   Notes:
4694   Use SNESGetSNESLineSearch() to retrieve the preconditioner context (for example,
4695   to configure it using the API).
4696 
4697   Level: developer
4698 
4699 .keywords: SNES, set, linesearch
4700 .seealso: SNESGetSNESLineSearch()
4701 @*/
4702 PetscErrorCode SNESSetSNESLineSearch(SNES snes, SNESLineSearch linesearch)
4703 {
4704   PetscErrorCode ierr;
4705 
4706   PetscFunctionBegin;
4707   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4708   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
4709   PetscCheckSameComm(snes, 1, linesearch, 2);
4710   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
4711   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
4712   snes->linesearch = linesearch;
4713   ierr = PetscLogObjectParent(snes, snes->linesearch);CHKERRQ(ierr);
4714   PetscFunctionReturn(0);
4715 }
4716 
4717 #undef __FUNCT__
4718 #define __FUNCT__ "SNESGetSNESLineSearch"
4719 /*@C
4720   SNESGetSNESLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
4721   or creates a default line search instance associated with the SNES and returns it.
4722 
4723   Not Collective
4724 
4725   Input Parameter:
4726 . snes - iterative context obtained from SNESCreate()
4727 
4728   Output Parameter:
4729 . linesearch - linesearch context
4730 
4731   Level: developer
4732 
4733 .keywords: SNES, get, linesearch
4734 .seealso: SNESSetSNESLineSearch()
4735 @*/
4736 PetscErrorCode SNESGetSNESLineSearch(SNES snes, SNESLineSearch *linesearch)
4737 {
4738   PetscErrorCode ierr;
4739   const char     *optionsprefix;
4740 
4741   PetscFunctionBegin;
4742   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4743   PetscValidPointer(linesearch, 2);
4744   if (!snes->linesearch) {
4745     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
4746     ierr = SNESLineSearchCreate(((PetscObject) snes)->comm, &snes->linesearch);CHKERRQ(ierr);
4747     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
4748     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
4749     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
4750     ierr = PetscLogObjectParent(snes, snes->linesearch);CHKERRQ(ierr);
4751   }
4752   *linesearch = snes->linesearch;
4753   PetscFunctionReturn(0);
4754 }
4755 
4756 #if defined(PETSC_HAVE_MATLAB_ENGINE)
4757 #include <mex.h>
4758 
4759 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
4760 
4761 #undef __FUNCT__
4762 #define __FUNCT__ "SNESComputeFunction_Matlab"
4763 /*
4764    SNESComputeFunction_Matlab - Calls the function that has been set with
4765                          SNESSetFunctionMatlab().
4766 
4767    Collective on SNES
4768 
4769    Input Parameters:
4770 +  snes - the SNES context
4771 -  x - input vector
4772 
4773    Output Parameter:
4774 .  y - function vector, as set by SNESSetFunction()
4775 
4776    Notes:
4777    SNESComputeFunction() is typically used within nonlinear solvers
4778    implementations, so most users would not generally call this routine
4779    themselves.
4780 
4781    Level: developer
4782 
4783 .keywords: SNES, nonlinear, compute, function
4784 
4785 .seealso: SNESSetFunction(), SNESGetFunction()
4786 */
4787 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
4788 {
4789   PetscErrorCode    ierr;
4790   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4791   int               nlhs = 1,nrhs = 5;
4792   mxArray	    *plhs[1],*prhs[5];
4793   long long int     lx = 0,ly = 0,ls = 0;
4794 
4795   PetscFunctionBegin;
4796   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4797   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4798   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
4799   PetscCheckSameComm(snes,1,x,2);
4800   PetscCheckSameComm(snes,1,y,3);
4801 
4802   /* call Matlab function in ctx with arguments x and y */
4803 
4804   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4805   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4806   ierr = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
4807   prhs[0] =  mxCreateDoubleScalar((double)ls);
4808   prhs[1] =  mxCreateDoubleScalar((double)lx);
4809   prhs[2] =  mxCreateDoubleScalar((double)ly);
4810   prhs[3] =  mxCreateString(sctx->funcname);
4811   prhs[4] =  sctx->ctx;
4812   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
4813   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
4814   mxDestroyArray(prhs[0]);
4815   mxDestroyArray(prhs[1]);
4816   mxDestroyArray(prhs[2]);
4817   mxDestroyArray(prhs[3]);
4818   mxDestroyArray(plhs[0]);
4819   PetscFunctionReturn(0);
4820 }
4821 
4822 
4823 #undef __FUNCT__
4824 #define __FUNCT__ "SNESSetFunctionMatlab"
4825 /*
4826    SNESSetFunctionMatlab - Sets the function evaluation routine and function
4827    vector for use by the SNES routines in solving systems of nonlinear
4828    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4829 
4830    Logically Collective on SNES
4831 
4832    Input Parameters:
4833 +  snes - the SNES context
4834 .  r - vector to store function value
4835 -  func - function evaluation routine
4836 
4837    Calling sequence of func:
4838 $    func (SNES snes,Vec x,Vec f,void *ctx);
4839 
4840 
4841    Notes:
4842    The Newton-like methods typically solve linear systems of the form
4843 $      f'(x) x = -f(x),
4844    where f'(x) denotes the Jacobian matrix and f(x) is the function.
4845 
4846    Level: beginner
4847 
4848 .keywords: SNES, nonlinear, set, function
4849 
4850 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4851 */
4852 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *func,mxArray *ctx)
4853 {
4854   PetscErrorCode    ierr;
4855   SNESMatlabContext *sctx;
4856 
4857   PetscFunctionBegin;
4858   /* currently sctx is memory bleed */
4859   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4860   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4861   /*
4862      This should work, but it doesn't
4863   sctx->ctx = ctx;
4864   mexMakeArrayPersistent(sctx->ctx);
4865   */
4866   sctx->ctx = mxDuplicateArray(ctx);
4867   ierr = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
4868   PetscFunctionReturn(0);
4869 }
4870 
4871 #undef __FUNCT__
4872 #define __FUNCT__ "SNESComputeJacobian_Matlab"
4873 /*
4874    SNESComputeJacobian_Matlab - Calls the function that has been set with
4875                          SNESSetJacobianMatlab().
4876 
4877    Collective on SNES
4878 
4879    Input Parameters:
4880 +  snes - the SNES context
4881 .  x - input vector
4882 .  A, B - the matrices
4883 -  ctx - user context
4884 
4885    Output Parameter:
4886 .  flag - structure of the matrix
4887 
4888    Level: developer
4889 
4890 .keywords: SNES, nonlinear, compute, function
4891 
4892 .seealso: SNESSetFunction(), SNESGetFunction()
4893 @*/
4894 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat *A,Mat *B,MatStructure *flag, void *ctx)
4895 {
4896   PetscErrorCode    ierr;
4897   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4898   int               nlhs = 2,nrhs = 6;
4899   mxArray	    *plhs[2],*prhs[6];
4900   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
4901 
4902   PetscFunctionBegin;
4903   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4904   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4905 
4906   /* call Matlab function in ctx with arguments x and y */
4907 
4908   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4909   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4910   ierr = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
4911   ierr = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
4912   prhs[0] =  mxCreateDoubleScalar((double)ls);
4913   prhs[1] =  mxCreateDoubleScalar((double)lx);
4914   prhs[2] =  mxCreateDoubleScalar((double)lA);
4915   prhs[3] =  mxCreateDoubleScalar((double)lB);
4916   prhs[4] =  mxCreateString(sctx->funcname);
4917   prhs[5] =  sctx->ctx;
4918   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
4919   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
4920   *flag   =  (MatStructure) mxGetScalar(plhs[1]);CHKERRQ(ierr);
4921   mxDestroyArray(prhs[0]);
4922   mxDestroyArray(prhs[1]);
4923   mxDestroyArray(prhs[2]);
4924   mxDestroyArray(prhs[3]);
4925   mxDestroyArray(prhs[4]);
4926   mxDestroyArray(plhs[0]);
4927   mxDestroyArray(plhs[1]);
4928   PetscFunctionReturn(0);
4929 }
4930 
4931 
4932 #undef __FUNCT__
4933 #define __FUNCT__ "SNESSetJacobianMatlab"
4934 /*
4935    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
4936    vector for use by the SNES routines in solving systems of nonlinear
4937    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4938 
4939    Logically Collective on SNES
4940 
4941    Input Parameters:
4942 +  snes - the SNES context
4943 .  A,B - Jacobian matrices
4944 .  func - function evaluation routine
4945 -  ctx - user context
4946 
4947    Calling sequence of func:
4948 $    flag = func (SNES snes,Vec x,Mat A,Mat B,void *ctx);
4949 
4950 
4951    Level: developer
4952 
4953 .keywords: SNES, nonlinear, set, function
4954 
4955 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4956 */
4957 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *func,mxArray *ctx)
4958 {
4959   PetscErrorCode    ierr;
4960   SNESMatlabContext *sctx;
4961 
4962   PetscFunctionBegin;
4963   /* currently sctx is memory bleed */
4964   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4965   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4966   /*
4967      This should work, but it doesn't
4968   sctx->ctx = ctx;
4969   mexMakeArrayPersistent(sctx->ctx);
4970   */
4971   sctx->ctx = mxDuplicateArray(ctx);
4972   ierr = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
4973   PetscFunctionReturn(0);
4974 }
4975 
4976 #undef __FUNCT__
4977 #define __FUNCT__ "SNESMonitor_Matlab"
4978 /*
4979    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
4980 
4981    Collective on SNES
4982 
4983 .seealso: SNESSetFunction(), SNESGetFunction()
4984 @*/
4985 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
4986 {
4987   PetscErrorCode  ierr;
4988   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4989   int             nlhs = 1,nrhs = 6;
4990   mxArray	  *plhs[1],*prhs[6];
4991   long long int   lx = 0,ls = 0;
4992   Vec             x=snes->vec_sol;
4993 
4994   PetscFunctionBegin;
4995   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4996 
4997   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4998   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4999   prhs[0] =  mxCreateDoubleScalar((double)ls);
5000   prhs[1] =  mxCreateDoubleScalar((double)it);
5001   prhs[2] =  mxCreateDoubleScalar((double)fnorm);
5002   prhs[3] =  mxCreateDoubleScalar((double)lx);
5003   prhs[4] =  mxCreateString(sctx->funcname);
5004   prhs[5] =  sctx->ctx;
5005   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
5006   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
5007   mxDestroyArray(prhs[0]);
5008   mxDestroyArray(prhs[1]);
5009   mxDestroyArray(prhs[2]);
5010   mxDestroyArray(prhs[3]);
5011   mxDestroyArray(prhs[4]);
5012   mxDestroyArray(plhs[0]);
5013   PetscFunctionReturn(0);
5014 }
5015 
5016 
5017 #undef __FUNCT__
5018 #define __FUNCT__ "SNESMonitorSetMatlab"
5019 /*
5020    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
5021 
5022    Level: developer
5023 
5024 .keywords: SNES, nonlinear, set, function
5025 
5026 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5027 */
5028 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *func,mxArray *ctx)
5029 {
5030   PetscErrorCode    ierr;
5031   SNESMatlabContext *sctx;
5032 
5033   PetscFunctionBegin;
5034   /* currently sctx is memory bleed */
5035   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
5036   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
5037   /*
5038      This should work, but it doesn't
5039   sctx->ctx = ctx;
5040   mexMakeArrayPersistent(sctx->ctx);
5041   */
5042   sctx->ctx = mxDuplicateArray(ctx);
5043   ierr = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,PETSC_NULL);CHKERRQ(ierr);
5044   PetscFunctionReturn(0);
5045 }
5046 
5047 #endif
5048