xref: /petsc/src/snes/interface/snes.c (revision a64e098fc20714e9cef7e27e1bf2de9a50c27852)
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;
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 
130 #undef __FUNCT__
131 #define __FUNCT__ "SNESView"
132 /*@C
133    SNESView - Prints the SNES data structure.
134 
135    Collective on SNES
136 
137    Input Parameters:
138 +  SNES - the SNES context
139 -  viewer - visualization context
140 
141    Options Database Key:
142 .  -snes_view - Calls SNESView() at end of SNESSolve()
143 
144    Notes:
145    The available visualization contexts include
146 +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
147 -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
148          output where only the first processor opens
149          the file.  All other processors send their
150          data to the first processor to print.
151 
152    The user can open an alternative visualization context with
153    PetscViewerASCIIOpen() - output to a specified file.
154 
155    Level: beginner
156 
157 .keywords: SNES, view
158 
159 .seealso: PetscViewerASCIIOpen()
160 @*/
161 PetscErrorCode  SNESView(SNES snes,PetscViewer viewer)
162 {
163   SNESKSPEW           *kctx;
164   PetscErrorCode      ierr;
165   KSP                 ksp;
166   SNESLineSearch      linesearch;
167   PetscBool           iascii,isstring;
168 
169   PetscFunctionBegin;
170   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
171   if (!viewer) {
172     ierr = PetscViewerASCIIGetStdout(((PetscObject)snes)->comm,&viewer);CHKERRQ(ierr);
173   }
174   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
175   PetscCheckSameComm(snes,1,viewer,2);
176 
177   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
178   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
179   if (iascii) {
180     ierr = PetscObjectPrintClassNamePrefixType((PetscObject)snes,viewer,"SNES Object");CHKERRQ(ierr);
181     if (snes->ops->view) {
182       ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
183       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
184       ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
185     }
186     ierr = PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, maximum function evaluations=%D\n",snes->max_its,snes->max_funcs);CHKERRQ(ierr);
187     ierr = PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%G, absolute=%G, solution=%G\n",
188                  snes->rtol,snes->abstol,snes->stol);CHKERRQ(ierr);
189     ierr = PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",snes->linear_its);CHKERRQ(ierr);
190     ierr = PetscViewerASCIIPrintf(viewer,"  total number of function evaluations=%D\n",snes->nfuncs);CHKERRQ(ierr);
191     if (snes->ksp_ewconv) {
192       kctx = (SNESKSPEW *)snes->kspconvctx;
193       if (kctx) {
194         ierr = PetscViewerASCIIPrintf(viewer,"  Eisenstat-Walker computation of KSP relative tolerance (version %D)\n",kctx->version);CHKERRQ(ierr);
195         ierr = PetscViewerASCIIPrintf(viewer,"    rtol_0=%G, rtol_max=%G, threshold=%G\n",kctx->rtol_0,kctx->rtol_max,kctx->threshold);CHKERRQ(ierr);
196         ierr = PetscViewerASCIIPrintf(viewer,"    gamma=%G, alpha=%G, alpha2=%G\n",kctx->gamma,kctx->alpha,kctx->alpha2);CHKERRQ(ierr);
197       }
198     }
199     if (snes->lagpreconditioner == -1) {
200       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is never rebuilt\n");CHKERRQ(ierr);
201     } else if (snes->lagpreconditioner > 1) {
202       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is rebuilt every %D new Jacobians\n",snes->lagpreconditioner);CHKERRQ(ierr);
203     }
204     if (snes->lagjacobian == -1) {
205       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is never rebuilt\n");CHKERRQ(ierr);
206     } else if (snes->lagjacobian > 1) {
207       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is rebuilt every %D SNES iterations\n",snes->lagjacobian);CHKERRQ(ierr);
208     }
209   } else if (isstring) {
210     const char *type;
211     ierr = SNESGetType(snes,&type);CHKERRQ(ierr);
212     ierr = PetscViewerStringSPrintf(viewer," %-3.3s",type);CHKERRQ(ierr);
213   }
214   if (snes->pc && snes->usespc) {
215     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
216     ierr = SNESView(snes->pc, viewer);CHKERRQ(ierr);
217     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
218   }
219   if (snes->usesksp) {
220     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
221     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
222     ierr = KSPView(ksp,viewer);CHKERRQ(ierr);
223     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
224   }
225   if (snes->linesearch) {
226     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
227     ierr = SNESGetSNESLineSearch(snes, &linesearch);CHKERRQ(ierr);
228     ierr = SNESLineSearchView(linesearch, viewer);CHKERRQ(ierr);
229     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
230   }
231   PetscFunctionReturn(0);
232 }
233 
234 /*
235   We retain a list of functions that also take SNES command
236   line options. These are called at the end SNESSetFromOptions()
237 */
238 #define MAXSETFROMOPTIONS 5
239 static PetscInt numberofsetfromoptions;
240 static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);
241 
242 #undef __FUNCT__
243 #define __FUNCT__ "SNESAddOptionsChecker"
244 /*@C
245   SNESAddOptionsChecker - Adds an additional function to check for SNES options.
246 
247   Not Collective
248 
249   Input Parameter:
250 . snescheck - function that checks for options
251 
252   Level: developer
253 
254 .seealso: SNESSetFromOptions()
255 @*/
256 PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
257 {
258   PetscFunctionBegin;
259   if (numberofsetfromoptions >= MAXSETFROMOPTIONS) {
260     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %D allowed", MAXSETFROMOPTIONS);
261   }
262   othersetfromoptions[numberofsetfromoptions++] = snescheck;
263   PetscFunctionReturn(0);
264 }
265 
266 extern PetscErrorCode  SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);
267 
268 #undef __FUNCT__
269 #define __FUNCT__ "SNESSetUpMatrixFree_Private"
270 static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool  hasOperator, PetscInt version)
271 {
272   Mat            J;
273   KSP            ksp;
274   PC             pc;
275   PetscBool      match;
276   PetscErrorCode ierr;
277 
278   PetscFunctionBegin;
279   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
280 
281   if(!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
282     Mat A = snes->jacobian, B = snes->jacobian_pre;
283     ierr = MatGetVecs(A ? A : B, PETSC_NULL,&snes->vec_func);CHKERRQ(ierr);
284   }
285 
286   if (version == 1) {
287     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
288     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
289     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
290   } else if (version == 2) {
291     if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
292 #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128)
293     ierr = SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);CHKERRQ(ierr);
294 #else
295     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator rutines (version 2)");
296 #endif
297   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator rutines, only version 1 and 2");
298 
299   ierr = PetscInfo1(snes,"Setting default matrix-free operator routines (version %D)\n", version);CHKERRQ(ierr);
300   if (hasOperator) {
301     /* This version replaces the user provided Jacobian matrix with a
302        matrix-free version but still employs the user-provided preconditioner matrix. */
303     ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);
304   } else {
305     /* This version replaces both the user-provided Jacobian and the user-
306        provided preconditioner matrix with the default matrix free version. */
307     void *functx;
308     ierr = SNESGetFunction(snes,PETSC_NULL,PETSC_NULL,&functx);CHKERRQ(ierr);
309     ierr = SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,functx);CHKERRQ(ierr);
310     /* Force no preconditioner */
311     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
312     ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
313     ierr = PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);CHKERRQ(ierr);
314     if (!match) {
315       ierr = PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");CHKERRQ(ierr);
316       ierr = PCSetType(pc,PCNONE);CHKERRQ(ierr);
317     }
318   }
319   ierr = MatDestroy(&J);CHKERRQ(ierr);
320   PetscFunctionReturn(0);
321 }
322 
323 #undef __FUNCT__
324 #define __FUNCT__ "DMRestrictHook_SNESVecSol"
325 static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
326 {
327   SNES snes = (SNES)ctx;
328   PetscErrorCode ierr;
329   Vec Xfine,Xfine_named = PETSC_NULL,Xcoarse;
330 
331   PetscFunctionBegin;
332   if (dmfine == snes->dm) Xfine = snes->vec_sol;
333   else {
334     ierr = DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);
335     Xfine = Xfine_named;
336   }
337   ierr = DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
338   ierr = MatRestrict(Restrict,Xfine,Xcoarse);CHKERRQ(ierr);
339   ierr = VecPointwiseMult(Xcoarse,Xcoarse,Rscale);CHKERRQ(ierr);
340   ierr = DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
341   if (Xfine_named) {ierr = DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);}
342   PetscFunctionReturn(0);
343 }
344 
345 #undef __FUNCT__
346 #define __FUNCT__ "KSPComputeOperators_SNES"
347 /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
348  * safely call SNESGetDM() in their residual evaluation routine. */
349 static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,MatStructure *mstruct,void *ctx)
350 {
351   SNES snes = (SNES)ctx;
352   PetscErrorCode ierr;
353   Mat Asave = A,Bsave = B;
354   Vec X,Xnamed = PETSC_NULL;
355   DM dmsave;
356 
357   PetscFunctionBegin;
358   dmsave = snes->dm;
359   ierr = KSPGetDM(ksp,&snes->dm);CHKERRQ(ierr);
360   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
361   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
362     ierr = DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
363     X = Xnamed;
364   }
365   ierr = SNESComputeJacobian(snes,X,&A,&B,mstruct);CHKERRQ(ierr);
366   if (A != Asave || B != Bsave) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_SUP,"No support for changing matrices at this time");
367   if (Xnamed) {
368     ierr = DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
369   }
370   snes->dm = dmsave;
371   PetscFunctionReturn(0);
372 }
373 
374 #undef __FUNCT__
375 #define __FUNCT__ "SNESSetUpMatrices"
376 /*@
377    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()
378 
379    Collective
380 
381    Input Arguments:
382 .  snes - snes to configure
383 
384    Level: developer
385 
386 .seealso: SNESSetUp()
387 @*/
388 PetscErrorCode SNESSetUpMatrices(SNES snes)
389 {
390   PetscErrorCode ierr;
391   DM             dm;
392   SNESDM         sdm;
393 
394   PetscFunctionBegin;
395   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
396   ierr = DMSNESGetContext(dm,&sdm);CHKERRQ(ierr);
397   if (!sdm->computejacobian) {
398     Mat J,B;
399     ierr = DMCreateMatrix(snes->dm,MATAIJ,&B);CHKERRQ(ierr);
400     if (snes->mf_operator) {
401       ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
402       ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
403       ierr = MatSetFromOptions(J);CHKERRQ(ierr);
404     } else {
405       J = B;
406       ierr = PetscObjectReference((PetscObject)J);CHKERRQ(ierr);
407     }
408     ierr = SNESSetJacobian(snes,J,B,SNESDMComputeJacobian,PETSC_NULL);CHKERRQ(ierr);
409     ierr = MatDestroy(&J);CHKERRQ(ierr);
410     ierr = MatDestroy(&B);CHKERRQ(ierr);
411   } else if (!snes->jacobian && sdm->computejacobian == MatMFFDComputeJacobian) {
412     Mat J;
413     void *functx;
414     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
415     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
416     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
417     ierr = SNESGetFunction(snes,PETSC_NULL,PETSC_NULL,&functx);CHKERRQ(ierr);
418     ierr = SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,functx);CHKERRQ(ierr);
419     ierr = MatDestroy(&J);CHKERRQ(ierr);
420   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
421     Mat J,B;
422     void *functx;
423     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
424     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
425     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
426     ierr = DMCreateMatrix(snes->dm,MATAIJ,&B);CHKERRQ(ierr);
427     ierr = SNESGetFunction(snes,PETSC_NULL,PETSC_NULL,&functx);CHKERRQ(ierr);
428     ierr = SNESSetJacobian(snes,J,B,SNESDMComputeJacobian,functx);CHKERRQ(ierr);
429     ierr = MatDestroy(&J);CHKERRQ(ierr);
430     ierr = MatDestroy(&B);CHKERRQ(ierr);
431   } else if (!snes->jacobian_pre) {
432     Mat J,B;
433     J = snes->jacobian;
434     ierr = DMCreateMatrix(snes->dm,MATAIJ,&B);CHKERRQ(ierr);
435     ierr = SNESSetJacobian(snes,J?J:B,B,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
436     ierr = MatDestroy(&B);CHKERRQ(ierr);
437   }
438   {
439     PetscBool flg = PETSC_FALSE;
440     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_kspcompute",&flg,PETSC_NULL);CHKERRQ(ierr);
441     if (flg) {                  /* Plan to transition to this model */
442       KSP ksp;
443       ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
444       ierr = KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);CHKERRQ(ierr);
445       ierr = DMCoarsenHookAdd(snes->dm,PETSC_NULL,DMRestrictHook_SNESVecSol,snes);CHKERRQ(ierr);
446     }
447   }
448   PetscFunctionReturn(0);
449 }
450 
451 #undef __FUNCT__
452 #define __FUNCT__ "SNESSetFromOptions"
453 /*@
454    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.
455 
456    Collective on SNES
457 
458    Input Parameter:
459 .  snes - the SNES context
460 
461    Options Database Keys:
462 +  -snes_type <type> - ls, tr, ngmres, ncg, richardson, qn, vi, fas
463 .  -snes_stol - convergence tolerance in terms of the norm
464                 of the change in the solution between steps
465 .  -snes_atol <abstol> - absolute tolerance of residual norm
466 .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
467 .  -snes_max_it <max_it> - maximum number of iterations
468 .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
469 .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
470 .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
471 .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
472 .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
473 .  -snes_trtol <trtol> - trust region tolerance
474 .  -snes_no_convergence_test - skip convergence test in nonlinear
475                                solver; hence iterations will continue until max_it
476                                or some other criterion is reached. Saves expense
477                                of convergence test
478 .  -snes_monitor <optional filename> - prints residual norm at each iteration. if no
479                                        filename given prints to stdout
480 .  -snes_monitor_solution - plots solution at each iteration
481 .  -snes_monitor_residual - plots residual (not its norm) at each iteration
482 .  -snes_monitor_solution_update - plots update to solution at each iteration
483 .  -snes_monitor_draw - plots residual norm at each iteration
484 .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
485 .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
486 -  -snes_converged_reason - print the reason for convergence/divergence after each solve
487 
488     Options Database for Eisenstat-Walker method:
489 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
490 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
491 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
492 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
493 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
494 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
495 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
496 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
497 
498    Notes:
499    To see all options, run your program with the -help option or consult
500    the <A href="../../docs/manual.pdf#nameddest=ch_snes">SNES chapter of the users manual</A>.
501 
502    Level: beginner
503 
504 .keywords: SNES, nonlinear, set, options, database
505 
506 .seealso: SNESSetOptionsPrefix()
507 @*/
508 PetscErrorCode  SNESSetFromOptions(SNES snes)
509 {
510   PetscBool               flg,mf,mf_operator,pcset;
511   PetscInt                i,indx,lag,mf_version,grids;
512   MatStructure            matflag;
513   const char              *deft = SNESLS;
514   const char              *convtests[] = {"default","skip"};
515   SNESKSPEW               *kctx = NULL;
516   char                    type[256], monfilename[PETSC_MAX_PATH_LEN];
517   PetscViewer             monviewer;
518   PetscErrorCode          ierr;
519   const char              *optionsprefix;
520 
521   PetscFunctionBegin;
522   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
523 
524   if (!SNESRegisterAllCalled) {ierr = SNESRegisterAll(PETSC_NULL);CHKERRQ(ierr);}
525   ierr = PetscObjectOptionsBegin((PetscObject)snes);CHKERRQ(ierr);
526     if (((PetscObject)snes)->type_name) { deft = ((PetscObject)snes)->type_name; }
527     ierr = PetscOptionsList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);CHKERRQ(ierr);
528     if (flg) {
529       ierr = SNESSetType(snes,type);CHKERRQ(ierr);
530     } else if (!((PetscObject)snes)->type_name) {
531       ierr = SNESSetType(snes,deft);CHKERRQ(ierr);
532     }
533     /* not used here, but called so will go into help messaage */
534     ierr = PetscOptionsName("-snes_view","Print detailed information on solver used","SNESView",0);CHKERRQ(ierr);
535 
536     ierr = PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,0);CHKERRQ(ierr);
537     ierr = PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,0);CHKERRQ(ierr);
538 
539     ierr = PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,0);CHKERRQ(ierr);
540     ierr = PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,PETSC_NULL);CHKERRQ(ierr);
541     ierr = PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,PETSC_NULL);CHKERRQ(ierr);
542     ierr = PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,PETSC_NULL);CHKERRQ(ierr);
543     ierr = PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,PETSC_NULL);CHKERRQ(ierr);
544     ierr = PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,PETSC_NULL);CHKERRQ(ierr);
545 
546     ierr = PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);CHKERRQ(ierr);
547     if (flg) {
548       ierr = SNESSetLagPreconditioner(snes,lag);CHKERRQ(ierr);
549     }
550     ierr = PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);CHKERRQ(ierr);
551     if (flg) {
552       ierr = SNESSetLagJacobian(snes,lag);CHKERRQ(ierr);
553     }
554     ierr = PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);CHKERRQ(ierr);
555     if (flg) {
556       ierr = SNESSetGridSequence(snes,grids);CHKERRQ(ierr);
557     }
558 
559     ierr = PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);CHKERRQ(ierr);
560     if (flg) {
561       switch (indx) {
562       case 0: ierr = SNESSetConvergenceTest(snes,SNESDefaultConverged,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr); break;
563       case 1: ierr = SNESSetConvergenceTest(snes,SNESSkipConverged,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);    break;
564       }
565     }
566 
567     ierr = PetscOptionsBool("-snes_converged_reason","Print reason for converged or diverged","SNESSolve",snes->printreason,&snes->printreason,PETSC_NULL);CHKERRQ(ierr);
568 
569     ierr = PetscOptionsEList("-snes_norm_type","SNES Norm type","SNESSetNormType",SNESNormTypes,5,"function",&indx,&flg);CHKERRQ(ierr);
570     if (flg) { ierr = SNESSetNormType(snes,(SNESNormType)indx);CHKERRQ(ierr); }
571 
572     kctx = (SNESKSPEW *)snes->kspconvctx;
573 
574     ierr = PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,PETSC_NULL);CHKERRQ(ierr);
575 
576     ierr = PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,0);CHKERRQ(ierr);
577     ierr = PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,0);CHKERRQ(ierr);
578     ierr = PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,0);CHKERRQ(ierr);
579     ierr = PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,0);CHKERRQ(ierr);
580     ierr = PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,0);CHKERRQ(ierr);
581     ierr = PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,0);CHKERRQ(ierr);
582     ierr = PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,0);CHKERRQ(ierr);
583 
584     flg  = PETSC_FALSE;
585     ierr = PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
586     if (flg) {ierr = SNESMonitorCancel(snes);CHKERRQ(ierr);}
587 
588     ierr = PetscOptionsString("-snes_monitor","Monitor norm of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
589     if (flg) {
590       ierr = PetscViewerASCIIOpen(((PetscObject)snes)->comm,monfilename,&monviewer);CHKERRQ(ierr);
591       ierr = SNESMonitorSet(snes,SNESMonitorDefault,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
592     }
593 
594     ierr = PetscOptionsString("-snes_monitor_range","Monitor range of elements of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
595     if (flg) {
596       ierr = SNESMonitorSet(snes,SNESMonitorRange,0,0);CHKERRQ(ierr);
597     }
598 
599     ierr = PetscOptionsString("-snes_ratiomonitor","Monitor ratios of norms of function","SNESMonitorSetRatio","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
600     if (flg) {
601       ierr = PetscViewerASCIIOpen(((PetscObject)snes)->comm,monfilename,&monviewer);CHKERRQ(ierr);
602       ierr = SNESMonitorSetRatio(snes,monviewer);CHKERRQ(ierr);
603     }
604 
605     ierr = PetscOptionsString("-snes_monitor_short","Monitor norm of function (fewer digits)","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
606     if (flg) {
607       ierr = PetscViewerASCIIOpen(((PetscObject)snes)->comm,monfilename,&monviewer);CHKERRQ(ierr);
608       ierr = SNESMonitorSet(snes,SNESMonitorDefaultShort,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
609     }
610 
611     ierr = PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
612     if (flg) {ierr = PetscPythonMonitorSet((PetscObject)snes,monfilename);CHKERRQ(ierr);}
613 
614     flg  = PETSC_FALSE;
615     ierr = PetscOptionsBool("-snes_monitor_solution","Plot solution at each iteration","SNESMonitorSolution",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
616     if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolution,0,0);CHKERRQ(ierr);}
617     flg  = PETSC_FALSE;
618     ierr = PetscOptionsBool("-snes_monitor_solution_update","Plot correction at each iteration","SNESMonitorSolutionUpdate",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
619     if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolutionUpdate,0,0);CHKERRQ(ierr);}
620     flg  = PETSC_FALSE;
621     ierr = PetscOptionsBool("-snes_monitor_residual","Plot residual at each iteration","SNESMonitorResidual",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
622     if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorResidual,0,0);CHKERRQ(ierr);}
623     flg  = PETSC_FALSE;
624     ierr = PetscOptionsBool("-snes_monitor_draw","Plot function norm at each iteration","SNESMonitorLG",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
625     if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorLG,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);}
626     flg  = PETSC_FALSE;
627     ierr = PetscOptionsBool("-snes_monitor_range_draw","Plot function range at each iteration","SNESMonitorLG",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
628     if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorLGRange,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);}
629 
630     flg  = PETSC_FALSE;
631     ierr = PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESDefaultComputeJacobian",flg,&flg,PETSC_NULL);CHKERRQ(ierr);
632     if (flg) {
633       void *functx;
634       ierr = SNESGetFunction(snes,PETSC_NULL,PETSC_NULL,&functx);CHKERRQ(ierr);
635       ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESDefaultComputeJacobian,functx);CHKERRQ(ierr);
636       ierr = PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");CHKERRQ(ierr);
637     }
638 
639     mf = mf_operator = PETSC_FALSE;
640     flg = PETSC_FALSE;
641     ierr = PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&mf_operator,&flg);CHKERRQ(ierr);
642     if (flg && mf_operator) {
643       snes->mf_operator = PETSC_TRUE;
644       mf = PETSC_TRUE;
645     }
646     flg = PETSC_FALSE;
647     ierr = PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&mf,&flg);CHKERRQ(ierr);
648     if (!flg && mf_operator) mf = PETSC_TRUE;
649     mf_version = 1;
650     ierr = PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",mf_version,&mf_version,0);CHKERRQ(ierr);
651 
652 
653     /* GS Options */
654     ierr = PetscOptionsInt("-snes_gs_sweeps","Number of sweeps of GS to apply","SNESComputeGS",snes->gssweeps,&snes->gssweeps,PETSC_NULL);CHKERRQ(ierr);
655 
656     for(i = 0; i < numberofsetfromoptions; i++) {
657       ierr = (*othersetfromoptions[i])(snes);CHKERRQ(ierr);
658     }
659 
660     if (snes->ops->setfromoptions) {
661       ierr = (*snes->ops->setfromoptions)(snes);CHKERRQ(ierr);
662     }
663 
664     /* process any options handlers added with PetscObjectAddOptionsHandler() */
665     ierr = PetscObjectProcessOptionsHandlers((PetscObject)snes);CHKERRQ(ierr);
666   ierr = PetscOptionsEnd();CHKERRQ(ierr);
667 
668   if (mf) { ierr = SNESSetUpMatrixFree_Private(snes, mf_operator, mf_version);CHKERRQ(ierr); }
669 
670   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
671   ierr = KSPGetOperators(snes->ksp,PETSC_NULL,PETSC_NULL,&matflag);
672   ierr = KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre,matflag);CHKERRQ(ierr);
673   ierr = KSPSetFromOptions(snes->ksp);CHKERRQ(ierr);
674 
675   if (!snes->linesearch) {
676     ierr = SNESGetSNESLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
677   }
678   ierr = SNESLineSearchSetFromOptions(snes->linesearch);CHKERRQ(ierr);
679 
680   /* if someone has set the SNES PC type, create it. */
681   ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
682   ierr = PetscOptionsHasName(optionsprefix, "-npc_snes_type", &pcset);CHKERRQ(ierr);
683   if (pcset && (!snes->pc)) {
684     ierr = SNESGetPC(snes, &snes->pc);CHKERRQ(ierr);
685   }
686   PetscFunctionReturn(0);
687 }
688 
689 #undef __FUNCT__
690 #define __FUNCT__ "SNESSetComputeApplicationContext"
691 /*@
692    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
693    the nonlinear solvers.
694 
695    Logically Collective on SNES
696 
697    Input Parameters:
698 +  snes - the SNES context
699 .  compute - function to compute the context
700 -  destroy - function to destroy the context
701 
702    Level: intermediate
703 
704 .keywords: SNES, nonlinear, set, application, context
705 
706 .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
707 @*/
708 PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
709 {
710   PetscFunctionBegin;
711   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
712   snes->ops->usercompute = compute;
713   snes->ops->userdestroy = destroy;
714   PetscFunctionReturn(0);
715 }
716 
717 #undef __FUNCT__
718 #define __FUNCT__ "SNESSetApplicationContext"
719 /*@
720    SNESSetApplicationContext - Sets the optional user-defined context for
721    the nonlinear solvers.
722 
723    Logically Collective on SNES
724 
725    Input Parameters:
726 +  snes - the SNES context
727 -  usrP - optional user context
728 
729    Level: intermediate
730 
731 .keywords: SNES, nonlinear, set, application, context
732 
733 .seealso: SNESGetApplicationContext()
734 @*/
735 PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
736 {
737   PetscErrorCode ierr;
738   KSP            ksp;
739 
740   PetscFunctionBegin;
741   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
742   ierr       = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
743   ierr       = KSPSetApplicationContext(ksp,usrP);CHKERRQ(ierr);
744   snes->user = usrP;
745   PetscFunctionReturn(0);
746 }
747 
748 #undef __FUNCT__
749 #define __FUNCT__ "SNESGetApplicationContext"
750 /*@
751    SNESGetApplicationContext - Gets the user-defined context for the
752    nonlinear solvers.
753 
754    Not Collective
755 
756    Input Parameter:
757 .  snes - SNES context
758 
759    Output Parameter:
760 .  usrP - user context
761 
762    Level: intermediate
763 
764 .keywords: SNES, nonlinear, get, application, context
765 
766 .seealso: SNESSetApplicationContext()
767 @*/
768 PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
769 {
770   PetscFunctionBegin;
771   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
772   *(void**)usrP = snes->user;
773   PetscFunctionReturn(0);
774 }
775 
776 #undef __FUNCT__
777 #define __FUNCT__ "SNESGetIterationNumber"
778 /*@
779    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
780    at this time.
781 
782    Not Collective
783 
784    Input Parameter:
785 .  snes - SNES context
786 
787    Output Parameter:
788 .  iter - iteration number
789 
790    Notes:
791    For example, during the computation of iteration 2 this would return 1.
792 
793    This is useful for using lagged Jacobians (where one does not recompute the
794    Jacobian at each SNES iteration). For example, the code
795 .vb
796       ierr = SNESGetIterationNumber(snes,&it);
797       if (!(it % 2)) {
798         [compute Jacobian here]
799       }
800 .ve
801    can be used in your ComputeJacobian() function to cause the Jacobian to be
802    recomputed every second SNES iteration.
803 
804    Level: intermediate
805 
806 .keywords: SNES, nonlinear, get, iteration, number,
807 
808 .seealso:   SNESGetFunctionNorm(), SNESGetLinearSolveIterations()
809 @*/
810 PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt* iter)
811 {
812   PetscFunctionBegin;
813   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
814   PetscValidIntPointer(iter,2);
815   *iter = snes->iter;
816   PetscFunctionReturn(0);
817 }
818 
819 #undef __FUNCT__
820 #define __FUNCT__ "SNESSetIterationNumber"
821 /*@
822    SNESSetIterationNumber - Sets the current iteration number.
823 
824    Not Collective
825 
826    Input Parameter:
827 .  snes - SNES context
828 .  iter - iteration number
829 
830    Level: developer
831 
832 .keywords: SNES, nonlinear, set, iteration, number,
833 
834 .seealso:   SNESGetFunctionNorm(), SNESGetLinearSolveIterations()
835 @*/
836 PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
837 {
838   PetscErrorCode ierr;
839 
840   PetscFunctionBegin;
841   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
842   ierr = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
843   snes->iter = iter;
844   ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
845   PetscFunctionReturn(0);
846 }
847 
848 #undef __FUNCT__
849 #define __FUNCT__ "SNESGetFunctionNorm"
850 /*@
851    SNESGetFunctionNorm - Gets the norm of the current function that was set
852    with SNESSSetFunction().
853 
854    Collective on SNES
855 
856    Input Parameter:
857 .  snes - SNES context
858 
859    Output Parameter:
860 .  fnorm - 2-norm of function
861 
862    Level: intermediate
863 
864 .keywords: SNES, nonlinear, get, function, norm
865 
866 .seealso: SNESGetFunction(), SNESGetIterationNumber(), SNESGetLinearSolveIterations()
867 @*/
868 PetscErrorCode  SNESGetFunctionNorm(SNES snes,PetscReal *fnorm)
869 {
870   PetscFunctionBegin;
871   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
872   PetscValidScalarPointer(fnorm,2);
873   *fnorm = snes->norm;
874   PetscFunctionReturn(0);
875 }
876 
877 
878 #undef __FUNCT__
879 #define __FUNCT__ "SNESSetFunctionNorm"
880 /*@
881    SNESSetFunctionNorm - Sets the 2-norm of the current function computed using VecNorm().
882 
883    Collective on SNES
884 
885    Input Parameter:
886 .  snes - SNES context
887 .  fnorm - 2-norm of function
888 
889    Level: developer
890 
891 .keywords: SNES, nonlinear, set, function, norm
892 
893 .seealso: SNESSetFunction(), SNESSetIterationNumber(), VecNorm().
894 @*/
895 PetscErrorCode  SNESSetFunctionNorm(SNES snes,PetscReal fnorm)
896 {
897 
898   PetscErrorCode ierr;
899 
900   PetscFunctionBegin;
901   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
902   ierr = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
903   snes->norm = fnorm;
904   ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
905   PetscFunctionReturn(0);
906 }
907 
908 #undef __FUNCT__
909 #define __FUNCT__ "SNESGetNonlinearStepFailures"
910 /*@
911    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
912    attempted by the nonlinear solver.
913 
914    Not Collective
915 
916    Input Parameter:
917 .  snes - SNES context
918 
919    Output Parameter:
920 .  nfails - number of unsuccessful steps attempted
921 
922    Notes:
923    This counter is reset to zero for each successive call to SNESSolve().
924 
925    Level: intermediate
926 
927 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
928 
929 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
930           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
931 @*/
932 PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt* nfails)
933 {
934   PetscFunctionBegin;
935   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
936   PetscValidIntPointer(nfails,2);
937   *nfails = snes->numFailures;
938   PetscFunctionReturn(0);
939 }
940 
941 #undef __FUNCT__
942 #define __FUNCT__ "SNESSetMaxNonlinearStepFailures"
943 /*@
944    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
945    attempted by the nonlinear solver before it gives up.
946 
947    Not Collective
948 
949    Input Parameters:
950 +  snes     - SNES context
951 -  maxFails - maximum of unsuccessful steps
952 
953    Level: intermediate
954 
955 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
956 
957 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
958           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
959 @*/
960 PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
961 {
962   PetscFunctionBegin;
963   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
964   snes->maxFailures = maxFails;
965   PetscFunctionReturn(0);
966 }
967 
968 #undef __FUNCT__
969 #define __FUNCT__ "SNESGetMaxNonlinearStepFailures"
970 /*@
971    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
972    attempted by the nonlinear solver before it gives up.
973 
974    Not Collective
975 
976    Input Parameter:
977 .  snes     - SNES context
978 
979    Output Parameter:
980 .  maxFails - maximum of unsuccessful steps
981 
982    Level: intermediate
983 
984 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
985 
986 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
987           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
988 
989 @*/
990 PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
991 {
992   PetscFunctionBegin;
993   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
994   PetscValidIntPointer(maxFails,2);
995   *maxFails = snes->maxFailures;
996   PetscFunctionReturn(0);
997 }
998 
999 #undef __FUNCT__
1000 #define __FUNCT__ "SNESGetNumberFunctionEvals"
1001 /*@
1002    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1003      done by SNES.
1004 
1005    Not Collective
1006 
1007    Input Parameter:
1008 .  snes     - SNES context
1009 
1010    Output Parameter:
1011 .  nfuncs - number of evaluations
1012 
1013    Level: intermediate
1014 
1015 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1016 
1017 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures()
1018 @*/
1019 PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1020 {
1021   PetscFunctionBegin;
1022   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1023   PetscValidIntPointer(nfuncs,2);
1024   *nfuncs = snes->nfuncs;
1025   PetscFunctionReturn(0);
1026 }
1027 
1028 #undef __FUNCT__
1029 #define __FUNCT__ "SNESGetLinearSolveFailures"
1030 /*@
1031    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1032    linear solvers.
1033 
1034    Not Collective
1035 
1036    Input Parameter:
1037 .  snes - SNES context
1038 
1039    Output Parameter:
1040 .  nfails - number of failed solves
1041 
1042    Notes:
1043    This counter is reset to zero for each successive call to SNESSolve().
1044 
1045    Level: intermediate
1046 
1047 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1048 
1049 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1050 @*/
1051 PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt* nfails)
1052 {
1053   PetscFunctionBegin;
1054   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1055   PetscValidIntPointer(nfails,2);
1056   *nfails = snes->numLinearSolveFailures;
1057   PetscFunctionReturn(0);
1058 }
1059 
1060 #undef __FUNCT__
1061 #define __FUNCT__ "SNESSetMaxLinearSolveFailures"
1062 /*@
1063    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1064    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE
1065 
1066    Logically Collective on SNES
1067 
1068    Input Parameters:
1069 +  snes     - SNES context
1070 -  maxFails - maximum allowed linear solve failures
1071 
1072    Level: intermediate
1073 
1074    Notes: By default this is 0; that is SNES returns on the first failed linear solve
1075 
1076 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1077 
1078 .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1079 @*/
1080 PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1081 {
1082   PetscFunctionBegin;
1083   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1084   PetscValidLogicalCollectiveInt(snes,maxFails,2);
1085   snes->maxLinearSolveFailures = maxFails;
1086   PetscFunctionReturn(0);
1087 }
1088 
1089 #undef __FUNCT__
1090 #define __FUNCT__ "SNESGetMaxLinearSolveFailures"
1091 /*@
1092    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1093      are allowed before SNES terminates
1094 
1095    Not Collective
1096 
1097    Input Parameter:
1098 .  snes     - SNES context
1099 
1100    Output Parameter:
1101 .  maxFails - maximum of unsuccessful solves allowed
1102 
1103    Level: intermediate
1104 
1105    Notes: By default this is 1; that is SNES returns on the first failed linear solve
1106 
1107 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1108 
1109 .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1110 @*/
1111 PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1112 {
1113   PetscFunctionBegin;
1114   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1115   PetscValidIntPointer(maxFails,2);
1116   *maxFails = snes->maxLinearSolveFailures;
1117   PetscFunctionReturn(0);
1118 }
1119 
1120 #undef __FUNCT__
1121 #define __FUNCT__ "SNESGetLinearSolveIterations"
1122 /*@
1123    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1124    used by the nonlinear solver.
1125 
1126    Not Collective
1127 
1128    Input Parameter:
1129 .  snes - SNES context
1130 
1131    Output Parameter:
1132 .  lits - number of linear iterations
1133 
1134    Notes:
1135    This counter is reset to zero for each successive call to SNESSolve().
1136 
1137    Level: intermediate
1138 
1139 .keywords: SNES, nonlinear, get, number, linear, iterations
1140 
1141 .seealso:  SNESGetIterationNumber(), SNESGetFunctionNorm(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures()
1142 @*/
1143 PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt* lits)
1144 {
1145   PetscFunctionBegin;
1146   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1147   PetscValidIntPointer(lits,2);
1148   *lits = snes->linear_its;
1149   PetscFunctionReturn(0);
1150 }
1151 
1152 #undef __FUNCT__
1153 #define __FUNCT__ "SNESGetKSP"
1154 /*@
1155    SNESGetKSP - Returns the KSP context for a SNES solver.
1156 
1157    Not Collective, but if SNES object is parallel, then KSP object is parallel
1158 
1159    Input Parameter:
1160 .  snes - the SNES context
1161 
1162    Output Parameter:
1163 .  ksp - the KSP context
1164 
1165    Notes:
1166    The user can then directly manipulate the KSP context to set various
1167    options, etc.  Likewise, the user can then extract and manipulate the
1168    PC contexts as well.
1169 
1170    Level: beginner
1171 
1172 .keywords: SNES, nonlinear, get, KSP, context
1173 
1174 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1175 @*/
1176 PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
1177 {
1178   PetscErrorCode ierr;
1179 
1180   PetscFunctionBegin;
1181   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1182   PetscValidPointer(ksp,2);
1183 
1184   if (!snes->ksp) {
1185     ierr = KSPCreate(((PetscObject)snes)->comm,&snes->ksp);CHKERRQ(ierr);
1186     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);CHKERRQ(ierr);
1187     ierr = PetscLogObjectParent(snes,snes->ksp);CHKERRQ(ierr);
1188   }
1189   *ksp = snes->ksp;
1190   PetscFunctionReturn(0);
1191 }
1192 
1193 #undef __FUNCT__
1194 #define __FUNCT__ "SNESSetKSP"
1195 /*@
1196    SNESSetKSP - Sets a KSP context for the SNES object to use
1197 
1198    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm
1199 
1200    Input Parameters:
1201 +  snes - the SNES context
1202 -  ksp - the KSP context
1203 
1204    Notes:
1205    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1206    so this routine is rarely needed.
1207 
1208    The KSP object that is already in the SNES object has its reference count
1209    decreased by one.
1210 
1211    Level: developer
1212 
1213 .keywords: SNES, nonlinear, get, KSP, context
1214 
1215 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1216 @*/
1217 PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1218 {
1219   PetscErrorCode ierr;
1220 
1221   PetscFunctionBegin;
1222   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1223   PetscValidHeaderSpecific(ksp,KSP_CLASSID,2);
1224   PetscCheckSameComm(snes,1,ksp,2);
1225   ierr = PetscObjectReference((PetscObject)ksp);CHKERRQ(ierr);
1226   if (snes->ksp) {ierr = PetscObjectDereference((PetscObject)snes->ksp);CHKERRQ(ierr);}
1227   snes->ksp = ksp;
1228   PetscFunctionReturn(0);
1229 }
1230 
1231 #if 0
1232 #undef __FUNCT__
1233 #define __FUNCT__ "SNESPublish_Petsc"
1234 static PetscErrorCode SNESPublish_Petsc(PetscObject obj)
1235 {
1236   PetscFunctionBegin;
1237   PetscFunctionReturn(0);
1238 }
1239 #endif
1240 
1241 /* -----------------------------------------------------------*/
1242 #undef __FUNCT__
1243 #define __FUNCT__ "SNESCreate"
1244 /*@
1245    SNESCreate - Creates a nonlinear solver context.
1246 
1247    Collective on MPI_Comm
1248 
1249    Input Parameters:
1250 .  comm - MPI communicator
1251 
1252    Output Parameter:
1253 .  outsnes - the new SNES context
1254 
1255    Options Database Keys:
1256 +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1257                and no preconditioning matrix
1258 .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1259                products, and a user-provided preconditioning matrix
1260                as set by SNESSetJacobian()
1261 -   -snes_fd - Uses (slow!) finite differences to compute Jacobian
1262 
1263    Level: beginner
1264 
1265 .keywords: SNES, nonlinear, create, context
1266 
1267 .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()
1268 
1269 @*/
1270 PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1271 {
1272   PetscErrorCode      ierr;
1273   SNES                snes;
1274   SNESKSPEW           *kctx;
1275 
1276   PetscFunctionBegin;
1277   PetscValidPointer(outsnes,2);
1278   *outsnes = PETSC_NULL;
1279 #ifndef PETSC_USE_DYNAMIC_LIBRARIES
1280   ierr = SNESInitializePackage(PETSC_NULL);CHKERRQ(ierr);
1281 #endif
1282 
1283   ierr = PetscHeaderCreate(snes,_p_SNES,struct _SNESOps,SNES_CLASSID,0,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);CHKERRQ(ierr);
1284 
1285   snes->ops->converged    = SNESDefaultConverged;
1286   snes->usesksp           = PETSC_TRUE;
1287   snes->tolerancesset     = PETSC_FALSE;
1288   snes->max_its           = 50;
1289   snes->max_funcs         = 10000;
1290   snes->norm              = 0.0;
1291   snes->normtype          = SNES_NORM_FUNCTION;
1292   snes->rtol              = 1.e-8;
1293   snes->ttol              = 0.0;
1294   snes->abstol            = 1.e-50;
1295   snes->stol              = 1.e-8;
1296   snes->deltatol          = 1.e-12;
1297   snes->nfuncs            = 0;
1298   snes->numFailures       = 0;
1299   snes->maxFailures       = 1;
1300   snes->linear_its        = 0;
1301   snes->lagjacobian       = 1;
1302   snes->lagpreconditioner = 1;
1303   snes->numbermonitors    = 0;
1304   snes->data              = 0;
1305   snes->setupcalled       = PETSC_FALSE;
1306   snes->ksp_ewconv        = PETSC_FALSE;
1307   snes->nwork             = 0;
1308   snes->work              = 0;
1309   snes->nvwork            = 0;
1310   snes->vwork             = 0;
1311   snes->conv_hist_len     = 0;
1312   snes->conv_hist_max     = 0;
1313   snes->conv_hist         = PETSC_NULL;
1314   snes->conv_hist_its     = PETSC_NULL;
1315   snes->conv_hist_reset   = PETSC_TRUE;
1316   snes->vec_func_init_set = PETSC_FALSE;
1317   snes->norm_init         = 0.;
1318   snes->norm_init_set     = PETSC_FALSE;
1319   snes->reason            = SNES_CONVERGED_ITERATING;
1320   snes->gssweeps          = 1;
1321 
1322   snes->numLinearSolveFailures = 0;
1323   snes->maxLinearSolveFailures = 1;
1324 
1325   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1326   ierr = PetscNewLog(snes,SNESKSPEW,&kctx);CHKERRQ(ierr);
1327   snes->kspconvctx  = (void*)kctx;
1328   kctx->version     = 2;
1329   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1330                              this was too large for some test cases */
1331   kctx->rtol_last   = 0.0;
1332   kctx->rtol_max    = .9;
1333   kctx->gamma       = 1.0;
1334   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1335   kctx->alpha2      = kctx->alpha;
1336   kctx->threshold   = .1;
1337   kctx->lresid_last = 0.0;
1338   kctx->norm_last   = 0.0;
1339 
1340   *outsnes = snes;
1341   PetscFunctionReturn(0);
1342 }
1343 
1344 #undef __FUNCT__
1345 #define __FUNCT__ "SNESSetFunction"
1346 /*@C
1347    SNESSetFunction - Sets the function evaluation routine and function
1348    vector for use by the SNES routines in solving systems of nonlinear
1349    equations.
1350 
1351    Logically Collective on SNES
1352 
1353    Input Parameters:
1354 +  snes - the SNES context
1355 .  r - vector to store function value
1356 .  func - function evaluation routine
1357 -  ctx - [optional] user-defined context for private data for the
1358          function evaluation routine (may be PETSC_NULL)
1359 
1360    Calling sequence of func:
1361 $    func (SNES snes,Vec x,Vec f,void *ctx);
1362 
1363 +  snes - the SNES context
1364 .  x - state at which to evaluate residual
1365 .  f - vector to put residual
1366 -  ctx - optional user-defined function context
1367 
1368    Notes:
1369    The Newton-like methods typically solve linear systems of the form
1370 $      f'(x) x = -f(x),
1371    where f'(x) denotes the Jacobian matrix and f(x) is the function.
1372 
1373    Level: beginner
1374 
1375 .keywords: SNES, nonlinear, set, function
1376 
1377 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard()
1378 @*/
1379 PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*func)(SNES,Vec,Vec,void*),void *ctx)
1380 {
1381   PetscErrorCode ierr;
1382   DM             dm;
1383 
1384   PetscFunctionBegin;
1385   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1386   if (r) {
1387     PetscValidHeaderSpecific(r,VEC_CLASSID,2);
1388     PetscCheckSameComm(snes,1,r,2);
1389     ierr = PetscObjectReference((PetscObject)r);CHKERRQ(ierr);
1390     ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
1391     snes->vec_func = r;
1392   }
1393   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1394   ierr = DMSNESSetFunction(dm,func,ctx);CHKERRQ(ierr);
1395   PetscFunctionReturn(0);
1396 }
1397 
1398 
1399 #undef __FUNCT__
1400 #define __FUNCT__ "SNESSetInitialFunction"
1401 /*@C
1402    SNESSetInitialFunction - Sets the function vector to be used as the
1403    function norm at the initialization of the method.  In some
1404    instances, the user has precomputed the function before calling
1405    SNESSolve.  This function allows one to avoid a redundant call
1406    to SNESComputeFunction in that case.
1407 
1408    Logically Collective on SNES
1409 
1410    Input Parameters:
1411 +  snes - the SNES context
1412 -  f - vector to store function value
1413 
1414    Notes:
1415    This should not be modified during the solution procedure.
1416 
1417    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1418 
1419    Level: developer
1420 
1421 .keywords: SNES, nonlinear, set, function
1422 
1423 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1424 @*/
1425 PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1426 {
1427   PetscErrorCode ierr;
1428   Vec            vec_func;
1429 
1430   PetscFunctionBegin;
1431   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1432   PetscValidHeaderSpecific(f,VEC_CLASSID,2);
1433   PetscCheckSameComm(snes,1,f,2);
1434   ierr = SNESGetFunction(snes,&vec_func,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
1435   ierr = VecCopy(f, vec_func);CHKERRQ(ierr);
1436   snes->vec_func_init_set = PETSC_TRUE;
1437   PetscFunctionReturn(0);
1438 }
1439 
1440 
1441 #undef __FUNCT__
1442 #define __FUNCT__ "SNESSetInitialFunctionNorm"
1443 /*@C
1444    SNESSetInitialFunctionNorm - Sets the function norm to be used as the function norm
1445    at the initialization of the  method.  In some instances, the user has precomputed
1446    the function and its norm before calling SNESSolve.  This function allows one to
1447    avoid a redundant call to SNESComputeFunction() and VecNorm() in that case.
1448 
1449    Logically Collective on SNES
1450 
1451    Input Parameters:
1452 +  snes - the SNES context
1453 -  fnorm - the norm of F as set by SNESSetInitialFunction()
1454 
1455    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1456 
1457    Level: developer
1458 
1459 .keywords: SNES, nonlinear, set, function, norm
1460 
1461 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunction()
1462 @*/
1463 PetscErrorCode  SNESSetInitialFunctionNorm(SNES snes, PetscReal fnorm)
1464 {
1465   PetscFunctionBegin;
1466   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1467   snes->norm_init = fnorm;
1468   snes->norm_init_set = PETSC_TRUE;
1469   PetscFunctionReturn(0);
1470 }
1471 
1472 #undef __FUNCT__
1473 #define __FUNCT__ "SNESSetNormType"
1474 /*@
1475    SNESSetNormType - Sets the SNESNormType used in covergence and monitoring
1476    of the SNES method.
1477 
1478    Logically Collective on SNES
1479 
1480    Input Parameters:
1481 +  snes - the SNES context
1482 -  normtype - the type of the norm used
1483 
1484    Notes:
1485    Only certain SNES methods support certain SNESNormTypes.  Most require evaluation
1486    of the nonlinear function and the taking of its norm at every iteration to
1487    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1488    (SNESGS) and the like do not require the norm of the function to be computed, and therfore
1489    may either be monitored for convergence or not.  As these are often used as nonlinear
1490    preconditioners, monitoring the norm of their error is not a useful enterprise within
1491    their solution.
1492 
1493    Level: developer
1494 
1495 .keywords: SNES, nonlinear, set, function, norm, type
1496 
1497 .seealso: SNESGetNormType(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormType
1498 @*/
1499 PetscErrorCode  SNESSetNormType(SNES snes, SNESNormType normtype)
1500 {
1501   PetscFunctionBegin;
1502   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1503   snes->normtype = normtype;
1504   PetscFunctionReturn(0);
1505 }
1506 
1507 
1508 #undef __FUNCT__
1509 #define __FUNCT__ "SNESGetNormType"
1510 /*@
1511    SNESGetNormType - Gets the SNESNormType used in covergence and monitoring
1512    of the SNES method.
1513 
1514    Logically Collective on SNES
1515 
1516    Input Parameters:
1517 +  snes - the SNES context
1518 -  normtype - the type of the norm used
1519 
1520    Level: advanced
1521 
1522 .keywords: SNES, nonlinear, set, function, norm, type
1523 
1524 .seealso: SNESSetNormType(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormType
1525 @*/
1526 PetscErrorCode  SNESGetNormType(SNES snes, SNESNormType *normtype)
1527 {
1528   PetscFunctionBegin;
1529   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1530   *normtype = snes->normtype;
1531   PetscFunctionReturn(0);
1532 }
1533 
1534 #undef __FUNCT__
1535 #define __FUNCT__ "SNESSetGS"
1536 /*@C
1537    SNESSetGS - Sets the user nonlinear Gauss-Seidel routine for
1538    use with composed nonlinear solvers.
1539 
1540    Input Parameters:
1541 +  snes   - the SNES context
1542 .  gsfunc - function evaluation routine
1543 -  ctx    - [optional] user-defined context for private data for the
1544             smoother evaluation routine (may be PETSC_NULL)
1545 
1546    Calling sequence of func:
1547 $    func (SNES snes,Vec x,Vec b,void *ctx);
1548 
1549 +  X   - solution vector
1550 .  B   - RHS vector
1551 -  ctx - optional user-defined Gauss-Seidel context
1552 
1553    Notes:
1554    The GS routines are used by the composed nonlinear solver to generate
1555     a problem appropriate update to the solution, particularly FAS.
1556 
1557    Level: intermediate
1558 
1559 .keywords: SNES, nonlinear, set, Gauss-Seidel
1560 
1561 .seealso: SNESGetFunction(), SNESComputeGS()
1562 @*/
1563 PetscErrorCode SNESSetGS(SNES snes,PetscErrorCode (*gsfunc)(SNES,Vec,Vec,void*),void *ctx)
1564 {
1565   PetscErrorCode ierr;
1566   DM dm;
1567 
1568   PetscFunctionBegin;
1569   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1570   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1571   ierr = DMSNESSetGS(dm,gsfunc,ctx);CHKERRQ(ierr);
1572   PetscFunctionReturn(0);
1573 }
1574 
1575 #undef __FUNCT__
1576 #define __FUNCT__ "SNESSetGSSweeps"
1577 /*@
1578    SNESSetGSSweeps - Sets the number of sweeps of GS to use.
1579 
1580    Input Parameters:
1581 +  snes   - the SNES context
1582 -  sweeps  - the number of sweeps of GS to perform.
1583 
1584    Level: intermediate
1585 
1586 .keywords: SNES, nonlinear, set, Gauss-Siedel
1587 
1588 .seealso: SNESSetGS(), SNESGetGS(), SNESSetPC(), SNESGetGSSweeps()
1589 @*/
1590 
1591 PetscErrorCode SNESSetGSSweeps(SNES snes, PetscInt sweeps) {
1592   PetscFunctionBegin;
1593   snes->gssweeps = sweeps;
1594   PetscFunctionReturn(0);
1595 }
1596 
1597 
1598 #undef __FUNCT__
1599 #define __FUNCT__ "SNESGetGSSweeps"
1600 /*@
1601    SNESGetGSSweeps - Gets the number of sweeps GS will use.
1602 
1603    Input Parameters:
1604 .  snes   - the SNES context
1605 
1606    Output Parameters:
1607 .  sweeps  - the number of sweeps of GS to perform.
1608 
1609    Level: intermediate
1610 
1611 .keywords: SNES, nonlinear, set, Gauss-Siedel
1612 
1613 .seealso: SNESSetGS(), SNESGetGS(), SNESSetPC(), SNESSetGSSweeps()
1614 @*/
1615 PetscErrorCode SNESGetGSSweeps(SNES snes, PetscInt * sweeps) {
1616   PetscFunctionBegin;
1617   *sweeps = snes->gssweeps;
1618   PetscFunctionReturn(0);
1619 }
1620 
1621 #undef __FUNCT__
1622 #define __FUNCT__ "SNESPicardComputeFunction"
1623 PetscErrorCode  SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
1624 {
1625   PetscErrorCode ierr;
1626   void *functx,*jacctx;
1627 
1628   PetscFunctionBegin;
1629   ierr = SNESGetFunction(snes,PETSC_NULL,PETSC_NULL,&functx);CHKERRQ(ierr);
1630   ierr = SNESGetJacobian(snes,PETSC_NULL,PETSC_NULL,PETSC_NULL,&jacctx);CHKERRQ(ierr);
1631   /*  A(x)*x - b(x) */
1632   ierr = (*snes->ops->computepjacobian)(snes,x,&snes->jacobian,&snes->jacobian_pre,&snes->matstruct,jacctx);CHKERRQ(ierr);
1633   ierr = (*snes->ops->computepfunction)(snes,x,f,functx);CHKERRQ(ierr);
1634   ierr = VecView(x,PETSC_VIEWER_BINARY_WORLD);CHKERRQ(ierr);
1635   ierr = VecView(f,PETSC_VIEWER_BINARY_WORLD);CHKERRQ(ierr);
1636   ierr = VecScale(f,-1.0);CHKERRQ(ierr);
1637   ierr = MatMultAdd(snes->jacobian_pre,x,f,f);CHKERRQ(ierr);
1638   PetscFunctionReturn(0);
1639 }
1640 
1641 #undef __FUNCT__
1642 #define __FUNCT__ "SNESPicardComputeJacobian"
1643 PetscErrorCode  SNESPicardComputeJacobian(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx)
1644 {
1645   PetscFunctionBegin;
1646   *flag = snes->matstruct;
1647   PetscFunctionReturn(0);
1648 }
1649 
1650 #undef __FUNCT__
1651 #define __FUNCT__ "SNESSetPicard"
1652 /*@C
1653    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)
1654 
1655    Logically Collective on SNES
1656 
1657    Input Parameters:
1658 +  snes - the SNES context
1659 .  r - vector to store function value
1660 .  func - function evaluation routine
1661 .  jmat - normally the same as mat but you can pass another matrix for which you compute the Jacobian of A(x) x - b(x) (see jmat below)
1662 .  mat - matrix to store A
1663 .  mfunc  - function to compute matrix value
1664 -  ctx - [optional] user-defined context for private data for the
1665          function evaluation routine (may be PETSC_NULL)
1666 
1667    Calling sequence of func:
1668 $    func (SNES snes,Vec x,Vec f,void *ctx);
1669 
1670 +  f - function vector
1671 -  ctx - optional user-defined function context
1672 
1673    Calling sequence of mfunc:
1674 $     mfunc (SNES snes,Vec x,Mat *jmat,Mat *mat,int *flag,void *ctx);
1675 
1676 +  x - input vector
1677 .  jmat - Form Jacobian 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(),
1678           normally just pass mat in this location
1679 .  mat - form A(x) matrix
1680 .  flag - flag indicating information about the preconditioner matrix
1681    structure (same as flag in KSPSetOperators()), one of SAME_NONZERO_PATTERN,DIFFERENT_NONZERO_PATTERN,SAME_PRECONDITIONER
1682 -  ctx - [optional] user-defined Jacobian context
1683 
1684    Notes:
1685     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both
1686 
1687 $     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}
1688 $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.
1689 
1690      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.
1691 
1692    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
1693    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)
1694 
1695    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
1696    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
1697    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).
1698 
1699    Level: beginner
1700 
1701 .keywords: SNES, nonlinear, set, function
1702 
1703 .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard()
1704 @*/
1705 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)
1706 {
1707   PetscErrorCode ierr;
1708   PetscFunctionBegin;
1709   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1710   snes->ops->computepfunction = func;
1711   snes->ops->computepjacobian = mfunc;
1712   ierr = SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);CHKERRQ(ierr);
1713   ierr = SNESSetJacobian(snes,jmat,mat,SNESPicardComputeJacobian,ctx);CHKERRQ(ierr);
1714   PetscFunctionReturn(0);
1715 }
1716 
1717 #undef __FUNCT__
1718 #define __FUNCT__ "SNESSetComputeInitialGuess"
1719 /*@C
1720    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem
1721 
1722    Logically Collective on SNES
1723 
1724    Input Parameters:
1725 +  snes - the SNES context
1726 .  func - function evaluation routine
1727 -  ctx - [optional] user-defined context for private data for the
1728          function evaluation routine (may be PETSC_NULL)
1729 
1730    Calling sequence of func:
1731 $    func (SNES snes,Vec x,void *ctx);
1732 
1733 .  f - function vector
1734 -  ctx - optional user-defined function context
1735 
1736    Level: intermediate
1737 
1738 .keywords: SNES, nonlinear, set, function
1739 
1740 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
1741 @*/
1742 PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
1743 {
1744   PetscFunctionBegin;
1745   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1746   if (func) snes->ops->computeinitialguess = func;
1747   if (ctx)  snes->initialguessP            = ctx;
1748   PetscFunctionReturn(0);
1749 }
1750 
1751 /* --------------------------------------------------------------- */
1752 #undef __FUNCT__
1753 #define __FUNCT__ "SNESGetRhs"
1754 /*@C
1755    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
1756    it assumes a zero right hand side.
1757 
1758    Logically Collective on SNES
1759 
1760    Input Parameter:
1761 .  snes - the SNES context
1762 
1763    Output Parameter:
1764 .  rhs - the right hand side vector or PETSC_NULL if the right hand side vector is null
1765 
1766    Level: intermediate
1767 
1768 .keywords: SNES, nonlinear, get, function, right hand side
1769 
1770 .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
1771 @*/
1772 PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
1773 {
1774   PetscFunctionBegin;
1775   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1776   PetscValidPointer(rhs,2);
1777   *rhs = snes->vec_rhs;
1778   PetscFunctionReturn(0);
1779 }
1780 
1781 #undef __FUNCT__
1782 #define __FUNCT__ "SNESComputeFunction"
1783 /*@
1784    SNESComputeFunction - Calls the function that has been set with
1785                          SNESSetFunction().
1786 
1787    Collective on SNES
1788 
1789    Input Parameters:
1790 +  snes - the SNES context
1791 -  x - input vector
1792 
1793    Output Parameter:
1794 .  y - function vector, as set by SNESSetFunction()
1795 
1796    Notes:
1797    SNESComputeFunction() is typically used within nonlinear solvers
1798    implementations, so most users would not generally call this routine
1799    themselves.
1800 
1801    Level: developer
1802 
1803 .keywords: SNES, nonlinear, compute, function
1804 
1805 .seealso: SNESSetFunction(), SNESGetFunction()
1806 @*/
1807 PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
1808 {
1809   PetscErrorCode ierr;
1810   DM             dm;
1811   SNESDM         sdm;
1812 
1813   PetscFunctionBegin;
1814   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1815   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
1816   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
1817   PetscCheckSameComm(snes,1,x,2);
1818   PetscCheckSameComm(snes,1,y,3);
1819   VecValidValues(x,2,PETSC_TRUE);
1820 
1821   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1822   ierr = DMSNESGetContext(dm,&sdm);CHKERRQ(ierr);
1823   ierr = PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
1824   if (sdm->computefunction) {
1825     PetscStackPush("SNES user function");
1826     ierr = (*sdm->computefunction)(snes,x,y,sdm->functionctx);CHKERRQ(ierr);
1827     PetscStackPop;
1828   } else if (snes->dm) {
1829     ierr = DMComputeFunction(snes->dm,x,y);CHKERRQ(ierr);
1830   } else if (snes->vec_rhs) {
1831     ierr = MatMult(snes->jacobian, x, y);CHKERRQ(ierr);
1832   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
1833   if (snes->vec_rhs) {
1834     ierr = VecAXPY(y,-1.0,snes->vec_rhs);CHKERRQ(ierr);
1835   }
1836   snes->nfuncs++;
1837   ierr = PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
1838   VecValidValues(y,3,PETSC_FALSE);
1839   PetscFunctionReturn(0);
1840 }
1841 
1842 #undef __FUNCT__
1843 #define __FUNCT__ "SNESComputeGS"
1844 /*@
1845    SNESComputeGS - Calls the Gauss-Seidel function that has been set with
1846                    SNESSetGS().
1847 
1848    Collective on SNES
1849 
1850    Input Parameters:
1851 +  snes - the SNES context
1852 .  x - input vector
1853 -  b - rhs vector
1854 
1855    Output Parameter:
1856 .  x - new solution vector
1857 
1858    Notes:
1859    SNESComputeGS() is typically used within composed nonlinear solver
1860    implementations, so most users would not generally call this routine
1861    themselves.
1862 
1863    Level: developer
1864 
1865 .keywords: SNES, nonlinear, compute, function
1866 
1867 .seealso: SNESSetGS(), SNESComputeFunction()
1868 @*/
1869 PetscErrorCode  SNESComputeGS(SNES snes,Vec b,Vec x)
1870 {
1871   PetscErrorCode ierr;
1872   PetscInt i;
1873   DM dm;
1874   SNESDM sdm;
1875 
1876   PetscFunctionBegin;
1877   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1878   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
1879   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,3);
1880   PetscCheckSameComm(snes,1,x,2);
1881   if(b) PetscCheckSameComm(snes,1,b,3);
1882   if (b) VecValidValues(b,2,PETSC_TRUE);
1883   ierr = PetscLogEventBegin(SNES_GSEval,snes,x,b,0);CHKERRQ(ierr);
1884   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1885   ierr = DMSNESGetContext(dm,&sdm);CHKERRQ(ierr);
1886   if (sdm->computegs) {
1887     for (i = 0; i < snes->gssweeps; i++) {
1888       PetscStackPush("SNES user GS");
1889       ierr = (*sdm->computegs)(snes,x,b,sdm->gsctx);CHKERRQ(ierr);
1890       PetscStackPop;
1891     }
1892   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetGS() before SNESComputeGS(), likely called from SNESSolve().");
1893   ierr = PetscLogEventEnd(SNES_GSEval,snes,x,b,0);CHKERRQ(ierr);
1894   VecValidValues(x,3,PETSC_FALSE);
1895   PetscFunctionReturn(0);
1896 }
1897 
1898 
1899 #undef __FUNCT__
1900 #define __FUNCT__ "SNESComputeJacobian"
1901 /*@
1902    SNESComputeJacobian - Computes the Jacobian matrix that has been
1903    set with SNESSetJacobian().
1904 
1905    Collective on SNES and Mat
1906 
1907    Input Parameters:
1908 +  snes - the SNES context
1909 -  x - input vector
1910 
1911    Output Parameters:
1912 +  A - Jacobian matrix
1913 .  B - optional preconditioning matrix
1914 -  flag - flag indicating matrix structure (one of, SAME_NONZERO_PATTERN,DIFFERENT_NONZERO_PATTERN,SAME_PRECONDITIONER)
1915 
1916   Options Database Keys:
1917 +    -snes_lag_preconditioner <lag>
1918 .    -snes_lag_jacobian <lag>
1919 .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
1920 .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
1921 .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
1922 .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
1923 .    -snes_compare_coloring - Compute the finite differece Jacobian using coloring and display norms of difference
1924 .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
1925 .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
1926 .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
1927 .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
1928 .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
1929 -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences
1930 
1931 
1932    Notes:
1933    Most users should not need to explicitly call this routine, as it
1934    is used internally within the nonlinear solvers.
1935 
1936    See KSPSetOperators() for important information about setting the
1937    flag parameter.
1938 
1939    Level: developer
1940 
1941 .keywords: SNES, compute, Jacobian, matrix
1942 
1943 .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
1944 @*/
1945 PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat *A,Mat *B,MatStructure *flg)
1946 {
1947   PetscErrorCode ierr;
1948   PetscBool      flag;
1949   DM             dm;
1950   SNESDM         sdm;
1951 
1952   PetscFunctionBegin;
1953   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1954   PetscValidHeaderSpecific(X,VEC_CLASSID,2);
1955   PetscValidPointer(flg,5);
1956   PetscCheckSameComm(snes,1,X,2);
1957   VecValidValues(X,2,PETSC_TRUE);
1958   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1959   ierr = DMSNESGetContext(dm,&sdm);CHKERRQ(ierr);
1960   if (!sdm->computejacobian) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");
1961 
1962   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */
1963 
1964   if (snes->lagjacobian == -2) {
1965     snes->lagjacobian = -1;
1966     ierr = PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");CHKERRQ(ierr);
1967   } else if (snes->lagjacobian == -1) {
1968     *flg = SAME_PRECONDITIONER;
1969     ierr = PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");CHKERRQ(ierr);
1970     ierr = PetscObjectTypeCompare((PetscObject)*A,MATMFFD,&flag);CHKERRQ(ierr);
1971     if (flag) {
1972       ierr = MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1973       ierr = MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1974     }
1975     PetscFunctionReturn(0);
1976   } else if (snes->lagjacobian > 1 && snes->iter % snes->lagjacobian) {
1977     *flg = SAME_PRECONDITIONER;
1978     ierr = PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);CHKERRQ(ierr);
1979     ierr = PetscObjectTypeCompare((PetscObject)*A,MATMFFD,&flag);CHKERRQ(ierr);
1980     if (flag) {
1981       ierr = MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1982       ierr = MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1983     }
1984     PetscFunctionReturn(0);
1985   }
1986 
1987   *flg = DIFFERENT_NONZERO_PATTERN;
1988   ierr = PetscLogEventBegin(SNES_JacobianEval,snes,X,*A,*B);CHKERRQ(ierr);
1989   PetscStackPush("SNES user Jacobian function");
1990   ierr = (*sdm->computejacobian)(snes,X,A,B,flg,sdm->jacobianctx);CHKERRQ(ierr);
1991   PetscStackPop;
1992   ierr = PetscLogEventEnd(SNES_JacobianEval,snes,X,*A,*B);CHKERRQ(ierr);
1993 
1994   if (snes->lagpreconditioner == -2) {
1995     ierr = PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");CHKERRQ(ierr);
1996     snes->lagpreconditioner = -1;
1997   } else if (snes->lagpreconditioner == -1) {
1998     *flg = SAME_PRECONDITIONER;
1999     ierr = PetscInfo(snes,"Reusing preconditioner because lag is -1\n");CHKERRQ(ierr);
2000   } else if (snes->lagpreconditioner > 1 && snes->iter % snes->lagpreconditioner) {
2001     *flg = SAME_PRECONDITIONER;
2002     ierr = PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);CHKERRQ(ierr);
2003   }
2004 
2005   /* make sure user returned a correct Jacobian and preconditioner */
2006   /* PetscValidHeaderSpecific(*A,MAT_CLASSID,3);
2007     PetscValidHeaderSpecific(*B,MAT_CLASSID,4);   */
2008   {
2009     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2010     ierr  = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit",&flag,PETSC_NULL);CHKERRQ(ierr);
2011     ierr  = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",&flag_draw,PETSC_NULL);CHKERRQ(ierr);
2012     ierr  = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",&flag_contour,PETSC_NULL);CHKERRQ(ierr);
2013     ierr  = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_operator",&flag_operator,PETSC_NULL);CHKERRQ(ierr);
2014     if (flag || flag_draw || flag_contour) {
2015       Mat Bexp_mine = PETSC_NULL,Bexp,FDexp;
2016       MatStructure mstruct;
2017       PetscViewer vdraw,vstdout;
2018       PetscBool flg;
2019       if (flag_operator) {
2020         ierr = MatComputeExplicitOperator(*A,&Bexp_mine);CHKERRQ(ierr);
2021         Bexp = Bexp_mine;
2022       } else {
2023         /* See if the preconditioning matrix can be viewed and added directly */
2024         ierr = PetscObjectTypeCompareAny((PetscObject)*B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");CHKERRQ(ierr);
2025         if (flg) Bexp = *B;
2026         else {
2027           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2028           ierr = MatComputeExplicitOperator(*B,&Bexp_mine);CHKERRQ(ierr);
2029           Bexp = Bexp_mine;
2030         }
2031       }
2032       ierr = MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);CHKERRQ(ierr);
2033       ierr = SNESDefaultComputeJacobian(snes,X,&FDexp,&FDexp,&mstruct,NULL);CHKERRQ(ierr);
2034       ierr = PetscViewerASCIIGetStdout(((PetscObject)snes)->comm,&vstdout);CHKERRQ(ierr);
2035       if (flag_draw || flag_contour) {
2036         ierr = PetscViewerDrawOpen(((PetscObject)snes)->comm,0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2037         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2038       } else vdraw = PETSC_NULL;
2039       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator?"Jacobian":"preconditioning Jacobian");CHKERRQ(ierr);
2040       if (flag) {ierr = MatView(Bexp,vstdout);CHKERRQ(ierr);}
2041       if (vdraw) {ierr = MatView(Bexp,vdraw);CHKERRQ(ierr);}
2042       ierr = PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");CHKERRQ(ierr);
2043       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2044       if (vdraw) {ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);}
2045       ierr = MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2046       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");CHKERRQ(ierr);
2047       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2048       if (vdraw) {              /* Always use contour for the difference */
2049         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2050         ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);
2051         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2052       }
2053       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2054       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2055       ierr = MatDestroy(&Bexp_mine);CHKERRQ(ierr);
2056       ierr = MatDestroy(&FDexp);CHKERRQ(ierr);
2057     }
2058   }
2059   {
2060     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2061     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2062     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring",&flag,PETSC_NULL);CHKERRQ(ierr);
2063     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_display",&flag_display,PETSC_NULL);CHKERRQ(ierr);
2064     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",&flag_draw,PETSC_NULL);CHKERRQ(ierr);
2065     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",&flag_contour,PETSC_NULL);CHKERRQ(ierr);
2066     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",&flag_threshold,PETSC_NULL);CHKERRQ(ierr);
2067     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,PETSC_NULL);CHKERRQ(ierr);
2068     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,PETSC_NULL);CHKERRQ(ierr);
2069     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2070       Mat Bfd;
2071       MatStructure mstruct;
2072       PetscViewer vdraw,vstdout;
2073       ISColoring iscoloring;
2074       MatFDColoring matfdcoloring;
2075       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2076       void *funcctx;
2077       PetscReal norm1,norm2,normmax;
2078 
2079       ierr = MatDuplicate(*B,MAT_DO_NOT_COPY_VALUES,&Bfd);CHKERRQ(ierr);
2080       ierr = MatGetColoring(Bfd,MATCOLORINGSL,&iscoloring);CHKERRQ(ierr);
2081       ierr = MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);CHKERRQ(ierr);
2082       ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr);
2083 
2084       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2085       ierr = SNESGetFunction(snes,PETSC_NULL,&func,&funcctx);CHKERRQ(ierr);
2086       ierr = MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode(*)(void))func,funcctx);CHKERRQ(ierr);
2087       ierr = PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);CHKERRQ(ierr);
2088       ierr = PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");CHKERRQ(ierr);
2089       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2090       ierr = MatFDColoringApply(Bfd,matfdcoloring,X,&mstruct,snes);CHKERRQ(ierr);
2091       ierr = MatFDColoringDestroy(&matfdcoloring);CHKERRQ(ierr);
2092 
2093       ierr = PetscViewerASCIIGetStdout(((PetscObject)snes)->comm,&vstdout);CHKERRQ(ierr);
2094       if (flag_draw || flag_contour) {
2095         ierr = PetscViewerDrawOpen(((PetscObject)snes)->comm,0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2096         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2097       } else vdraw = PETSC_NULL;
2098       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");CHKERRQ(ierr);
2099       if (flag_display) {ierr = MatView(*B,vstdout);CHKERRQ(ierr);}
2100       if (vdraw) {ierr = MatView(*B,vdraw);CHKERRQ(ierr);}
2101       ierr = PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");CHKERRQ(ierr);
2102       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2103       if (vdraw) {ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);}
2104       ierr = MatAYPX(Bfd,-1.0,*B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2105       ierr = MatNorm(Bfd,NORM_1,&norm1);CHKERRQ(ierr);
2106       ierr = MatNorm(Bfd,NORM_FROBENIUS,&norm2);CHKERRQ(ierr);
2107       ierr = MatNorm(Bfd,NORM_MAX,&normmax);CHKERRQ(ierr);
2108       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%G normFrob=%G normmax=%G\n",norm1,norm2,normmax);CHKERRQ(ierr);
2109       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2110       if (vdraw) {              /* Always use contour for the difference */
2111         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2112         ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);
2113         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2114       }
2115       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2116 
2117       if (flag_threshold) {
2118         PetscInt bs,rstart,rend,i;
2119         ierr = MatGetBlockSize(*B,&bs);CHKERRQ(ierr);
2120         ierr = MatGetOwnershipRange(*B,&rstart,&rend);CHKERRQ(ierr);
2121         for (i=rstart; i<rend; i++) {
2122           const PetscScalar *ba,*ca;
2123           const PetscInt *bj,*cj;
2124           PetscInt bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2125           PetscReal maxentry = 0,maxdiff = 0,maxrdiff = 0;
2126           ierr = MatGetRow(*B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2127           ierr = MatGetRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2128           if (bn != cn) SETERRQ(((PetscObject)*A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2129           for (j=0; j<bn; j++) {
2130             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2131             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2132               maxentrycol = bj[j];
2133               maxentry = PetscRealPart(ba[j]);
2134             }
2135             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2136               maxdiffcol = bj[j];
2137               maxdiff = PetscRealPart(ca[j]);
2138             }
2139             if (rdiff > maxrdiff) {
2140               maxrdiffcol = bj[j];
2141               maxrdiff = rdiff;
2142             }
2143           }
2144           if (maxrdiff > 1) {
2145             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);
2146             for (j=0; j<bn; j++) {
2147               PetscReal rdiff;
2148               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2149               if (rdiff > 1) {
2150                 ierr = PetscViewerASCIIPrintf(vstdout," (%D,%G:%G)",bj[j],PetscRealPart(ba[j]),PetscRealPart(ca[j]));CHKERRQ(ierr);
2151               }
2152             }
2153             ierr = PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);CHKERRQ(ierr);
2154           }
2155           ierr = MatRestoreRow(*B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2156           ierr = MatRestoreRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2157         }
2158       }
2159       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2160       ierr = MatDestroy(&Bfd);CHKERRQ(ierr);
2161     }
2162   }
2163   PetscFunctionReturn(0);
2164 }
2165 
2166 #undef __FUNCT__
2167 #define __FUNCT__ "SNESSetJacobian"
2168 /*@C
2169    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2170    location to store the matrix.
2171 
2172    Logically Collective on SNES and Mat
2173 
2174    Input Parameters:
2175 +  snes - the SNES context
2176 .  A - Jacobian matrix
2177 .  B - preconditioner matrix (usually same as the Jacobian)
2178 .  func - Jacobian evaluation routine (if PETSC_NULL then SNES retains any previously set value)
2179 -  ctx - [optional] user-defined context for private data for the
2180          Jacobian evaluation routine (may be PETSC_NULL) (if PETSC_NULL then SNES retains any previously set value)
2181 
2182    Calling sequence of func:
2183 $     func (SNES snes,Vec x,Mat *A,Mat *B,int *flag,void *ctx);
2184 
2185 +  x - input vector
2186 .  A - Jacobian matrix
2187 .  B - preconditioner matrix, usually the same as A
2188 .  flag - flag indicating information about the preconditioner matrix
2189    structure (same as flag in KSPSetOperators()), one of SAME_NONZERO_PATTERN,DIFFERENT_NONZERO_PATTERN,SAME_PRECONDITIONER
2190 -  ctx - [optional] user-defined Jacobian context
2191 
2192    Notes:
2193    See KSPSetOperators() for important information about setting the flag
2194    output parameter in the routine func().  Be sure to read this information!
2195 
2196    The routine func() takes Mat * as the matrix arguments rather than Mat.
2197    This allows the Jacobian evaluation routine to replace A and/or B with a
2198    completely new new matrix structure (not just different matrix elements)
2199    when appropriate, for instance, if the nonzero structure is changing
2200    throughout the global iterations.
2201 
2202    If the A matrix and B matrix are different you must call MatAssemblyBegin/End() on
2203    each matrix.
2204 
2205    If using SNESDefaultComputeJacobianColor() to assemble a Jacobian, the ctx argument
2206    must be a MatFDColoring.
2207 
2208    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2209    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.
2210 
2211    Level: beginner
2212 
2213 .keywords: SNES, nonlinear, set, Jacobian, matrix
2214 
2215 .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESDefaultComputeJacobianColor(), MatStructure
2216 @*/
2217 PetscErrorCode  SNESSetJacobian(SNES snes,Mat A,Mat B,PetscErrorCode (*func)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void *ctx)
2218 {
2219   PetscErrorCode ierr;
2220   DM             dm;
2221 
2222   PetscFunctionBegin;
2223   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2224   if (A) PetscValidHeaderSpecific(A,MAT_CLASSID,2);
2225   if (B) PetscValidHeaderSpecific(B,MAT_CLASSID,3);
2226   if (A) PetscCheckSameComm(snes,1,A,2);
2227   if (B) PetscCheckSameComm(snes,1,B,3);
2228   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2229   ierr = DMSNESSetJacobian(dm,func,ctx);CHKERRQ(ierr);
2230   if (A) {
2231     ierr = PetscObjectReference((PetscObject)A);CHKERRQ(ierr);
2232     ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2233     snes->jacobian = A;
2234   }
2235   if (B) {
2236     ierr = PetscObjectReference((PetscObject)B);CHKERRQ(ierr);
2237     ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2238     snes->jacobian_pre = B;
2239   }
2240   PetscFunctionReturn(0);
2241 }
2242 
2243 #undef __FUNCT__
2244 #define __FUNCT__ "SNESGetJacobian"
2245 /*@C
2246    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2247    provided context for evaluating the Jacobian.
2248 
2249    Not Collective, but Mat object will be parallel if SNES object is
2250 
2251    Input Parameter:
2252 .  snes - the nonlinear solver context
2253 
2254    Output Parameters:
2255 +  A - location to stash Jacobian matrix (or PETSC_NULL)
2256 .  B - location to stash preconditioner matrix (or PETSC_NULL)
2257 .  func - location to put Jacobian function (or PETSC_NULL)
2258 -  ctx - location to stash Jacobian ctx (or PETSC_NULL)
2259 
2260    Level: advanced
2261 
2262 .seealso: SNESSetJacobian(), SNESComputeJacobian()
2263 @*/
2264 PetscErrorCode SNESGetJacobian(SNES snes,Mat *A,Mat *B,PetscErrorCode (**func)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void **ctx)
2265 {
2266   PetscErrorCode ierr;
2267   DM             dm;
2268   SNESDM         sdm;
2269 
2270   PetscFunctionBegin;
2271   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2272   if (A)    *A    = snes->jacobian;
2273   if (B)    *B    = snes->jacobian_pre;
2274   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2275   ierr = DMSNESGetContext(dm,&sdm);CHKERRQ(ierr);
2276   if (func) *func = sdm->computejacobian;
2277   if (ctx)  *ctx  = sdm->jacobianctx;
2278   PetscFunctionReturn(0);
2279 }
2280 
2281 /* ----- Routines to initialize and destroy a nonlinear solver ---- */
2282 
2283 #undef __FUNCT__
2284 #define __FUNCT__ "SNESSetUp"
2285 /*@
2286    SNESSetUp - Sets up the internal data structures for the later use
2287    of a nonlinear solver.
2288 
2289    Collective on SNES
2290 
2291    Input Parameters:
2292 .  snes - the SNES context
2293 
2294    Notes:
2295    For basic use of the SNES solvers the user need not explicitly call
2296    SNESSetUp(), since these actions will automatically occur during
2297    the call to SNESSolve().  However, if one wishes to control this
2298    phase separately, SNESSetUp() should be called after SNESCreate()
2299    and optional routines of the form SNESSetXXX(), but before SNESSolve().
2300 
2301    Level: advanced
2302 
2303 .keywords: SNES, nonlinear, setup
2304 
2305 .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
2306 @*/
2307 PetscErrorCode  SNESSetUp(SNES snes)
2308 {
2309   PetscErrorCode ierr;
2310   DM             dm;
2311   SNESDM         sdm;
2312 
2313   PetscFunctionBegin;
2314   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2315   if (snes->setupcalled) PetscFunctionReturn(0);
2316 
2317   if (!((PetscObject)snes)->type_name) {
2318     ierr = SNESSetType(snes,SNESLS);CHKERRQ(ierr);
2319   }
2320 
2321   ierr = SNESGetFunction(snes,&snes->vec_func,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
2322   if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
2323   if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
2324 
2325   if (!snes->vec_sol_update /* && snes->vec_sol */) {
2326     ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
2327     ierr = PetscLogObjectParent(snes,snes->vec_sol_update);CHKERRQ(ierr);
2328   }
2329 
2330   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2331   ierr = DMSNESSetUpLegacy(dm);CHKERRQ(ierr); /* To be removed when function routines are taken out of the DM package */
2332   ierr = DMSNESGetContext(dm,&sdm);CHKERRQ(ierr);
2333   if (!sdm->computefunction) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Must provide a residual function with SNESSetFunction(), DMSNESSetFunction(), DMDASNESSetFunctionLocal(), etc");
2334   if (!snes->vec_func) {
2335     ierr = DMCreateGlobalVector(dm,&snes->vec_func);CHKERRQ(ierr);
2336   }
2337 
2338   if (!snes->ksp) {ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);}
2339 
2340   if (!snes->linesearch) {ierr = SNESGetSNESLineSearch(snes, &snes->linesearch);}
2341 
2342   if (snes->ops->usercompute && !snes->user) {
2343     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2344   }
2345 
2346   if (snes->ops->setup) {
2347     ierr = (*snes->ops->setup)(snes);CHKERRQ(ierr);
2348   }
2349 
2350   snes->setupcalled = PETSC_TRUE;
2351   PetscFunctionReturn(0);
2352 }
2353 
2354 #undef __FUNCT__
2355 #define __FUNCT__ "SNESReset"
2356 /*@
2357    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats
2358 
2359    Collective on SNES
2360 
2361    Input Parameter:
2362 .  snes - iterative context obtained from SNESCreate()
2363 
2364    Level: intermediate
2365 
2366    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()
2367 
2368 .keywords: SNES, destroy
2369 
2370 .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
2371 @*/
2372 PetscErrorCode  SNESReset(SNES snes)
2373 {
2374   PetscErrorCode ierr;
2375 
2376   PetscFunctionBegin;
2377   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2378   if (snes->ops->userdestroy && snes->user) {
2379     ierr       = (*snes->ops->userdestroy)((void**)&snes->user);CHKERRQ(ierr);
2380     snes->user = PETSC_NULL;
2381   }
2382   if (snes->pc) {
2383     ierr = SNESReset(snes->pc);CHKERRQ(ierr);
2384   }
2385 
2386   if (snes->ops->reset) {
2387     ierr = (*snes->ops->reset)(snes);CHKERRQ(ierr);
2388   }
2389   if (snes->ksp) {
2390     ierr = KSPReset(snes->ksp);CHKERRQ(ierr);
2391   }
2392 
2393   if (snes->linesearch) {
2394     ierr = SNESLineSearchReset(snes->linesearch);CHKERRQ(ierr);
2395   }
2396 
2397   ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
2398   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
2399   ierr = VecDestroy(&snes->vec_sol_update);CHKERRQ(ierr);
2400   ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
2401   ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2402   ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2403   ierr = VecDestroyVecs(snes->nwork,&snes->work);CHKERRQ(ierr);
2404   ierr = VecDestroyVecs(snes->nvwork,&snes->vwork);CHKERRQ(ierr);
2405   snes->nwork = snes->nvwork = 0;
2406   snes->setupcalled = PETSC_FALSE;
2407   PetscFunctionReturn(0);
2408 }
2409 
2410 #undef __FUNCT__
2411 #define __FUNCT__ "SNESDestroy"
2412 /*@
2413    SNESDestroy - Destroys the nonlinear solver context that was created
2414    with SNESCreate().
2415 
2416    Collective on SNES
2417 
2418    Input Parameter:
2419 .  snes - the SNES context
2420 
2421    Level: beginner
2422 
2423 .keywords: SNES, nonlinear, destroy
2424 
2425 .seealso: SNESCreate(), SNESSolve()
2426 @*/
2427 PetscErrorCode  SNESDestroy(SNES *snes)
2428 {
2429   PetscErrorCode ierr;
2430 
2431   PetscFunctionBegin;
2432   if (!*snes) PetscFunctionReturn(0);
2433   PetscValidHeaderSpecific((*snes),SNES_CLASSID,1);
2434   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; PetscFunctionReturn(0);}
2435 
2436   ierr = SNESReset((*snes));CHKERRQ(ierr);
2437   ierr = SNESDestroy(&(*snes)->pc);CHKERRQ(ierr);
2438 
2439   /* if memory was published with AMS then destroy it */
2440   ierr = PetscObjectDepublish((*snes));CHKERRQ(ierr);
2441   if ((*snes)->ops->destroy) {ierr = (*((*snes))->ops->destroy)((*snes));CHKERRQ(ierr);}
2442 
2443   ierr = DMDestroy(&(*snes)->dm);CHKERRQ(ierr);
2444   ierr = KSPDestroy(&(*snes)->ksp);CHKERRQ(ierr);
2445   ierr = SNESLineSearchDestroy(&(*snes)->linesearch);CHKERRQ(ierr);
2446 
2447   ierr = PetscFree((*snes)->kspconvctx);CHKERRQ(ierr);
2448   if ((*snes)->ops->convergeddestroy) {
2449     ierr = (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);CHKERRQ(ierr);
2450   }
2451   if ((*snes)->conv_malloc) {
2452     ierr = PetscFree((*snes)->conv_hist);CHKERRQ(ierr);
2453     ierr = PetscFree((*snes)->conv_hist_its);CHKERRQ(ierr);
2454   }
2455   ierr = SNESMonitorCancel((*snes));CHKERRQ(ierr);
2456   ierr = PetscHeaderDestroy(snes);CHKERRQ(ierr);
2457  PetscFunctionReturn(0);
2458 }
2459 
2460 /* ----------- Routines to set solver parameters ---------- */
2461 
2462 #undef __FUNCT__
2463 #define __FUNCT__ "SNESSetLagPreconditioner"
2464 /*@
2465    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.
2466 
2467    Logically Collective on SNES
2468 
2469    Input Parameters:
2470 +  snes - the SNES context
2471 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2472          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2473 
2474    Options Database Keys:
2475 .    -snes_lag_preconditioner <lag>
2476 
2477    Notes:
2478    The default is 1
2479    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2480    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use
2481 
2482    Level: intermediate
2483 
2484 .keywords: SNES, nonlinear, set, convergence, tolerances
2485 
2486 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2487 
2488 @*/
2489 PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
2490 {
2491   PetscFunctionBegin;
2492   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2493   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2494   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2495   PetscValidLogicalCollectiveInt(snes,lag,2);
2496   snes->lagpreconditioner = lag;
2497   PetscFunctionReturn(0);
2498 }
2499 
2500 #undef __FUNCT__
2501 #define __FUNCT__ "SNESSetGridSequence"
2502 /*@
2503    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does
2504 
2505    Logically Collective on SNES
2506 
2507    Input Parameters:
2508 +  snes - the SNES context
2509 -  steps - the number of refinements to do, defaults to 0
2510 
2511    Options Database Keys:
2512 .    -snes_grid_sequence <steps>
2513 
2514    Level: intermediate
2515 
2516    Notes:
2517    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2518 
2519 .keywords: SNES, nonlinear, set, convergence, tolerances
2520 
2521 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2522 
2523 @*/
2524 PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
2525 {
2526   PetscFunctionBegin;
2527   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2528   PetscValidLogicalCollectiveInt(snes,steps,2);
2529   snes->gridsequence = steps;
2530   PetscFunctionReturn(0);
2531 }
2532 
2533 #undef __FUNCT__
2534 #define __FUNCT__ "SNESGetLagPreconditioner"
2535 /*@
2536    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt
2537 
2538    Not Collective
2539 
2540    Input Parameter:
2541 .  snes - the SNES context
2542 
2543    Output Parameter:
2544 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2545          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2546 
2547    Options Database Keys:
2548 .    -snes_lag_preconditioner <lag>
2549 
2550    Notes:
2551    The default is 1
2552    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2553 
2554    Level: intermediate
2555 
2556 .keywords: SNES, nonlinear, set, convergence, tolerances
2557 
2558 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()
2559 
2560 @*/
2561 PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
2562 {
2563   PetscFunctionBegin;
2564   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2565   *lag = snes->lagpreconditioner;
2566   PetscFunctionReturn(0);
2567 }
2568 
2569 #undef __FUNCT__
2570 #define __FUNCT__ "SNESSetLagJacobian"
2571 /*@
2572    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
2573      often the preconditioner is rebuilt.
2574 
2575    Logically Collective on SNES
2576 
2577    Input Parameters:
2578 +  snes - the SNES context
2579 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2580          the Jacobian is built etc. -2 means rebuild at next chance but then never again
2581 
2582    Options Database Keys:
2583 .    -snes_lag_jacobian <lag>
2584 
2585    Notes:
2586    The default is 1
2587    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2588    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
2589    at the next Newton step but never again (unless it is reset to another value)
2590 
2591    Level: intermediate
2592 
2593 .keywords: SNES, nonlinear, set, convergence, tolerances
2594 
2595 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()
2596 
2597 @*/
2598 PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
2599 {
2600   PetscFunctionBegin;
2601   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2602   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2603   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2604   PetscValidLogicalCollectiveInt(snes,lag,2);
2605   snes->lagjacobian = lag;
2606   PetscFunctionReturn(0);
2607 }
2608 
2609 #undef __FUNCT__
2610 #define __FUNCT__ "SNESGetLagJacobian"
2611 /*@
2612    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt
2613 
2614    Not Collective
2615 
2616    Input Parameter:
2617 .  snes - the SNES context
2618 
2619    Output Parameter:
2620 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2621          the Jacobian is built etc.
2622 
2623    Options Database Keys:
2624 .    -snes_lag_jacobian <lag>
2625 
2626    Notes:
2627    The default is 1
2628    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2629 
2630    Level: intermediate
2631 
2632 .keywords: SNES, nonlinear, set, convergence, tolerances
2633 
2634 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()
2635 
2636 @*/
2637 PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
2638 {
2639   PetscFunctionBegin;
2640   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2641   *lag = snes->lagjacobian;
2642   PetscFunctionReturn(0);
2643 }
2644 
2645 #undef __FUNCT__
2646 #define __FUNCT__ "SNESSetTolerances"
2647 /*@
2648    SNESSetTolerances - Sets various parameters used in convergence tests.
2649 
2650    Logically Collective on SNES
2651 
2652    Input Parameters:
2653 +  snes - the SNES context
2654 .  abstol - absolute convergence tolerance
2655 .  rtol - relative convergence tolerance
2656 .  stol -  convergence tolerance in terms of the norm
2657            of the change in the solution between steps
2658 .  maxit - maximum number of iterations
2659 -  maxf - maximum number of function evaluations
2660 
2661    Options Database Keys:
2662 +    -snes_atol <abstol> - Sets abstol
2663 .    -snes_rtol <rtol> - Sets rtol
2664 .    -snes_stol <stol> - Sets stol
2665 .    -snes_max_it <maxit> - Sets maxit
2666 -    -snes_max_funcs <maxf> - Sets maxf
2667 
2668    Notes:
2669    The default maximum number of iterations is 50.
2670    The default maximum number of function evaluations is 1000.
2671 
2672    Level: intermediate
2673 
2674 .keywords: SNES, nonlinear, set, convergence, tolerances
2675 
2676 .seealso: SNESSetTrustRegionTolerance()
2677 @*/
2678 PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
2679 {
2680   PetscFunctionBegin;
2681   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2682   PetscValidLogicalCollectiveReal(snes,abstol,2);
2683   PetscValidLogicalCollectiveReal(snes,rtol,3);
2684   PetscValidLogicalCollectiveReal(snes,stol,4);
2685   PetscValidLogicalCollectiveInt(snes,maxit,5);
2686   PetscValidLogicalCollectiveInt(snes,maxf,6);
2687 
2688   if (abstol != PETSC_DEFAULT) {
2689     if (abstol < 0.0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %G must be non-negative",abstol);
2690     snes->abstol = abstol;
2691   }
2692   if (rtol != PETSC_DEFAULT) {
2693     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);
2694     snes->rtol = rtol;
2695   }
2696   if (stol != PETSC_DEFAULT) {
2697     if (stol < 0.0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %G must be non-negative",stol);
2698     snes->stol = stol;
2699   }
2700   if (maxit != PETSC_DEFAULT) {
2701     if (maxit < 0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
2702     snes->max_its = maxit;
2703   }
2704   if (maxf != PETSC_DEFAULT) {
2705     if (maxf < 0) SETERRQ1(((PetscObject)snes)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
2706     snes->max_funcs = maxf;
2707   }
2708   snes->tolerancesset = PETSC_TRUE;
2709   PetscFunctionReturn(0);
2710 }
2711 
2712 #undef __FUNCT__
2713 #define __FUNCT__ "SNESGetTolerances"
2714 /*@
2715    SNESGetTolerances - Gets various parameters used in convergence tests.
2716 
2717    Not Collective
2718 
2719    Input Parameters:
2720 +  snes - the SNES context
2721 .  atol - absolute convergence tolerance
2722 .  rtol - relative convergence tolerance
2723 .  stol -  convergence tolerance in terms of the norm
2724            of the change in the solution between steps
2725 .  maxit - maximum number of iterations
2726 -  maxf - maximum number of function evaluations
2727 
2728    Notes:
2729    The user can specify PETSC_NULL for any parameter that is not needed.
2730 
2731    Level: intermediate
2732 
2733 .keywords: SNES, nonlinear, get, convergence, tolerances
2734 
2735 .seealso: SNESSetTolerances()
2736 @*/
2737 PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
2738 {
2739   PetscFunctionBegin;
2740   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2741   if (atol)  *atol  = snes->abstol;
2742   if (rtol)  *rtol  = snes->rtol;
2743   if (stol)  *stol  = snes->stol;
2744   if (maxit) *maxit = snes->max_its;
2745   if (maxf)  *maxf  = snes->max_funcs;
2746   PetscFunctionReturn(0);
2747 }
2748 
2749 #undef __FUNCT__
2750 #define __FUNCT__ "SNESSetTrustRegionTolerance"
2751 /*@
2752    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.
2753 
2754    Logically Collective on SNES
2755 
2756    Input Parameters:
2757 +  snes - the SNES context
2758 -  tol - tolerance
2759 
2760    Options Database Key:
2761 .  -snes_trtol <tol> - Sets tol
2762 
2763    Level: intermediate
2764 
2765 .keywords: SNES, nonlinear, set, trust region, tolerance
2766 
2767 .seealso: SNESSetTolerances()
2768 @*/
2769 PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
2770 {
2771   PetscFunctionBegin;
2772   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2773   PetscValidLogicalCollectiveReal(snes,tol,2);
2774   snes->deltatol = tol;
2775   PetscFunctionReturn(0);
2776 }
2777 
2778 /*
2779    Duplicate the lg monitors for SNES from KSP; for some reason with
2780    dynamic libraries things don't work under Sun4 if we just use
2781    macros instead of functions
2782 */
2783 #undef __FUNCT__
2784 #define __FUNCT__ "SNESMonitorLG"
2785 PetscErrorCode  SNESMonitorLG(SNES snes,PetscInt it,PetscReal norm,void *ctx)
2786 {
2787   PetscErrorCode ierr;
2788 
2789   PetscFunctionBegin;
2790   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2791   ierr = KSPMonitorLG((KSP)snes,it,norm,ctx);CHKERRQ(ierr);
2792   PetscFunctionReturn(0);
2793 }
2794 
2795 #undef __FUNCT__
2796 #define __FUNCT__ "SNESMonitorLGCreate"
2797 PetscErrorCode  SNESMonitorLGCreate(const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *draw)
2798 {
2799   PetscErrorCode ierr;
2800 
2801   PetscFunctionBegin;
2802   ierr = KSPMonitorLGCreate(host,label,x,y,m,n,draw);CHKERRQ(ierr);
2803   PetscFunctionReturn(0);
2804 }
2805 
2806 #undef __FUNCT__
2807 #define __FUNCT__ "SNESMonitorLGDestroy"
2808 PetscErrorCode  SNESMonitorLGDestroy(PetscDrawLG *draw)
2809 {
2810   PetscErrorCode ierr;
2811 
2812   PetscFunctionBegin;
2813   ierr = KSPMonitorLGDestroy(draw);CHKERRQ(ierr);
2814   PetscFunctionReturn(0);
2815 }
2816 
2817 extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
2818 #undef __FUNCT__
2819 #define __FUNCT__ "SNESMonitorLGRange"
2820 PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
2821 {
2822   PetscDrawLG      lg;
2823   PetscErrorCode   ierr;
2824   PetscReal        x,y,per;
2825   PetscViewer      v = (PetscViewer)monctx;
2826   static PetscReal prev; /* should be in the context */
2827   PetscDraw        draw;
2828   PetscFunctionBegin;
2829   if (!monctx) {
2830     MPI_Comm    comm;
2831 
2832     ierr   = PetscObjectGetComm((PetscObject)snes,&comm);CHKERRQ(ierr);
2833     v      = PETSC_VIEWER_DRAW_(comm);
2834   }
2835   ierr   = PetscViewerDrawGetDrawLG(v,0,&lg);CHKERRQ(ierr);
2836   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
2837   ierr   = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
2838   ierr   = PetscDrawSetTitle(draw,"Residual norm");CHKERRQ(ierr);
2839   x = (PetscReal) n;
2840   if (rnorm > 0.0) y = log10(rnorm); else y = -15.0;
2841   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
2842   if (n < 20 || !(n % 5)) {
2843     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
2844   }
2845 
2846   ierr = PetscViewerDrawGetDrawLG(v,1,&lg);CHKERRQ(ierr);
2847   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
2848   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
2849   ierr = PetscDrawSetTitle(draw,"% elemts > .2*max elemt");CHKERRQ(ierr);
2850   ierr =  SNESMonitorRange_Private(snes,n,&per);CHKERRQ(ierr);
2851   x = (PetscReal) n;
2852   y = 100.0*per;
2853   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
2854   if (n < 20 || !(n % 5)) {
2855     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
2856   }
2857 
2858   ierr = PetscViewerDrawGetDrawLG(v,2,&lg);CHKERRQ(ierr);
2859   if (!n) {prev = rnorm;ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
2860   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
2861   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");CHKERRQ(ierr);
2862   x = (PetscReal) n;
2863   y = (prev - rnorm)/prev;
2864   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
2865   if (n < 20 || !(n % 5)) {
2866     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
2867   }
2868 
2869   ierr = PetscViewerDrawGetDrawLG(v,3,&lg);CHKERRQ(ierr);
2870   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
2871   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
2872   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");CHKERRQ(ierr);
2873   x = (PetscReal) n;
2874   y = (prev - rnorm)/(prev*per);
2875   if (n > 2) { /*skip initial crazy value */
2876     ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
2877   }
2878   if (n < 20 || !(n % 5)) {
2879     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
2880   }
2881   prev = rnorm;
2882   PetscFunctionReturn(0);
2883 }
2884 
2885 #undef __FUNCT__
2886 #define __FUNCT__ "SNESMonitorLGRangeCreate"
2887 PetscErrorCode  SNESMonitorLGRangeCreate(const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *draw)
2888 {
2889   PetscErrorCode ierr;
2890 
2891   PetscFunctionBegin;
2892   ierr = KSPMonitorLGCreate(host,label,x,y,m,n,draw);CHKERRQ(ierr);
2893   PetscFunctionReturn(0);
2894 }
2895 
2896 #undef __FUNCT__
2897 #define __FUNCT__ "SNESMonitorLGRangeDestroy"
2898 PetscErrorCode  SNESMonitorLGRangeDestroy(PetscDrawLG *draw)
2899 {
2900   PetscErrorCode ierr;
2901 
2902   PetscFunctionBegin;
2903   ierr = KSPMonitorLGDestroy(draw);CHKERRQ(ierr);
2904   PetscFunctionReturn(0);
2905 }
2906 
2907 #undef __FUNCT__
2908 #define __FUNCT__ "SNESMonitor"
2909 /*@
2910    SNESMonitor - runs the user provided monitor routines, if they exist
2911 
2912    Collective on SNES
2913 
2914    Input Parameters:
2915 +  snes - nonlinear solver context obtained from SNESCreate()
2916 .  iter - iteration number
2917 -  rnorm - relative norm of the residual
2918 
2919    Notes:
2920    This routine is called by the SNES implementations.
2921    It does not typically need to be called by the user.
2922 
2923    Level: developer
2924 
2925 .seealso: SNESMonitorSet()
2926 @*/
2927 PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
2928 {
2929   PetscErrorCode ierr;
2930   PetscInt       i,n = snes->numbermonitors;
2931 
2932   PetscFunctionBegin;
2933   for (i=0; i<n; i++) {
2934     ierr = (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);CHKERRQ(ierr);
2935   }
2936   PetscFunctionReturn(0);
2937 }
2938 
2939 /* ------------ Routines to set performance monitoring options ----------- */
2940 
2941 #undef __FUNCT__
2942 #define __FUNCT__ "SNESMonitorSet"
2943 /*@C
2944    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
2945    iteration of the nonlinear solver to display the iteration's
2946    progress.
2947 
2948    Logically Collective on SNES
2949 
2950    Input Parameters:
2951 +  snes - the SNES context
2952 .  func - monitoring routine
2953 .  mctx - [optional] user-defined context for private data for the
2954           monitor routine (use PETSC_NULL if no context is desired)
2955 -  monitordestroy - [optional] routine that frees monitor context
2956           (may be PETSC_NULL)
2957 
2958    Calling sequence of func:
2959 $     int func(SNES snes,PetscInt its, PetscReal norm,void *mctx)
2960 
2961 +    snes - the SNES context
2962 .    its - iteration number
2963 .    norm - 2-norm function value (may be estimated)
2964 -    mctx - [optional] monitoring context
2965 
2966    Options Database Keys:
2967 +    -snes_monitor        - sets SNESMonitorDefault()
2968 .    -snes_monitor_draw    - sets line graph monitor,
2969                             uses SNESMonitorLGCreate()
2970 -    -snes_monitor_cancel - cancels all monitors that have
2971                             been hardwired into a code by
2972                             calls to SNESMonitorSet(), but
2973                             does not cancel those set via
2974                             the options database.
2975 
2976    Notes:
2977    Several different monitoring routines may be set by calling
2978    SNESMonitorSet() multiple times; all will be called in the
2979    order in which they were set.
2980 
2981    Fortran notes: Only a single monitor function can be set for each SNES object
2982 
2983    Level: intermediate
2984 
2985 .keywords: SNES, nonlinear, set, monitor
2986 
2987 .seealso: SNESMonitorDefault(), SNESMonitorCancel()
2988 @*/
2989 PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*monitor)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
2990 {
2991   PetscInt       i;
2992   PetscErrorCode ierr;
2993 
2994   PetscFunctionBegin;
2995   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2996   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
2997   for (i=0; i<snes->numbermonitors;i++) {
2998     if (monitor == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
2999       if (monitordestroy) {
3000         ierr = (*monitordestroy)(&mctx);CHKERRQ(ierr);
3001       }
3002       PetscFunctionReturn(0);
3003     }
3004   }
3005   snes->monitor[snes->numbermonitors]           = monitor;
3006   snes->monitordestroy[snes->numbermonitors]    = monitordestroy;
3007   snes->monitorcontext[snes->numbermonitors++]  = (void*)mctx;
3008   PetscFunctionReturn(0);
3009 }
3010 
3011 #undef __FUNCT__
3012 #define __FUNCT__ "SNESMonitorCancel"
3013 /*@C
3014    SNESMonitorCancel - Clears all the monitor functions for a SNES object.
3015 
3016    Logically Collective on SNES
3017 
3018    Input Parameters:
3019 .  snes - the SNES context
3020 
3021    Options Database Key:
3022 .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3023     into a code by calls to SNESMonitorSet(), but does not cancel those
3024     set via the options database
3025 
3026    Notes:
3027    There is no way to clear one specific monitor from a SNES object.
3028 
3029    Level: intermediate
3030 
3031 .keywords: SNES, nonlinear, set, monitor
3032 
3033 .seealso: SNESMonitorDefault(), SNESMonitorSet()
3034 @*/
3035 PetscErrorCode  SNESMonitorCancel(SNES snes)
3036 {
3037   PetscErrorCode ierr;
3038   PetscInt       i;
3039 
3040   PetscFunctionBegin;
3041   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3042   for (i=0; i<snes->numbermonitors; i++) {
3043     if (snes->monitordestroy[i]) {
3044       ierr = (*snes->monitordestroy[i])(&snes->monitorcontext[i]);CHKERRQ(ierr);
3045     }
3046   }
3047   snes->numbermonitors = 0;
3048   PetscFunctionReturn(0);
3049 }
3050 
3051 #undef __FUNCT__
3052 #define __FUNCT__ "SNESSetConvergenceTest"
3053 /*@C
3054    SNESSetConvergenceTest - Sets the function that is to be used
3055    to test for convergence of the nonlinear iterative solution.
3056 
3057    Logically Collective on SNES
3058 
3059    Input Parameters:
3060 +  snes - the SNES context
3061 .  func - routine to test for convergence
3062 .  cctx - [optional] context for private data for the convergence routine  (may be PETSC_NULL)
3063 -  destroy - [optional] destructor for the context (may be PETSC_NULL; PETSC_NULL_FUNCTION in Fortran)
3064 
3065    Calling sequence of func:
3066 $     PetscErrorCode func (SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)
3067 
3068 +    snes - the SNES context
3069 .    it - current iteration (0 is the first and is before any Newton step)
3070 .    cctx - [optional] convergence context
3071 .    reason - reason for convergence/divergence
3072 .    xnorm - 2-norm of current iterate
3073 .    gnorm - 2-norm of current step
3074 -    f - 2-norm of function
3075 
3076    Level: advanced
3077 
3078 .keywords: SNES, nonlinear, set, convergence, test
3079 
3080 .seealso: SNESDefaultConverged(), SNESSkipConverged()
3081 @*/
3082 PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*func)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
3083 {
3084   PetscErrorCode ierr;
3085 
3086   PetscFunctionBegin;
3087   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3088   if (!func) func = SNESSkipConverged;
3089   if (snes->ops->convergeddestroy) {
3090     ierr = (*snes->ops->convergeddestroy)(snes->cnvP);CHKERRQ(ierr);
3091   }
3092   snes->ops->converged        = func;
3093   snes->ops->convergeddestroy = destroy;
3094   snes->cnvP                  = cctx;
3095   PetscFunctionReturn(0);
3096 }
3097 
3098 #undef __FUNCT__
3099 #define __FUNCT__ "SNESGetConvergedReason"
3100 /*@
3101    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.
3102 
3103    Not Collective
3104 
3105    Input Parameter:
3106 .  snes - the SNES context
3107 
3108    Output Parameter:
3109 .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3110             manual pages for the individual convergence tests for complete lists
3111 
3112    Level: intermediate
3113 
3114    Notes: Can only be called after the call the SNESSolve() is complete.
3115 
3116 .keywords: SNES, nonlinear, set, convergence, test
3117 
3118 .seealso: SNESSetConvergenceTest(), SNESConvergedReason
3119 @*/
3120 PetscErrorCode  SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
3121 {
3122   PetscFunctionBegin;
3123   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3124   PetscValidPointer(reason,2);
3125   *reason = snes->reason;
3126   PetscFunctionReturn(0);
3127 }
3128 
3129 #undef __FUNCT__
3130 #define __FUNCT__ "SNESSetConvergenceHistory"
3131 /*@
3132    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.
3133 
3134    Logically Collective on SNES
3135 
3136    Input Parameters:
3137 +  snes - iterative context obtained from SNESCreate()
3138 .  a   - array to hold history, this array will contain the function norms computed at each step
3139 .  its - integer array holds the number of linear iterations for each solve.
3140 .  na  - size of a and its
3141 -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
3142            else it continues storing new values for new nonlinear solves after the old ones
3143 
3144    Notes:
3145    If 'a' and 'its' are PETSC_NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
3146    default array of length 10000 is allocated.
3147 
3148    This routine is useful, e.g., when running a code for purposes
3149    of accurate performance monitoring, when no I/O should be done
3150    during the section of code that is being timed.
3151 
3152    Level: intermediate
3153 
3154 .keywords: SNES, set, convergence, history
3155 
3156 .seealso: SNESGetConvergenceHistory()
3157 
3158 @*/
3159 PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool  reset)
3160 {
3161   PetscErrorCode ierr;
3162 
3163   PetscFunctionBegin;
3164   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3165   if (na)  PetscValidScalarPointer(a,2);
3166   if (its) PetscValidIntPointer(its,3);
3167   if (na == PETSC_DECIDE || na == PETSC_DEFAULT || !a) {
3168     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
3169     ierr = PetscMalloc(na*sizeof(PetscReal),&a);CHKERRQ(ierr);
3170     ierr = PetscMalloc(na*sizeof(PetscInt),&its);CHKERRQ(ierr);
3171     snes->conv_malloc   = PETSC_TRUE;
3172   }
3173   snes->conv_hist       = a;
3174   snes->conv_hist_its   = its;
3175   snes->conv_hist_max   = na;
3176   snes->conv_hist_len   = 0;
3177   snes->conv_hist_reset = reset;
3178   PetscFunctionReturn(0);
3179 }
3180 
3181 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3182 #include <engine.h>   /* MATLAB include file */
3183 #include <mex.h>      /* MATLAB include file */
3184 EXTERN_C_BEGIN
3185 #undef __FUNCT__
3186 #define __FUNCT__ "SNESGetConvergenceHistoryMatlab"
3187 mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
3188 {
3189   mxArray        *mat;
3190   PetscInt       i;
3191   PetscReal      *ar;
3192 
3193   PetscFunctionBegin;
3194   mat  = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
3195   ar   = (PetscReal*) mxGetData(mat);
3196   for (i=0; i<snes->conv_hist_len; i++) {
3197     ar[i] = snes->conv_hist[i];
3198   }
3199   PetscFunctionReturn(mat);
3200 }
3201 EXTERN_C_END
3202 #endif
3203 
3204 
3205 #undef __FUNCT__
3206 #define __FUNCT__ "SNESGetConvergenceHistory"
3207 /*@C
3208    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.
3209 
3210    Not Collective
3211 
3212    Input Parameter:
3213 .  snes - iterative context obtained from SNESCreate()
3214 
3215    Output Parameters:
3216 .  a   - array to hold history
3217 .  its - integer array holds the number of linear iterations (or
3218          negative if not converged) for each solve.
3219 -  na  - size of a and its
3220 
3221    Notes:
3222     The calling sequence for this routine in Fortran is
3223 $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
3224 
3225    This routine is useful, e.g., when running a code for purposes
3226    of accurate performance monitoring, when no I/O should be done
3227    during the section of code that is being timed.
3228 
3229    Level: intermediate
3230 
3231 .keywords: SNES, get, convergence, history
3232 
3233 .seealso: SNESSetConvergencHistory()
3234 
3235 @*/
3236 PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
3237 {
3238   PetscFunctionBegin;
3239   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3240   if (a)   *a   = snes->conv_hist;
3241   if (its) *its = snes->conv_hist_its;
3242   if (na)  *na  = snes->conv_hist_len;
3243   PetscFunctionReturn(0);
3244 }
3245 
3246 #undef __FUNCT__
3247 #define __FUNCT__ "SNESSetUpdate"
3248 /*@C
3249   SNESSetUpdate - Sets the general-purpose update function called
3250   at the beginning of every iteration of the nonlinear solve. Specifically
3251   it is called just before the Jacobian is "evaluated".
3252 
3253   Logically Collective on SNES
3254 
3255   Input Parameters:
3256 . snes - The nonlinear solver context
3257 . func - The function
3258 
3259   Calling sequence of func:
3260 . func (SNES snes, PetscInt step);
3261 
3262 . step - The current step of the iteration
3263 
3264   Level: advanced
3265 
3266   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()
3267         This is not used by most users.
3268 
3269 .keywords: SNES, update
3270 
3271 .seealso SNESDefaultUpdate(), SNESSetJacobian(), SNESSolve()
3272 @*/
3273 PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
3274 {
3275   PetscFunctionBegin;
3276   PetscValidHeaderSpecific(snes, SNES_CLASSID,1);
3277   snes->ops->update = func;
3278   PetscFunctionReturn(0);
3279 }
3280 
3281 #undef __FUNCT__
3282 #define __FUNCT__ "SNESDefaultUpdate"
3283 /*@
3284   SNESDefaultUpdate - The default update function which does nothing.
3285 
3286   Not collective
3287 
3288   Input Parameters:
3289 . snes - The nonlinear solver context
3290 . step - The current step of the iteration
3291 
3292   Level: intermediate
3293 
3294 .keywords: SNES, update
3295 .seealso SNESSetUpdate(), SNESDefaultRhsBC(), SNESDefaultShortolutionBC()
3296 @*/
3297 PetscErrorCode  SNESDefaultUpdate(SNES snes, PetscInt step)
3298 {
3299   PetscFunctionBegin;
3300   PetscFunctionReturn(0);
3301 }
3302 
3303 #undef __FUNCT__
3304 #define __FUNCT__ "SNESScaleStep_Private"
3305 /*
3306    SNESScaleStep_Private - Scales a step so that its length is less than the
3307    positive parameter delta.
3308 
3309     Input Parameters:
3310 +   snes - the SNES context
3311 .   y - approximate solution of linear system
3312 .   fnorm - 2-norm of current function
3313 -   delta - trust region size
3314 
3315     Output Parameters:
3316 +   gpnorm - predicted function norm at the new point, assuming local
3317     linearization.  The value is zero if the step lies within the trust
3318     region, and exceeds zero otherwise.
3319 -   ynorm - 2-norm of the step
3320 
3321     Note:
3322     For non-trust region methods such as SNESLS, the parameter delta
3323     is set to be the maximum allowable step size.
3324 
3325 .keywords: SNES, nonlinear, scale, step
3326 */
3327 PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
3328 {
3329   PetscReal      nrm;
3330   PetscScalar    cnorm;
3331   PetscErrorCode ierr;
3332 
3333   PetscFunctionBegin;
3334   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3335   PetscValidHeaderSpecific(y,VEC_CLASSID,2);
3336   PetscCheckSameComm(snes,1,y,2);
3337 
3338   ierr = VecNorm(y,NORM_2,&nrm);CHKERRQ(ierr);
3339   if (nrm > *delta) {
3340      nrm = *delta/nrm;
3341      *gpnorm = (1.0 - nrm)*(*fnorm);
3342      cnorm = nrm;
3343      ierr = VecScale(y,cnorm);CHKERRQ(ierr);
3344      *ynorm = *delta;
3345   } else {
3346      *gpnorm = 0.0;
3347      *ynorm = nrm;
3348   }
3349   PetscFunctionReturn(0);
3350 }
3351 
3352 #undef __FUNCT__
3353 #define __FUNCT__ "SNESSolve"
3354 /*@C
3355    SNESSolve - Solves a nonlinear system F(x) = b.
3356    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3357 
3358    Collective on SNES
3359 
3360    Input Parameters:
3361 +  snes - the SNES context
3362 .  b - the constant part of the equation F(x) = b, or PETSC_NULL to use zero.
3363 -  x - the solution vector.
3364 
3365    Notes:
3366    The user should initialize the vector,x, with the initial guess
3367    for the nonlinear solve prior to calling SNESSolve.  In particular,
3368    to employ an initial guess of zero, the user should explicitly set
3369    this vector to zero by calling VecSet().
3370 
3371    Level: beginner
3372 
3373 .keywords: SNES, nonlinear, solve
3374 
3375 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3376 @*/
3377 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3378 {
3379   PetscErrorCode ierr;
3380   PetscBool      flg;
3381   char           filename[PETSC_MAX_PATH_LEN];
3382   PetscViewer    viewer;
3383   PetscInt       grid;
3384   Vec            xcreated = PETSC_NULL;
3385   DM             dm;
3386 
3387   PetscFunctionBegin;
3388   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3389   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3390   if (x) PetscCheckSameComm(snes,1,x,3);
3391   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3392   if (b) PetscCheckSameComm(snes,1,b,2);
3393 
3394   if (!x) {
3395     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3396     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3397     x    = xcreated;
3398   }
3399 
3400   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm));CHKERRQ(ierr);}
3401   for (grid=0; grid<snes->gridsequence+1; grid++) {
3402 
3403     /* set solution vector */
3404     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3405     ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3406     snes->vec_sol = x;
3407     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3408 
3409     /* set affine vector if provided */
3410     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3411     ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3412     snes->vec_rhs = b;
3413 
3414     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3415 
3416     if (!grid) {
3417       if (snes->ops->computeinitialguess) {
3418         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3419       } else if (snes->dm) {
3420         PetscBool ig;
3421         ierr = DMHasInitialGuess(snes->dm,&ig);CHKERRQ(ierr);
3422         if (ig) {
3423           ierr = DMComputeInitialGuess(snes->dm,snes->vec_sol);CHKERRQ(ierr);
3424         }
3425       }
3426     }
3427 
3428     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3429     snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;
3430 
3431     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3432     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3433     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3434     if (snes->domainerror){
3435       snes->reason      = SNES_DIVERGED_FUNCTION_DOMAIN;
3436       snes->domainerror = PETSC_FALSE;
3437     }
3438     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3439 
3440     ierr = PetscOptionsGetString(((PetscObject)snes)->prefix,"-snes_view",filename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
3441     if (flg && !PetscPreLoadingOn) {
3442       ierr = PetscViewerASCIIOpen(((PetscObject)snes)->comm,filename,&viewer);CHKERRQ(ierr);
3443       ierr = SNESView(snes,viewer);CHKERRQ(ierr);
3444       ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3445     }
3446 
3447     flg  = PETSC_FALSE;
3448     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,PETSC_NULL);CHKERRQ(ierr);
3449     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
3450     if (snes->printreason) {
3451       ierr = PetscViewerASCIIAddTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3452       if (snes->reason > 0) {
3453         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3454       } else {
3455         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);
3456       }
3457       ierr = PetscViewerASCIISubtractTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3458     }
3459 
3460     flg = PETSC_FALSE;
3461     ierr = PetscOptionsGetString(((PetscObject)snes)->prefix,"-snes_view_solution_vtk",filename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
3462     if (flg) {
3463       PetscViewer viewer;
3464       ierr = PetscViewerCreate(((PetscObject)snes)->comm,&viewer);CHKERRQ(ierr);
3465       ierr = PetscViewerSetType(viewer,PETSCVIEWERVTK);CHKERRQ(ierr);
3466       ierr = PetscViewerFileSetName(viewer,filename);CHKERRQ(ierr);
3467       ierr = VecView(snes->vec_sol,viewer);CHKERRQ(ierr);
3468       ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3469     }
3470 
3471     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
3472     if (grid <  snes->gridsequence) {
3473       DM  fine;
3474       Vec xnew;
3475       Mat interp;
3476 
3477       ierr = DMRefine(snes->dm,((PetscObject)snes)->comm,&fine);CHKERRQ(ierr);
3478       if (!fine) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
3479       ierr = DMCreateInterpolation(snes->dm,fine,&interp,PETSC_NULL);CHKERRQ(ierr);
3480       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
3481       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
3482       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
3483       ierr = MatDestroy(&interp);CHKERRQ(ierr);
3484       x    = xnew;
3485 
3486       ierr = SNESReset(snes);CHKERRQ(ierr);
3487       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
3488       ierr = DMDestroy(&fine);CHKERRQ(ierr);
3489       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(((PetscObject)snes)->comm));CHKERRQ(ierr);
3490     }
3491   }
3492   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
3493   PetscFunctionReturn(0);
3494 }
3495 
3496 /* --------- Internal routines for SNES Package --------- */
3497 
3498 #undef __FUNCT__
3499 #define __FUNCT__ "SNESSetType"
3500 /*@C
3501    SNESSetType - Sets the method for the nonlinear solver.
3502 
3503    Collective on SNES
3504 
3505    Input Parameters:
3506 +  snes - the SNES context
3507 -  type - a known method
3508 
3509    Options Database Key:
3510 .  -snes_type <type> - Sets the method; use -help for a list
3511    of available methods (for instance, ls or tr)
3512 
3513    Notes:
3514    See "petsc/include/petscsnes.h" for available methods (for instance)
3515 +    SNESLS - Newton's method with line search
3516      (systems of nonlinear equations)
3517 .    SNESTR - Newton's method with trust region
3518      (systems of nonlinear equations)
3519 
3520   Normally, it is best to use the SNESSetFromOptions() command and then
3521   set the SNES solver type from the options database rather than by using
3522   this routine.  Using the options database provides the user with
3523   maximum flexibility in evaluating the many nonlinear solvers.
3524   The SNESSetType() routine is provided for those situations where it
3525   is necessary to set the nonlinear solver independently of the command
3526   line or options database.  This might be the case, for example, when
3527   the choice of solver changes during the execution of the program,
3528   and the user's application is taking responsibility for choosing the
3529   appropriate method.
3530 
3531   Level: intermediate
3532 
3533 .keywords: SNES, set, type
3534 
3535 .seealso: SNESType, SNESCreate()
3536 
3537 @*/
3538 PetscErrorCode  SNESSetType(SNES snes,const SNESType type)
3539 {
3540   PetscErrorCode ierr,(*r)(SNES);
3541   PetscBool      match;
3542 
3543   PetscFunctionBegin;
3544   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3545   PetscValidCharPointer(type,2);
3546 
3547   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
3548   if (match) PetscFunctionReturn(0);
3549 
3550   ierr =  PetscFListFind(SNESList,((PetscObject)snes)->comm,type,PETSC_TRUE,(void (**)(void)) &r);CHKERRQ(ierr);
3551   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
3552   /* Destroy the previous private SNES context */
3553   if (snes->ops->destroy) {
3554     ierr = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
3555     snes->ops->destroy = PETSC_NULL;
3556   }
3557   /* Reinitialize function pointers in SNESOps structure */
3558   snes->ops->setup          = 0;
3559   snes->ops->solve          = 0;
3560   snes->ops->view           = 0;
3561   snes->ops->setfromoptions = 0;
3562   snes->ops->destroy        = 0;
3563   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
3564   snes->setupcalled = PETSC_FALSE;
3565   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
3566   ierr = (*r)(snes);CHKERRQ(ierr);
3567 #if defined(PETSC_HAVE_AMS)
3568   if (PetscAMSPublishAll) {
3569     ierr = PetscObjectAMSPublish((PetscObject)snes);CHKERRQ(ierr);
3570   }
3571 #endif
3572   PetscFunctionReturn(0);
3573 }
3574 
3575 
3576 /* --------------------------------------------------------------------- */
3577 #undef __FUNCT__
3578 #define __FUNCT__ "SNESRegisterDestroy"
3579 /*@
3580    SNESRegisterDestroy - Frees the list of nonlinear solvers that were
3581    registered by SNESRegisterDynamic().
3582 
3583    Not Collective
3584 
3585    Level: advanced
3586 
3587 .keywords: SNES, nonlinear, register, destroy
3588 
3589 .seealso: SNESRegisterAll(), SNESRegisterAll()
3590 @*/
3591 PetscErrorCode  SNESRegisterDestroy(void)
3592 {
3593   PetscErrorCode ierr;
3594 
3595   PetscFunctionBegin;
3596   ierr = PetscFListDestroy(&SNESList);CHKERRQ(ierr);
3597   SNESRegisterAllCalled = PETSC_FALSE;
3598   PetscFunctionReturn(0);
3599 }
3600 
3601 #undef __FUNCT__
3602 #define __FUNCT__ "SNESGetType"
3603 /*@C
3604    SNESGetType - Gets the SNES method type and name (as a string).
3605 
3606    Not Collective
3607 
3608    Input Parameter:
3609 .  snes - nonlinear solver context
3610 
3611    Output Parameter:
3612 .  type - SNES method (a character string)
3613 
3614    Level: intermediate
3615 
3616 .keywords: SNES, nonlinear, get, type, name
3617 @*/
3618 PetscErrorCode  SNESGetType(SNES snes,const SNESType *type)
3619 {
3620   PetscFunctionBegin;
3621   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3622   PetscValidPointer(type,2);
3623   *type = ((PetscObject)snes)->type_name;
3624   PetscFunctionReturn(0);
3625 }
3626 
3627 #undef __FUNCT__
3628 #define __FUNCT__ "SNESGetSolution"
3629 /*@
3630    SNESGetSolution - Returns the vector where the approximate solution is
3631    stored. This is the fine grid solution when using SNESSetGridSequence().
3632 
3633    Not Collective, but Vec is parallel if SNES is parallel
3634 
3635    Input Parameter:
3636 .  snes - the SNES context
3637 
3638    Output Parameter:
3639 .  x - the solution
3640 
3641    Level: intermediate
3642 
3643 .keywords: SNES, nonlinear, get, solution
3644 
3645 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
3646 @*/
3647 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
3648 {
3649   PetscFunctionBegin;
3650   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3651   PetscValidPointer(x,2);
3652   *x = snes->vec_sol;
3653   PetscFunctionReturn(0);
3654 }
3655 
3656 #undef __FUNCT__
3657 #define __FUNCT__ "SNESGetSolutionUpdate"
3658 /*@
3659    SNESGetSolutionUpdate - Returns the vector where the solution update is
3660    stored.
3661 
3662    Not Collective, but Vec is parallel if SNES is parallel
3663 
3664    Input Parameter:
3665 .  snes - the SNES context
3666 
3667    Output Parameter:
3668 .  x - the solution update
3669 
3670    Level: advanced
3671 
3672 .keywords: SNES, nonlinear, get, solution, update
3673 
3674 .seealso: SNESGetSolution(), SNESGetFunction()
3675 @*/
3676 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
3677 {
3678   PetscFunctionBegin;
3679   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3680   PetscValidPointer(x,2);
3681   *x = snes->vec_sol_update;
3682   PetscFunctionReturn(0);
3683 }
3684 
3685 #undef __FUNCT__
3686 #define __FUNCT__ "SNESGetFunction"
3687 /*@C
3688    SNESGetFunction - Returns the vector where the function is stored.
3689 
3690    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
3691 
3692    Input Parameter:
3693 .  snes - the SNES context
3694 
3695    Output Parameter:
3696 +  r - the function (or PETSC_NULL)
3697 .  func - the function (or PETSC_NULL)
3698 -  ctx - the function context (or PETSC_NULL)
3699 
3700    Level: advanced
3701 
3702 .keywords: SNES, nonlinear, get, function
3703 
3704 .seealso: SNESSetFunction(), SNESGetSolution()
3705 @*/
3706 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**func)(SNES,Vec,Vec,void*),void **ctx)
3707 {
3708   PetscErrorCode ierr;
3709   DM             dm;
3710 
3711   PetscFunctionBegin;
3712   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3713   if (r) {
3714     if (!snes->vec_func) {
3715       if (snes->vec_rhs) {
3716         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
3717       } else if (snes->vec_sol) {
3718         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
3719       } else if (snes->dm) {
3720         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
3721       }
3722     }
3723     *r = snes->vec_func;
3724   }
3725   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3726   ierr = DMSNESGetFunction(dm,func,ctx);CHKERRQ(ierr);
3727   PetscFunctionReturn(0);
3728 }
3729 
3730 /*@C
3731    SNESGetGS - Returns the GS function and context.
3732 
3733    Input Parameter:
3734 .  snes - the SNES context
3735 
3736    Output Parameter:
3737 +  gsfunc - the function (or PETSC_NULL)
3738 -  ctx    - the function context (or PETSC_NULL)
3739 
3740    Level: advanced
3741 
3742 .keywords: SNES, nonlinear, get, function
3743 
3744 .seealso: SNESSetGS(), SNESGetFunction()
3745 @*/
3746 
3747 #undef __FUNCT__
3748 #define __FUNCT__ "SNESGetGS"
3749 PetscErrorCode SNESGetGS (SNES snes, PetscErrorCode(**func)(SNES, Vec, Vec, void*), void ** ctx)
3750 {
3751   PetscErrorCode ierr;
3752   DM             dm;
3753 
3754   PetscFunctionBegin;
3755   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3756   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3757   ierr = DMSNESGetGS(dm,func,ctx);CHKERRQ(ierr);
3758   PetscFunctionReturn(0);
3759 }
3760 
3761 #undef __FUNCT__
3762 #define __FUNCT__ "SNESSetOptionsPrefix"
3763 /*@C
3764    SNESSetOptionsPrefix - Sets the prefix used for searching for all
3765    SNES options in the database.
3766 
3767    Logically Collective on SNES
3768 
3769    Input Parameter:
3770 +  snes - the SNES context
3771 -  prefix - the prefix to prepend to all option names
3772 
3773    Notes:
3774    A hyphen (-) must NOT be given at the beginning of the prefix name.
3775    The first character of all runtime options is AUTOMATICALLY the hyphen.
3776 
3777    Level: advanced
3778 
3779 .keywords: SNES, set, options, prefix, database
3780 
3781 .seealso: SNESSetFromOptions()
3782 @*/
3783 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
3784 {
3785   PetscErrorCode ierr;
3786 
3787   PetscFunctionBegin;
3788   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3789   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
3790   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
3791   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
3792   PetscFunctionReturn(0);
3793 }
3794 
3795 #undef __FUNCT__
3796 #define __FUNCT__ "SNESAppendOptionsPrefix"
3797 /*@C
3798    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
3799    SNES options in the database.
3800 
3801    Logically Collective on SNES
3802 
3803    Input Parameters:
3804 +  snes - the SNES context
3805 -  prefix - the prefix to prepend to all option names
3806 
3807    Notes:
3808    A hyphen (-) must NOT be given at the beginning of the prefix name.
3809    The first character of all runtime options is AUTOMATICALLY the hyphen.
3810 
3811    Level: advanced
3812 
3813 .keywords: SNES, append, options, prefix, database
3814 
3815 .seealso: SNESGetOptionsPrefix()
3816 @*/
3817 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
3818 {
3819   PetscErrorCode ierr;
3820 
3821   PetscFunctionBegin;
3822   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3823   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
3824   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
3825   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
3826   PetscFunctionReturn(0);
3827 }
3828 
3829 #undef __FUNCT__
3830 #define __FUNCT__ "SNESGetOptionsPrefix"
3831 /*@C
3832    SNESGetOptionsPrefix - Sets the prefix used for searching for all
3833    SNES options in the database.
3834 
3835    Not Collective
3836 
3837    Input Parameter:
3838 .  snes - the SNES context
3839 
3840    Output Parameter:
3841 .  prefix - pointer to the prefix string used
3842 
3843    Notes: On the fortran side, the user should pass in a string 'prefix' of
3844    sufficient length to hold the prefix.
3845 
3846    Level: advanced
3847 
3848 .keywords: SNES, get, options, prefix, database
3849 
3850 .seealso: SNESAppendOptionsPrefix()
3851 @*/
3852 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
3853 {
3854   PetscErrorCode ierr;
3855 
3856   PetscFunctionBegin;
3857   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3858   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
3859   PetscFunctionReturn(0);
3860 }
3861 
3862 
3863 #undef __FUNCT__
3864 #define __FUNCT__ "SNESRegister"
3865 /*@C
3866   SNESRegister - See SNESRegisterDynamic()
3867 
3868   Level: advanced
3869 @*/
3870 PetscErrorCode  SNESRegister(const char sname[],const char path[],const char name[],PetscErrorCode (*function)(SNES))
3871 {
3872   char           fullname[PETSC_MAX_PATH_LEN];
3873   PetscErrorCode ierr;
3874 
3875   PetscFunctionBegin;
3876   ierr = PetscFListConcat(path,name,fullname);CHKERRQ(ierr);
3877   ierr = PetscFListAdd(&SNESList,sname,fullname,(void (*)(void))function);CHKERRQ(ierr);
3878   PetscFunctionReturn(0);
3879 }
3880 
3881 #undef __FUNCT__
3882 #define __FUNCT__ "SNESTestLocalMin"
3883 PetscErrorCode  SNESTestLocalMin(SNES snes)
3884 {
3885   PetscErrorCode ierr;
3886   PetscInt       N,i,j;
3887   Vec            u,uh,fh;
3888   PetscScalar    value;
3889   PetscReal      norm;
3890 
3891   PetscFunctionBegin;
3892   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
3893   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
3894   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
3895 
3896   /* currently only works for sequential */
3897   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");
3898   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
3899   for (i=0; i<N; i++) {
3900     ierr = VecCopy(u,uh);CHKERRQ(ierr);
3901     ierr  = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
3902     for (j=-10; j<11; j++) {
3903       value = PetscSign(j)*exp(PetscAbs(j)-10.0);
3904       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
3905       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
3906       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
3907       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
3908       value = -value;
3909       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
3910     }
3911   }
3912   ierr = VecDestroy(&uh);CHKERRQ(ierr);
3913   ierr = VecDestroy(&fh);CHKERRQ(ierr);
3914   PetscFunctionReturn(0);
3915 }
3916 
3917 #undef __FUNCT__
3918 #define __FUNCT__ "SNESKSPSetUseEW"
3919 /*@
3920    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
3921    computing relative tolerance for linear solvers within an inexact
3922    Newton method.
3923 
3924    Logically Collective on SNES
3925 
3926    Input Parameters:
3927 +  snes - SNES context
3928 -  flag - PETSC_TRUE or PETSC_FALSE
3929 
3930     Options Database:
3931 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
3932 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
3933 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
3934 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
3935 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
3936 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
3937 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
3938 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
3939 
3940    Notes:
3941    Currently, the default is to use a constant relative tolerance for
3942    the inner linear solvers.  Alternatively, one can use the
3943    Eisenstat-Walker method, where the relative convergence tolerance
3944    is reset at each Newton iteration according progress of the nonlinear
3945    solver.
3946 
3947    Level: advanced
3948 
3949    Reference:
3950    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
3951    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
3952 
3953 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
3954 
3955 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
3956 @*/
3957 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool  flag)
3958 {
3959   PetscFunctionBegin;
3960   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3961   PetscValidLogicalCollectiveBool(snes,flag,2);
3962   snes->ksp_ewconv = flag;
3963   PetscFunctionReturn(0);
3964 }
3965 
3966 #undef __FUNCT__
3967 #define __FUNCT__ "SNESKSPGetUseEW"
3968 /*@
3969    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
3970    for computing relative tolerance for linear solvers within an
3971    inexact Newton method.
3972 
3973    Not Collective
3974 
3975    Input Parameter:
3976 .  snes - SNES context
3977 
3978    Output Parameter:
3979 .  flag - PETSC_TRUE or PETSC_FALSE
3980 
3981    Notes:
3982    Currently, the default is to use a constant relative tolerance for
3983    the inner linear solvers.  Alternatively, one can use the
3984    Eisenstat-Walker method, where the relative convergence tolerance
3985    is reset at each Newton iteration according progress of the nonlinear
3986    solver.
3987 
3988    Level: advanced
3989 
3990    Reference:
3991    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
3992    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
3993 
3994 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
3995 
3996 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
3997 @*/
3998 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
3999 {
4000   PetscFunctionBegin;
4001   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4002   PetscValidPointer(flag,2);
4003   *flag = snes->ksp_ewconv;
4004   PetscFunctionReturn(0);
4005 }
4006 
4007 #undef __FUNCT__
4008 #define __FUNCT__ "SNESKSPSetParametersEW"
4009 /*@
4010    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4011    convergence criteria for the linear solvers within an inexact
4012    Newton method.
4013 
4014    Logically Collective on SNES
4015 
4016    Input Parameters:
4017 +    snes - SNES context
4018 .    version - version 1, 2 (default is 2) or 3
4019 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4020 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4021 .    gamma - multiplicative factor for version 2 rtol computation
4022              (0 <= gamma2 <= 1)
4023 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4024 .    alpha2 - power for safeguard
4025 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4026 
4027    Note:
4028    Version 3 was contributed by Luis Chacon, June 2006.
4029 
4030    Use PETSC_DEFAULT to retain the default for any of the parameters.
4031 
4032    Level: advanced
4033 
4034    Reference:
4035    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4036    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4037    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4038 
4039 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4040 
4041 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4042 @*/
4043 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,
4044 							    PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4045 {
4046   SNESKSPEW *kctx;
4047   PetscFunctionBegin;
4048   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4049   kctx = (SNESKSPEW*)snes->kspconvctx;
4050   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4051   PetscValidLogicalCollectiveInt(snes,version,2);
4052   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4053   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4054   PetscValidLogicalCollectiveReal(snes,gamma,5);
4055   PetscValidLogicalCollectiveReal(snes,alpha,6);
4056   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4057   PetscValidLogicalCollectiveReal(snes,threshold,8);
4058 
4059   if (version != PETSC_DEFAULT)   kctx->version   = version;
4060   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4061   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4062   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4063   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4064   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4065   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4066 
4067   if (kctx->version < 1 || kctx->version > 3) {
4068     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 and 3 are supported: %D",kctx->version);
4069   }
4070   if (kctx->rtol_0 < 0.0 || kctx->rtol_0 >= 1.0) {
4071     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_0 < 1.0: %G",kctx->rtol_0);
4072   }
4073   if (kctx->rtol_max < 0.0 || kctx->rtol_max >= 1.0) {
4074     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_max (%G) < 1.0\n",kctx->rtol_max);
4075   }
4076   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) {
4077     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%G) <= 1.0\n",kctx->gamma);
4078   }
4079   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) {
4080     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%G) <= 2.0\n",kctx->alpha);
4081   }
4082   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) {
4083     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%G) < 1.0\n",kctx->threshold);
4084   }
4085   PetscFunctionReturn(0);
4086 }
4087 
4088 #undef __FUNCT__
4089 #define __FUNCT__ "SNESKSPGetParametersEW"
4090 /*@
4091    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4092    convergence criteria for the linear solvers within an inexact
4093    Newton method.
4094 
4095    Not Collective
4096 
4097    Input Parameters:
4098      snes - SNES context
4099 
4100    Output Parameters:
4101 +    version - version 1, 2 (default is 2) or 3
4102 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4103 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4104 .    gamma - multiplicative factor for version 2 rtol computation
4105              (0 <= gamma2 <= 1)
4106 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4107 .    alpha2 - power for safeguard
4108 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4109 
4110    Level: advanced
4111 
4112 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4113 
4114 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4115 @*/
4116 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,
4117 							    PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4118 {
4119   SNESKSPEW *kctx;
4120   PetscFunctionBegin;
4121   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4122   kctx = (SNESKSPEW*)snes->kspconvctx;
4123   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4124   if(version)   *version   = kctx->version;
4125   if(rtol_0)    *rtol_0    = kctx->rtol_0;
4126   if(rtol_max)  *rtol_max  = kctx->rtol_max;
4127   if(gamma)     *gamma     = kctx->gamma;
4128   if(alpha)     *alpha     = kctx->alpha;
4129   if(alpha2)    *alpha2    = kctx->alpha2;
4130   if(threshold) *threshold = kctx->threshold;
4131   PetscFunctionReturn(0);
4132 }
4133 
4134 #undef __FUNCT__
4135 #define __FUNCT__ "SNESKSPEW_PreSolve"
4136 static PetscErrorCode SNESKSPEW_PreSolve(SNES snes, KSP ksp, Vec b, Vec x)
4137 {
4138   PetscErrorCode ierr;
4139   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4140   PetscReal      rtol=PETSC_DEFAULT,stol;
4141 
4142   PetscFunctionBegin;
4143   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context exists");
4144   if (!snes->iter) { /* first time in, so use the original user rtol */
4145     rtol = kctx->rtol_0;
4146   } else {
4147     if (kctx->version == 1) {
4148       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4149       if (rtol < 0.0) rtol = -rtol;
4150       stol = pow(kctx->rtol_last,kctx->alpha2);
4151       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4152     } else if (kctx->version == 2) {
4153       rtol = kctx->gamma * pow(snes->norm/kctx->norm_last,kctx->alpha);
4154       stol = kctx->gamma * pow(kctx->rtol_last,kctx->alpha);
4155       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4156     } else if (kctx->version == 3) {/* contributed by Luis Chacon, June 2006. */
4157       rtol = kctx->gamma * pow(snes->norm/kctx->norm_last,kctx->alpha);
4158       /* safeguard: avoid sharp decrease of rtol */
4159       stol = kctx->gamma*pow(kctx->rtol_last,kctx->alpha);
4160       stol = PetscMax(rtol,stol);
4161       rtol = PetscMin(kctx->rtol_0,stol);
4162       /* safeguard: avoid oversolving */
4163       stol = kctx->gamma*(snes->ttol)/snes->norm;
4164       stol = PetscMax(rtol,stol);
4165       rtol = PetscMin(kctx->rtol_0,stol);
4166     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4167   }
4168   /* safeguard: avoid rtol greater than one */
4169   rtol = PetscMin(rtol,kctx->rtol_max);
4170   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4171   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%G\n",snes->iter,kctx->version,rtol);CHKERRQ(ierr);
4172   PetscFunctionReturn(0);
4173 }
4174 
4175 #undef __FUNCT__
4176 #define __FUNCT__ "SNESKSPEW_PostSolve"
4177 static PetscErrorCode SNESKSPEW_PostSolve(SNES snes, KSP ksp, Vec b, Vec x)
4178 {
4179   PetscErrorCode ierr;
4180   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4181   PCSide         pcside;
4182   Vec            lres;
4183 
4184   PetscFunctionBegin;
4185   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context exists");
4186   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4187   ierr = SNESGetFunctionNorm(snes,&kctx->norm_last);CHKERRQ(ierr);
4188   if (kctx->version == 1) {
4189     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4190     if (pcside == PC_RIGHT) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4191       /* KSP residual is true linear residual */
4192       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4193     } else {
4194       /* KSP residual is preconditioned residual */
4195       /* compute true linear residual norm */
4196       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4197       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4198       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4199       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4200       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4201     }
4202   }
4203   PetscFunctionReturn(0);
4204 }
4205 
4206 #undef __FUNCT__
4207 #define __FUNCT__ "SNES_KSPSolve"
4208 PetscErrorCode SNES_KSPSolve(SNES snes, KSP ksp, Vec b, Vec x)
4209 {
4210   PetscErrorCode ierr;
4211 
4212   PetscFunctionBegin;
4213   if (snes->ksp_ewconv) { ierr = SNESKSPEW_PreSolve(snes,ksp,b,x);CHKERRQ(ierr);  }
4214   ierr = KSPSolve(ksp,b,x);CHKERRQ(ierr);
4215   if (snes->ksp_ewconv) { ierr = SNESKSPEW_PostSolve(snes,ksp,b,x);CHKERRQ(ierr); }
4216   PetscFunctionReturn(0);
4217 }
4218 
4219 #undef __FUNCT__
4220 #define __FUNCT__ "SNESSetDM"
4221 /*@
4222    SNESSetDM - Sets the DM that may be used by some preconditioners
4223 
4224    Logically Collective on SNES
4225 
4226    Input Parameters:
4227 +  snes - the preconditioner context
4228 -  dm - the dm
4229 
4230    Level: intermediate
4231 
4232 
4233 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4234 @*/
4235 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4236 {
4237   PetscErrorCode ierr;
4238   KSP            ksp;
4239   SNESDM         sdm;
4240 
4241   PetscFunctionBegin;
4242   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4243   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4244   if (snes->dm) {               /* Move the SNESDM context over to the new DM unless the new DM already has one */
4245     PetscContainer oldcontainer,container;
4246     ierr = PetscObjectQuery((PetscObject)snes->dm,"SNESDM",(PetscObject*)&oldcontainer);CHKERRQ(ierr);
4247     ierr = PetscObjectQuery((PetscObject)dm,"SNESDM",(PetscObject*)&container);CHKERRQ(ierr);
4248     if (oldcontainer && !container) {
4249       ierr = DMSNESCopyContext(snes->dm,dm);CHKERRQ(ierr);
4250       ierr = DMSNESGetContext(snes->dm,&sdm);CHKERRQ(ierr);
4251       if (sdm->originaldm == snes->dm) { /* Grant write privileges to the replacement DM */
4252         sdm->originaldm = dm;
4253       }
4254     }
4255     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4256   }
4257   snes->dm = dm;
4258   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4259   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4260   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4261   if (snes->pc) {
4262     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4263   }
4264   PetscFunctionReturn(0);
4265 }
4266 
4267 #undef __FUNCT__
4268 #define __FUNCT__ "SNESGetDM"
4269 /*@
4270    SNESGetDM - Gets the DM that may be used by some preconditioners
4271 
4272    Not Collective but DM obtained is parallel on SNES
4273 
4274    Input Parameter:
4275 . snes - the preconditioner context
4276 
4277    Output Parameter:
4278 .  dm - the dm
4279 
4280    Level: intermediate
4281 
4282 
4283 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4284 @*/
4285 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4286 {
4287   PetscErrorCode ierr;
4288 
4289   PetscFunctionBegin;
4290   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4291   if (!snes->dm) {
4292     ierr = DMShellCreate(((PetscObject)snes)->comm,&snes->dm);CHKERRQ(ierr);
4293   }
4294   *dm = snes->dm;
4295   PetscFunctionReturn(0);
4296 }
4297 
4298 #undef __FUNCT__
4299 #define __FUNCT__ "SNESSetPC"
4300 /*@
4301   SNESSetPC - Sets the nonlinear preconditioner to be used.
4302 
4303   Collective on SNES
4304 
4305   Input Parameters:
4306 + snes - iterative context obtained from SNESCreate()
4307 - pc   - the preconditioner object
4308 
4309   Notes:
4310   Use SNESGetPC() to retrieve the preconditioner context (for example,
4311   to configure it using the API).
4312 
4313   Level: developer
4314 
4315 .keywords: SNES, set, precondition
4316 .seealso: SNESGetPC()
4317 @*/
4318 PetscErrorCode SNESSetPC(SNES snes, SNES pc)
4319 {
4320   PetscErrorCode ierr;
4321 
4322   PetscFunctionBegin;
4323   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4324   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4325   PetscCheckSameComm(snes, 1, pc, 2);
4326   ierr = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4327   ierr = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4328   snes->pc = pc;
4329   ierr = PetscLogObjectParent(snes, snes->pc);CHKERRQ(ierr);
4330   PetscFunctionReturn(0);
4331 }
4332 
4333 #undef __FUNCT__
4334 #define __FUNCT__ "SNESGetPC"
4335 /*@
4336   SNESGetPC - Returns a pointer to the nonlinear preconditioning context set with SNESSetPC().
4337 
4338   Not Collective
4339 
4340   Input Parameter:
4341 . snes - iterative context obtained from SNESCreate()
4342 
4343   Output Parameter:
4344 . pc - preconditioner context
4345 
4346   Level: developer
4347 
4348 .keywords: SNES, get, preconditioner
4349 .seealso: SNESSetPC()
4350 @*/
4351 PetscErrorCode SNESGetPC(SNES snes, SNES *pc)
4352 {
4353   PetscErrorCode              ierr;
4354   SNESLineSearch              linesearch;
4355   SNESLineSearch              pclinesearch;
4356   void                        *lsprectx,*lspostctx;
4357   SNESLineSearchPreCheckFunc  lsprefunc;
4358   SNESLineSearchPostCheckFunc lspostfunc;
4359   DM                          dm;
4360   const char                  *optionsprefix;
4361 
4362   PetscFunctionBegin;
4363   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4364   PetscValidPointer(pc, 2);
4365   if (!snes->pc) {
4366     ierr = SNESCreate(((PetscObject) snes)->comm,&snes->pc);CHKERRQ(ierr);
4367     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4368     ierr = PetscLogObjectParent(snes,snes->pc);CHKERRQ(ierr);
4369     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4370     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4371     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4372 
4373     /* copy the DM over */
4374     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4375     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
4376 
4377    /* copy the function pointers over */
4378     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
4379 
4380      /* default to 1 iteration */
4381     ierr = SNESSetTolerances(snes->pc, snes->pc->abstol, snes->pc->rtol, snes->pc->stol, 1, snes->pc->max_funcs);CHKERRQ(ierr);
4382     ierr = SNESSetNormType(snes->pc, SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
4383     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
4384 
4385 
4386     /* copy the line search context over */
4387     ierr = SNESGetSNESLineSearch(snes,&linesearch);CHKERRQ(ierr);
4388     ierr = SNESGetSNESLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
4389     ierr = SNESLineSearchGetPreCheck(linesearch,&lsprefunc,&lsprectx);CHKERRQ(ierr);
4390     ierr = SNESLineSearchGetPostCheck(linesearch,&lspostfunc,&lspostctx);CHKERRQ(ierr);
4391     ierr = SNESLineSearchSetPreCheck(pclinesearch,lsprefunc,lsprectx);CHKERRQ(ierr);
4392     ierr = SNESLineSearchSetPostCheck(pclinesearch,lspostfunc,lspostctx);CHKERRQ(ierr);
4393     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);CHKERRQ(ierr);
4394   }
4395   *pc = snes->pc;
4396   PetscFunctionReturn(0);
4397 }
4398 
4399 #undef __FUNCT__
4400 #define __FUNCT__ "SNESSetSNESLineSearch"
4401 /*@
4402   SNESSetSNESLineSearch - Sets the linesearch on the SNES instance.
4403 
4404   Collective on SNES
4405 
4406   Input Parameters:
4407 + snes - iterative context obtained from SNESCreate()
4408 - linesearch   - the linesearch object
4409 
4410   Notes:
4411   Use SNESGetSNESLineSearch() to retrieve the preconditioner context (for example,
4412   to configure it using the API).
4413 
4414   Level: developer
4415 
4416 .keywords: SNES, set, linesearch
4417 .seealso: SNESGetSNESLineSearch()
4418 @*/
4419 PetscErrorCode SNESSetSNESLineSearch(SNES snes, SNESLineSearch linesearch)
4420 {
4421   PetscErrorCode ierr;
4422 
4423   PetscFunctionBegin;
4424   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4425   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
4426   PetscCheckSameComm(snes, 1, linesearch, 2);
4427   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
4428   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
4429   snes->linesearch = linesearch;
4430   ierr = PetscLogObjectParent(snes, snes->linesearch);CHKERRQ(ierr);
4431   PetscFunctionReturn(0);
4432 }
4433 
4434 #undef __FUNCT__
4435 #define __FUNCT__ "SNESGetSNESLineSearch"
4436 /*@C
4437   SNESGetSNESLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
4438   or creates a default line search instance associated with the SNES and returns it.
4439 
4440   Not Collective
4441 
4442   Input Parameter:
4443 . snes - iterative context obtained from SNESCreate()
4444 
4445   Output Parameter:
4446 . linesearch - linesearch context
4447 
4448   Level: developer
4449 
4450 .keywords: SNES, get, linesearch
4451 .seealso: SNESSetSNESLineSearch()
4452 @*/
4453 PetscErrorCode SNESGetSNESLineSearch(SNES snes, SNESLineSearch *linesearch)
4454 {
4455   PetscErrorCode ierr;
4456   const char     *optionsprefix;
4457 
4458   PetscFunctionBegin;
4459   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4460   PetscValidPointer(linesearch, 2);
4461   if (!snes->linesearch) {
4462     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
4463     ierr = SNESLineSearchCreate(((PetscObject) snes)->comm, &snes->linesearch);CHKERRQ(ierr);
4464     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
4465     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
4466     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
4467     ierr = PetscLogObjectParent(snes, snes->linesearch);CHKERRQ(ierr);
4468   }
4469   *linesearch = snes->linesearch;
4470   PetscFunctionReturn(0);
4471 }
4472 
4473 #if defined(PETSC_HAVE_MATLAB_ENGINE)
4474 #include <mex.h>
4475 
4476 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
4477 
4478 #undef __FUNCT__
4479 #define __FUNCT__ "SNESComputeFunction_Matlab"
4480 /*
4481    SNESComputeFunction_Matlab - Calls the function that has been set with
4482                          SNESSetFunctionMatlab().
4483 
4484    Collective on SNES
4485 
4486    Input Parameters:
4487 +  snes - the SNES context
4488 -  x - input vector
4489 
4490    Output Parameter:
4491 .  y - function vector, as set by SNESSetFunction()
4492 
4493    Notes:
4494    SNESComputeFunction() is typically used within nonlinear solvers
4495    implementations, so most users would not generally call this routine
4496    themselves.
4497 
4498    Level: developer
4499 
4500 .keywords: SNES, nonlinear, compute, function
4501 
4502 .seealso: SNESSetFunction(), SNESGetFunction()
4503 */
4504 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
4505 {
4506   PetscErrorCode    ierr;
4507   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4508   int               nlhs = 1,nrhs = 5;
4509   mxArray	    *plhs[1],*prhs[5];
4510   long long int     lx = 0,ly = 0,ls = 0;
4511 
4512   PetscFunctionBegin;
4513   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4514   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4515   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
4516   PetscCheckSameComm(snes,1,x,2);
4517   PetscCheckSameComm(snes,1,y,3);
4518 
4519   /* call Matlab function in ctx with arguments x and y */
4520 
4521   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4522   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4523   ierr = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
4524   prhs[0] =  mxCreateDoubleScalar((double)ls);
4525   prhs[1] =  mxCreateDoubleScalar((double)lx);
4526   prhs[2] =  mxCreateDoubleScalar((double)ly);
4527   prhs[3] =  mxCreateString(sctx->funcname);
4528   prhs[4] =  sctx->ctx;
4529   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
4530   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
4531   mxDestroyArray(prhs[0]);
4532   mxDestroyArray(prhs[1]);
4533   mxDestroyArray(prhs[2]);
4534   mxDestroyArray(prhs[3]);
4535   mxDestroyArray(plhs[0]);
4536   PetscFunctionReturn(0);
4537 }
4538 
4539 
4540 #undef __FUNCT__
4541 #define __FUNCT__ "SNESSetFunctionMatlab"
4542 /*
4543    SNESSetFunctionMatlab - Sets the function evaluation routine and function
4544    vector for use by the SNES routines in solving systems of nonlinear
4545    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4546 
4547    Logically Collective on SNES
4548 
4549    Input Parameters:
4550 +  snes - the SNES context
4551 .  r - vector to store function value
4552 -  func - function evaluation routine
4553 
4554    Calling sequence of func:
4555 $    func (SNES snes,Vec x,Vec f,void *ctx);
4556 
4557 
4558    Notes:
4559    The Newton-like methods typically solve linear systems of the form
4560 $      f'(x) x = -f(x),
4561    where f'(x) denotes the Jacobian matrix and f(x) is the function.
4562 
4563    Level: beginner
4564 
4565 .keywords: SNES, nonlinear, set, function
4566 
4567 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4568 */
4569 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *func,mxArray *ctx)
4570 {
4571   PetscErrorCode    ierr;
4572   SNESMatlabContext *sctx;
4573 
4574   PetscFunctionBegin;
4575   /* currently sctx is memory bleed */
4576   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4577   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4578   /*
4579      This should work, but it doesn't
4580   sctx->ctx = ctx;
4581   mexMakeArrayPersistent(sctx->ctx);
4582   */
4583   sctx->ctx = mxDuplicateArray(ctx);
4584   ierr = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
4585   PetscFunctionReturn(0);
4586 }
4587 
4588 #undef __FUNCT__
4589 #define __FUNCT__ "SNESComputeJacobian_Matlab"
4590 /*
4591    SNESComputeJacobian_Matlab - Calls the function that has been set with
4592                          SNESSetJacobianMatlab().
4593 
4594    Collective on SNES
4595 
4596    Input Parameters:
4597 +  snes - the SNES context
4598 .  x - input vector
4599 .  A, B - the matrices
4600 -  ctx - user context
4601 
4602    Output Parameter:
4603 .  flag - structure of the matrix
4604 
4605    Level: developer
4606 
4607 .keywords: SNES, nonlinear, compute, function
4608 
4609 .seealso: SNESSetFunction(), SNESGetFunction()
4610 @*/
4611 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat *A,Mat *B,MatStructure *flag, void *ctx)
4612 {
4613   PetscErrorCode    ierr;
4614   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4615   int               nlhs = 2,nrhs = 6;
4616   mxArray	    *plhs[2],*prhs[6];
4617   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
4618 
4619   PetscFunctionBegin;
4620   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4621   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4622 
4623   /* call Matlab function in ctx with arguments x and y */
4624 
4625   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4626   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4627   ierr = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
4628   ierr = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
4629   prhs[0] =  mxCreateDoubleScalar((double)ls);
4630   prhs[1] =  mxCreateDoubleScalar((double)lx);
4631   prhs[2] =  mxCreateDoubleScalar((double)lA);
4632   prhs[3] =  mxCreateDoubleScalar((double)lB);
4633   prhs[4] =  mxCreateString(sctx->funcname);
4634   prhs[5] =  sctx->ctx;
4635   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
4636   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
4637   *flag   =  (MatStructure) mxGetScalar(plhs[1]);CHKERRQ(ierr);
4638   mxDestroyArray(prhs[0]);
4639   mxDestroyArray(prhs[1]);
4640   mxDestroyArray(prhs[2]);
4641   mxDestroyArray(prhs[3]);
4642   mxDestroyArray(prhs[4]);
4643   mxDestroyArray(plhs[0]);
4644   mxDestroyArray(plhs[1]);
4645   PetscFunctionReturn(0);
4646 }
4647 
4648 
4649 #undef __FUNCT__
4650 #define __FUNCT__ "SNESSetJacobianMatlab"
4651 /*
4652    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
4653    vector for use by the SNES routines in solving systems of nonlinear
4654    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4655 
4656    Logically Collective on SNES
4657 
4658    Input Parameters:
4659 +  snes - the SNES context
4660 .  A,B - Jacobian matrices
4661 .  func - function evaluation routine
4662 -  ctx - user context
4663 
4664    Calling sequence of func:
4665 $    flag = func (SNES snes,Vec x,Mat A,Mat B,void *ctx);
4666 
4667 
4668    Level: developer
4669 
4670 .keywords: SNES, nonlinear, set, function
4671 
4672 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4673 */
4674 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *func,mxArray *ctx)
4675 {
4676   PetscErrorCode    ierr;
4677   SNESMatlabContext *sctx;
4678 
4679   PetscFunctionBegin;
4680   /* currently sctx is memory bleed */
4681   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4682   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4683   /*
4684      This should work, but it doesn't
4685   sctx->ctx = ctx;
4686   mexMakeArrayPersistent(sctx->ctx);
4687   */
4688   sctx->ctx = mxDuplicateArray(ctx);
4689   ierr = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
4690   PetscFunctionReturn(0);
4691 }
4692 
4693 #undef __FUNCT__
4694 #define __FUNCT__ "SNESMonitor_Matlab"
4695 /*
4696    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
4697 
4698    Collective on SNES
4699 
4700 .seealso: SNESSetFunction(), SNESGetFunction()
4701 @*/
4702 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
4703 {
4704   PetscErrorCode  ierr;
4705   SNESMatlabContext *sctx = (SNESMatlabContext *)ctx;
4706   int             nlhs = 1,nrhs = 6;
4707   mxArray	  *plhs[1],*prhs[6];
4708   long long int   lx = 0,ls = 0;
4709   Vec             x=snes->vec_sol;
4710 
4711   PetscFunctionBegin;
4712   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4713 
4714   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4715   ierr = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4716   prhs[0] =  mxCreateDoubleScalar((double)ls);
4717   prhs[1] =  mxCreateDoubleScalar((double)it);
4718   prhs[2] =  mxCreateDoubleScalar((double)fnorm);
4719   prhs[3] =  mxCreateDoubleScalar((double)lx);
4720   prhs[4] =  mxCreateString(sctx->funcname);
4721   prhs[5] =  sctx->ctx;
4722   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
4723   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
4724   mxDestroyArray(prhs[0]);
4725   mxDestroyArray(prhs[1]);
4726   mxDestroyArray(prhs[2]);
4727   mxDestroyArray(prhs[3]);
4728   mxDestroyArray(prhs[4]);
4729   mxDestroyArray(plhs[0]);
4730   PetscFunctionReturn(0);
4731 }
4732 
4733 
4734 #undef __FUNCT__
4735 #define __FUNCT__ "SNESMonitorSetMatlab"
4736 /*
4737    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
4738 
4739    Level: developer
4740 
4741 .keywords: SNES, nonlinear, set, function
4742 
4743 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4744 */
4745 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *func,mxArray *ctx)
4746 {
4747   PetscErrorCode    ierr;
4748   SNESMatlabContext *sctx;
4749 
4750   PetscFunctionBegin;
4751   /* currently sctx is memory bleed */
4752   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4753   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4754   /*
4755      This should work, but it doesn't
4756   sctx->ctx = ctx;
4757   mexMakeArrayPersistent(sctx->ctx);
4758   */
4759   sctx->ctx = mxDuplicateArray(ctx);
4760   ierr = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,PETSC_NULL);CHKERRQ(ierr);
4761   PetscFunctionReturn(0);
4762 }
4763 
4764 #endif
4765