xref: /petsc/src/snes/interface/snes.c (revision 021e0df48735593a4b10a8d433fd5ac359e13c2e)
1 
2 #include <petsc-private/snesimpl.h>      /*I "petscsnes.h"  I*/
3 #include <petscdmshell.h>
4 
5 PetscBool         SNESRegisterAllCalled = PETSC_FALSE;
6 PetscFunctionList SNESList              = NULL;
7 
8 /* Logging support */
9 PetscClassId  SNES_CLASSID, DMSNES_CLASSID;
10 PetscLogEvent SNES_Solve, SNES_FunctionEval, SNES_JacobianEval, SNES_NGSEval, SNES_NGSFuncEval, SNES_NPCSolve;
11 
12 #undef __FUNCT__
13 #define __FUNCT__ "SNESSetErrorIfNotConverged"
14 /*@
15    SNESSetErrorIfNotConverged - Causes SNESSolve() to generate an error if the solver has not converged.
16 
17    Logically Collective on SNES
18 
19    Input Parameters:
20 +  snes - iterative context obtained from SNESCreate()
21 -  flg - PETSC_TRUE indicates you want the error generated
22 
23    Options database keys:
24 .  -snes_error_if_not_converged : this takes an optional truth value (0/1/no/yes/true/false)
25 
26    Level: intermediate
27 
28    Notes:
29     Normally PETSc continues if a linear solver fails to converge, you can call SNESGetConvergedReason() after a SNESSolve()
30     to determine if it has converged.
31 
32 .keywords: SNES, set, initial guess, nonzero
33 
34 .seealso: SNESGetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
35 @*/
36 PetscErrorCode  SNESSetErrorIfNotConverged(SNES snes,PetscBool flg)
37 {
38   PetscFunctionBegin;
39   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
40   PetscValidLogicalCollectiveBool(snes,flg,2);
41   snes->errorifnotconverged = flg;
42   PetscFunctionReturn(0);
43 }
44 
45 #undef __FUNCT__
46 #define __FUNCT__ "SNESGetErrorIfNotConverged"
47 /*@
48    SNESGetErrorIfNotConverged - Will SNESSolve() generate an error if the solver does not converge?
49 
50    Not Collective
51 
52    Input Parameter:
53 .  snes - iterative context obtained from SNESCreate()
54 
55    Output Parameter:
56 .  flag - PETSC_TRUE if it will generate an error, else PETSC_FALSE
57 
58    Level: intermediate
59 
60 .keywords: SNES, set, initial guess, nonzero
61 
62 .seealso:  SNESSetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
63 @*/
64 PetscErrorCode  SNESGetErrorIfNotConverged(SNES snes,PetscBool  *flag)
65 {
66   PetscFunctionBegin;
67   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
68   PetscValidPointer(flag,2);
69   *flag = snes->errorifnotconverged;
70   PetscFunctionReturn(0);
71 }
72 
73 #undef __FUNCT__
74 #define __FUNCT__ "SNESSetFunctionDomainError"
75 /*@
76    SNESSetFunctionDomainError - tells SNES that the input vector to your SNESFunction is not
77      in the functions domain. For example, negative pressure.
78 
79    Logically Collective on SNES
80 
81    Input Parameters:
82 .  snes - the SNES context
83 
84    Level: advanced
85 
86 .keywords: SNES, view
87 
88 .seealso: SNESCreate(), SNESSetFunction(), SNESFunction
89 @*/
90 PetscErrorCode  SNESSetFunctionDomainError(SNES snes)
91 {
92   PetscFunctionBegin;
93   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
94   snes->domainerror = PETSC_TRUE;
95   PetscFunctionReturn(0);
96 }
97 
98 #undef __FUNCT__
99 #define __FUNCT__ "SNESGetFunctionDomainError"
100 /*@
101    SNESGetFunctionDomainError - Gets the status of the domain error after a call to SNESComputeFunction;
102 
103    Logically Collective on SNES
104 
105    Input Parameters:
106 .  snes - the SNES context
107 
108    Output Parameters:
109 .  domainerror - Set to PETSC_TRUE if there's a domain error; PETSC_FALSE otherwise.
110 
111    Level: advanced
112 
113 .keywords: SNES, view
114 
115 .seealso: SNESSetFunctionDomainError(), SNESComputeFunction()
116 @*/
117 PetscErrorCode  SNESGetFunctionDomainError(SNES snes, PetscBool *domainerror)
118 {
119   PetscFunctionBegin;
120   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
121   PetscValidPointer(domainerror, 2);
122   *domainerror = snes->domainerror;
123   PetscFunctionReturn(0);
124 }
125 
126 #undef __FUNCT__
127 #define __FUNCT__ "SNESLoad"
128 /*@C
129   SNESLoad - Loads a SNES that has been stored in binary  with SNESView().
130 
131   Collective on PetscViewer
132 
133   Input Parameters:
134 + newdm - the newly loaded SNES, this needs to have been created with SNESCreate() or
135            some related function before a call to SNESLoad().
136 - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()
137 
138    Level: intermediate
139 
140   Notes:
141    The type is determined by the data in the file, any type set into the SNES before this call is ignored.
142 
143   Notes for advanced users:
144   Most users should not need to know the details of the binary storage
145   format, since SNESLoad() and TSView() completely hide these details.
146   But for anyone who's interested, the standard binary matrix storage
147   format is
148 .vb
149      has not yet been determined
150 .ve
151 
152 .seealso: PetscViewerBinaryOpen(), SNESView(), MatLoad(), VecLoad()
153 @*/
154 PetscErrorCode  SNESLoad(SNES snes, PetscViewer viewer)
155 {
156   PetscErrorCode ierr;
157   PetscBool      isbinary;
158   PetscInt       classid;
159   char           type[256];
160   KSP            ksp;
161   DM             dm;
162   DMSNES         dmsnes;
163 
164   PetscFunctionBegin;
165   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
166   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
167   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
168   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");
169 
170   ierr = PetscViewerBinaryRead(viewer,&classid,1,PETSC_INT);CHKERRQ(ierr);
171   if (classid != SNES_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONG,"Not SNES next in file");
172   ierr = PetscViewerBinaryRead(viewer,type,256,PETSC_CHAR);CHKERRQ(ierr);
173   ierr = SNESSetType(snes, type);CHKERRQ(ierr);
174   if (snes->ops->load) {
175     ierr = (*snes->ops->load)(snes,viewer);CHKERRQ(ierr);
176   }
177   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
178   ierr = DMGetDMSNES(dm,&dmsnes);CHKERRQ(ierr);
179   ierr = DMSNESLoad(dmsnes,viewer);CHKERRQ(ierr);
180   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
181   ierr = KSPLoad(ksp,viewer);CHKERRQ(ierr);
182   PetscFunctionReturn(0);
183 }
184 
185 #include <petscdraw.h>
186 #if defined(PETSC_HAVE_SAWS)
187 #include <petscviewersaws.h>
188 #endif
189 #undef __FUNCT__
190 #define __FUNCT__ "SNESView"
191 /*@C
192    SNESView - Prints the SNES data structure.
193 
194    Collective on SNES
195 
196    Input Parameters:
197 +  SNES - the SNES context
198 -  viewer - visualization context
199 
200    Options Database Key:
201 .  -snes_view - Calls SNESView() at end of SNESSolve()
202 
203    Notes:
204    The available visualization contexts include
205 +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
206 -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
207          output where only the first processor opens
208          the file.  All other processors send their
209          data to the first processor to print.
210 
211    The user can open an alternative visualization context with
212    PetscViewerASCIIOpen() - output to a specified file.
213 
214    Level: beginner
215 
216 .keywords: SNES, view
217 
218 .seealso: PetscViewerASCIIOpen()
219 @*/
220 PetscErrorCode  SNESView(SNES snes,PetscViewer viewer)
221 {
222   SNESKSPEW      *kctx;
223   PetscErrorCode ierr;
224   KSP            ksp;
225   SNESLineSearch linesearch;
226   PetscBool      iascii,isstring,isbinary,isdraw;
227   DMSNES         dmsnes;
228 #if defined(PETSC_HAVE_SAWS)
229   PetscBool      isams;
230 #endif
231 
232   PetscFunctionBegin;
233   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
234   if (!viewer) {
235     ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&viewer);CHKERRQ(ierr);
236   }
237   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
238   PetscCheckSameComm(snes,1,viewer,2);
239 
240   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
241   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
242   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
243   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);CHKERRQ(ierr);
244 #if defined(PETSC_HAVE_SAWS)
245   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&isams);CHKERRQ(ierr);
246 #endif
247   if (iascii) {
248     ierr = PetscObjectPrintClassNamePrefixType((PetscObject)snes,viewer);CHKERRQ(ierr);
249     if (!snes->setupcalled) {
250       ierr = PetscViewerASCIIPrintf(viewer,"  SNES has not been set up so information may be incomplete\n");CHKERRQ(ierr);
251     }
252     if (snes->ops->view) {
253       ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
254       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
255       ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
256     }
257     ierr = PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, maximum function evaluations=%D\n",snes->max_its,snes->max_funcs);CHKERRQ(ierr);
258     ierr = PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%g, absolute=%g, solution=%g\n",(double)snes->rtol,(double)snes->abstol,(double)snes->stol);CHKERRQ(ierr);
259     ierr = PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",snes->linear_its);CHKERRQ(ierr);
260     ierr = PetscViewerASCIIPrintf(viewer,"  total number of function evaluations=%D\n",snes->nfuncs);CHKERRQ(ierr);
261     if (snes->gridsequence) {
262       ierr = PetscViewerASCIIPrintf(viewer,"  total number of grid sequence refinements=%D\n",snes->gridsequence);CHKERRQ(ierr);
263     }
264     if (snes->ksp_ewconv) {
265       kctx = (SNESKSPEW*)snes->kspconvctx;
266       if (kctx) {
267         ierr = PetscViewerASCIIPrintf(viewer,"  Eisenstat-Walker computation of KSP relative tolerance (version %D)\n",kctx->version);CHKERRQ(ierr);
268         ierr = PetscViewerASCIIPrintf(viewer,"    rtol_0=%g, rtol_max=%g, threshold=%g\n",(double)kctx->rtol_0,(double)kctx->rtol_max,(double)kctx->threshold);CHKERRQ(ierr);
269         ierr = PetscViewerASCIIPrintf(viewer,"    gamma=%g, alpha=%g, alpha2=%g\n",(double)kctx->gamma,(double)kctx->alpha,(double)kctx->alpha2);CHKERRQ(ierr);
270       }
271     }
272     if (snes->lagpreconditioner == -1) {
273       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is never rebuilt\n");CHKERRQ(ierr);
274     } else if (snes->lagpreconditioner > 1) {
275       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is rebuilt every %D new Jacobians\n",snes->lagpreconditioner);CHKERRQ(ierr);
276     }
277     if (snes->lagjacobian == -1) {
278       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is never rebuilt\n");CHKERRQ(ierr);
279     } else if (snes->lagjacobian > 1) {
280       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is rebuilt every %D SNES iterations\n",snes->lagjacobian);CHKERRQ(ierr);
281     }
282   } else if (isstring) {
283     const char *type;
284     ierr = SNESGetType(snes,&type);CHKERRQ(ierr);
285     ierr = PetscViewerStringSPrintf(viewer," %-3.3s",type);CHKERRQ(ierr);
286   } else if (isbinary) {
287     PetscInt    classid = SNES_FILE_CLASSID;
288     MPI_Comm    comm;
289     PetscMPIInt rank;
290     char        type[256];
291 
292     ierr = PetscObjectGetComm((PetscObject)snes,&comm);CHKERRQ(ierr);
293     ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
294     if (!rank) {
295       ierr = PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);CHKERRQ(ierr);
296       ierr = PetscStrncpy(type,((PetscObject)snes)->type_name,sizeof(type));CHKERRQ(ierr);
297       ierr = PetscViewerBinaryWrite(viewer,type,sizeof(type),PETSC_CHAR,PETSC_FALSE);CHKERRQ(ierr);
298     }
299     if (snes->ops->view) {
300       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
301     }
302   } else if (isdraw) {
303     PetscDraw draw;
304     char      str[36];
305     PetscReal x,y,bottom,h;
306 
307     ierr   = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
308     ierr   = PetscDrawGetCurrentPoint(draw,&x,&y);CHKERRQ(ierr);
309     ierr   = PetscStrcpy(str,"SNES: ");CHKERRQ(ierr);
310     ierr   = PetscStrcat(str,((PetscObject)snes)->type_name);CHKERRQ(ierr);
311     ierr   = PetscDrawBoxedString(draw,x,y,PETSC_DRAW_BLUE,PETSC_DRAW_BLACK,str,NULL,&h);CHKERRQ(ierr);
312     bottom = y - h;
313     ierr   = PetscDrawPushCurrentPoint(draw,x,bottom);CHKERRQ(ierr);
314     if (snes->ops->view) {
315       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
316     }
317 #if defined(PETSC_HAVE_SAWS)
318   } else if (isams) {
319     PetscMPIInt rank;
320     const char *name;
321 
322     ierr = PetscObjectGetName((PetscObject)snes,&name);CHKERRQ(ierr);
323     ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRQ(ierr);
324     if (!((PetscObject)snes)->amsmem && !rank) {
325       char       dir[1024];
326 
327       ierr = PetscObjectViewSAWs((PetscObject)snes,viewer);CHKERRQ(ierr);
328       ierr = PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);CHKERRQ(ierr);
329       PetscStackCallSAWs(SAWs_Register,(dir,&snes->iter,1,SAWs_READ,SAWs_INT));
330       if (!snes->conv_hist) {
331         ierr = SNESSetConvergenceHistory(snes,NULL,NULL,PETSC_DECIDE,PETSC_TRUE);CHKERRQ(ierr);
332       }
333       ierr = PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/conv_hist",name);CHKERRQ(ierr);
334       PetscStackCallSAWs(SAWs_Register,(dir,snes->conv_hist,10,SAWs_READ,SAWs_DOUBLE));
335     }
336 #endif
337   }
338   if (snes->linesearch) {
339     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
340     ierr = SNESGetLineSearch(snes, &linesearch);CHKERRQ(ierr);
341     ierr = SNESLineSearchView(linesearch, viewer);CHKERRQ(ierr);
342     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
343   }
344   if (snes->pc && snes->usespc) {
345     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
346     ierr = SNESView(snes->pc, viewer);CHKERRQ(ierr);
347     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
348   }
349   ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
350   ierr = DMGetDMSNES(snes->dm,&dmsnes);CHKERRQ(ierr);
351   ierr = DMSNESView(dmsnes, viewer);CHKERRQ(ierr);
352   ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
353   if (snes->usesksp) {
354     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
355     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
356     ierr = KSPView(ksp,viewer);CHKERRQ(ierr);
357     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
358   }
359   if (isdraw) {
360     PetscDraw draw;
361     ierr = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
362     ierr = PetscDrawPopCurrentPoint(draw);CHKERRQ(ierr);
363   }
364   PetscFunctionReturn(0);
365 }
366 
367 /*
368   We retain a list of functions that also take SNES command
369   line options. These are called at the end SNESSetFromOptions()
370 */
371 #define MAXSETFROMOPTIONS 5
372 static PetscInt numberofsetfromoptions;
373 static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);
374 
375 #undef __FUNCT__
376 #define __FUNCT__ "SNESAddOptionsChecker"
377 /*@C
378   SNESAddOptionsChecker - Adds an additional function to check for SNES options.
379 
380   Not Collective
381 
382   Input Parameter:
383 . snescheck - function that checks for options
384 
385   Level: developer
386 
387 .seealso: SNESSetFromOptions()
388 @*/
389 PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
390 {
391   PetscFunctionBegin;
392   if (numberofsetfromoptions >= MAXSETFROMOPTIONS) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %D allowed", MAXSETFROMOPTIONS);
393   othersetfromoptions[numberofsetfromoptions++] = snescheck;
394   PetscFunctionReturn(0);
395 }
396 
397 extern PetscErrorCode  SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);
398 
399 #undef __FUNCT__
400 #define __FUNCT__ "SNESSetUpMatrixFree_Private"
401 static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
402 {
403   Mat            J;
404   KSP            ksp;
405   PC             pc;
406   PetscBool      match;
407   PetscErrorCode ierr;
408 
409   PetscFunctionBegin;
410   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
411 
412   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
413     Mat A = snes->jacobian, B = snes->jacobian_pre;
414     ierr = MatGetVecs(A ? A : B, NULL,&snes->vec_func);CHKERRQ(ierr);
415   }
416 
417   if (version == 1) {
418     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
419     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
420     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
421   } else if (version == 2) {
422     if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
423 #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128)
424     ierr = SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);CHKERRQ(ierr);
425 #else
426     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator rutines (version 2)");
427 #endif
428   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator rutines, only version 1 and 2");
429 
430   ierr = PetscInfo1(snes,"Setting default matrix-free operator routines (version %D)\n", version);CHKERRQ(ierr);
431   if (hasOperator) {
432 
433     /* This version replaces the user provided Jacobian matrix with a
434        matrix-free version but still employs the user-provided preconditioner matrix. */
435     ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);
436   } else {
437     /* This version replaces both the user-provided Jacobian and the user-
438      provided preconditioner Jacobian with the default matrix free version. */
439     if ((snes->pcside == PC_LEFT) && snes->pc) {
440       if (!snes->jacobian){ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);}
441     } else {
442       ierr = SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,0);CHKERRQ(ierr);
443     }
444     /* Force no preconditioner */
445     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
446     ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
447     ierr = PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);CHKERRQ(ierr);
448     if (!match) {
449       ierr = PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");CHKERRQ(ierr);
450       ierr = PCSetType(pc,PCNONE);CHKERRQ(ierr);
451     }
452   }
453   ierr = MatDestroy(&J);CHKERRQ(ierr);
454   PetscFunctionReturn(0);
455 }
456 
457 #undef __FUNCT__
458 #define __FUNCT__ "DMRestrictHook_SNESVecSol"
459 static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
460 {
461   SNES           snes = (SNES)ctx;
462   PetscErrorCode ierr;
463   Vec            Xfine,Xfine_named = NULL,Xcoarse;
464 
465   PetscFunctionBegin;
466   if (PetscLogPrintInfo) {
467     PetscInt finelevel,coarselevel,fineclevel,coarseclevel;
468     ierr = DMGetRefineLevel(dmfine,&finelevel);CHKERRQ(ierr);
469     ierr = DMGetCoarsenLevel(dmfine,&fineclevel);CHKERRQ(ierr);
470     ierr = DMGetRefineLevel(dmcoarse,&coarselevel);CHKERRQ(ierr);
471     ierr = DMGetCoarsenLevel(dmcoarse,&coarseclevel);CHKERRQ(ierr);
472     ierr = PetscInfo4(dmfine,"Restricting SNES solution vector from level %D-%D to level %D-%D\n",finelevel,fineclevel,coarselevel,coarseclevel);CHKERRQ(ierr);
473   }
474   if (dmfine == snes->dm) Xfine = snes->vec_sol;
475   else {
476     ierr  = DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);
477     Xfine = Xfine_named;
478   }
479   ierr = DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
480   ierr = MatRestrict(Restrict,Xfine,Xcoarse);CHKERRQ(ierr);
481   ierr = VecPointwiseMult(Xcoarse,Xcoarse,Rscale);CHKERRQ(ierr);
482   ierr = DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
483   if (Xfine_named) {ierr = DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);}
484   PetscFunctionReturn(0);
485 }
486 
487 #undef __FUNCT__
488 #define __FUNCT__ "DMCoarsenHook_SNESVecSol"
489 static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm,DM dmc,void *ctx)
490 {
491   PetscErrorCode ierr;
492 
493   PetscFunctionBegin;
494   ierr = DMCoarsenHookAdd(dmc,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,ctx);CHKERRQ(ierr);
495   PetscFunctionReturn(0);
496 }
497 
498 #undef __FUNCT__
499 #define __FUNCT__ "KSPComputeOperators_SNES"
500 /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
501  * safely call SNESGetDM() in their residual evaluation routine. */
502 static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,void *ctx)
503 {
504   SNES           snes = (SNES)ctx;
505   PetscErrorCode ierr;
506   Mat            Asave = A,Bsave = B;
507   Vec            X,Xnamed = NULL;
508   DM             dmsave;
509   void           *ctxsave;
510   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
511 
512   PetscFunctionBegin;
513   dmsave = snes->dm;
514   ierr   = KSPGetDM(ksp,&snes->dm);CHKERRQ(ierr);
515   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
516   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
517     ierr = DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
518     X    = Xnamed;
519     ierr = SNESGetJacobian(snes,NULL,NULL,&jac,&ctxsave);CHKERRQ(ierr);
520     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
521     if (jac == SNESComputeJacobianDefaultColor) {
522       ierr = SNESSetJacobian(snes,NULL,NULL,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
523     }
524   }
525   /* put the previous context back */
526 
527   ierr = SNESComputeJacobian(snes,X,A,B);CHKERRQ(ierr);
528   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) {
529     ierr = SNESSetJacobian(snes,NULL,NULL,jac,ctxsave);CHKERRQ(ierr);
530   }
531 
532   if (A != Asave || B != Bsave) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_SUP,"No support for changing matrices at this time");
533   if (Xnamed) {
534     ierr = DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
535   }
536   snes->dm = dmsave;
537   PetscFunctionReturn(0);
538 }
539 
540 #undef __FUNCT__
541 #define __FUNCT__ "SNESSetUpMatrices"
542 /*@
543    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()
544 
545    Collective
546 
547    Input Arguments:
548 .  snes - snes to configure
549 
550    Level: developer
551 
552 .seealso: SNESSetUp()
553 @*/
554 PetscErrorCode SNESSetUpMatrices(SNES snes)
555 {
556   PetscErrorCode ierr;
557   DM             dm;
558   DMSNES         sdm;
559 
560   PetscFunctionBegin;
561   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
562   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
563   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_PLIB,"DMSNES not properly configured");
564   else if (!snes->jacobian && snes->mf) {
565     Mat  J;
566     void *functx;
567     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
568     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
569     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
570     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
571     ierr = SNESSetJacobian(snes,J,J,0,0);CHKERRQ(ierr);
572     ierr = MatDestroy(&J);CHKERRQ(ierr);
573   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
574     Mat J,B;
575     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
576     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
577     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
578     ierr = DMCreateMatrix(snes->dm,&B);CHKERRQ(ierr);
579     /* sdm->computejacobian was already set to reach here */
580     ierr = SNESSetJacobian(snes,J,B,NULL,NULL);CHKERRQ(ierr);
581     ierr = MatDestroy(&J);CHKERRQ(ierr);
582     ierr = MatDestroy(&B);CHKERRQ(ierr);
583   } else if (!snes->jacobian_pre) {
584     Mat J,B;
585     J    = snes->jacobian;
586     ierr = DMCreateMatrix(snes->dm,&B);CHKERRQ(ierr);
587     ierr = SNESSetJacobian(snes,J ? J : B,B,NULL,NULL);CHKERRQ(ierr);
588     ierr = MatDestroy(&B);CHKERRQ(ierr);
589   }
590   {
591     KSP ksp;
592     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
593     ierr = KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);CHKERRQ(ierr);
594     ierr = DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);CHKERRQ(ierr);
595   }
596   PetscFunctionReturn(0);
597 }
598 
599 #undef __FUNCT__
600 #define __FUNCT__ "SNESSetFromOptions"
601 /*@
602    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.
603 
604    Collective on SNES
605 
606    Input Parameter:
607 .  snes - the SNES context
608 
609    Options Database Keys:
610 +  -snes_type <type> - newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas, SNESType for complete list
611 .  -snes_stol - convergence tolerance in terms of the norm
612                 of the change in the solution between steps
613 .  -snes_atol <abstol> - absolute tolerance of residual norm
614 .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
615 .  -snes_max_it <max_it> - maximum number of iterations
616 .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
617 .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
618 .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
619 .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
620 .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
621 .  -snes_trtol <trtol> - trust region tolerance
622 .  -snes_no_convergence_test - skip convergence test in nonlinear
623                                solver; hence iterations will continue until max_it
624                                or some other criterion is reached. Saves expense
625                                of convergence test
626 .  -snes_monitor <optional filename> - prints residual norm at each iteration. if no
627                                        filename given prints to stdout
628 .  -snes_monitor_solution - plots solution at each iteration
629 .  -snes_monitor_residual - plots residual (not its norm) at each iteration
630 .  -snes_monitor_solution_update - plots update to solution at each iteration
631 .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
632 .  -snes_monitor_lg_range - plots residual norm at each iteration
633 .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
634 .  -snes_fd_color - use finite differences with coloring to compute Jacobian
635 .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
636 -  -snes_converged_reason - print the reason for convergence/divergence after each solve
637 
638     Options Database for Eisenstat-Walker method:
639 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
640 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
641 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
642 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
643 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
644 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
645 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
646 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
647 
648    Notes:
649    To see all options, run your program with the -help option or consult
650    Users-Manual: ch_snes
651 
652    Level: beginner
653 
654 .keywords: SNES, nonlinear, set, options, database
655 
656 .seealso: SNESSetOptionsPrefix()
657 @*/
658 PetscErrorCode  SNESSetFromOptions(SNES snes)
659 {
660   PetscBool      flg,pcset,persist;
661   PetscInt       i,indx,lag,grids;
662   const char     *deft        = SNESNEWTONLS;
663   const char     *convtests[] = {"default","skip"};
664   SNESKSPEW      *kctx        = NULL;
665   char           type[256], monfilename[PETSC_MAX_PATH_LEN];
666   PetscViewer    monviewer;
667   PetscErrorCode ierr;
668   PCSide         pcside;
669   const char     *optionsprefix;
670 
671   PetscFunctionBegin;
672   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
673   if (!SNESRegisterAllCalled) {ierr = SNESRegisterAll();CHKERRQ(ierr);}
674   ierr = PetscObjectOptionsBegin((PetscObject)snes);CHKERRQ(ierr);
675   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
676   ierr = PetscOptionsFList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);CHKERRQ(ierr);
677   if (flg) {
678     ierr = SNESSetType(snes,type);CHKERRQ(ierr);
679   } else if (!((PetscObject)snes)->type_name) {
680     ierr = SNESSetType(snes,deft);CHKERRQ(ierr);
681   }
682   ierr = PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,0);CHKERRQ(ierr);
683   ierr = PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,0);CHKERRQ(ierr);
684 
685   ierr = PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,0);CHKERRQ(ierr);
686   ierr = PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,NULL);CHKERRQ(ierr);
687   ierr = PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,NULL);CHKERRQ(ierr);
688   ierr = PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,NULL);CHKERRQ(ierr);
689   ierr = PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,NULL);CHKERRQ(ierr);
690   ierr = PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,NULL);CHKERRQ(ierr);
691 
692   ierr = PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);CHKERRQ(ierr);
693   if (flg) {
694     ierr = SNESSetLagPreconditioner(snes,lag);CHKERRQ(ierr);
695   }
696   ierr = PetscOptionsBool("-snes_lag_preconditioner_persists","Preconditioner lagging through multiple solves","SNESSetLagPreconditionerPersists",snes->lagjac_persist,&persist,&flg);CHKERRQ(ierr);
697   if (flg) {
698     ierr = SNESSetLagPreconditionerPersists(snes,persist);CHKERRQ(ierr);
699   }
700   ierr = PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);CHKERRQ(ierr);
701   if (flg) {
702     ierr = SNESSetLagJacobian(snes,lag);CHKERRQ(ierr);
703   }
704   ierr = PetscOptionsBool("-snes_lag_jacobian_persists","Jacobian lagging through multiple solves","SNESSetLagJacobianPersists",snes->lagjac_persist,&persist,&flg);CHKERRQ(ierr);
705   if (flg) {
706     ierr = SNESSetLagJacobianPersists(snes,persist);CHKERRQ(ierr);
707   }
708 
709   ierr = PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);CHKERRQ(ierr);
710   if (flg) {
711     ierr = SNESSetGridSequence(snes,grids);CHKERRQ(ierr);
712   }
713 
714   ierr = PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);CHKERRQ(ierr);
715   if (flg) {
716     switch (indx) {
717     case 0: ierr = SNESSetConvergenceTest(snes,SNESConvergedDefault,NULL,NULL);CHKERRQ(ierr); break;
718     case 1: ierr = SNESSetConvergenceTest(snes,SNESConvergedSkip,NULL,NULL);CHKERRQ(ierr);    break;
719     }
720   }
721 
722   ierr = PetscOptionsBool("-snes_converged_reason","Print reason for converged or diverged","SNESSolve",snes->printreason,&snes->printreason,NULL);CHKERRQ(ierr);
723 
724   ierr = PetscOptionsEList("-snes_norm_schedule","SNES Norm schedule","SNESSetNormSchedule",SNESNormSchedules,5,"function",&indx,&flg);CHKERRQ(ierr);
725   if (flg) { ierr = SNESSetNormSchedule(snes,(SNESNormSchedule)indx);CHKERRQ(ierr); }
726 
727   ierr = PetscOptionsEList("-snes_function_type","SNES Norm schedule","SNESSetFunctionType",SNESFunctionTypes,2,"unpreconditioned",&indx,&flg);CHKERRQ(ierr);
728   if (flg) { ierr = SNESSetFunctionType(snes,(SNESFunctionType)indx);CHKERRQ(ierr); }
729 
730   kctx = (SNESKSPEW*)snes->kspconvctx;
731 
732   ierr = PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,NULL);CHKERRQ(ierr);
733 
734   ierr = PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,0);CHKERRQ(ierr);
735   ierr = PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,0);CHKERRQ(ierr);
736   ierr = PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,0);CHKERRQ(ierr);
737   ierr = PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,0);CHKERRQ(ierr);
738   ierr = PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,0);CHKERRQ(ierr);
739   ierr = PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,0);CHKERRQ(ierr);
740   ierr = PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,0);CHKERRQ(ierr);
741 
742   flg  = PETSC_FALSE;
743   ierr = PetscOptionsBool("-snes_check_jacobian","Check each Jacobian with a differenced one","SNESUpdateCheckJacobian",flg,&flg,NULL);CHKERRQ(ierr);
744   if (flg) {
745     ierr = SNESSetUpdate(snes,SNESUpdateCheckJacobian);CHKERRQ(ierr);
746   }
747 
748   flg  = PETSC_FALSE;
749   ierr = PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,NULL);CHKERRQ(ierr);
750   if (flg) {ierr = SNESMonitorCancel(snes);CHKERRQ(ierr);}
751 
752   ierr = PetscOptionsString("-snes_monitor","Monitor norm of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
753   if (flg) {
754     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
755     ierr = SNESMonitorSet(snes,SNESMonitorDefault,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
756   }
757 
758   ierr = PetscOptionsString("-snes_monitor_range","Monitor range of elements of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
759   if (flg) {
760     ierr = SNESMonitorSet(snes,SNESMonitorRange,0,0);CHKERRQ(ierr);
761   }
762 
763   ierr = PetscOptionsString("-snes_ratiomonitor","Monitor ratios of norms of function","SNESMonitorSetRatio","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
764   if (flg) {
765     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
766     ierr = SNESMonitorSetRatio(snes,monviewer);CHKERRQ(ierr);
767   }
768 
769   ierr = PetscOptionsString("-snes_monitor_short","Monitor norm of function (fewer digits)","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
770   if (flg) {
771     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
772     ierr = SNESMonitorSet(snes,SNESMonitorDefaultShort,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
773   }
774 
775   ierr = PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
776   if (flg) {ierr = PetscPythonMonitorSet((PetscObject)snes,monfilename);CHKERRQ(ierr);}
777 
778   flg  = PETSC_FALSE;
779   ierr = PetscOptionsBool("-snes_monitor_solution","Plot solution at each iteration","SNESMonitorSolution",flg,&flg,NULL);CHKERRQ(ierr);
780   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolution,0,0);CHKERRQ(ierr);}
781   flg  = PETSC_FALSE;
782   ierr = PetscOptionsBool("-snes_monitor_solution_update","Plot correction at each iteration","SNESMonitorSolutionUpdate",flg,&flg,NULL);CHKERRQ(ierr);
783   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolutionUpdate,0,0);CHKERRQ(ierr);}
784   flg  = PETSC_FALSE;
785   ierr = PetscOptionsBool("-snes_monitor_residual","Plot residual at each iteration","SNESMonitorResidual",flg,&flg,NULL);CHKERRQ(ierr);
786   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorResidual,0,0);CHKERRQ(ierr);}
787   flg  = PETSC_FALSE;
788   ierr = PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,NULL);CHKERRQ(ierr);
789   if (flg) {
790     PetscDrawLG ctx;
791 
792     ierr = SNESMonitorLGCreate(0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
793     ierr = SNESMonitorSet(snes,SNESMonitorLGResidualNorm,ctx,(PetscErrorCode (*)(void**))SNESMonitorLGDestroy);CHKERRQ(ierr);
794   }
795   flg  = PETSC_FALSE;
796   ierr = PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);CHKERRQ(ierr);
797   if (flg) {
798     PetscViewer ctx;
799 
800     ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
801     ierr = SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
802   }
803 
804   flg  = PETSC_FALSE;
805   ierr = PetscOptionsBool("-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",flg,&flg,NULL);CHKERRQ(ierr);
806   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorJacUpdateSpectrum,0,0);CHKERRQ(ierr);}
807 
808 
809   ierr = PetscOptionsString("-snes_monitor_fields","Monitor norm of function per field","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
810   if (flg) {
811     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
812     ierr = SNESMonitorSet(snes,SNESMonitorFields,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
813   }
814 
815   flg  = PETSC_FALSE;
816   ierr = PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);CHKERRQ(ierr);
817   if (flg) {
818     void *functx;
819     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
820     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);CHKERRQ(ierr);
821     ierr = PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");CHKERRQ(ierr);
822   }
823 
824   flg  = PETSC_FALSE;
825   ierr = PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);CHKERRQ(ierr);
826   if (flg) {
827     ierr = SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);CHKERRQ(ierr);
828   }
829 
830   flg  = PETSC_FALSE;
831   ierr = PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);CHKERRQ(ierr);
832   if (flg) {
833     DM             dm;
834     DMSNES         sdm;
835     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
836     ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
837     sdm->jacobianctx = NULL;
838     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
839     ierr = PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");CHKERRQ(ierr);
840   }
841 
842   flg  = PETSC_FALSE;
843   ierr = PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf_operator,&flg);CHKERRQ(ierr);
844   if (flg && snes->mf_operator) {
845     snes->mf_operator = PETSC_TRUE;
846     snes->mf          = PETSC_TRUE;
847   }
848   flg  = PETSC_FALSE;
849   ierr = PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf,&flg);CHKERRQ(ierr);
850   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
851   ierr = PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,0);CHKERRQ(ierr);
852 
853   flg  = PETSC_FALSE;
854   ierr = SNESGetNPCSide(snes,&pcside);CHKERRQ(ierr);
855   ierr = PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetNPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);CHKERRQ(ierr);
856   if (flg) {ierr = SNESSetNPCSide(snes,pcside);CHKERRQ(ierr);}
857 
858 #if defined(PETSC_HAVE_SAWS)
859   /*
860     Publish convergence information using SAWs
861   */
862   flg  = PETSC_FALSE;
863   ierr = PetscOptionsBool("-snes_monitor_saws","Publish SNES progress using SAWs","SNESMonitorSet",flg,&flg,NULL);CHKERRQ(ierr);
864   if (flg) {
865     void *ctx;
866     ierr = SNESMonitorSAWsCreate(snes,&ctx);CHKERRQ(ierr);
867     ierr = SNESMonitorSet(snes,SNESMonitorSAWs,ctx,SNESMonitorSAWsDestroy);CHKERRQ(ierr);
868   }
869 #endif
870 #if defined(PETSC_HAVE_SAWS)
871   {
872   PetscBool set;
873   flg  = PETSC_FALSE;
874   ierr = PetscOptionsBool("-snes_saws_block","Block for SAWs at end of SNESSolve","PetscObjectSAWsBlock",((PetscObject)snes)->amspublishblock,&flg,&set);CHKERRQ(ierr);
875   if (set) {
876     ierr = PetscObjectSAWsSetBlock((PetscObject)snes,flg);CHKERRQ(ierr);
877   }
878   }
879 #endif
880 
881   for (i = 0; i < numberofsetfromoptions; i++) {
882     ierr = (*othersetfromoptions[i])(snes);CHKERRQ(ierr);
883   }
884 
885   if (snes->ops->setfromoptions) {
886     ierr = (*snes->ops->setfromoptions)(snes);CHKERRQ(ierr);
887   }
888 
889   /* process any options handlers added with PetscObjectAddOptionsHandler() */
890   ierr = PetscObjectProcessOptionsHandlers((PetscObject)snes);CHKERRQ(ierr);
891   ierr = PetscOptionsEnd();CHKERRQ(ierr);
892 
893   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
894   ierr = KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);CHKERRQ(ierr);
895   ierr = KSPSetFromOptions(snes->ksp);CHKERRQ(ierr);
896 
897   if (!snes->linesearch) {
898     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
899   }
900   ierr = SNESLineSearchSetFromOptions(snes->linesearch);CHKERRQ(ierr);
901 
902   /* if someone has set the SNES NPC type, create it. */
903   ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
904   ierr = PetscOptionsHasName(optionsprefix, "-npc_snes_type", &pcset);CHKERRQ(ierr);
905   if (pcset && (!snes->pc)) {
906     ierr = SNESGetNPC(snes, &snes->pc);CHKERRQ(ierr);
907   }
908   PetscFunctionReturn(0);
909 }
910 
911 #undef __FUNCT__
912 #define __FUNCT__ "SNESSetComputeApplicationContext"
913 /*@C
914    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
915    the nonlinear solvers.
916 
917    Logically Collective on SNES
918 
919    Input Parameters:
920 +  snes - the SNES context
921 .  compute - function to compute the context
922 -  destroy - function to destroy the context
923 
924    Level: intermediate
925 
926    Notes:
927    This function is currently not available from Fortran.
928 
929 .keywords: SNES, nonlinear, set, application, context
930 
931 .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
932 @*/
933 PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
934 {
935   PetscFunctionBegin;
936   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
937   snes->ops->usercompute = compute;
938   snes->ops->userdestroy = destroy;
939   PetscFunctionReturn(0);
940 }
941 
942 #undef __FUNCT__
943 #define __FUNCT__ "SNESSetApplicationContext"
944 /*@
945    SNESSetApplicationContext - Sets the optional user-defined context for
946    the nonlinear solvers.
947 
948    Logically Collective on SNES
949 
950    Input Parameters:
951 +  snes - the SNES context
952 -  usrP - optional user context
953 
954    Level: intermediate
955 
956 .keywords: SNES, nonlinear, set, application, context
957 
958 .seealso: SNESGetApplicationContext()
959 @*/
960 PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
961 {
962   PetscErrorCode ierr;
963   KSP            ksp;
964 
965   PetscFunctionBegin;
966   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
967   ierr       = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
968   ierr       = KSPSetApplicationContext(ksp,usrP);CHKERRQ(ierr);
969   snes->user = usrP;
970   PetscFunctionReturn(0);
971 }
972 
973 #undef __FUNCT__
974 #define __FUNCT__ "SNESGetApplicationContext"
975 /*@
976    SNESGetApplicationContext - Gets the user-defined context for the
977    nonlinear solvers.
978 
979    Not Collective
980 
981    Input Parameter:
982 .  snes - SNES context
983 
984    Output Parameter:
985 .  usrP - user context
986 
987    Level: intermediate
988 
989 .keywords: SNES, nonlinear, get, application, context
990 
991 .seealso: SNESSetApplicationContext()
992 @*/
993 PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
994 {
995   PetscFunctionBegin;
996   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
997   *(void**)usrP = snes->user;
998   PetscFunctionReturn(0);
999 }
1000 
1001 #undef __FUNCT__
1002 #define __FUNCT__ "SNESGetIterationNumber"
1003 /*@
1004    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
1005    at this time.
1006 
1007    Not Collective
1008 
1009    Input Parameter:
1010 .  snes - SNES context
1011 
1012    Output Parameter:
1013 .  iter - iteration number
1014 
1015    Notes:
1016    For example, during the computation of iteration 2 this would return 1.
1017 
1018    This is useful for using lagged Jacobians (where one does not recompute the
1019    Jacobian at each SNES iteration). For example, the code
1020 .vb
1021       ierr = SNESGetIterationNumber(snes,&it);
1022       if (!(it % 2)) {
1023         [compute Jacobian here]
1024       }
1025 .ve
1026    can be used in your ComputeJacobian() function to cause the Jacobian to be
1027    recomputed every second SNES iteration.
1028 
1029    Level: intermediate
1030 
1031 .keywords: SNES, nonlinear, get, iteration, number,
1032 
1033 .seealso:   SNESGetLinearSolveIterations()
1034 @*/
1035 PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
1036 {
1037   PetscFunctionBegin;
1038   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1039   PetscValidIntPointer(iter,2);
1040   *iter = snes->iter;
1041   PetscFunctionReturn(0);
1042 }
1043 
1044 #undef __FUNCT__
1045 #define __FUNCT__ "SNESSetIterationNumber"
1046 /*@
1047    SNESSetIterationNumber - Sets the current iteration number.
1048 
1049    Not Collective
1050 
1051    Input Parameter:
1052 .  snes - SNES context
1053 .  iter - iteration number
1054 
1055    Level: developer
1056 
1057 .keywords: SNES, nonlinear, set, iteration, number,
1058 
1059 .seealso:   SNESGetLinearSolveIterations()
1060 @*/
1061 PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
1062 {
1063   PetscErrorCode ierr;
1064 
1065   PetscFunctionBegin;
1066   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1067   ierr       = PetscObjectSAWsTakeAccess((PetscObject)snes);CHKERRQ(ierr);
1068   snes->iter = iter;
1069   ierr       = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr);
1070   PetscFunctionReturn(0);
1071 }
1072 
1073 #undef __FUNCT__
1074 #define __FUNCT__ "SNESGetNonlinearStepFailures"
1075 /*@
1076    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1077    attempted by the nonlinear solver.
1078 
1079    Not Collective
1080 
1081    Input Parameter:
1082 .  snes - SNES context
1083 
1084    Output Parameter:
1085 .  nfails - number of unsuccessful steps attempted
1086 
1087    Notes:
1088    This counter is reset to zero for each successive call to SNESSolve().
1089 
1090    Level: intermediate
1091 
1092 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1093 
1094 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1095           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
1096 @*/
1097 PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
1098 {
1099   PetscFunctionBegin;
1100   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1101   PetscValidIntPointer(nfails,2);
1102   *nfails = snes->numFailures;
1103   PetscFunctionReturn(0);
1104 }
1105 
1106 #undef __FUNCT__
1107 #define __FUNCT__ "SNESSetMaxNonlinearStepFailures"
1108 /*@
1109    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1110    attempted by the nonlinear solver before it gives up.
1111 
1112    Not Collective
1113 
1114    Input Parameters:
1115 +  snes     - SNES context
1116 -  maxFails - maximum of unsuccessful steps
1117 
1118    Level: intermediate
1119 
1120 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1121 
1122 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1123           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1124 @*/
1125 PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1126 {
1127   PetscFunctionBegin;
1128   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1129   snes->maxFailures = maxFails;
1130   PetscFunctionReturn(0);
1131 }
1132 
1133 #undef __FUNCT__
1134 #define __FUNCT__ "SNESGetMaxNonlinearStepFailures"
1135 /*@
1136    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1137    attempted by the nonlinear solver before it gives up.
1138 
1139    Not Collective
1140 
1141    Input Parameter:
1142 .  snes     - SNES context
1143 
1144    Output Parameter:
1145 .  maxFails - maximum of unsuccessful steps
1146 
1147    Level: intermediate
1148 
1149 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1150 
1151 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1152           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1153 
1154 @*/
1155 PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1156 {
1157   PetscFunctionBegin;
1158   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1159   PetscValidIntPointer(maxFails,2);
1160   *maxFails = snes->maxFailures;
1161   PetscFunctionReturn(0);
1162 }
1163 
1164 #undef __FUNCT__
1165 #define __FUNCT__ "SNESGetNumberFunctionEvals"
1166 /*@
1167    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1168      done by SNES.
1169 
1170    Not Collective
1171 
1172    Input Parameter:
1173 .  snes     - SNES context
1174 
1175    Output Parameter:
1176 .  nfuncs - number of evaluations
1177 
1178    Level: intermediate
1179 
1180    Notes: Reset every time SNESSolve is called unless SNESSetCountersReset() is used.
1181 
1182 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1183 
1184 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(), SNESSetCountersReset()
1185 @*/
1186 PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1187 {
1188   PetscFunctionBegin;
1189   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1190   PetscValidIntPointer(nfuncs,2);
1191   *nfuncs = snes->nfuncs;
1192   PetscFunctionReturn(0);
1193 }
1194 
1195 #undef __FUNCT__
1196 #define __FUNCT__ "SNESGetLinearSolveFailures"
1197 /*@
1198    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1199    linear solvers.
1200 
1201    Not Collective
1202 
1203    Input Parameter:
1204 .  snes - SNES context
1205 
1206    Output Parameter:
1207 .  nfails - number of failed solves
1208 
1209    Notes:
1210    This counter is reset to zero for each successive call to SNESSolve().
1211 
1212    Level: intermediate
1213 
1214 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1215 
1216 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1217 @*/
1218 PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
1219 {
1220   PetscFunctionBegin;
1221   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1222   PetscValidIntPointer(nfails,2);
1223   *nfails = snes->numLinearSolveFailures;
1224   PetscFunctionReturn(0);
1225 }
1226 
1227 #undef __FUNCT__
1228 #define __FUNCT__ "SNESSetMaxLinearSolveFailures"
1229 /*@
1230    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1231    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE
1232 
1233    Logically Collective on SNES
1234 
1235    Input Parameters:
1236 +  snes     - SNES context
1237 -  maxFails - maximum allowed linear solve failures
1238 
1239    Level: intermediate
1240 
1241    Notes: By default this is 0; that is SNES returns on the first failed linear solve
1242 
1243 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1244 
1245 .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1246 @*/
1247 PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1248 {
1249   PetscFunctionBegin;
1250   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1251   PetscValidLogicalCollectiveInt(snes,maxFails,2);
1252   snes->maxLinearSolveFailures = maxFails;
1253   PetscFunctionReturn(0);
1254 }
1255 
1256 #undef __FUNCT__
1257 #define __FUNCT__ "SNESGetMaxLinearSolveFailures"
1258 /*@
1259    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1260      are allowed before SNES terminates
1261 
1262    Not Collective
1263 
1264    Input Parameter:
1265 .  snes     - SNES context
1266 
1267    Output Parameter:
1268 .  maxFails - maximum of unsuccessful solves allowed
1269 
1270    Level: intermediate
1271 
1272    Notes: By default this is 1; that is SNES returns on the first failed linear solve
1273 
1274 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1275 
1276 .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1277 @*/
1278 PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1279 {
1280   PetscFunctionBegin;
1281   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1282   PetscValidIntPointer(maxFails,2);
1283   *maxFails = snes->maxLinearSolveFailures;
1284   PetscFunctionReturn(0);
1285 }
1286 
1287 #undef __FUNCT__
1288 #define __FUNCT__ "SNESGetLinearSolveIterations"
1289 /*@
1290    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1291    used by the nonlinear solver.
1292 
1293    Not Collective
1294 
1295    Input Parameter:
1296 .  snes - SNES context
1297 
1298    Output Parameter:
1299 .  lits - number of linear iterations
1300 
1301    Notes:
1302    This counter is reset to zero for each successive call to SNESSolve() unless SNESSetCountersReset() is used.
1303 
1304    Level: intermediate
1305 
1306 .keywords: SNES, nonlinear, get, number, linear, iterations
1307 
1308 .seealso:  SNESGetIterationNumber(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
1309 @*/
1310 PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
1311 {
1312   PetscFunctionBegin;
1313   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1314   PetscValidIntPointer(lits,2);
1315   *lits = snes->linear_its;
1316   PetscFunctionReturn(0);
1317 }
1318 
1319 #undef __FUNCT__
1320 #define __FUNCT__ "SNESSetCountersReset"
1321 /*@
1322    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1323    are reset every time SNESSolve() is called.
1324 
1325    Logically Collective on SNES
1326 
1327    Input Parameter:
1328 +  snes - SNES context
1329 -  reset - whether to reset the counters or not
1330 
1331    Notes:
1332    This is automatically called with FALSE
1333 
1334    Level: developer
1335 
1336 .keywords: SNES, nonlinear, set, reset, number, linear, iterations
1337 
1338 .seealso:  SNESGetNumberFunctionEvals(), SNESGetNumberLinearSolveIterations(), SNESGetNPC()
1339 @*/
1340 PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
1341 {
1342   PetscFunctionBegin;
1343   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1344   PetscValidLogicalCollectiveBool(snes,reset,2);
1345   snes->counters_reset = reset;
1346   PetscFunctionReturn(0);
1347 }
1348 
1349 
1350 #undef __FUNCT__
1351 #define __FUNCT__ "SNESSetKSP"
1352 /*@
1353    SNESSetKSP - Sets a KSP context for the SNES object to use
1354 
1355    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm
1356 
1357    Input Parameters:
1358 +  snes - the SNES context
1359 -  ksp - the KSP context
1360 
1361    Notes:
1362    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1363    so this routine is rarely needed.
1364 
1365    The KSP object that is already in the SNES object has its reference count
1366    decreased by one.
1367 
1368    Level: developer
1369 
1370 .keywords: SNES, nonlinear, get, KSP, context
1371 
1372 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1373 @*/
1374 PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1375 {
1376   PetscErrorCode ierr;
1377 
1378   PetscFunctionBegin;
1379   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1380   PetscValidHeaderSpecific(ksp,KSP_CLASSID,2);
1381   PetscCheckSameComm(snes,1,ksp,2);
1382   ierr = PetscObjectReference((PetscObject)ksp);CHKERRQ(ierr);
1383   if (snes->ksp) {ierr = PetscObjectDereference((PetscObject)snes->ksp);CHKERRQ(ierr);}
1384   snes->ksp = ksp;
1385   PetscFunctionReturn(0);
1386 }
1387 
1388 /* -----------------------------------------------------------*/
1389 #undef __FUNCT__
1390 #define __FUNCT__ "SNESCreate"
1391 /*@
1392    SNESCreate - Creates a nonlinear solver context.
1393 
1394    Collective on MPI_Comm
1395 
1396    Input Parameters:
1397 .  comm - MPI communicator
1398 
1399    Output Parameter:
1400 .  outsnes - the new SNES context
1401 
1402    Options Database Keys:
1403 +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1404                and no preconditioning matrix
1405 .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1406                products, and a user-provided preconditioning matrix
1407                as set by SNESSetJacobian()
1408 -   -snes_fd - Uses (slow!) finite differences to compute Jacobian
1409 
1410    Level: beginner
1411 
1412 .keywords: SNES, nonlinear, create, context
1413 
1414 .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()
1415 
1416 @*/
1417 PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1418 {
1419   PetscErrorCode ierr;
1420   SNES           snes;
1421   SNESKSPEW      *kctx;
1422 
1423   PetscFunctionBegin;
1424   PetscValidPointer(outsnes,2);
1425   *outsnes = NULL;
1426   ierr = SNESInitializePackage();CHKERRQ(ierr);
1427 
1428   ierr = PetscHeaderCreate(snes,_p_SNES,struct _SNESOps,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);CHKERRQ(ierr);
1429 
1430   snes->ops->converged    = SNESConvergedDefault;
1431   snes->usesksp           = PETSC_TRUE;
1432   snes->tolerancesset     = PETSC_FALSE;
1433   snes->max_its           = 50;
1434   snes->max_funcs         = 10000;
1435   snes->norm              = 0.0;
1436   snes->normschedule      = SNES_NORM_ALWAYS;
1437   snes->functype          = SNES_FUNCTION_DEFAULT;
1438 #if defined(PETSC_USE_REAL_SINGLE)
1439   snes->rtol              = 1.e-5;
1440 #else
1441   snes->rtol              = 1.e-8;
1442 #endif
1443   snes->ttol              = 0.0;
1444 #if defined(PETSC_USE_REAL_SINGLE)
1445   snes->abstol            = 1.e-25;
1446 #else
1447   snes->abstol            = 1.e-50;
1448 #endif
1449   snes->stol              = 1.e-8;
1450 #if defined(PETSC_USE_REAL_SINGLE)
1451   snes->deltatol          = 1.e-6;
1452 #else
1453   snes->deltatol          = 1.e-12;
1454 #endif
1455   snes->nfuncs            = 0;
1456   snes->numFailures       = 0;
1457   snes->maxFailures       = 1;
1458   snes->linear_its        = 0;
1459   snes->lagjacobian       = 1;
1460   snes->jac_iter          = 0;
1461   snes->lagjac_persist    = PETSC_FALSE;
1462   snes->lagpreconditioner = 1;
1463   snes->pre_iter          = 0;
1464   snes->lagpre_persist    = PETSC_FALSE;
1465   snes->numbermonitors    = 0;
1466   snes->data              = 0;
1467   snes->setupcalled       = PETSC_FALSE;
1468   snes->ksp_ewconv        = PETSC_FALSE;
1469   snes->nwork             = 0;
1470   snes->work              = 0;
1471   snes->nvwork            = 0;
1472   snes->vwork             = 0;
1473   snes->conv_hist_len     = 0;
1474   snes->conv_hist_max     = 0;
1475   snes->conv_hist         = NULL;
1476   snes->conv_hist_its     = NULL;
1477   snes->conv_hist_reset   = PETSC_TRUE;
1478   snes->counters_reset    = PETSC_TRUE;
1479   snes->vec_func_init_set = PETSC_FALSE;
1480   snes->reason            = SNES_CONVERGED_ITERATING;
1481   snes->pcside            = PC_RIGHT;
1482 
1483   snes->mf          = PETSC_FALSE;
1484   snes->mf_operator = PETSC_FALSE;
1485   snes->mf_version  = 1;
1486 
1487   snes->numLinearSolveFailures = 0;
1488   snes->maxLinearSolveFailures = 1;
1489 
1490   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1491   ierr = PetscNewLog(snes,&kctx);CHKERRQ(ierr);
1492 
1493   snes->kspconvctx  = (void*)kctx;
1494   kctx->version     = 2;
1495   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1496                              this was too large for some test cases */
1497   kctx->rtol_last   = 0.0;
1498   kctx->rtol_max    = .9;
1499   kctx->gamma       = 1.0;
1500   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1501   kctx->alpha2      = kctx->alpha;
1502   kctx->threshold   = .1;
1503   kctx->lresid_last = 0.0;
1504   kctx->norm_last   = 0.0;
1505 
1506   *outsnes = snes;
1507   PetscFunctionReturn(0);
1508 }
1509 
1510 /*MC
1511     SNESFunction - functional form used to convey the nonlinear function to be solved by SNES
1512 
1513      Synopsis:
1514      #include <petscsnes.h>
1515      SNESFunction(SNES snes,Vec x,Vec f,void *ctx);
1516 
1517      Input Parameters:
1518 +     snes - the SNES context
1519 .     x    - state at which to evaluate residual
1520 -     ctx     - optional user-defined function context, passed in with SNESSetFunction()
1521 
1522      Output Parameter:
1523 .     f  - vector to put residual (function value)
1524 
1525    Level: intermediate
1526 
1527 .seealso:   SNESSetFunction(), SNESGetFunction()
1528 M*/
1529 
1530 #undef __FUNCT__
1531 #define __FUNCT__ "SNESSetFunction"
1532 /*@C
1533    SNESSetFunction - Sets the function evaluation routine and function
1534    vector for use by the SNES routines in solving systems of nonlinear
1535    equations.
1536 
1537    Logically Collective on SNES
1538 
1539    Input Parameters:
1540 +  snes - the SNES context
1541 .  r - vector to store function value
1542 .  f - function evaluation routine; see SNESFunction for calling sequence details
1543 -  ctx - [optional] user-defined context for private data for the
1544          function evaluation routine (may be NULL)
1545 
1546    Notes:
1547    The Newton-like methods typically solve linear systems of the form
1548 $      f'(x) x = -f(x),
1549    where f'(x) denotes the Jacobian matrix and f(x) is the function.
1550 
1551    Level: beginner
1552 
1553 .keywords: SNES, nonlinear, set, function
1554 
1555 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
1556 @*/
1557 PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1558 {
1559   PetscErrorCode ierr;
1560   DM             dm;
1561 
1562   PetscFunctionBegin;
1563   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1564   if (r) {
1565     PetscValidHeaderSpecific(r,VEC_CLASSID,2);
1566     PetscCheckSameComm(snes,1,r,2);
1567     ierr = PetscObjectReference((PetscObject)r);CHKERRQ(ierr);
1568     ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
1569 
1570     snes->vec_func = r;
1571   }
1572   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1573   ierr = DMSNESSetFunction(dm,f,ctx);CHKERRQ(ierr);
1574   PetscFunctionReturn(0);
1575 }
1576 
1577 
1578 #undef __FUNCT__
1579 #define __FUNCT__ "SNESSetInitialFunction"
1580 /*@C
1581    SNESSetInitialFunction - Sets the function vector to be used as the
1582    function norm at the initialization of the method.  In some
1583    instances, the user has precomputed the function before calling
1584    SNESSolve.  This function allows one to avoid a redundant call
1585    to SNESComputeFunction in that case.
1586 
1587    Logically Collective on SNES
1588 
1589    Input Parameters:
1590 +  snes - the SNES context
1591 -  f - vector to store function value
1592 
1593    Notes:
1594    This should not be modified during the solution procedure.
1595 
1596    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1597 
1598    Level: developer
1599 
1600 .keywords: SNES, nonlinear, set, function
1601 
1602 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1603 @*/
1604 PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1605 {
1606   PetscErrorCode ierr;
1607   Vec            vec_func;
1608 
1609   PetscFunctionBegin;
1610   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1611   PetscValidHeaderSpecific(f,VEC_CLASSID,2);
1612   PetscCheckSameComm(snes,1,f,2);
1613   if (snes->pcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
1614     snes->vec_func_init_set = PETSC_FALSE;
1615     PetscFunctionReturn(0);
1616   }
1617   ierr = SNESGetFunction(snes,&vec_func,NULL,NULL);CHKERRQ(ierr);
1618   ierr = VecCopy(f, vec_func);CHKERRQ(ierr);
1619 
1620   snes->vec_func_init_set = PETSC_TRUE;
1621   PetscFunctionReturn(0);
1622 }
1623 
1624 #undef __FUNCT__
1625 #define __FUNCT__ "SNESSetNormSchedule"
1626 /*@
1627    SNESSetNormSchedule - Sets the SNESNormSchedule used in covergence and monitoring
1628    of the SNES method.
1629 
1630    Logically Collective on SNES
1631 
1632    Input Parameters:
1633 +  snes - the SNES context
1634 -  normschedule - the frequency of norm computation
1635 
1636    Notes:
1637    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1638    of the nonlinear function and the taking of its norm at every iteration to
1639    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1640    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1641    may either be monitored for convergence or not.  As these are often used as nonlinear
1642    preconditioners, monitoring the norm of their error is not a useful enterprise within
1643    their solution.
1644 
1645    Level: developer
1646 
1647 .keywords: SNES, nonlinear, set, function, norm, type
1648 
1649 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1650 @*/
1651 PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
1652 {
1653   PetscFunctionBegin;
1654   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1655   snes->normschedule = normschedule;
1656   PetscFunctionReturn(0);
1657 }
1658 
1659 
1660 #undef __FUNCT__
1661 #define __FUNCT__ "SNESGetNormSchedule"
1662 /*@
1663    SNESGetNormSchedule - Gets the SNESNormSchedule used in covergence and monitoring
1664    of the SNES method.
1665 
1666    Logically Collective on SNES
1667 
1668    Input Parameters:
1669 +  snes - the SNES context
1670 -  normschedule - the type of the norm used
1671 
1672    Level: advanced
1673 
1674 .keywords: SNES, nonlinear, set, function, norm, type
1675 
1676 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1677 @*/
1678 PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
1679 {
1680   PetscFunctionBegin;
1681   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1682   *normschedule = snes->normschedule;
1683   PetscFunctionReturn(0);
1684 }
1685 
1686 
1687 #undef __FUNCT__
1688 #define __FUNCT__ "SNESSetFunctionType"
1689 /*@C
1690    SNESSetFunctionType - Sets the SNESNormSchedule used in covergence and monitoring
1691    of the SNES method.
1692 
1693    Logically Collective on SNES
1694 
1695    Input Parameters:
1696 +  snes - the SNES context
1697 -  normschedule - the frequency of norm computation
1698 
1699    Notes:
1700    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1701    of the nonlinear function and the taking of its norm at every iteration to
1702    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1703    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1704    may either be monitored for convergence or not.  As these are often used as nonlinear
1705    preconditioners, monitoring the norm of their error is not a useful enterprise within
1706    their solution.
1707 
1708    Level: developer
1709 
1710 .keywords: SNES, nonlinear, set, function, norm, type
1711 
1712 .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1713 @*/
1714 PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
1715 {
1716   PetscFunctionBegin;
1717   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1718   snes->functype = type;
1719   PetscFunctionReturn(0);
1720 }
1721 
1722 
1723 #undef __FUNCT__
1724 #define __FUNCT__ "SNESGetFunctionType"
1725 /*@C
1726    SNESGetFunctionType - Gets the SNESNormSchedule used in covergence and monitoring
1727    of the SNES method.
1728 
1729    Logically Collective on SNES
1730 
1731    Input Parameters:
1732 +  snes - the SNES context
1733 -  normschedule - the type of the norm used
1734 
1735    Level: advanced
1736 
1737 .keywords: SNES, nonlinear, set, function, norm, type
1738 
1739 .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1740 @*/
1741 PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
1742 {
1743   PetscFunctionBegin;
1744   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1745   *type = snes->functype;
1746   PetscFunctionReturn(0);
1747 }
1748 
1749 /*MC
1750     SNESNGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function
1751 
1752      Synopsis:
1753      #include <petscsnes.h>
1754 $    SNESNGSFunction(SNES snes,Vec x,Vec b,void *ctx);
1755 
1756 +  X   - solution vector
1757 .  B   - RHS vector
1758 -  ctx - optional user-defined Gauss-Seidel context
1759 
1760    Level: intermediate
1761 
1762 .seealso:   SNESSetNGS(), SNESGetNGS()
1763 M*/
1764 
1765 #undef __FUNCT__
1766 #define __FUNCT__ "SNESSetNGS"
1767 /*@C
1768    SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
1769    use with composed nonlinear solvers.
1770 
1771    Input Parameters:
1772 +  snes   - the SNES context
1773 .  f - function evaluation routine to apply Gauss-Seidel see SNESNGSFunction
1774 -  ctx    - [optional] user-defined context for private data for the
1775             smoother evaluation routine (may be NULL)
1776 
1777    Notes:
1778    The NGS routines are used by the composed nonlinear solver to generate
1779     a problem appropriate update to the solution, particularly FAS.
1780 
1781    Level: intermediate
1782 
1783 .keywords: SNES, nonlinear, set, Gauss-Seidel
1784 
1785 .seealso: SNESGetFunction(), SNESComputeNGS()
1786 @*/
1787 PetscErrorCode SNESSetNGS(SNES snes,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1788 {
1789   PetscErrorCode ierr;
1790   DM             dm;
1791 
1792   PetscFunctionBegin;
1793   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1794   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1795   ierr = DMSNESSetNGS(dm,f,ctx);CHKERRQ(ierr);
1796   PetscFunctionReturn(0);
1797 }
1798 
1799 #undef __FUNCT__
1800 #define __FUNCT__ "SNESPicardComputeFunction"
1801 PETSC_EXTERN PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
1802 {
1803   PetscErrorCode ierr;
1804   DM             dm;
1805   DMSNES         sdm;
1806 
1807   PetscFunctionBegin;
1808   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1809   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
1810   /*  A(x)*x - b(x) */
1811   if (sdm->ops->computepfunction) {
1812     ierr = (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);CHKERRQ(ierr);
1813   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");
1814 
1815   if (sdm->ops->computepjacobian) {
1816     ierr = (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);CHKERRQ(ierr);
1817   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard matrix.");
1818   ierr = VecScale(f,-1.0);CHKERRQ(ierr);
1819   ierr = MatMultAdd(snes->jacobian,x,f,f);CHKERRQ(ierr);
1820   PetscFunctionReturn(0);
1821 }
1822 
1823 #undef __FUNCT__
1824 #define __FUNCT__ "SNESPicardComputeJacobian"
1825 PETSC_EXTERN PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
1826 {
1827   PetscFunctionBegin;
1828   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
1829   PetscFunctionReturn(0);
1830 }
1831 
1832 #undef __FUNCT__
1833 #define __FUNCT__ "SNESSetPicard"
1834 /*@C
1835    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)
1836 
1837    Logically Collective on SNES
1838 
1839    Input Parameters:
1840 +  snes - the SNES context
1841 .  r - vector to store function value
1842 .  b - function evaluation routine
1843 .  Amat - matrix with which A(x) x - b(x) is to be computed
1844 .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
1845 .  J  - function to compute matrix value
1846 -  ctx - [optional] user-defined context for private data for the
1847          function evaluation routine (may be NULL)
1848 
1849    Notes:
1850     We do not recomemend using this routine. It is far better to provide the nonlinear function F() and some approximation to the Jacobian and use
1851     an approximate Newton solver. This interface is provided to allow porting/testing a previous Picard based code in PETSc before converting it to approximate Newton.
1852 
1853     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both
1854 
1855 $     Solves the equation A(x) x = b(x) via the defect correction algorithm A(x^{n}) (x^{n+1} - x^{n}) = b(x^{n}) - A(x^{n})x^{n}
1856 $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.
1857 
1858      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.
1859 
1860    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
1861    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)
1862 
1863    There is some controversity over the definition of a Picard iteration for nonlinear systems but almost everyone agrees that it involves a linear solve and some
1864    believe it is the iteration  A(x^{n}) x^{n+1} = b(x^{n}) hence we use the name Picard. If anyone has an authoritative  reference that defines the Picard iteration
1865    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).
1866 
1867    Level: intermediate
1868 
1869 .keywords: SNES, nonlinear, set, function
1870 
1871 .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard()
1872 @*/
1873 PetscErrorCode  SNESSetPicard(SNES snes,Vec r,PetscErrorCode (*b)(SNES,Vec,Vec,void*),Mat Amat, Mat Pmat, PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
1874 {
1875   PetscErrorCode ierr;
1876   DM             dm;
1877 
1878   PetscFunctionBegin;
1879   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1880   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
1881   ierr = DMSNESSetPicard(dm,b,J,ctx);CHKERRQ(ierr);
1882   ierr = SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);CHKERRQ(ierr);
1883   ierr = SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);CHKERRQ(ierr);
1884   PetscFunctionReturn(0);
1885 }
1886 
1887 #undef __FUNCT__
1888 #define __FUNCT__ "SNESGetPicard"
1889 /*@C
1890    SNESGetPicard - Returns the context for the Picard iteration
1891 
1892    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
1893 
1894    Input Parameter:
1895 .  snes - the SNES context
1896 
1897    Output Parameter:
1898 +  r - the function (or NULL)
1899 .  f - the function (or NULL); see SNESFunction for calling sequence details
1900 .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
1901 .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
1902 .  J - the function for matrix evaluation (or NULL); see SNESJacobianFunction for calling sequence details
1903 -  ctx - the function context (or NULL)
1904 
1905    Level: advanced
1906 
1907 .keywords: SNES, nonlinear, get, function
1908 
1909 .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
1910 @*/
1911 PetscErrorCode  SNESGetPicard(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),Mat *Amat, Mat *Pmat, PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
1912 {
1913   PetscErrorCode ierr;
1914   DM             dm;
1915 
1916   PetscFunctionBegin;
1917   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1918   ierr = SNESGetFunction(snes,r,NULL,NULL);CHKERRQ(ierr);
1919   ierr = SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);CHKERRQ(ierr);
1920   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1921   ierr = DMSNESGetPicard(dm,f,J,ctx);CHKERRQ(ierr);
1922   PetscFunctionReturn(0);
1923 }
1924 
1925 #undef __FUNCT__
1926 #define __FUNCT__ "SNESSetComputeInitialGuess"
1927 /*@C
1928    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem
1929 
1930    Logically Collective on SNES
1931 
1932    Input Parameters:
1933 +  snes - the SNES context
1934 .  func - function evaluation routine
1935 -  ctx - [optional] user-defined context for private data for the
1936          function evaluation routine (may be NULL)
1937 
1938    Calling sequence of func:
1939 $    func (SNES snes,Vec x,void *ctx);
1940 
1941 .  f - function vector
1942 -  ctx - optional user-defined function context
1943 
1944    Level: intermediate
1945 
1946 .keywords: SNES, nonlinear, set, function
1947 
1948 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
1949 @*/
1950 PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
1951 {
1952   PetscFunctionBegin;
1953   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1954   if (func) snes->ops->computeinitialguess = func;
1955   if (ctx)  snes->initialguessP            = ctx;
1956   PetscFunctionReturn(0);
1957 }
1958 
1959 /* --------------------------------------------------------------- */
1960 #undef __FUNCT__
1961 #define __FUNCT__ "SNESGetRhs"
1962 /*@C
1963    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
1964    it assumes a zero right hand side.
1965 
1966    Logically Collective on SNES
1967 
1968    Input Parameter:
1969 .  snes - the SNES context
1970 
1971    Output Parameter:
1972 .  rhs - the right hand side vector or NULL if the right hand side vector is null
1973 
1974    Level: intermediate
1975 
1976 .keywords: SNES, nonlinear, get, function, right hand side
1977 
1978 .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
1979 @*/
1980 PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
1981 {
1982   PetscFunctionBegin;
1983   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1984   PetscValidPointer(rhs,2);
1985   *rhs = snes->vec_rhs;
1986   PetscFunctionReturn(0);
1987 }
1988 
1989 #undef __FUNCT__
1990 #define __FUNCT__ "SNESComputeFunction"
1991 /*@
1992    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().
1993 
1994    Collective on SNES
1995 
1996    Input Parameters:
1997 +  snes - the SNES context
1998 -  x - input vector
1999 
2000    Output Parameter:
2001 .  y - function vector, as set by SNESSetFunction()
2002 
2003    Notes:
2004    SNESComputeFunction() is typically used within nonlinear solvers
2005    implementations, so most users would not generally call this routine
2006    themselves.
2007 
2008    Level: developer
2009 
2010 .keywords: SNES, nonlinear, compute, function
2011 
2012 .seealso: SNESSetFunction(), SNESGetFunction()
2013 @*/
2014 PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
2015 {
2016   PetscErrorCode ierr;
2017   DM             dm;
2018   DMSNES         sdm;
2019 
2020   PetscFunctionBegin;
2021   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2022   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2023   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
2024   PetscCheckSameComm(snes,1,x,2);
2025   PetscCheckSameComm(snes,1,y,3);
2026   ierr = VecValidValues(x,2,PETSC_TRUE);CHKERRQ(ierr);
2027 
2028   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2029   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2030   if (sdm->ops->computefunction) {
2031     ierr = PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2032     PetscStackPush("SNES user function");
2033     ierr = (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);CHKERRQ(ierr);
2034     PetscStackPop;
2035     ierr = PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
2036   } else if (snes->vec_rhs) {
2037     ierr = MatMult(snes->jacobian, x, y);CHKERRQ(ierr);
2038   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2039   if (snes->vec_rhs) {
2040     ierr = VecAXPY(y,-1.0,snes->vec_rhs);CHKERRQ(ierr);
2041   }
2042   snes->nfuncs++;
2043   ierr = VecValidValues(y,3,PETSC_FALSE);CHKERRQ(ierr);
2044   PetscFunctionReturn(0);
2045 }
2046 
2047 #undef __FUNCT__
2048 #define __FUNCT__ "SNESComputeNGS"
2049 /*@
2050    SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  SNESSetNGS().
2051 
2052    Collective on SNES
2053 
2054    Input Parameters:
2055 +  snes - the SNES context
2056 .  x - input vector
2057 -  b - rhs vector
2058 
2059    Output Parameter:
2060 .  x - new solution vector
2061 
2062    Notes:
2063    SNESComputeNGS() is typically used within composed nonlinear solver
2064    implementations, so most users would not generally call this routine
2065    themselves.
2066 
2067    Level: developer
2068 
2069 .keywords: SNES, nonlinear, compute, function
2070 
2071 .seealso: SNESSetNGS(), SNESComputeFunction()
2072 @*/
2073 PetscErrorCode  SNESComputeNGS(SNES snes,Vec b,Vec x)
2074 {
2075   PetscErrorCode ierr;
2076   DM             dm;
2077   DMSNES         sdm;
2078 
2079   PetscFunctionBegin;
2080   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2081   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2082   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,3);
2083   PetscCheckSameComm(snes,1,x,2);
2084   if (b) PetscCheckSameComm(snes,1,b,3);
2085   if (b) {ierr = VecValidValues(b,2,PETSC_TRUE);CHKERRQ(ierr);}
2086   ierr = PetscLogEventBegin(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2087   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2088   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2089   if (sdm->ops->computegs) {
2090     PetscStackPush("SNES user NGS");
2091     ierr = (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);CHKERRQ(ierr);
2092     PetscStackPop;
2093   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
2094   ierr = PetscLogEventEnd(SNES_NGSEval,snes,x,b,0);CHKERRQ(ierr);
2095   ierr = VecValidValues(x,3,PETSC_FALSE);CHKERRQ(ierr);
2096   PetscFunctionReturn(0);
2097 }
2098 
2099 #undef __FUNCT__
2100 #define __FUNCT__ "SNESComputeJacobian"
2101 /*@
2102    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().
2103 
2104    Collective on SNES and Mat
2105 
2106    Input Parameters:
2107 +  snes - the SNES context
2108 -  x - input vector
2109 
2110    Output Parameters:
2111 +  A - Jacobian matrix
2112 -  B - optional preconditioning matrix
2113 
2114   Options Database Keys:
2115 +    -snes_lag_preconditioner <lag>
2116 .    -snes_lag_jacobian <lag>
2117 .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2118 .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2119 .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2120 .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2121 .    -snes_compare_coloring - Compute the finite differece Jacobian using coloring and display norms of difference
2122 .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
2123 .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2124 .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2125 .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2126 .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
2127 -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences
2128 
2129 
2130    Notes:
2131    Most users should not need to explicitly call this routine, as it
2132    is used internally within the nonlinear solvers.
2133 
2134    See KSPSetOperators() for important information about setting the
2135    flag parameter.
2136 
2137    Level: developer
2138 
2139 .keywords: SNES, compute, Jacobian, matrix
2140 
2141 .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2142 @*/
2143 PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat A,Mat B)
2144 {
2145   PetscErrorCode ierr;
2146   PetscBool      flag;
2147   DM             dm;
2148   DMSNES         sdm;
2149 
2150   PetscFunctionBegin;
2151   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2152   PetscValidHeaderSpecific(X,VEC_CLASSID,2);
2153   PetscCheckSameComm(snes,1,X,2);
2154   ierr = VecValidValues(X,2,PETSC_TRUE);CHKERRQ(ierr);
2155   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2156   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2157 
2158   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");
2159 
2160   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */
2161 
2162   if (snes->lagjacobian == -2) {
2163     snes->lagjacobian = -1;
2164 
2165     ierr = PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");CHKERRQ(ierr);
2166   } else if (snes->lagjacobian == -1) {
2167     ierr = PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");CHKERRQ(ierr);
2168     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2169     if (flag) {
2170       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2171       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2172     }
2173     PetscFunctionReturn(0);
2174   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2175     ierr = PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);CHKERRQ(ierr);
2176     ierr = PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);CHKERRQ(ierr);
2177     if (flag) {
2178       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2179       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2180     }
2181     PetscFunctionReturn(0);
2182   }
2183   if (snes->pc && snes->pcside == PC_LEFT) {
2184       ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2185       ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2186       PetscFunctionReturn(0);
2187   }
2188 
2189   ierr = PetscLogEventBegin(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2190 
2191   PetscStackPush("SNES user Jacobian function");
2192   ierr = (*sdm->ops->computejacobian)(snes,X,A,B,sdm->jacobianctx);CHKERRQ(ierr);
2193   PetscStackPop;
2194 
2195   ierr = PetscLogEventEnd(SNES_JacobianEval,snes,X,A,B);CHKERRQ(ierr);
2196 
2197   if (snes->lagpreconditioner == -2) {
2198     ierr = PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");CHKERRQ(ierr);
2199     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2200     snes->lagpreconditioner = -1;
2201   } else if (snes->lagpreconditioner == -1) {
2202     ierr = PetscInfo(snes,"Reusing preconditioner because lag is -1\n");CHKERRQ(ierr);
2203     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2204   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2205     ierr = PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);CHKERRQ(ierr);
2206     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);CHKERRQ(ierr);
2207   } else {
2208     ierr = PetscInfo(snes,"Rebuilding preconditioner\n");CHKERRQ(ierr);
2209     ierr = KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);CHKERRQ(ierr);
2210   }
2211 
2212   /* make sure user returned a correct Jacobian and preconditioner */
2213   /* PetscValidHeaderSpecific(A,MAT_CLASSID,3);
2214     PetscValidHeaderSpecific(B,MAT_CLASSID,4);   */
2215   {
2216     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2217     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit",&flag,NULL);CHKERRQ(ierr);
2218     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",&flag_draw,NULL);CHKERRQ(ierr);
2219     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2220     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_operator",&flag_operator,NULL);CHKERRQ(ierr);
2221     if (flag || flag_draw || flag_contour) {
2222       Mat          Bexp_mine = NULL,Bexp,FDexp;
2223       PetscViewer  vdraw,vstdout;
2224       PetscBool    flg;
2225       if (flag_operator) {
2226         ierr = MatComputeExplicitOperator(A,&Bexp_mine);CHKERRQ(ierr);
2227         Bexp = Bexp_mine;
2228       } else {
2229         /* See if the preconditioning matrix can be viewed and added directly */
2230         ierr = PetscObjectTypeCompareAny((PetscObject)B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");CHKERRQ(ierr);
2231         if (flg) Bexp = B;
2232         else {
2233           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2234           ierr = MatComputeExplicitOperator(B,&Bexp_mine);CHKERRQ(ierr);
2235           Bexp = Bexp_mine;
2236         }
2237       }
2238       ierr = MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);CHKERRQ(ierr);
2239       ierr = SNESComputeJacobianDefault(snes,X,FDexp,FDexp,NULL);CHKERRQ(ierr);
2240       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2241       if (flag_draw || flag_contour) {
2242         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2243         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2244       } else vdraw = NULL;
2245       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");CHKERRQ(ierr);
2246       if (flag) {ierr = MatView(Bexp,vstdout);CHKERRQ(ierr);}
2247       if (vdraw) {ierr = MatView(Bexp,vdraw);CHKERRQ(ierr);}
2248       ierr = PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");CHKERRQ(ierr);
2249       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2250       if (vdraw) {ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);}
2251       ierr = MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2252       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");CHKERRQ(ierr);
2253       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2254       if (vdraw) {              /* Always use contour for the difference */
2255         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2256         ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);
2257         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2258       }
2259       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2260       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2261       ierr = MatDestroy(&Bexp_mine);CHKERRQ(ierr);
2262       ierr = MatDestroy(&FDexp);CHKERRQ(ierr);
2263     }
2264   }
2265   {
2266     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2267     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2268     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring",&flag,NULL);CHKERRQ(ierr);
2269     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_display",&flag_display,NULL);CHKERRQ(ierr);
2270     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",&flag_draw,NULL);CHKERRQ(ierr);
2271     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2272     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",&flag_threshold,NULL);CHKERRQ(ierr);
2273     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);CHKERRQ(ierr);
2274     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);CHKERRQ(ierr);
2275     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2276       Mat            Bfd;
2277       PetscViewer    vdraw,vstdout;
2278       MatColoring    coloring;
2279       ISColoring     iscoloring;
2280       MatFDColoring  matfdcoloring;
2281       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2282       void           *funcctx;
2283       PetscReal      norm1,norm2,normmax;
2284 
2285       ierr = MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);CHKERRQ(ierr);
2286       ierr = MatColoringCreate(Bfd,&coloring);CHKERRQ(ierr);
2287       ierr = MatColoringSetType(coloring,MATCOLORINGSL);CHKERRQ(ierr);
2288       ierr = MatColoringSetFromOptions(coloring);CHKERRQ(ierr);
2289       ierr = MatColoringApply(coloring,&iscoloring);CHKERRQ(ierr);
2290       ierr = MatColoringDestroy(&coloring);CHKERRQ(ierr);
2291       ierr = MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);CHKERRQ(ierr);
2292       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2293       ierr = MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);CHKERRQ(ierr);
2294       ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr);
2295 
2296       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2297       ierr = SNESGetFunction(snes,NULL,&func,&funcctx);CHKERRQ(ierr);
2298       ierr = MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);CHKERRQ(ierr);
2299       ierr = PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);CHKERRQ(ierr);
2300       ierr = PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");CHKERRQ(ierr);
2301       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2302       ierr = MatFDColoringApply(Bfd,matfdcoloring,X,snes);CHKERRQ(ierr);
2303       ierr = MatFDColoringDestroy(&matfdcoloring);CHKERRQ(ierr);
2304 
2305       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2306       if (flag_draw || flag_contour) {
2307         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2308         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2309       } else vdraw = NULL;
2310       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");CHKERRQ(ierr);
2311       if (flag_display) {ierr = MatView(B,vstdout);CHKERRQ(ierr);}
2312       if (vdraw) {ierr = MatView(B,vdraw);CHKERRQ(ierr);}
2313       ierr = PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");CHKERRQ(ierr);
2314       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2315       if (vdraw) {ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);}
2316       ierr = MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2317       ierr = MatNorm(Bfd,NORM_1,&norm1);CHKERRQ(ierr);
2318       ierr = MatNorm(Bfd,NORM_FROBENIUS,&norm2);CHKERRQ(ierr);
2319       ierr = MatNorm(Bfd,NORM_MAX,&normmax);CHKERRQ(ierr);
2320       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%g normFrob=%g normmax=%g\n",(double)norm1,(double)norm2,(double)normmax);CHKERRQ(ierr);
2321       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2322       if (vdraw) {              /* Always use contour for the difference */
2323         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2324         ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);
2325         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2326       }
2327       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2328 
2329       if (flag_threshold) {
2330         PetscInt bs,rstart,rend,i;
2331         ierr = MatGetBlockSize(B,&bs);CHKERRQ(ierr);
2332         ierr = MatGetOwnershipRange(B,&rstart,&rend);CHKERRQ(ierr);
2333         for (i=rstart; i<rend; i++) {
2334           const PetscScalar *ba,*ca;
2335           const PetscInt    *bj,*cj;
2336           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2337           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2338           ierr = MatGetRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2339           ierr = MatGetRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2340           if (bn != cn) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2341           for (j=0; j<bn; j++) {
2342             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2343             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2344               maxentrycol = bj[j];
2345               maxentry    = PetscRealPart(ba[j]);
2346             }
2347             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2348               maxdiffcol = bj[j];
2349               maxdiff    = PetscRealPart(ca[j]);
2350             }
2351             if (rdiff > maxrdiff) {
2352               maxrdiffcol = bj[j];
2353               maxrdiff    = rdiff;
2354             }
2355           }
2356           if (maxrdiff > 1) {
2357             ierr = PetscViewerASCIIPrintf(vstdout,"row %D (maxentry=%g at %D, maxdiff=%g at %D, maxrdiff=%g at %D):",i,(double)maxentry,maxentrycol,(double)maxdiff,maxdiffcol,(double)maxrdiff,maxrdiffcol);CHKERRQ(ierr);
2358             for (j=0; j<bn; j++) {
2359               PetscReal rdiff;
2360               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2361               if (rdiff > 1) {
2362                 ierr = PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));CHKERRQ(ierr);
2363               }
2364             }
2365             ierr = PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);CHKERRQ(ierr);
2366           }
2367           ierr = MatRestoreRow(B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2368           ierr = MatRestoreRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2369         }
2370       }
2371       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2372       ierr = MatDestroy(&Bfd);CHKERRQ(ierr);
2373     }
2374   }
2375   PetscFunctionReturn(0);
2376 }
2377 
2378 /*MC
2379     SNESJacobianFunction - function used to convey the nonlinear Jacobian of the function to be solved by SNES
2380 
2381      Synopsis:
2382      #include <petscsnes.h>
2383 $     SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);
2384 
2385 +  x - input vector
2386 .  Amat - the matrix that defines the (approximate) Jacobian
2387 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2388 -  ctx - [optional] user-defined Jacobian context
2389 
2390    Level: intermediate
2391 
2392 .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2393 M*/
2394 
2395 #undef __FUNCT__
2396 #define __FUNCT__ "SNESSetJacobian"
2397 /*@C
2398    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2399    location to store the matrix.
2400 
2401    Logically Collective on SNES and Mat
2402 
2403    Input Parameters:
2404 +  snes - the SNES context
2405 .  Amat - the matrix that defines the (approximate) Jacobian
2406 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2407 .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value)
2408 -  ctx - [optional] user-defined context for private data for the
2409          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)
2410 
2411    Notes:
2412    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
2413    each matrix.
2414 
2415    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
2416    must be a MatFDColoring.
2417 
2418    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2419    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.
2420 
2421    Level: beginner
2422 
2423 .keywords: SNES, nonlinear, set, Jacobian, matrix
2424 
2425 .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J, SNESSetPicard()
2426 @*/
2427 PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2428 {
2429   PetscErrorCode ierr;
2430   DM             dm;
2431 
2432   PetscFunctionBegin;
2433   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2434   if (Amat) PetscValidHeaderSpecific(Amat,MAT_CLASSID,2);
2435   if (Pmat) PetscValidHeaderSpecific(Pmat,MAT_CLASSID,3);
2436   if (Amat) PetscCheckSameComm(snes,1,Amat,2);
2437   if (Pmat) PetscCheckSameComm(snes,1,Pmat,3);
2438   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2439   ierr = DMSNESSetJacobian(dm,J,ctx);CHKERRQ(ierr);
2440   if (Amat) {
2441     ierr = PetscObjectReference((PetscObject)Amat);CHKERRQ(ierr);
2442     ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2443 
2444     snes->jacobian = Amat;
2445   }
2446   if (Pmat) {
2447     ierr = PetscObjectReference((PetscObject)Pmat);CHKERRQ(ierr);
2448     ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2449 
2450     snes->jacobian_pre = Pmat;
2451   }
2452   PetscFunctionReturn(0);
2453 }
2454 
2455 #undef __FUNCT__
2456 #define __FUNCT__ "SNESGetJacobian"
2457 /*@C
2458    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2459    provided context for evaluating the Jacobian.
2460 
2461    Not Collective, but Mat object will be parallel if SNES object is
2462 
2463    Input Parameter:
2464 .  snes - the nonlinear solver context
2465 
2466    Output Parameters:
2467 +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
2468 .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
2469 .  J - location to put Jacobian function (or NULL)
2470 -  ctx - location to stash Jacobian ctx (or NULL)
2471 
2472    Level: advanced
2473 
2474 .seealso: SNESSetJacobian(), SNESComputeJacobian()
2475 @*/
2476 PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
2477 {
2478   PetscErrorCode ierr;
2479   DM             dm;
2480   DMSNES         sdm;
2481 
2482   PetscFunctionBegin;
2483   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2484   if (Amat) *Amat = snes->jacobian;
2485   if (Pmat) *Pmat = snes->jacobian_pre;
2486   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2487   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2488   if (J) *J = sdm->ops->computejacobian;
2489   if (ctx) *ctx = sdm->jacobianctx;
2490   PetscFunctionReturn(0);
2491 }
2492 
2493 #undef __FUNCT__
2494 #define __FUNCT__ "SNESSetUp"
2495 /*@
2496    SNESSetUp - Sets up the internal data structures for the later use
2497    of a nonlinear solver.
2498 
2499    Collective on SNES
2500 
2501    Input Parameters:
2502 .  snes - the SNES context
2503 
2504    Notes:
2505    For basic use of the SNES solvers the user need not explicitly call
2506    SNESSetUp(), since these actions will automatically occur during
2507    the call to SNESSolve().  However, if one wishes to control this
2508    phase separately, SNESSetUp() should be called after SNESCreate()
2509    and optional routines of the form SNESSetXXX(), but before SNESSolve().
2510 
2511    Level: advanced
2512 
2513 .keywords: SNES, nonlinear, setup
2514 
2515 .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
2516 @*/
2517 PetscErrorCode  SNESSetUp(SNES snes)
2518 {
2519   PetscErrorCode ierr;
2520   DM             dm;
2521   DMSNES         sdm;
2522   SNESLineSearch linesearch, pclinesearch;
2523   void           *lsprectx,*lspostctx;
2524   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
2525   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
2526   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2527   Vec            f,fpc;
2528   void           *funcctx;
2529   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
2530   void           *jacctx,*appctx;
2531   Mat            j,jpre;
2532 
2533   PetscFunctionBegin;
2534   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2535   if (snes->setupcalled) PetscFunctionReturn(0);
2536 
2537   if (!((PetscObject)snes)->type_name) {
2538     ierr = SNESSetType(snes,SNESNEWTONLS);CHKERRQ(ierr);
2539   }
2540 
2541   ierr = SNESGetFunction(snes,&snes->vec_func,NULL,NULL);CHKERRQ(ierr);
2542 
2543   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2544   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2545   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
2546   if (!sdm->ops->computejacobian) {
2547     ierr = DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);CHKERRQ(ierr);
2548   }
2549   if (!snes->vec_func) {
2550     ierr = DMCreateGlobalVector(dm,&snes->vec_func);CHKERRQ(ierr);
2551   }
2552 
2553   if (!snes->ksp) {
2554     ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);
2555   }
2556 
2557   if (!snes->linesearch) {
2558     ierr = SNESGetLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
2559   }
2560   ierr = SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);CHKERRQ(ierr);
2561 
2562   if (snes->pc && (snes->pcside == PC_LEFT)) {
2563     snes->mf          = PETSC_TRUE;
2564     snes->mf_operator = PETSC_FALSE;
2565   }
2566 
2567   if (snes->pc) {
2568     /* copy the DM over */
2569     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2570     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
2571 
2572     ierr = SNESGetFunction(snes,&f,&func,&funcctx);CHKERRQ(ierr);
2573     ierr = VecDuplicate(f,&fpc);CHKERRQ(ierr);
2574     ierr = SNESSetFunction(snes->pc,fpc,func,funcctx);CHKERRQ(ierr);
2575     ierr = SNESGetJacobian(snes,&j,&jpre,&jac,&jacctx);CHKERRQ(ierr);
2576     ierr = SNESSetJacobian(snes->pc,j,jpre,jac,jacctx);CHKERRQ(ierr);
2577     ierr = SNESGetApplicationContext(snes,&appctx);CHKERRQ(ierr);
2578     ierr = SNESSetApplicationContext(snes->pc,appctx);CHKERRQ(ierr);
2579     ierr = VecDestroy(&fpc);CHKERRQ(ierr);
2580 
2581     /* copy the function pointers over */
2582     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
2583 
2584     /* default to 1 iteration */
2585     ierr = SNESSetTolerances(snes->pc,0.0,0.0,0.0,1,snes->pc->max_funcs);CHKERRQ(ierr);
2586     if (snes->pcside==PC_RIGHT) {
2587       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
2588     } else {
2589       ierr = SNESSetNormSchedule(snes->pc,SNES_NORM_NONE);CHKERRQ(ierr);
2590     }
2591     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
2592 
2593     /* copy the line search context over */
2594     ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2595     ierr = SNESGetLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
2596     ierr = SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);CHKERRQ(ierr);
2597     ierr = SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);CHKERRQ(ierr);
2598     ierr = SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);CHKERRQ(ierr);
2599     ierr = SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);CHKERRQ(ierr);
2600     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);CHKERRQ(ierr);
2601   }
2602   if (snes->mf) {
2603     ierr = SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);CHKERRQ(ierr);
2604   }
2605   if (snes->ops->usercompute && !snes->user) {
2606     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2607   }
2608 
2609   snes->jac_iter = 0;
2610   snes->pre_iter = 0;
2611 
2612   if (snes->ops->setup) {
2613     ierr = (*snes->ops->setup)(snes);CHKERRQ(ierr);
2614   }
2615 
2616   if (snes->pc && (snes->pcside == PC_LEFT)) {
2617     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
2618       ierr = SNESGetLineSearch(snes,&linesearch);CHKERRQ(ierr);
2619       ierr = SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultNPC);CHKERRQ(ierr);
2620     }
2621   }
2622 
2623   snes->setupcalled = PETSC_TRUE;
2624   PetscFunctionReturn(0);
2625 }
2626 
2627 #undef __FUNCT__
2628 #define __FUNCT__ "SNESReset"
2629 /*@
2630    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats
2631 
2632    Collective on SNES
2633 
2634    Input Parameter:
2635 .  snes - iterative context obtained from SNESCreate()
2636 
2637    Level: intermediate
2638 
2639    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()
2640 
2641 .keywords: SNES, destroy
2642 
2643 .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
2644 @*/
2645 PetscErrorCode  SNESReset(SNES snes)
2646 {
2647   PetscErrorCode ierr;
2648 
2649   PetscFunctionBegin;
2650   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2651   if (snes->ops->userdestroy && snes->user) {
2652     ierr       = (*snes->ops->userdestroy)((void**)&snes->user);CHKERRQ(ierr);
2653     snes->user = NULL;
2654   }
2655   if (snes->pc) {
2656     ierr = SNESReset(snes->pc);CHKERRQ(ierr);
2657   }
2658 
2659   if (snes->ops->reset) {
2660     ierr = (*snes->ops->reset)(snes);CHKERRQ(ierr);
2661   }
2662   if (snes->ksp) {
2663     ierr = KSPReset(snes->ksp);CHKERRQ(ierr);
2664   }
2665 
2666   if (snes->linesearch) {
2667     ierr = SNESLineSearchReset(snes->linesearch);CHKERRQ(ierr);
2668   }
2669 
2670   ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
2671   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
2672   ierr = VecDestroy(&snes->vec_sol_update);CHKERRQ(ierr);
2673   ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
2674   ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2675   ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2676   ierr = VecDestroyVecs(snes->nwork,&snes->work);CHKERRQ(ierr);
2677   ierr = VecDestroyVecs(snes->nvwork,&snes->vwork);CHKERRQ(ierr);
2678 
2679   snes->nwork       = snes->nvwork = 0;
2680   snes->setupcalled = PETSC_FALSE;
2681   PetscFunctionReturn(0);
2682 }
2683 
2684 #undef __FUNCT__
2685 #define __FUNCT__ "SNESDestroy"
2686 /*@
2687    SNESDestroy - Destroys the nonlinear solver context that was created
2688    with SNESCreate().
2689 
2690    Collective on SNES
2691 
2692    Input Parameter:
2693 .  snes - the SNES context
2694 
2695    Level: beginner
2696 
2697 .keywords: SNES, nonlinear, destroy
2698 
2699 .seealso: SNESCreate(), SNESSolve()
2700 @*/
2701 PetscErrorCode  SNESDestroy(SNES *snes)
2702 {
2703   PetscErrorCode ierr;
2704 
2705   PetscFunctionBegin;
2706   if (!*snes) PetscFunctionReturn(0);
2707   PetscValidHeaderSpecific((*snes),SNES_CLASSID,1);
2708   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; PetscFunctionReturn(0);}
2709 
2710   ierr = SNESReset((*snes));CHKERRQ(ierr);
2711   ierr = SNESDestroy(&(*snes)->pc);CHKERRQ(ierr);
2712 
2713   /* if memory was published with SAWs then destroy it */
2714   ierr = PetscObjectSAWsViewOff((PetscObject)*snes);CHKERRQ(ierr);
2715   if ((*snes)->ops->destroy) {ierr = (*((*snes))->ops->destroy)((*snes));CHKERRQ(ierr);}
2716 
2717   ierr = DMDestroy(&(*snes)->dm);CHKERRQ(ierr);
2718   ierr = KSPDestroy(&(*snes)->ksp);CHKERRQ(ierr);
2719   ierr = SNESLineSearchDestroy(&(*snes)->linesearch);CHKERRQ(ierr);
2720 
2721   ierr = PetscFree((*snes)->kspconvctx);CHKERRQ(ierr);
2722   if ((*snes)->ops->convergeddestroy) {
2723     ierr = (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);CHKERRQ(ierr);
2724   }
2725   if ((*snes)->conv_malloc) {
2726     ierr = PetscFree((*snes)->conv_hist);CHKERRQ(ierr);
2727     ierr = PetscFree((*snes)->conv_hist_its);CHKERRQ(ierr);
2728   }
2729   ierr = SNESMonitorCancel((*snes));CHKERRQ(ierr);
2730   ierr = PetscHeaderDestroy(snes);CHKERRQ(ierr);
2731   PetscFunctionReturn(0);
2732 }
2733 
2734 /* ----------- Routines to set solver parameters ---------- */
2735 
2736 #undef __FUNCT__
2737 #define __FUNCT__ "SNESSetLagPreconditioner"
2738 /*@
2739    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.
2740 
2741    Logically Collective on SNES
2742 
2743    Input Parameters:
2744 +  snes - the SNES context
2745 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2746          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2747 
2748    Options Database Keys:
2749 .    -snes_lag_preconditioner <lag>
2750 
2751    Notes:
2752    The default is 1
2753    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2754    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use
2755 
2756    Level: intermediate
2757 
2758 .keywords: SNES, nonlinear, set, convergence, tolerances
2759 
2760 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2761 
2762 @*/
2763 PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
2764 {
2765   PetscFunctionBegin;
2766   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2767   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2768   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2769   PetscValidLogicalCollectiveInt(snes,lag,2);
2770   snes->lagpreconditioner = lag;
2771   PetscFunctionReturn(0);
2772 }
2773 
2774 #undef __FUNCT__
2775 #define __FUNCT__ "SNESSetGridSequence"
2776 /*@
2777    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does
2778 
2779    Logically Collective on SNES
2780 
2781    Input Parameters:
2782 +  snes - the SNES context
2783 -  steps - the number of refinements to do, defaults to 0
2784 
2785    Options Database Keys:
2786 .    -snes_grid_sequence <steps>
2787 
2788    Level: intermediate
2789 
2790    Notes:
2791    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2792 
2793 .keywords: SNES, nonlinear, set, convergence, tolerances
2794 
2795 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2796 
2797 @*/
2798 PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
2799 {
2800   PetscFunctionBegin;
2801   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2802   PetscValidLogicalCollectiveInt(snes,steps,2);
2803   snes->gridsequence = steps;
2804   PetscFunctionReturn(0);
2805 }
2806 
2807 #undef __FUNCT__
2808 #define __FUNCT__ "SNESGetLagPreconditioner"
2809 /*@
2810    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt
2811 
2812    Not Collective
2813 
2814    Input Parameter:
2815 .  snes - the SNES context
2816 
2817    Output Parameter:
2818 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2819          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2820 
2821    Options Database Keys:
2822 .    -snes_lag_preconditioner <lag>
2823 
2824    Notes:
2825    The default is 1
2826    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2827 
2828    Level: intermediate
2829 
2830 .keywords: SNES, nonlinear, set, convergence, tolerances
2831 
2832 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()
2833 
2834 @*/
2835 PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
2836 {
2837   PetscFunctionBegin;
2838   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2839   *lag = snes->lagpreconditioner;
2840   PetscFunctionReturn(0);
2841 }
2842 
2843 #undef __FUNCT__
2844 #define __FUNCT__ "SNESSetLagJacobian"
2845 /*@
2846    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
2847      often the preconditioner is rebuilt.
2848 
2849    Logically Collective on SNES
2850 
2851    Input Parameters:
2852 +  snes - the SNES context
2853 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2854          the Jacobian is built etc. -2 means rebuild at next chance but then never again
2855 
2856    Options Database Keys:
2857 .    -snes_lag_jacobian <lag>
2858 
2859    Notes:
2860    The default is 1
2861    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2862    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
2863    at the next Newton step but never again (unless it is reset to another value)
2864 
2865    Level: intermediate
2866 
2867 .keywords: SNES, nonlinear, set, convergence, tolerances
2868 
2869 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()
2870 
2871 @*/
2872 PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
2873 {
2874   PetscFunctionBegin;
2875   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2876   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2877   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2878   PetscValidLogicalCollectiveInt(snes,lag,2);
2879   snes->lagjacobian = lag;
2880   PetscFunctionReturn(0);
2881 }
2882 
2883 #undef __FUNCT__
2884 #define __FUNCT__ "SNESGetLagJacobian"
2885 /*@
2886    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt
2887 
2888    Not Collective
2889 
2890    Input Parameter:
2891 .  snes - the SNES context
2892 
2893    Output Parameter:
2894 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2895          the Jacobian is built etc.
2896 
2897    Options Database Keys:
2898 .    -snes_lag_jacobian <lag>
2899 
2900    Notes:
2901    The default is 1
2902    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2903 
2904    Level: intermediate
2905 
2906 .keywords: SNES, nonlinear, set, convergence, tolerances
2907 
2908 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()
2909 
2910 @*/
2911 PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
2912 {
2913   PetscFunctionBegin;
2914   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2915   *lag = snes->lagjacobian;
2916   PetscFunctionReturn(0);
2917 }
2918 
2919 #undef __FUNCT__
2920 #define __FUNCT__ "SNESSetLagJacobianPersists"
2921 /*@
2922    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves
2923 
2924    Logically collective on SNES
2925 
2926    Input Parameter:
2927 +  snes - the SNES context
2928 -   flg - jacobian lagging persists if true
2929 
2930    Options Database Keys:
2931 .    -snes_lag_jacobian_persists <flg>
2932 
2933    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
2934    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
2935    timesteps may present huge efficiency gains.
2936 
2937    Level: developer
2938 
2939 .keywords: SNES, nonlinear, lag
2940 
2941 .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
2942 
2943 @*/
2944 PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
2945 {
2946   PetscFunctionBegin;
2947   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2948   PetscValidLogicalCollectiveBool(snes,flg,2);
2949   snes->lagjac_persist = flg;
2950   PetscFunctionReturn(0);
2951 }
2952 
2953 #undef __FUNCT__
2954 #define __FUNCT__ "SNESSetLagPreconditionerPersists"
2955 /*@
2956    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple solves
2957 
2958    Logically Collective on SNES
2959 
2960    Input Parameter:
2961 +  snes - the SNES context
2962 -   flg - preconditioner lagging persists if true
2963 
2964    Options Database Keys:
2965 .    -snes_lag_jacobian_persists <flg>
2966 
2967    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
2968    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
2969    several timesteps may present huge efficiency gains.
2970 
2971    Level: developer
2972 
2973 .keywords: SNES, nonlinear, lag
2974 
2975 .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()
2976 
2977 @*/
2978 PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
2979 {
2980   PetscFunctionBegin;
2981   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2982   PetscValidLogicalCollectiveBool(snes,flg,2);
2983   snes->lagpre_persist = flg;
2984   PetscFunctionReturn(0);
2985 }
2986 
2987 #undef __FUNCT__
2988 #define __FUNCT__ "SNESSetTolerances"
2989 /*@
2990    SNESSetTolerances - Sets various parameters used in convergence tests.
2991 
2992    Logically Collective on SNES
2993 
2994    Input Parameters:
2995 +  snes - the SNES context
2996 .  abstol - absolute convergence tolerance
2997 .  rtol - relative convergence tolerance
2998 .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
2999 .  maxit - maximum number of iterations
3000 -  maxf - maximum number of function evaluations
3001 
3002    Options Database Keys:
3003 +    -snes_atol <abstol> - Sets abstol
3004 .    -snes_rtol <rtol> - Sets rtol
3005 .    -snes_stol <stol> - Sets stol
3006 .    -snes_max_it <maxit> - Sets maxit
3007 -    -snes_max_funcs <maxf> - Sets maxf
3008 
3009    Notes:
3010    The default maximum number of iterations is 50.
3011    The default maximum number of function evaluations is 1000.
3012 
3013    Level: intermediate
3014 
3015 .keywords: SNES, nonlinear, set, convergence, tolerances
3016 
3017 .seealso: SNESSetTrustRegionTolerance()
3018 @*/
3019 PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
3020 {
3021   PetscFunctionBegin;
3022   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3023   PetscValidLogicalCollectiveReal(snes,abstol,2);
3024   PetscValidLogicalCollectiveReal(snes,rtol,3);
3025   PetscValidLogicalCollectiveReal(snes,stol,4);
3026   PetscValidLogicalCollectiveInt(snes,maxit,5);
3027   PetscValidLogicalCollectiveInt(snes,maxf,6);
3028 
3029   if (abstol != PETSC_DEFAULT) {
3030     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %g must be non-negative",(double)abstol);
3031     snes->abstol = abstol;
3032   }
3033   if (rtol != PETSC_DEFAULT) {
3034     if (rtol < 0.0 || 1.0 <= rtol) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Relative tolerance %g must be non-negative and less than 1.0",(double)rtol);
3035     snes->rtol = rtol;
3036   }
3037   if (stol != PETSC_DEFAULT) {
3038     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %g must be non-negative",(double)stol);
3039     snes->stol = stol;
3040   }
3041   if (maxit != PETSC_DEFAULT) {
3042     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
3043     snes->max_its = maxit;
3044   }
3045   if (maxf != PETSC_DEFAULT) {
3046     if (maxf < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
3047     snes->max_funcs = maxf;
3048   }
3049   snes->tolerancesset = PETSC_TRUE;
3050   PetscFunctionReturn(0);
3051 }
3052 
3053 #undef __FUNCT__
3054 #define __FUNCT__ "SNESGetTolerances"
3055 /*@
3056    SNESGetTolerances - Gets various parameters used in convergence tests.
3057 
3058    Not Collective
3059 
3060    Input Parameters:
3061 +  snes - the SNES context
3062 .  atol - absolute convergence tolerance
3063 .  rtol - relative convergence tolerance
3064 .  stol -  convergence tolerance in terms of the norm
3065            of the change in the solution between steps
3066 .  maxit - maximum number of iterations
3067 -  maxf - maximum number of function evaluations
3068 
3069    Notes:
3070    The user can specify NULL for any parameter that is not needed.
3071 
3072    Level: intermediate
3073 
3074 .keywords: SNES, nonlinear, get, convergence, tolerances
3075 
3076 .seealso: SNESSetTolerances()
3077 @*/
3078 PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3079 {
3080   PetscFunctionBegin;
3081   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3082   if (atol)  *atol  = snes->abstol;
3083   if (rtol)  *rtol  = snes->rtol;
3084   if (stol)  *stol  = snes->stol;
3085   if (maxit) *maxit = snes->max_its;
3086   if (maxf)  *maxf  = snes->max_funcs;
3087   PetscFunctionReturn(0);
3088 }
3089 
3090 #undef __FUNCT__
3091 #define __FUNCT__ "SNESSetTrustRegionTolerance"
3092 /*@
3093    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.
3094 
3095    Logically Collective on SNES
3096 
3097    Input Parameters:
3098 +  snes - the SNES context
3099 -  tol - tolerance
3100 
3101    Options Database Key:
3102 .  -snes_trtol <tol> - Sets tol
3103 
3104    Level: intermediate
3105 
3106 .keywords: SNES, nonlinear, set, trust region, tolerance
3107 
3108 .seealso: SNESSetTolerances()
3109 @*/
3110 PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3111 {
3112   PetscFunctionBegin;
3113   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3114   PetscValidLogicalCollectiveReal(snes,tol,2);
3115   snes->deltatol = tol;
3116   PetscFunctionReturn(0);
3117 }
3118 
3119 /*
3120    Duplicate the lg monitors for SNES from KSP; for some reason with
3121    dynamic libraries things don't work under Sun4 if we just use
3122    macros instead of functions
3123 */
3124 #undef __FUNCT__
3125 #define __FUNCT__ "SNESMonitorLGResidualNorm"
3126 PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,void *ctx)
3127 {
3128   PetscErrorCode ierr;
3129 
3130   PetscFunctionBegin;
3131   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3132   ierr = KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);CHKERRQ(ierr);
3133   PetscFunctionReturn(0);
3134 }
3135 
3136 #undef __FUNCT__
3137 #define __FUNCT__ "SNESMonitorLGCreate"
3138 PetscErrorCode  SNESMonitorLGCreate(const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *draw)
3139 {
3140   PetscErrorCode ierr;
3141 
3142   PetscFunctionBegin;
3143   ierr = KSPMonitorLGResidualNormCreate(host,label,x,y,m,n,draw);CHKERRQ(ierr);
3144   PetscFunctionReturn(0);
3145 }
3146 
3147 #undef __FUNCT__
3148 #define __FUNCT__ "SNESMonitorLGDestroy"
3149 PetscErrorCode  SNESMonitorLGDestroy(PetscDrawLG *draw)
3150 {
3151   PetscErrorCode ierr;
3152 
3153   PetscFunctionBegin;
3154   ierr = KSPMonitorLGResidualNormDestroy(draw);CHKERRQ(ierr);
3155   PetscFunctionReturn(0);
3156 }
3157 
3158 extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
3159 #undef __FUNCT__
3160 #define __FUNCT__ "SNESMonitorLGRange"
3161 PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3162 {
3163   PetscDrawLG      lg;
3164   PetscErrorCode   ierr;
3165   PetscReal        x,y,per;
3166   PetscViewer      v = (PetscViewer)monctx;
3167   static PetscReal prev; /* should be in the context */
3168   PetscDraw        draw;
3169 
3170   PetscFunctionBegin;
3171   ierr = PetscViewerDrawGetDrawLG(v,0,&lg);CHKERRQ(ierr);
3172   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3173   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3174   ierr = PetscDrawSetTitle(draw,"Residual norm");CHKERRQ(ierr);
3175   x    = (PetscReal)n;
3176   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
3177   else y = -15.0;
3178   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3179   if (n < 20 || !(n % 5)) {
3180     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3181   }
3182 
3183   ierr = PetscViewerDrawGetDrawLG(v,1,&lg);CHKERRQ(ierr);
3184   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3185   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3186   ierr = PetscDrawSetTitle(draw,"% elemts > .2*max elemt");CHKERRQ(ierr);
3187   ierr =  SNESMonitorRange_Private(snes,n,&per);CHKERRQ(ierr);
3188   x    = (PetscReal)n;
3189   y    = 100.0*per;
3190   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3191   if (n < 20 || !(n % 5)) {
3192     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3193   }
3194 
3195   ierr = PetscViewerDrawGetDrawLG(v,2,&lg);CHKERRQ(ierr);
3196   if (!n) {prev = rnorm;ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3197   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3198   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");CHKERRQ(ierr);
3199   x    = (PetscReal)n;
3200   y    = (prev - rnorm)/prev;
3201   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3202   if (n < 20 || !(n % 5)) {
3203     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3204   }
3205 
3206   ierr = PetscViewerDrawGetDrawLG(v,3,&lg);CHKERRQ(ierr);
3207   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3208   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3209   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");CHKERRQ(ierr);
3210   x    = (PetscReal)n;
3211   y    = (prev - rnorm)/(prev*per);
3212   if (n > 2) { /*skip initial crazy value */
3213     ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3214   }
3215   if (n < 20 || !(n % 5)) {
3216     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3217   }
3218   prev = rnorm;
3219   PetscFunctionReturn(0);
3220 }
3221 
3222 #undef __FUNCT__
3223 #define __FUNCT__ "SNESMonitor"
3224 /*@
3225    SNESMonitor - runs the user provided monitor routines, if they exist
3226 
3227    Collective on SNES
3228 
3229    Input Parameters:
3230 +  snes - nonlinear solver context obtained from SNESCreate()
3231 .  iter - iteration number
3232 -  rnorm - relative norm of the residual
3233 
3234    Notes:
3235    This routine is called by the SNES implementations.
3236    It does not typically need to be called by the user.
3237 
3238    Level: developer
3239 
3240 .seealso: SNESMonitorSet()
3241 @*/
3242 PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3243 {
3244   PetscErrorCode ierr;
3245   PetscInt       i,n = snes->numbermonitors;
3246 
3247   PetscFunctionBegin;
3248   for (i=0; i<n; i++) {
3249     ierr = (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);CHKERRQ(ierr);
3250   }
3251   PetscFunctionReturn(0);
3252 }
3253 
3254 /* ------------ Routines to set performance monitoring options ----------- */
3255 
3256 /*MC
3257     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver
3258 
3259      Synopsis:
3260      #include <petscsnes.h>
3261 $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)
3262 
3263 +    snes - the SNES context
3264 .    its - iteration number
3265 .    norm - 2-norm function value (may be estimated)
3266 -    mctx - [optional] monitoring context
3267 
3268    Level: advanced
3269 
3270 .seealso:   SNESMonitorSet(), SNESMonitorGet()
3271 M*/
3272 
3273 #undef __FUNCT__
3274 #define __FUNCT__ "SNESMonitorSet"
3275 /*@C
3276    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3277    iteration of the nonlinear solver to display the iteration's
3278    progress.
3279 
3280    Logically Collective on SNES
3281 
3282    Input Parameters:
3283 +  snes - the SNES context
3284 .  f - the monitor function, see SNESMonitorFunction for the calling sequence
3285 .  mctx - [optional] user-defined context for private data for the
3286           monitor routine (use NULL if no context is desired)
3287 -  monitordestroy - [optional] routine that frees monitor context
3288           (may be NULL)
3289 
3290    Options Database Keys:
3291 +    -snes_monitor        - sets SNESMonitorDefault()
3292 .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3293                             uses SNESMonitorLGCreate()
3294 -    -snes_monitor_cancel - cancels all monitors that have
3295                             been hardwired into a code by
3296                             calls to SNESMonitorSet(), but
3297                             does not cancel those set via
3298                             the options database.
3299 
3300    Notes:
3301    Several different monitoring routines may be set by calling
3302    SNESMonitorSet() multiple times; all will be called in the
3303    order in which they were set.
3304 
3305    Fortran notes: Only a single monitor function can be set for each SNES object
3306 
3307    Level: intermediate
3308 
3309 .keywords: SNES, nonlinear, set, monitor
3310 
3311 .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
3312 @*/
3313 PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*f)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3314 {
3315   PetscInt       i;
3316   PetscErrorCode ierr;
3317 
3318   PetscFunctionBegin;
3319   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3320   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3321   for (i=0; i<snes->numbermonitors;i++) {
3322     if (f == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
3323       if (monitordestroy) {
3324         ierr = (*monitordestroy)(&mctx);CHKERRQ(ierr);
3325       }
3326       PetscFunctionReturn(0);
3327     }
3328   }
3329   snes->monitor[snes->numbermonitors]          = f;
3330   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
3331   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
3332   PetscFunctionReturn(0);
3333 }
3334 
3335 #undef __FUNCT__
3336 #define __FUNCT__ "SNESMonitorCancel"
3337 /*@
3338    SNESMonitorCancel - Clears all the monitor functions for a SNES object.
3339 
3340    Logically Collective on SNES
3341 
3342    Input Parameters:
3343 .  snes - the SNES context
3344 
3345    Options Database Key:
3346 .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3347     into a code by calls to SNESMonitorSet(), but does not cancel those
3348     set via the options database
3349 
3350    Notes:
3351    There is no way to clear one specific monitor from a SNES object.
3352 
3353    Level: intermediate
3354 
3355 .keywords: SNES, nonlinear, set, monitor
3356 
3357 .seealso: SNESMonitorDefault(), SNESMonitorSet()
3358 @*/
3359 PetscErrorCode  SNESMonitorCancel(SNES snes)
3360 {
3361   PetscErrorCode ierr;
3362   PetscInt       i;
3363 
3364   PetscFunctionBegin;
3365   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3366   for (i=0; i<snes->numbermonitors; i++) {
3367     if (snes->monitordestroy[i]) {
3368       ierr = (*snes->monitordestroy[i])(&snes->monitorcontext[i]);CHKERRQ(ierr);
3369     }
3370   }
3371   snes->numbermonitors = 0;
3372   PetscFunctionReturn(0);
3373 }
3374 
3375 /*MC
3376     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver
3377 
3378      Synopsis:
3379      #include <petscsnes.h>
3380 $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)
3381 
3382 +    snes - the SNES context
3383 .    it - current iteration (0 is the first and is before any Newton step)
3384 .    cctx - [optional] convergence context
3385 .    reason - reason for convergence/divergence
3386 .    xnorm - 2-norm of current iterate
3387 .    gnorm - 2-norm of current step
3388 -    f - 2-norm of function
3389 
3390    Level: intermediate
3391 
3392 .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
3393 M*/
3394 
3395 #undef __FUNCT__
3396 #define __FUNCT__ "SNESSetConvergenceTest"
3397 /*@C
3398    SNESSetConvergenceTest - Sets the function that is to be used
3399    to test for convergence of the nonlinear iterative solution.
3400 
3401    Logically Collective on SNES
3402 
3403    Input Parameters:
3404 +  snes - the SNES context
3405 .  SNESConvergenceTestFunction - routine to test for convergence
3406 .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
3407 -  destroy - [optional] destructor for the context (may be NULL; NULL_FUNCTION in Fortran)
3408 
3409    Level: advanced
3410 
3411 .keywords: SNES, nonlinear, set, convergence, test
3412 
3413 .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
3414 @*/
3415 PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
3416 {
3417   PetscErrorCode ierr;
3418 
3419   PetscFunctionBegin;
3420   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3421   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
3422   if (snes->ops->convergeddestroy) {
3423     ierr = (*snes->ops->convergeddestroy)(snes->cnvP);CHKERRQ(ierr);
3424   }
3425   snes->ops->converged        = SNESConvergenceTestFunction;
3426   snes->ops->convergeddestroy = destroy;
3427   snes->cnvP                  = cctx;
3428   PetscFunctionReturn(0);
3429 }
3430 
3431 #undef __FUNCT__
3432 #define __FUNCT__ "SNESGetConvergedReason"
3433 /*@
3434    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.
3435 
3436    Not Collective
3437 
3438    Input Parameter:
3439 .  snes - the SNES context
3440 
3441    Output Parameter:
3442 .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3443             manual pages for the individual convergence tests for complete lists
3444 
3445    Level: intermediate
3446 
3447    Notes: Can only be called after the call the SNESSolve() is complete.
3448 
3449 .keywords: SNES, nonlinear, set, convergence, test
3450 
3451 .seealso: SNESSetConvergenceTest(), SNESConvergedReason
3452 @*/
3453 PetscErrorCode  SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
3454 {
3455   PetscFunctionBegin;
3456   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3457   PetscValidPointer(reason,2);
3458   *reason = snes->reason;
3459   PetscFunctionReturn(0);
3460 }
3461 
3462 #undef __FUNCT__
3463 #define __FUNCT__ "SNESSetConvergenceHistory"
3464 /*@
3465    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.
3466 
3467    Logically Collective on SNES
3468 
3469    Input Parameters:
3470 +  snes - iterative context obtained from SNESCreate()
3471 .  a   - array to hold history, this array will contain the function norms computed at each step
3472 .  its - integer array holds the number of linear iterations for each solve.
3473 .  na  - size of a and its
3474 -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
3475            else it continues storing new values for new nonlinear solves after the old ones
3476 
3477    Notes:
3478    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
3479    default array of length 10000 is allocated.
3480 
3481    This routine is useful, e.g., when running a code for purposes
3482    of accurate performance monitoring, when no I/O should be done
3483    during the section of code that is being timed.
3484 
3485    Level: intermediate
3486 
3487 .keywords: SNES, set, convergence, history
3488 
3489 .seealso: SNESGetConvergenceHistory()
3490 
3491 @*/
3492 PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
3493 {
3494   PetscErrorCode ierr;
3495 
3496   PetscFunctionBegin;
3497   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3498   if (a) PetscValidScalarPointer(a,2);
3499   if (its) PetscValidIntPointer(its,3);
3500   if (!a) {
3501     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
3502     ierr = PetscCalloc1(na,&a);CHKERRQ(ierr);
3503     ierr = PetscCalloc1(na,&its);CHKERRQ(ierr);
3504 
3505     snes->conv_malloc = PETSC_TRUE;
3506   }
3507   snes->conv_hist       = a;
3508   snes->conv_hist_its   = its;
3509   snes->conv_hist_max   = na;
3510   snes->conv_hist_len   = 0;
3511   snes->conv_hist_reset = reset;
3512   PetscFunctionReturn(0);
3513 }
3514 
3515 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3516 #include <engine.h>   /* MATLAB include file */
3517 #include <mex.h>      /* MATLAB include file */
3518 
3519 #undef __FUNCT__
3520 #define __FUNCT__ "SNESGetConvergenceHistoryMatlab"
3521 PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
3522 {
3523   mxArray   *mat;
3524   PetscInt  i;
3525   PetscReal *ar;
3526 
3527   PetscFunctionBegin;
3528   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
3529   ar  = (PetscReal*) mxGetData(mat);
3530   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
3531   PetscFunctionReturn(mat);
3532 }
3533 #endif
3534 
3535 #undef __FUNCT__
3536 #define __FUNCT__ "SNESGetConvergenceHistory"
3537 /*@C
3538    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.
3539 
3540    Not Collective
3541 
3542    Input Parameter:
3543 .  snes - iterative context obtained from SNESCreate()
3544 
3545    Output Parameters:
3546 .  a   - array to hold history
3547 .  its - integer array holds the number of linear iterations (or
3548          negative if not converged) for each solve.
3549 -  na  - size of a and its
3550 
3551    Notes:
3552     The calling sequence for this routine in Fortran is
3553 $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
3554 
3555    This routine is useful, e.g., when running a code for purposes
3556    of accurate performance monitoring, when no I/O should be done
3557    during the section of code that is being timed.
3558 
3559    Level: intermediate
3560 
3561 .keywords: SNES, get, convergence, history
3562 
3563 .seealso: SNESSetConvergencHistory()
3564 
3565 @*/
3566 PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
3567 {
3568   PetscFunctionBegin;
3569   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3570   if (a)   *a   = snes->conv_hist;
3571   if (its) *its = snes->conv_hist_its;
3572   if (na)  *na  = snes->conv_hist_len;
3573   PetscFunctionReturn(0);
3574 }
3575 
3576 #undef __FUNCT__
3577 #define __FUNCT__ "SNESSetUpdate"
3578 /*@C
3579   SNESSetUpdate - Sets the general-purpose update function called
3580   at the beginning of every iteration of the nonlinear solve. Specifically
3581   it is called just before the Jacobian is "evaluated".
3582 
3583   Logically Collective on SNES
3584 
3585   Input Parameters:
3586 . snes - The nonlinear solver context
3587 . func - The function
3588 
3589   Calling sequence of func:
3590 . func (SNES snes, PetscInt step);
3591 
3592 . step - The current step of the iteration
3593 
3594   Level: advanced
3595 
3596   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()
3597         This is not used by most users.
3598 
3599 .keywords: SNES, update
3600 
3601 .seealso SNESSetJacobian(), SNESSolve()
3602 @*/
3603 PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
3604 {
3605   PetscFunctionBegin;
3606   PetscValidHeaderSpecific(snes, SNES_CLASSID,1);
3607   snes->ops->update = func;
3608   PetscFunctionReturn(0);
3609 }
3610 
3611 #undef __FUNCT__
3612 #define __FUNCT__ "SNESScaleStep_Private"
3613 /*
3614    SNESScaleStep_Private - Scales a step so that its length is less than the
3615    positive parameter delta.
3616 
3617     Input Parameters:
3618 +   snes - the SNES context
3619 .   y - approximate solution of linear system
3620 .   fnorm - 2-norm of current function
3621 -   delta - trust region size
3622 
3623     Output Parameters:
3624 +   gpnorm - predicted function norm at the new point, assuming local
3625     linearization.  The value is zero if the step lies within the trust
3626     region, and exceeds zero otherwise.
3627 -   ynorm - 2-norm of the step
3628 
3629     Note:
3630     For non-trust region methods such as SNESNEWTONLS, the parameter delta
3631     is set to be the maximum allowable step size.
3632 
3633 .keywords: SNES, nonlinear, scale, step
3634 */
3635 PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
3636 {
3637   PetscReal      nrm;
3638   PetscScalar    cnorm;
3639   PetscErrorCode ierr;
3640 
3641   PetscFunctionBegin;
3642   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3643   PetscValidHeaderSpecific(y,VEC_CLASSID,2);
3644   PetscCheckSameComm(snes,1,y,2);
3645 
3646   ierr = VecNorm(y,NORM_2,&nrm);CHKERRQ(ierr);
3647   if (nrm > *delta) {
3648     nrm     = *delta/nrm;
3649     *gpnorm = (1.0 - nrm)*(*fnorm);
3650     cnorm   = nrm;
3651     ierr    = VecScale(y,cnorm);CHKERRQ(ierr);
3652     *ynorm  = *delta;
3653   } else {
3654     *gpnorm = 0.0;
3655     *ynorm  = nrm;
3656   }
3657   PetscFunctionReturn(0);
3658 }
3659 
3660 #undef __FUNCT__
3661 #define __FUNCT__ "SNESSolve"
3662 /*@C
3663    SNESSolve - Solves a nonlinear system F(x) = b.
3664    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3665 
3666    Collective on SNES
3667 
3668    Input Parameters:
3669 +  snes - the SNES context
3670 .  b - the constant part of the equation F(x) = b, or NULL to use zero.
3671 -  x - the solution vector.
3672 
3673    Notes:
3674    The user should initialize the vector,x, with the initial guess
3675    for the nonlinear solve prior to calling SNESSolve.  In particular,
3676    to employ an initial guess of zero, the user should explicitly set
3677    this vector to zero by calling VecSet().
3678 
3679    Level: beginner
3680 
3681 .keywords: SNES, nonlinear, solve
3682 
3683 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3684 @*/
3685 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3686 {
3687   PetscErrorCode    ierr;
3688   PetscBool         flg;
3689   PetscInt          grid;
3690   Vec               xcreated = NULL;
3691   DM                dm;
3692 
3693   PetscFunctionBegin;
3694   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3695   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3696   if (x) PetscCheckSameComm(snes,1,x,3);
3697   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3698   if (b) PetscCheckSameComm(snes,1,b,2);
3699 
3700   if (!x) {
3701     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3702     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3703     x    = xcreated;
3704   }
3705   ierr = SNESViewFromOptions(snes,NULL,"-snes_view_pre");CHKERRQ(ierr);
3706 
3707   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);}
3708   for (grid=0; grid<snes->gridsequence+1; grid++) {
3709 
3710     /* set solution vector */
3711     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3712     ierr          = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3713     snes->vec_sol = x;
3714     ierr          = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3715 
3716     /* set affine vector if provided */
3717     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3718     ierr          = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3719     snes->vec_rhs = b;
3720 
3721     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
3722     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
3723     if (!snes->vec_sol_update /* && snes->vec_sol */) {
3724       ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
3725       ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);CHKERRQ(ierr);
3726     }
3727     ierr = DMShellSetGlobalVector(dm,snes->vec_sol);CHKERRQ(ierr);
3728     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3729 
3730     if (!grid) {
3731       if (snes->ops->computeinitialguess) {
3732         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3733       }
3734     }
3735 
3736     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3737     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}
3738 
3739     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3740     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3741     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3742     if (snes->domainerror) {
3743       snes->reason      = SNES_DIVERGED_FUNCTION_DOMAIN;
3744       snes->domainerror = PETSC_FALSE;
3745     }
3746     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3747 
3748     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
3749     if (snes->lagpre_persist) snes->pre_iter += snes->iter;
3750 
3751     flg  = PETSC_FALSE;
3752     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,NULL);CHKERRQ(ierr);
3753     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
3754     if (snes->printreason) {
3755       ierr = PetscViewerASCIIAddTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3756       if (snes->reason > 0) {
3757         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3758       } else {
3759         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3760       }
3761       ierr = PetscViewerASCIISubtractTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3762     }
3763 
3764     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
3765     if (grid <  snes->gridsequence) {
3766       DM  fine;
3767       Vec xnew;
3768       Mat interp;
3769 
3770       ierr = DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);CHKERRQ(ierr);
3771       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
3772       ierr = DMCreateInterpolation(snes->dm,fine,&interp,NULL);CHKERRQ(ierr);
3773       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
3774       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
3775       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
3776       ierr = MatDestroy(&interp);CHKERRQ(ierr);
3777       x    = xnew;
3778 
3779       ierr = SNESReset(snes);CHKERRQ(ierr);
3780       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
3781       ierr = DMDestroy(&fine);CHKERRQ(ierr);
3782       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);
3783     }
3784   }
3785   ierr = SNESViewFromOptions(snes,NULL,"-snes_view");CHKERRQ(ierr);
3786   ierr = VecViewFromOptions(snes->vec_sol,((PetscObject)snes)->prefix,"-snes_view_solution");CHKERRQ(ierr);
3787 
3788   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
3789   ierr = PetscObjectSAWsBlock((PetscObject)snes);CHKERRQ(ierr);
3790   PetscFunctionReturn(0);
3791 }
3792 
3793 /* --------- Internal routines for SNES Package --------- */
3794 
3795 #undef __FUNCT__
3796 #define __FUNCT__ "SNESSetType"
3797 /*@C
3798    SNESSetType - Sets the method for the nonlinear solver.
3799 
3800    Collective on SNES
3801 
3802    Input Parameters:
3803 +  snes - the SNES context
3804 -  type - a known method
3805 
3806    Options Database Key:
3807 .  -snes_type <type> - Sets the method; use -help for a list
3808    of available methods (for instance, newtonls or newtontr)
3809 
3810    Notes:
3811    See "petsc/include/petscsnes.h" for available methods (for instance)
3812 +    SNESNEWTONLS - Newton's method with line search
3813      (systems of nonlinear equations)
3814 .    SNESNEWTONTR - Newton's method with trust region
3815      (systems of nonlinear equations)
3816 
3817   Normally, it is best to use the SNESSetFromOptions() command and then
3818   set the SNES solver type from the options database rather than by using
3819   this routine.  Using the options database provides the user with
3820   maximum flexibility in evaluating the many nonlinear solvers.
3821   The SNESSetType() routine is provided for those situations where it
3822   is necessary to set the nonlinear solver independently of the command
3823   line or options database.  This might be the case, for example, when
3824   the choice of solver changes during the execution of the program,
3825   and the user's application is taking responsibility for choosing the
3826   appropriate method.
3827 
3828     Developer Notes: SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
3829     the constructor in that list and calls it to create the spexific object.
3830 
3831   Level: intermediate
3832 
3833 .keywords: SNES, set, type
3834 
3835 .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()
3836 
3837 @*/
3838 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
3839 {
3840   PetscErrorCode ierr,(*r)(SNES);
3841   PetscBool      match;
3842 
3843   PetscFunctionBegin;
3844   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3845   PetscValidCharPointer(type,2);
3846 
3847   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
3848   if (match) PetscFunctionReturn(0);
3849 
3850   ierr =  PetscFunctionListFind(SNESList,type,&r);CHKERRQ(ierr);
3851   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
3852   /* Destroy the previous private SNES context */
3853   if (snes->ops->destroy) {
3854     ierr               = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
3855     snes->ops->destroy = NULL;
3856   }
3857   /* Reinitialize function pointers in SNESOps structure */
3858   snes->ops->setup          = 0;
3859   snes->ops->solve          = 0;
3860   snes->ops->view           = 0;
3861   snes->ops->setfromoptions = 0;
3862   snes->ops->destroy        = 0;
3863   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
3864   snes->setupcalled = PETSC_FALSE;
3865 
3866   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
3867   ierr = (*r)(snes);CHKERRQ(ierr);
3868   PetscFunctionReturn(0);
3869 }
3870 
3871 #undef __FUNCT__
3872 #define __FUNCT__ "SNESGetType"
3873 /*@C
3874    SNESGetType - Gets the SNES method type and name (as a string).
3875 
3876    Not Collective
3877 
3878    Input Parameter:
3879 .  snes - nonlinear solver context
3880 
3881    Output Parameter:
3882 .  type - SNES method (a character string)
3883 
3884    Level: intermediate
3885 
3886 .keywords: SNES, nonlinear, get, type, name
3887 @*/
3888 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
3889 {
3890   PetscFunctionBegin;
3891   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3892   PetscValidPointer(type,2);
3893   *type = ((PetscObject)snes)->type_name;
3894   PetscFunctionReturn(0);
3895 }
3896 
3897 #undef __FUNCT__
3898 #define __FUNCT__ "SNESGetSolution"
3899 /*@
3900    SNESGetSolution - Returns the vector where the approximate solution is
3901    stored. This is the fine grid solution when using SNESSetGridSequence().
3902 
3903    Not Collective, but Vec is parallel if SNES is parallel
3904 
3905    Input Parameter:
3906 .  snes - the SNES context
3907 
3908    Output Parameter:
3909 .  x - the solution
3910 
3911    Level: intermediate
3912 
3913 .keywords: SNES, nonlinear, get, solution
3914 
3915 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
3916 @*/
3917 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
3918 {
3919   PetscFunctionBegin;
3920   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3921   PetscValidPointer(x,2);
3922   *x = snes->vec_sol;
3923   PetscFunctionReturn(0);
3924 }
3925 
3926 #undef __FUNCT__
3927 #define __FUNCT__ "SNESGetSolutionUpdate"
3928 /*@
3929    SNESGetSolutionUpdate - Returns the vector where the solution update is
3930    stored.
3931 
3932    Not Collective, but Vec is parallel if SNES is parallel
3933 
3934    Input Parameter:
3935 .  snes - the SNES context
3936 
3937    Output Parameter:
3938 .  x - the solution update
3939 
3940    Level: advanced
3941 
3942 .keywords: SNES, nonlinear, get, solution, update
3943 
3944 .seealso: SNESGetSolution(), SNESGetFunction()
3945 @*/
3946 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
3947 {
3948   PetscFunctionBegin;
3949   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3950   PetscValidPointer(x,2);
3951   *x = snes->vec_sol_update;
3952   PetscFunctionReturn(0);
3953 }
3954 
3955 #undef __FUNCT__
3956 #define __FUNCT__ "SNESGetFunction"
3957 /*@C
3958    SNESGetFunction - Returns the vector where the function is stored.
3959 
3960    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
3961 
3962    Input Parameter:
3963 .  snes - the SNES context
3964 
3965    Output Parameter:
3966 +  r - the vector that is used to store residuals (or NULL if you don't want it)
3967 .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
3968 -  ctx - the function context (or NULL if you don't want it)
3969 
3970    Level: advanced
3971 
3972 .keywords: SNES, nonlinear, get, function
3973 
3974 .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
3975 @*/
3976 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
3977 {
3978   PetscErrorCode ierr;
3979   DM             dm;
3980 
3981   PetscFunctionBegin;
3982   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3983   if (r) {
3984     if (!snes->vec_func) {
3985       if (snes->vec_rhs) {
3986         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
3987       } else if (snes->vec_sol) {
3988         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
3989       } else if (snes->dm) {
3990         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
3991       }
3992     }
3993     *r = snes->vec_func;
3994   }
3995   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3996   ierr = DMSNESGetFunction(dm,f,ctx);CHKERRQ(ierr);
3997   PetscFunctionReturn(0);
3998 }
3999 
4000 /*@C
4001    SNESGetNGS - Returns the NGS function and context.
4002 
4003    Input Parameter:
4004 .  snes - the SNES context
4005 
4006    Output Parameter:
4007 +  f - the function (or NULL) see SNESNGSFunction for details
4008 -  ctx    - the function context (or NULL)
4009 
4010    Level: advanced
4011 
4012 .keywords: SNES, nonlinear, get, function
4013 
4014 .seealso: SNESSetNGS(), SNESGetFunction()
4015 @*/
4016 
4017 #undef __FUNCT__
4018 #define __FUNCT__ "SNESGetNGS"
4019 PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
4020 {
4021   PetscErrorCode ierr;
4022   DM             dm;
4023 
4024   PetscFunctionBegin;
4025   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4026   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
4027   ierr = DMSNESGetNGS(dm,f,ctx);CHKERRQ(ierr);
4028   PetscFunctionReturn(0);
4029 }
4030 
4031 #undef __FUNCT__
4032 #define __FUNCT__ "SNESSetOptionsPrefix"
4033 /*@C
4034    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4035    SNES options in the database.
4036 
4037    Logically Collective on SNES
4038 
4039    Input Parameter:
4040 +  snes - the SNES context
4041 -  prefix - the prefix to prepend to all option names
4042 
4043    Notes:
4044    A hyphen (-) must NOT be given at the beginning of the prefix name.
4045    The first character of all runtime options is AUTOMATICALLY the hyphen.
4046 
4047    Level: advanced
4048 
4049 .keywords: SNES, set, options, prefix, database
4050 
4051 .seealso: SNESSetFromOptions()
4052 @*/
4053 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4054 {
4055   PetscErrorCode ierr;
4056 
4057   PetscFunctionBegin;
4058   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4059   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4060   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4061   if (snes->linesearch) {
4062     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4063     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4064   }
4065   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4066   PetscFunctionReturn(0);
4067 }
4068 
4069 #undef __FUNCT__
4070 #define __FUNCT__ "SNESAppendOptionsPrefix"
4071 /*@C
4072    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4073    SNES options in the database.
4074 
4075    Logically Collective on SNES
4076 
4077    Input Parameters:
4078 +  snes - the SNES context
4079 -  prefix - the prefix to prepend to all option names
4080 
4081    Notes:
4082    A hyphen (-) must NOT be given at the beginning of the prefix name.
4083    The first character of all runtime options is AUTOMATICALLY the hyphen.
4084 
4085    Level: advanced
4086 
4087 .keywords: SNES, append, options, prefix, database
4088 
4089 .seealso: SNESGetOptionsPrefix()
4090 @*/
4091 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4092 {
4093   PetscErrorCode ierr;
4094 
4095   PetscFunctionBegin;
4096   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4097   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4098   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4099   if (snes->linesearch) {
4100     ierr = SNESGetLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4101     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4102   }
4103   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4104   PetscFunctionReturn(0);
4105 }
4106 
4107 #undef __FUNCT__
4108 #define __FUNCT__ "SNESGetOptionsPrefix"
4109 /*@C
4110    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4111    SNES options in the database.
4112 
4113    Not Collective
4114 
4115    Input Parameter:
4116 .  snes - the SNES context
4117 
4118    Output Parameter:
4119 .  prefix - pointer to the prefix string used
4120 
4121    Notes: On the fortran side, the user should pass in a string 'prefix' of
4122    sufficient length to hold the prefix.
4123 
4124    Level: advanced
4125 
4126 .keywords: SNES, get, options, prefix, database
4127 
4128 .seealso: SNESAppendOptionsPrefix()
4129 @*/
4130 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4131 {
4132   PetscErrorCode ierr;
4133 
4134   PetscFunctionBegin;
4135   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4136   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4137   PetscFunctionReturn(0);
4138 }
4139 
4140 
4141 #undef __FUNCT__
4142 #define __FUNCT__ "SNESRegister"
4143 /*@C
4144   SNESRegister - Adds a method to the nonlinear solver package.
4145 
4146    Not collective
4147 
4148    Input Parameters:
4149 +  name_solver - name of a new user-defined solver
4150 -  routine_create - routine to create method context
4151 
4152    Notes:
4153    SNESRegister() may be called multiple times to add several user-defined solvers.
4154 
4155    Sample usage:
4156 .vb
4157    SNESRegister("my_solver",MySolverCreate);
4158 .ve
4159 
4160    Then, your solver can be chosen with the procedural interface via
4161 $     SNESSetType(snes,"my_solver")
4162    or at runtime via the option
4163 $     -snes_type my_solver
4164 
4165    Level: advanced
4166 
4167     Note: If your function is not being put into a shared library then use SNESRegister() instead
4168 
4169 .keywords: SNES, nonlinear, register
4170 
4171 .seealso: SNESRegisterAll(), SNESRegisterDestroy()
4172 
4173   Level: advanced
4174 @*/
4175 PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
4176 {
4177   PetscErrorCode ierr;
4178 
4179   PetscFunctionBegin;
4180   ierr = PetscFunctionListAdd(&SNESList,sname,function);CHKERRQ(ierr);
4181   PetscFunctionReturn(0);
4182 }
4183 
4184 #undef __FUNCT__
4185 #define __FUNCT__ "SNESTestLocalMin"
4186 PetscErrorCode  SNESTestLocalMin(SNES snes)
4187 {
4188   PetscErrorCode ierr;
4189   PetscInt       N,i,j;
4190   Vec            u,uh,fh;
4191   PetscScalar    value;
4192   PetscReal      norm;
4193 
4194   PetscFunctionBegin;
4195   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4196   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4197   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4198 
4199   /* currently only works for sequential */
4200   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");CHKERRQ(ierr);
4201   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4202   for (i=0; i<N; i++) {
4203     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4204     ierr = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4205     for (j=-10; j<11; j++) {
4206       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
4207       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4208       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4209       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4210       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4211       value = -value;
4212       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4213     }
4214   }
4215   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4216   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4217   PetscFunctionReturn(0);
4218 }
4219 
4220 #undef __FUNCT__
4221 #define __FUNCT__ "SNESKSPSetUseEW"
4222 /*@
4223    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4224    computing relative tolerance for linear solvers within an inexact
4225    Newton method.
4226 
4227    Logically Collective on SNES
4228 
4229    Input Parameters:
4230 +  snes - SNES context
4231 -  flag - PETSC_TRUE or PETSC_FALSE
4232 
4233     Options Database:
4234 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4235 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4236 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4237 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4238 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4239 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4240 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4241 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4242 
4243    Notes:
4244    Currently, the default is to use a constant relative tolerance for
4245    the inner linear solvers.  Alternatively, one can use the
4246    Eisenstat-Walker method, where the relative convergence tolerance
4247    is reset at each Newton iteration according progress of the nonlinear
4248    solver.
4249 
4250    Level: advanced
4251 
4252    Reference:
4253    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4254    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4255 
4256 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4257 
4258 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4259 @*/
4260 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
4261 {
4262   PetscFunctionBegin;
4263   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4264   PetscValidLogicalCollectiveBool(snes,flag,2);
4265   snes->ksp_ewconv = flag;
4266   PetscFunctionReturn(0);
4267 }
4268 
4269 #undef __FUNCT__
4270 #define __FUNCT__ "SNESKSPGetUseEW"
4271 /*@
4272    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4273    for computing relative tolerance for linear solvers within an
4274    inexact Newton method.
4275 
4276    Not Collective
4277 
4278    Input Parameter:
4279 .  snes - SNES context
4280 
4281    Output Parameter:
4282 .  flag - PETSC_TRUE or PETSC_FALSE
4283 
4284    Notes:
4285    Currently, the default is to use a constant relative tolerance for
4286    the inner linear solvers.  Alternatively, one can use the
4287    Eisenstat-Walker method, where the relative convergence tolerance
4288    is reset at each Newton iteration according progress of the nonlinear
4289    solver.
4290 
4291    Level: advanced
4292 
4293    Reference:
4294    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4295    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4296 
4297 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4298 
4299 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4300 @*/
4301 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4302 {
4303   PetscFunctionBegin;
4304   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4305   PetscValidPointer(flag,2);
4306   *flag = snes->ksp_ewconv;
4307   PetscFunctionReturn(0);
4308 }
4309 
4310 #undef __FUNCT__
4311 #define __FUNCT__ "SNESKSPSetParametersEW"
4312 /*@
4313    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4314    convergence criteria for the linear solvers within an inexact
4315    Newton method.
4316 
4317    Logically Collective on SNES
4318 
4319    Input Parameters:
4320 +    snes - SNES context
4321 .    version - version 1, 2 (default is 2) or 3
4322 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4323 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4324 .    gamma - multiplicative factor for version 2 rtol computation
4325              (0 <= gamma2 <= 1)
4326 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4327 .    alpha2 - power for safeguard
4328 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4329 
4330    Note:
4331    Version 3 was contributed by Luis Chacon, June 2006.
4332 
4333    Use PETSC_DEFAULT to retain the default for any of the parameters.
4334 
4335    Level: advanced
4336 
4337    Reference:
4338    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4339    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4340    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4341 
4342 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4343 
4344 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4345 @*/
4346 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4347 {
4348   SNESKSPEW *kctx;
4349 
4350   PetscFunctionBegin;
4351   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4352   kctx = (SNESKSPEW*)snes->kspconvctx;
4353   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4354   PetscValidLogicalCollectiveInt(snes,version,2);
4355   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4356   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4357   PetscValidLogicalCollectiveReal(snes,gamma,5);
4358   PetscValidLogicalCollectiveReal(snes,alpha,6);
4359   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4360   PetscValidLogicalCollectiveReal(snes,threshold,8);
4361 
4362   if (version != PETSC_DEFAULT)   kctx->version   = version;
4363   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4364   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4365   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4366   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4367   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4368   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4369 
4370   if (kctx->version < 1 || kctx->version > 3) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 and 3 are supported: %D",kctx->version);
4371   if (kctx->rtol_0 < 0.0 || kctx->rtol_0 >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_0 < 1.0: %g",(double)kctx->rtol_0);
4372   if (kctx->rtol_max < 0.0 || kctx->rtol_max >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_max (%g) < 1.0\n",(double)kctx->rtol_max);
4373   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%g) <= 1.0\n",(double)kctx->gamma);
4374   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%g) <= 2.0\n",(double)kctx->alpha);
4375   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%g) < 1.0\n",(double)kctx->threshold);
4376   PetscFunctionReturn(0);
4377 }
4378 
4379 #undef __FUNCT__
4380 #define __FUNCT__ "SNESKSPGetParametersEW"
4381 /*@
4382    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4383    convergence criteria for the linear solvers within an inexact
4384    Newton method.
4385 
4386    Not Collective
4387 
4388    Input Parameters:
4389      snes - SNES context
4390 
4391    Output Parameters:
4392 +    version - version 1, 2 (default is 2) or 3
4393 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4394 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4395 .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
4396 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4397 .    alpha2 - power for safeguard
4398 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4399 
4400    Level: advanced
4401 
4402 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4403 
4404 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4405 @*/
4406 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4407 {
4408   SNESKSPEW *kctx;
4409 
4410   PetscFunctionBegin;
4411   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4412   kctx = (SNESKSPEW*)snes->kspconvctx;
4413   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4414   if (version)   *version   = kctx->version;
4415   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4416   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4417   if (gamma)     *gamma     = kctx->gamma;
4418   if (alpha)     *alpha     = kctx->alpha;
4419   if (alpha2)    *alpha2    = kctx->alpha2;
4420   if (threshold) *threshold = kctx->threshold;
4421   PetscFunctionReturn(0);
4422 }
4423 
4424 #undef __FUNCT__
4425 #define __FUNCT__ "KSPPreSolve_SNESEW"
4426  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4427 {
4428   PetscErrorCode ierr;
4429   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4430   PetscReal      rtol  = PETSC_DEFAULT,stol;
4431 
4432   PetscFunctionBegin;
4433   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4434   if (!snes->iter) {
4435     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
4436     ierr = VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);CHKERRQ(ierr);
4437   }
4438   else {
4439     if (kctx->version == 1) {
4440       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4441       if (rtol < 0.0) rtol = -rtol;
4442       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
4443       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4444     } else if (kctx->version == 2) {
4445       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4446       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
4447       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4448     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
4449       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4450       /* safeguard: avoid sharp decrease of rtol */
4451       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
4452       stol = PetscMax(rtol,stol);
4453       rtol = PetscMin(kctx->rtol_0,stol);
4454       /* safeguard: avoid oversolving */
4455       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
4456       stol = PetscMax(rtol,stol);
4457       rtol = PetscMin(kctx->rtol_0,stol);
4458     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4459   }
4460   /* safeguard: avoid rtol greater than one */
4461   rtol = PetscMin(rtol,kctx->rtol_max);
4462   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4463   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);CHKERRQ(ierr);
4464   PetscFunctionReturn(0);
4465 }
4466 
4467 #undef __FUNCT__
4468 #define __FUNCT__ "KSPPostSolve_SNESEW"
4469 PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
4470 {
4471   PetscErrorCode ierr;
4472   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4473   PCSide         pcside;
4474   Vec            lres;
4475 
4476   PetscFunctionBegin;
4477   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4478   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4479   kctx->norm_last = snes->norm;
4480   if (kctx->version == 1) {
4481     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4482     if (pcside == PC_RIGHT) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4483       /* KSP residual is true linear residual */
4484       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4485     } else {
4486       /* KSP residual is preconditioned residual */
4487       /* compute true linear residual norm */
4488       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4489       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4490       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4491       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4492       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4493     }
4494   }
4495   PetscFunctionReturn(0);
4496 }
4497 
4498 #undef __FUNCT__
4499 #define __FUNCT__ "SNESGetKSP"
4500 /*@
4501    SNESGetKSP - Returns the KSP context for a SNES solver.
4502 
4503    Not Collective, but if SNES object is parallel, then KSP object is parallel
4504 
4505    Input Parameter:
4506 .  snes - the SNES context
4507 
4508    Output Parameter:
4509 .  ksp - the KSP context
4510 
4511    Notes:
4512    The user can then directly manipulate the KSP context to set various
4513    options, etc.  Likewise, the user can then extract and manipulate the
4514    PC contexts as well.
4515 
4516    Level: beginner
4517 
4518 .keywords: SNES, nonlinear, get, KSP, context
4519 
4520 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
4521 @*/
4522 PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
4523 {
4524   PetscErrorCode ierr;
4525 
4526   PetscFunctionBegin;
4527   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4528   PetscValidPointer(ksp,2);
4529 
4530   if (!snes->ksp) {
4531     ierr = KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);CHKERRQ(ierr);
4532     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);CHKERRQ(ierr);
4533     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);CHKERRQ(ierr);
4534 
4535     ierr = KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);CHKERRQ(ierr);
4536     ierr = KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);CHKERRQ(ierr);
4537   }
4538   *ksp = snes->ksp;
4539   PetscFunctionReturn(0);
4540 }
4541 
4542 
4543 #include <petsc-private/dmimpl.h>
4544 #undef __FUNCT__
4545 #define __FUNCT__ "SNESSetDM"
4546 /*@
4547    SNESSetDM - Sets the DM that may be used by some preconditioners
4548 
4549    Logically Collective on SNES
4550 
4551    Input Parameters:
4552 +  snes - the preconditioner context
4553 -  dm - the dm
4554 
4555    Level: intermediate
4556 
4557 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4558 @*/
4559 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4560 {
4561   PetscErrorCode ierr;
4562   KSP            ksp;
4563   DMSNES         sdm;
4564 
4565   PetscFunctionBegin;
4566   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4567   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4568   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4569     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4570       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4571       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4572       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
4573     }
4574     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4575   }
4576   snes->dm     = dm;
4577   snes->dmAuto = PETSC_FALSE;
4578 
4579   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4580   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4581   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4582   if (snes->pc) {
4583     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4584     ierr = SNESSetNPCSide(snes,snes->pcside);CHKERRQ(ierr);
4585   }
4586   PetscFunctionReturn(0);
4587 }
4588 
4589 #undef __FUNCT__
4590 #define __FUNCT__ "SNESGetDM"
4591 /*@
4592    SNESGetDM - Gets the DM that may be used by some preconditioners
4593 
4594    Not Collective but DM obtained is parallel on SNES
4595 
4596    Input Parameter:
4597 . snes - the preconditioner context
4598 
4599    Output Parameter:
4600 .  dm - the dm
4601 
4602    Level: intermediate
4603 
4604 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4605 @*/
4606 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4607 {
4608   PetscErrorCode ierr;
4609 
4610   PetscFunctionBegin;
4611   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4612   if (!snes->dm) {
4613     ierr         = DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);CHKERRQ(ierr);
4614     snes->dmAuto = PETSC_TRUE;
4615   }
4616   *dm = snes->dm;
4617   PetscFunctionReturn(0);
4618 }
4619 
4620 #undef __FUNCT__
4621 #define __FUNCT__ "SNESSetNPC"
4622 /*@
4623   SNESSetNPC - Sets the nonlinear preconditioner to be used.
4624 
4625   Collective on SNES
4626 
4627   Input Parameters:
4628 + snes - iterative context obtained from SNESCreate()
4629 - pc   - the preconditioner object
4630 
4631   Notes:
4632   Use SNESGetNPC() to retrieve the preconditioner context (for example,
4633   to configure it using the API).
4634 
4635   Level: developer
4636 
4637 .keywords: SNES, set, precondition
4638 .seealso: SNESGetNPC()
4639 @*/
4640 PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
4641 {
4642   PetscErrorCode ierr;
4643 
4644   PetscFunctionBegin;
4645   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4646   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4647   PetscCheckSameComm(snes, 1, pc, 2);
4648   ierr     = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4649   ierr     = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4650   snes->pc = pc;
4651   ierr     = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->pc);CHKERRQ(ierr);
4652   PetscFunctionReturn(0);
4653 }
4654 
4655 #undef __FUNCT__
4656 #define __FUNCT__ "SNESGetNPC"
4657 /*@
4658   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.
4659 
4660   Not Collective
4661 
4662   Input Parameter:
4663 . snes - iterative context obtained from SNESCreate()
4664 
4665   Output Parameter:
4666 . pc - preconditioner context
4667 
4668   Notes: If a SNES was previously set with SNESSetNPC() then that SNES is returned.
4669 
4670   Level: developer
4671 
4672 .keywords: SNES, get, preconditioner
4673 .seealso: SNESSetNPC()
4674 @*/
4675 PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
4676 {
4677   PetscErrorCode ierr;
4678   const char     *optionsprefix;
4679 
4680   PetscFunctionBegin;
4681   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4682   PetscValidPointer(pc, 2);
4683   if (!snes->pc) {
4684     ierr = SNESCreate(PetscObjectComm((PetscObject)snes),&snes->pc);CHKERRQ(ierr);
4685     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4686     ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
4687     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4688     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4689     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4690     ierr = SNESSetCountersReset(snes->pc,PETSC_FALSE);CHKERRQ(ierr);
4691   }
4692   *pc = snes->pc;
4693   PetscFunctionReturn(0);
4694 }
4695 
4696 #undef __FUNCT__
4697 #define __FUNCT__ "SNESSetNPCSide"
4698 /*@
4699     SNESSetNPCSide - Sets the preconditioning side.
4700 
4701     Logically Collective on SNES
4702 
4703     Input Parameter:
4704 .   snes - iterative context obtained from SNESCreate()
4705 
4706     Output Parameter:
4707 .   side - the preconditioning side, where side is one of
4708 .vb
4709       PC_LEFT - left preconditioning (default)
4710       PC_RIGHT - right preconditioning
4711 .ve
4712 
4713     Options Database Keys:
4714 .   -snes_pc_side <right,left>
4715 
4716     Level: intermediate
4717 
4718 .keywords: SNES, set, right, left, side, preconditioner, flag
4719 
4720 .seealso: SNESGetNPCSide(), KSPSetPCSide()
4721 @*/
4722 PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
4723 {
4724   PetscFunctionBegin;
4725   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4726   PetscValidLogicalCollectiveEnum(snes,side,2);
4727   snes->pcside = side;
4728   PetscFunctionReturn(0);
4729 }
4730 
4731 #undef __FUNCT__
4732 #define __FUNCT__ "SNESGetNPCSide"
4733 /*@
4734     SNESGetNPCSide - Gets the preconditioning side.
4735 
4736     Not Collective
4737 
4738     Input Parameter:
4739 .   snes - iterative context obtained from SNESCreate()
4740 
4741     Output Parameter:
4742 .   side - the preconditioning side, where side is one of
4743 .vb
4744       PC_LEFT - left preconditioning (default)
4745       PC_RIGHT - right preconditioning
4746 .ve
4747 
4748     Level: intermediate
4749 
4750 .keywords: SNES, get, right, left, side, preconditioner, flag
4751 
4752 .seealso: SNESSetNPCSide(), KSPGetPCSide()
4753 @*/
4754 PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
4755 {
4756   PetscFunctionBegin;
4757   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4758   PetscValidPointer(side,2);
4759   *side = snes->pcside;
4760   PetscFunctionReturn(0);
4761 }
4762 
4763 #undef __FUNCT__
4764 #define __FUNCT__ "SNESSetLineSearch"
4765 /*@
4766   SNESSetLineSearch - Sets the linesearch on the SNES instance.
4767 
4768   Collective on SNES
4769 
4770   Input Parameters:
4771 + snes - iterative context obtained from SNESCreate()
4772 - linesearch   - the linesearch object
4773 
4774   Notes:
4775   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
4776   to configure it using the API).
4777 
4778   Level: developer
4779 
4780 .keywords: SNES, set, linesearch
4781 .seealso: SNESGetLineSearch()
4782 @*/
4783 PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
4784 {
4785   PetscErrorCode ierr;
4786 
4787   PetscFunctionBegin;
4788   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4789   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
4790   PetscCheckSameComm(snes, 1, linesearch, 2);
4791   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
4792   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
4793 
4794   snes->linesearch = linesearch;
4795 
4796   ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
4797   PetscFunctionReturn(0);
4798 }
4799 
4800 #undef __FUNCT__
4801 #define __FUNCT__ "SNESGetLineSearch"
4802 /*@
4803   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
4804   or creates a default line search instance associated with the SNES and returns it.
4805 
4806   Not Collective
4807 
4808   Input Parameter:
4809 . snes - iterative context obtained from SNESCreate()
4810 
4811   Output Parameter:
4812 . linesearch - linesearch context
4813 
4814   Level: beginner
4815 
4816 .keywords: SNES, get, linesearch
4817 .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
4818 @*/
4819 PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
4820 {
4821   PetscErrorCode ierr;
4822   const char     *optionsprefix;
4823 
4824   PetscFunctionBegin;
4825   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4826   PetscValidPointer(linesearch, 2);
4827   if (!snes->linesearch) {
4828     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
4829     ierr = SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);CHKERRQ(ierr);
4830     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
4831     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
4832     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
4833     ierr = PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);CHKERRQ(ierr);
4834   }
4835   *linesearch = snes->linesearch;
4836   PetscFunctionReturn(0);
4837 }
4838 
4839 #if defined(PETSC_HAVE_MATLAB_ENGINE)
4840 #include <mex.h>
4841 
4842 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
4843 
4844 #undef __FUNCT__
4845 #define __FUNCT__ "SNESComputeFunction_Matlab"
4846 /*
4847    SNESComputeFunction_Matlab - Calls the function that has been set with SNESSetFunctionMatlab().
4848 
4849    Collective on SNES
4850 
4851    Input Parameters:
4852 +  snes - the SNES context
4853 -  x - input vector
4854 
4855    Output Parameter:
4856 .  y - function vector, as set by SNESSetFunction()
4857 
4858    Notes:
4859    SNESComputeFunction() is typically used within nonlinear solvers
4860    implementations, so most users would not generally call this routine
4861    themselves.
4862 
4863    Level: developer
4864 
4865 .keywords: SNES, nonlinear, compute, function
4866 
4867 .seealso: SNESSetFunction(), SNESGetFunction()
4868 */
4869 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
4870 {
4871   PetscErrorCode    ierr;
4872   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
4873   int               nlhs  = 1,nrhs = 5;
4874   mxArray           *plhs[1],*prhs[5];
4875   long long int     lx = 0,ly = 0,ls = 0;
4876 
4877   PetscFunctionBegin;
4878   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4879   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4880   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
4881   PetscCheckSameComm(snes,1,x,2);
4882   PetscCheckSameComm(snes,1,y,3);
4883 
4884   /* call Matlab function in ctx with arguments x and y */
4885 
4886   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4887   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4888   ierr    = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
4889   prhs[0] = mxCreateDoubleScalar((double)ls);
4890   prhs[1] = mxCreateDoubleScalar((double)lx);
4891   prhs[2] = mxCreateDoubleScalar((double)ly);
4892   prhs[3] = mxCreateString(sctx->funcname);
4893   prhs[4] = sctx->ctx;
4894   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
4895   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
4896   mxDestroyArray(prhs[0]);
4897   mxDestroyArray(prhs[1]);
4898   mxDestroyArray(prhs[2]);
4899   mxDestroyArray(prhs[3]);
4900   mxDestroyArray(plhs[0]);
4901   PetscFunctionReturn(0);
4902 }
4903 
4904 #undef __FUNCT__
4905 #define __FUNCT__ "SNESSetFunctionMatlab"
4906 /*
4907    SNESSetFunctionMatlab - Sets the function evaluation routine and function
4908    vector for use by the SNES routines in solving systems of nonlinear
4909    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4910 
4911    Logically Collective on SNES
4912 
4913    Input Parameters:
4914 +  snes - the SNES context
4915 .  r - vector to store function value
4916 -  f - function evaluation routine
4917 
4918    Notes:
4919    The Newton-like methods typically solve linear systems of the form
4920 $      f'(x) x = -f(x),
4921    where f'(x) denotes the Jacobian matrix and f(x) is the function.
4922 
4923    Level: beginner
4924 
4925    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
4926 
4927 .keywords: SNES, nonlinear, set, function
4928 
4929 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4930 */
4931 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *f,mxArray *ctx)
4932 {
4933   PetscErrorCode    ierr;
4934   SNESMatlabContext *sctx;
4935 
4936   PetscFunctionBegin;
4937   /* currently sctx is memory bleed */
4938   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4939   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
4940   /*
4941      This should work, but it doesn't
4942   sctx->ctx = ctx;
4943   mexMakeArrayPersistent(sctx->ctx);
4944   */
4945   sctx->ctx = mxDuplicateArray(ctx);
4946   ierr      = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
4947   PetscFunctionReturn(0);
4948 }
4949 
4950 #undef __FUNCT__
4951 #define __FUNCT__ "SNESComputeJacobian_Matlab"
4952 /*
4953    SNESComputeJacobian_Matlab - Calls the function that has been set with SNESSetJacobianMatlab().
4954 
4955    Collective on SNES
4956 
4957    Input Parameters:
4958 +  snes - the SNES context
4959 .  x - input vector
4960 .  A, B - the matrices
4961 -  ctx - user context
4962 
4963    Output Parameter:
4964 .  flag - structure of the matrix
4965 
4966    Level: developer
4967 
4968 .keywords: SNES, nonlinear, compute, function
4969 
4970 .seealso: SNESSetFunction(), SNESGetFunction()
4971 @*/
4972 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat A,Mat B,MatStructure *flag, void *ctx)
4973 {
4974   PetscErrorCode    ierr;
4975   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
4976   int               nlhs  = 2,nrhs = 6;
4977   mxArray           *plhs[2],*prhs[6];
4978   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
4979 
4980   PetscFunctionBegin;
4981   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4982   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4983 
4984   /* call Matlab function in ctx with arguments x and y */
4985 
4986   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4987   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4988   ierr    = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
4989   ierr    = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
4990   prhs[0] = mxCreateDoubleScalar((double)ls);
4991   prhs[1] = mxCreateDoubleScalar((double)lx);
4992   prhs[2] = mxCreateDoubleScalar((double)lA);
4993   prhs[3] = mxCreateDoubleScalar((double)lB);
4994   prhs[4] = mxCreateString(sctx->funcname);
4995   prhs[5] = sctx->ctx;
4996   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
4997   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
4998   *flag   = (MatStructure) mxGetScalar(plhs[1]);CHKERRQ(ierr);
4999   mxDestroyArray(prhs[0]);
5000   mxDestroyArray(prhs[1]);
5001   mxDestroyArray(prhs[2]);
5002   mxDestroyArray(prhs[3]);
5003   mxDestroyArray(prhs[4]);
5004   mxDestroyArray(plhs[0]);
5005   mxDestroyArray(plhs[1]);
5006   PetscFunctionReturn(0);
5007 }
5008 
5009 #undef __FUNCT__
5010 #define __FUNCT__ "SNESSetJacobianMatlab"
5011 /*
5012    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
5013    vector for use by the SNES routines in solving systems of nonlinear
5014    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
5015 
5016    Logically Collective on SNES
5017 
5018    Input Parameters:
5019 +  snes - the SNES context
5020 .  A,B - Jacobian matrices
5021 .  J - function evaluation routine
5022 -  ctx - user context
5023 
5024    Level: developer
5025 
5026    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5027 
5028 .keywords: SNES, nonlinear, set, function
5029 
5030 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction(), J
5031 */
5032 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *J,mxArray *ctx)
5033 {
5034   PetscErrorCode    ierr;
5035   SNESMatlabContext *sctx;
5036 
5037   PetscFunctionBegin;
5038   /* currently sctx is memory bleed */
5039   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
5040   ierr = PetscStrallocpy(J,&sctx->funcname);CHKERRQ(ierr);
5041   /*
5042      This should work, but it doesn't
5043   sctx->ctx = ctx;
5044   mexMakeArrayPersistent(sctx->ctx);
5045   */
5046   sctx->ctx = mxDuplicateArray(ctx);
5047   ierr      = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
5048   PetscFunctionReturn(0);
5049 }
5050 
5051 #undef __FUNCT__
5052 #define __FUNCT__ "SNESMonitor_Matlab"
5053 /*
5054    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
5055 
5056    Collective on SNES
5057 
5058 .seealso: SNESSetFunction(), SNESGetFunction()
5059 @*/
5060 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
5061 {
5062   PetscErrorCode    ierr;
5063   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
5064   int               nlhs  = 1,nrhs = 6;
5065   mxArray           *plhs[1],*prhs[6];
5066   long long int     lx = 0,ls = 0;
5067   Vec               x  = snes->vec_sol;
5068 
5069   PetscFunctionBegin;
5070   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
5071 
5072   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
5073   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
5074   prhs[0] = mxCreateDoubleScalar((double)ls);
5075   prhs[1] = mxCreateDoubleScalar((double)it);
5076   prhs[2] = mxCreateDoubleScalar((double)fnorm);
5077   prhs[3] = mxCreateDoubleScalar((double)lx);
5078   prhs[4] = mxCreateString(sctx->funcname);
5079   prhs[5] = sctx->ctx;
5080   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
5081   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
5082   mxDestroyArray(prhs[0]);
5083   mxDestroyArray(prhs[1]);
5084   mxDestroyArray(prhs[2]);
5085   mxDestroyArray(prhs[3]);
5086   mxDestroyArray(prhs[4]);
5087   mxDestroyArray(plhs[0]);
5088   PetscFunctionReturn(0);
5089 }
5090 
5091 #undef __FUNCT__
5092 #define __FUNCT__ "SNESMonitorSetMatlab"
5093 /*
5094    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
5095 
5096    Level: developer
5097 
5098    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;
5099 
5100 .keywords: SNES, nonlinear, set, function
5101 
5102 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
5103 */
5104 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *f,mxArray *ctx)
5105 {
5106   PetscErrorCode    ierr;
5107   SNESMatlabContext *sctx;
5108 
5109   PetscFunctionBegin;
5110   /* currently sctx is memory bleed */
5111   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
5112   ierr = PetscStrallocpy(f,&sctx->funcname);CHKERRQ(ierr);
5113   /*
5114      This should work, but it doesn't
5115   sctx->ctx = ctx;
5116   mexMakeArrayPersistent(sctx->ctx);
5117   */
5118   sctx->ctx = mxDuplicateArray(ctx);
5119   ierr      = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,NULL);CHKERRQ(ierr);
5120   PetscFunctionReturn(0);
5121 }
5122 
5123 #endif
5124