xref: /petsc/src/snes/interface/snes.c (revision 988ea7d6cfcd11ddb37e50f03b34575f4eb92bde)
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_GSEval, 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_AMS)
187 #include <petscviewerams.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_AMS)
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_AMS)
245   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERAMS,&isams);CHKERRQ(ierr);
246 #endif
247   if (iascii) {
248     ierr = PetscObjectPrintClassNamePrefixType((PetscObject)snes,viewer,"SNES Object");CHKERRQ(ierr);
249     if (snes->ops->view) {
250       ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
251       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
252       ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
253     }
254     ierr = PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, maximum function evaluations=%D\n",snes->max_its,snes->max_funcs);CHKERRQ(ierr);
255     ierr = PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%G, absolute=%G, solution=%G\n",snes->rtol,snes->abstol,snes->stol);CHKERRQ(ierr);
256     ierr = PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",snes->linear_its);CHKERRQ(ierr);
257     ierr = PetscViewerASCIIPrintf(viewer,"  total number of function evaluations=%D\n",snes->nfuncs);CHKERRQ(ierr);
258     if (snes->gridsequence) {
259       ierr = PetscViewerASCIIPrintf(viewer,"  total number of grid sequence refinements=%D\n",snes->gridsequence);CHKERRQ(ierr);
260     }
261     if (snes->ksp_ewconv) {
262       kctx = (SNESKSPEW*)snes->kspconvctx;
263       if (kctx) {
264         ierr = PetscViewerASCIIPrintf(viewer,"  Eisenstat-Walker computation of KSP relative tolerance (version %D)\n",kctx->version);CHKERRQ(ierr);
265         ierr = PetscViewerASCIIPrintf(viewer,"    rtol_0=%G, rtol_max=%G, threshold=%G\n",kctx->rtol_0,kctx->rtol_max,kctx->threshold);CHKERRQ(ierr);
266         ierr = PetscViewerASCIIPrintf(viewer,"    gamma=%G, alpha=%G, alpha2=%G\n",kctx->gamma,kctx->alpha,kctx->alpha2);CHKERRQ(ierr);
267       }
268     }
269     if (snes->lagpreconditioner == -1) {
270       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is never rebuilt\n");CHKERRQ(ierr);
271     } else if (snes->lagpreconditioner > 1) {
272       ierr = PetscViewerASCIIPrintf(viewer,"  Preconditioned is rebuilt every %D new Jacobians\n",snes->lagpreconditioner);CHKERRQ(ierr);
273     }
274     if (snes->lagjacobian == -1) {
275       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is never rebuilt\n");CHKERRQ(ierr);
276     } else if (snes->lagjacobian > 1) {
277       ierr = PetscViewerASCIIPrintf(viewer,"  Jacobian is rebuilt every %D SNES iterations\n",snes->lagjacobian);CHKERRQ(ierr);
278     }
279   } else if (isstring) {
280     const char *type;
281     ierr = SNESGetType(snes,&type);CHKERRQ(ierr);
282     ierr = PetscViewerStringSPrintf(viewer," %-3.3s",type);CHKERRQ(ierr);
283   } else if (isbinary) {
284     PetscInt    classid = SNES_FILE_CLASSID;
285     MPI_Comm    comm;
286     PetscMPIInt rank;
287     char        type[256];
288 
289     ierr = PetscObjectGetComm((PetscObject)snes,&comm);CHKERRQ(ierr);
290     ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
291     if (!rank) {
292       ierr = PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);CHKERRQ(ierr);
293       ierr = PetscStrncpy(type,((PetscObject)snes)->type_name,256);CHKERRQ(ierr);
294       ierr = PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR,PETSC_FALSE);CHKERRQ(ierr);
295     }
296     if (snes->ops->view) {
297       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
298     }
299   } else if (isdraw) {
300     PetscDraw draw;
301     char      str[36];
302     PetscReal x,y,bottom,h;
303 
304     ierr   = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
305     ierr   = PetscDrawGetCurrentPoint(draw,&x,&y);CHKERRQ(ierr);
306     ierr   = PetscStrcpy(str,"SNES: ");CHKERRQ(ierr);
307     ierr   = PetscStrcat(str,((PetscObject)snes)->type_name);CHKERRQ(ierr);
308     ierr   = PetscDrawBoxedString(draw,x,y,PETSC_DRAW_BLUE,PETSC_DRAW_BLACK,str,NULL,&h);CHKERRQ(ierr);
309     bottom = y - h;
310     ierr   = PetscDrawPushCurrentPoint(draw,x,bottom);CHKERRQ(ierr);
311     if (snes->ops->view) {
312       ierr = (*snes->ops->view)(snes,viewer);CHKERRQ(ierr);
313     }
314 #if defined(PETSC_HAVE_AMS)
315   } else if (isams) {
316     if (((PetscObject)snes)->amsmem == -1) {
317       ierr = PetscObjectViewAMS((PetscObject)snes,viewer);CHKERRQ(ierr);
318       PetscStackCallAMS(AMS_Memory_take_access,(((PetscObject)snes)->amsmem));
319       PetscStackCallAMS(AMS_Memory_add_field,(((PetscObject)snes)->amsmem,"its",&snes->iter,1,AMS_INT,AMS_READ,AMS_COMMON,AMS_REDUCT_UNDEF));
320       if (!snes->conv_hist) {
321         ierr = SNESSetConvergenceHistory(snes,NULL,NULL,PETSC_DECIDE,PETSC_FALSE);CHKERRQ(ierr);
322       }
323       PetscStackCallAMS(AMS_Memory_add_field,(((PetscObject)snes)->amsmem,"conv_hist",snes->conv_hist,10,AMS_DOUBLE,AMS_READ,AMS_COMMON,AMS_REDUCT_UNDEF));
324       PetscStackCallAMS(AMS_Memory_grant_access,(((PetscObject)snes)->amsmem));
325     }
326 #endif
327   }
328   if (snes->linesearch) {
329     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
330     ierr = SNESGetSNESLineSearch(snes, &linesearch);CHKERRQ(ierr);
331     ierr = SNESLineSearchView(linesearch, viewer);CHKERRQ(ierr);
332     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
333   }
334   if (snes->pc && snes->usespc) {
335     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
336     ierr = SNESView(snes->pc, viewer);CHKERRQ(ierr);
337     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
338   }
339   ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
340   ierr = DMGetDMSNES(snes->dm,&dmsnes);CHKERRQ(ierr);
341   ierr = DMSNESView(dmsnes, viewer);CHKERRQ(ierr);
342   ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
343   if (snes->usesksp) {
344     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
345     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
346     ierr = KSPView(ksp,viewer);CHKERRQ(ierr);
347     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
348   }
349   if (isdraw) {
350     PetscDraw draw;
351     ierr = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
352     ierr = PetscDrawPopCurrentPoint(draw);CHKERRQ(ierr);
353   }
354   PetscFunctionReturn(0);
355 }
356 
357 /*
358   We retain a list of functions that also take SNES command
359   line options. These are called at the end SNESSetFromOptions()
360 */
361 #define MAXSETFROMOPTIONS 5
362 static PetscInt numberofsetfromoptions;
363 static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);
364 
365 #undef __FUNCT__
366 #define __FUNCT__ "SNESAddOptionsChecker"
367 /*@C
368   SNESAddOptionsChecker - Adds an additional function to check for SNES options.
369 
370   Not Collective
371 
372   Input Parameter:
373 . snescheck - function that checks for options
374 
375   Level: developer
376 
377 .seealso: SNESSetFromOptions()
378 @*/
379 PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
380 {
381   PetscFunctionBegin;
382   if (numberofsetfromoptions >= MAXSETFROMOPTIONS) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %D allowed", MAXSETFROMOPTIONS);
383   othersetfromoptions[numberofsetfromoptions++] = snescheck;
384   PetscFunctionReturn(0);
385 }
386 
387 extern PetscErrorCode  SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);
388 
389 #undef __FUNCT__
390 #define __FUNCT__ "SNESSetUpMatrixFree_Private"
391 static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
392 {
393   Mat            J;
394   KSP            ksp;
395   PC             pc;
396   PetscBool      match;
397   PetscErrorCode ierr;
398 
399   PetscFunctionBegin;
400   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
401 
402   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
403     Mat A = snes->jacobian, B = snes->jacobian_pre;
404     ierr = MatGetVecs(A ? A : B, NULL,&snes->vec_func);CHKERRQ(ierr);
405   }
406 
407   if (version == 1) {
408     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
409     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
410     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
411   } else if (version == 2) {
412     if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
413 #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128)
414     ierr = SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);CHKERRQ(ierr);
415 #else
416     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator rutines (version 2)");
417 #endif
418   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator rutines, only version 1 and 2");
419 
420   ierr = PetscInfo1(snes,"Setting default matrix-free operator routines (version %D)\n", version);CHKERRQ(ierr);
421   if (hasOperator) {
422 
423     /* This version replaces the user provided Jacobian matrix with a
424        matrix-free version but still employs the user-provided preconditioner matrix. */
425     ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);
426   } else {
427     /* This version replaces both the user-provided Jacobian and the user-
428      provided preconditioner Jacobian with the default matrix free version. */
429     if ((snes->pcside == PC_LEFT) && snes->pc) {
430       if (!snes->jacobian){ierr = SNESSetJacobian(snes,J,0,0,0);CHKERRQ(ierr);}
431     } else {
432       ierr = SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,0);CHKERRQ(ierr);
433     }
434     /* Force no preconditioner */
435     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
436     ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
437     ierr = PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);CHKERRQ(ierr);
438     if (!match) {
439       ierr = PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");CHKERRQ(ierr);
440       ierr = PCSetType(pc,PCNONE);CHKERRQ(ierr);
441     }
442   }
443   ierr = MatDestroy(&J);CHKERRQ(ierr);
444   PetscFunctionReturn(0);
445 }
446 
447 #undef __FUNCT__
448 #define __FUNCT__ "DMRestrictHook_SNESVecSol"
449 static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
450 {
451   SNES           snes = (SNES)ctx;
452   PetscErrorCode ierr;
453   Vec            Xfine,Xfine_named = NULL,Xcoarse;
454 
455   PetscFunctionBegin;
456   if (PetscLogPrintInfo) {
457     PetscInt finelevel,coarselevel,fineclevel,coarseclevel;
458     ierr = DMGetRefineLevel(dmfine,&finelevel);CHKERRQ(ierr);
459     ierr = DMGetCoarsenLevel(dmfine,&fineclevel);CHKERRQ(ierr);
460     ierr = DMGetRefineLevel(dmcoarse,&coarselevel);CHKERRQ(ierr);
461     ierr = DMGetCoarsenLevel(dmcoarse,&coarseclevel);CHKERRQ(ierr);
462     ierr = PetscInfo4(dmfine,"Restricting SNES solution vector from level %D-%D to level %D-%D\n",finelevel,fineclevel,coarselevel,coarseclevel);CHKERRQ(ierr);
463   }
464   if (dmfine == snes->dm) Xfine = snes->vec_sol;
465   else {
466     ierr  = DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);
467     Xfine = Xfine_named;
468   }
469   ierr = DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
470   ierr = MatRestrict(Restrict,Xfine,Xcoarse);CHKERRQ(ierr);
471   ierr = VecPointwiseMult(Xcoarse,Xcoarse,Rscale);CHKERRQ(ierr);
472   ierr = DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);CHKERRQ(ierr);
473   if (Xfine_named) {ierr = DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);CHKERRQ(ierr);}
474   PetscFunctionReturn(0);
475 }
476 
477 #undef __FUNCT__
478 #define __FUNCT__ "DMCoarsenHook_SNESVecSol"
479 static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm,DM dmc,void *ctx)
480 {
481   PetscErrorCode ierr;
482 
483   PetscFunctionBegin;
484   ierr = DMCoarsenHookAdd(dmc,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,ctx);CHKERRQ(ierr);
485   PetscFunctionReturn(0);
486 }
487 
488 #undef __FUNCT__
489 #define __FUNCT__ "KSPComputeOperators_SNES"
490 /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
491  * safely call SNESGetDM() in their residual evaluation routine. */
492 static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,MatStructure *mstruct,void *ctx)
493 {
494   SNES           snes = (SNES)ctx;
495   PetscErrorCode ierr;
496   Mat            Asave = A,Bsave = B;
497   Vec            X,Xnamed = NULL;
498   DM             dmsave;
499   void           *ctxsave;
500   PetscErrorCode (*jac)(SNES,Vec,Mat*,Mat*,MatStructure*,void*);
501 
502   PetscFunctionBegin;
503   dmsave = snes->dm;
504   ierr   = KSPGetDM(ksp,&snes->dm);CHKERRQ(ierr);
505   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
506   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
507     ierr = DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
508     X    = Xnamed;
509     ierr = SNESGetJacobian(snes,NULL,NULL,&jac,&ctxsave);CHKERRQ(ierr);
510     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
511     if (jac == SNESComputeJacobianDefaultColor) {
512       ierr = SNESSetJacobian(snes,NULL,NULL,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
513     }
514   }
515   /* put the previous context back */
516 
517   ierr = SNESComputeJacobian(snes,X,&A,&B,mstruct);CHKERRQ(ierr);
518   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) {
519     ierr = SNESSetJacobian(snes,NULL,NULL,jac,ctxsave);CHKERRQ(ierr);
520   }
521 
522   if (A != Asave || B != Bsave) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_SUP,"No support for changing matrices at this time");
523   if (Xnamed) {
524     ierr = DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);CHKERRQ(ierr);
525   }
526   snes->dm = dmsave;
527   PetscFunctionReturn(0);
528 }
529 
530 #undef __FUNCT__
531 #define __FUNCT__ "SNESSetUpMatrices"
532 /*@
533    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()
534 
535    Collective
536 
537    Input Arguments:
538 .  snes - snes to configure
539 
540    Level: developer
541 
542 .seealso: SNESSetUp()
543 @*/
544 PetscErrorCode SNESSetUpMatrices(SNES snes)
545 {
546   PetscErrorCode ierr;
547   DM             dm;
548   DMSNES         sdm;
549 
550   PetscFunctionBegin;
551   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
552   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
553   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_PLIB,"DMSNES not properly configured");
554   else if (!snes->jacobian && snes->mf) {
555     Mat  J;
556     void *functx;
557     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
558     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
559     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
560     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
561     ierr = SNESSetJacobian(snes,J,J,0,0);CHKERRQ(ierr);
562     ierr = MatDestroy(&J);CHKERRQ(ierr);
563   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
564     Mat J,B;
565     ierr = MatCreateSNESMF(snes,&J);CHKERRQ(ierr);
566     ierr = MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);CHKERRQ(ierr);
567     ierr = MatSetFromOptions(J);CHKERRQ(ierr);
568     ierr = DMCreateMatrix(snes->dm,MATAIJ,&B);CHKERRQ(ierr);
569     /* sdm->computejacobian was already set to reach here */
570     ierr = SNESSetJacobian(snes,J,B,NULL,NULL);CHKERRQ(ierr);
571     ierr = MatDestroy(&J);CHKERRQ(ierr);
572     ierr = MatDestroy(&B);CHKERRQ(ierr);
573   } else if (!snes->jacobian_pre) {
574     Mat J,B;
575     J    = snes->jacobian;
576     ierr = DMCreateMatrix(snes->dm,MATAIJ,&B);CHKERRQ(ierr);
577     ierr = SNESSetJacobian(snes,J ? J : B,B,NULL,NULL);CHKERRQ(ierr);
578     ierr = MatDestroy(&B);CHKERRQ(ierr);
579   }
580   {
581     KSP ksp;
582     ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
583     ierr = KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);CHKERRQ(ierr);
584     ierr = DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);CHKERRQ(ierr);
585   }
586   PetscFunctionReturn(0);
587 }
588 
589 #undef __FUNCT__
590 #define __FUNCT__ "SNESSetFromOptions"
591 /*@
592    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.
593 
594    Collective on SNES
595 
596    Input Parameter:
597 .  snes - the SNES context
598 
599    Options Database Keys:
600 +  -snes_type <type> - ls, tr, ngmres, ncg, richardson, qn, vi, fas
601 .  -snes_stol - convergence tolerance in terms of the norm
602                 of the change in the solution between steps
603 .  -snes_atol <abstol> - absolute tolerance of residual norm
604 .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
605 .  -snes_max_it <max_it> - maximum number of iterations
606 .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
607 .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
608 .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
609 .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
610 .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
611 .  -snes_trtol <trtol> - trust region tolerance
612 .  -snes_no_convergence_test - skip convergence test in nonlinear
613                                solver; hence iterations will continue until max_it
614                                or some other criterion is reached. Saves expense
615                                of convergence test
616 .  -snes_monitor <optional filename> - prints residual norm at each iteration. if no
617                                        filename given prints to stdout
618 .  -snes_monitor_solution - plots solution at each iteration
619 .  -snes_monitor_residual - plots residual (not its norm) at each iteration
620 .  -snes_monitor_solution_update - plots update to solution at each iteration
621 .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
622 .  -snes_monitor_lg_range - plots residual norm at each iteration
623 .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
624 .  -snes_fd_color - use finite differences with coloring to compute Jacobian
625 .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
626 -  -snes_converged_reason - print the reason for convergence/divergence after each solve
627 
628     Options Database for Eisenstat-Walker method:
629 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
630 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
631 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
632 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
633 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
634 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
635 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
636 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
637 
638    Notes:
639    To see all options, run your program with the -help option or consult
640    the <A href="../../docs/manual.pdf#nameddest=ch_snes">SNES chapter of the users manual</A>.
641 
642    Level: beginner
643 
644 .keywords: SNES, nonlinear, set, options, database
645 
646 .seealso: SNESSetOptionsPrefix()
647 @*/
648 PetscErrorCode  SNESSetFromOptions(SNES snes)
649 {
650   PetscBool      flg,pcset;
651   PetscInt       i,indx,lag,grids;
652   MatStructure   matflag;
653   const char     *deft        = SNESNEWTONLS;
654   const char     *convtests[] = {"default","skip"};
655   SNESKSPEW      *kctx        = NULL;
656   char           type[256], monfilename[PETSC_MAX_PATH_LEN];
657   PetscViewer    monviewer;
658   PetscErrorCode ierr;
659   PCSide         pcside;
660   const char     *optionsprefix;
661 
662   PetscFunctionBegin;
663   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
664 
665   if (!SNESRegisterAllCalled) {ierr = SNESRegisterAll(NULL);CHKERRQ(ierr);}
666   ierr = PetscObjectOptionsBegin((PetscObject)snes);CHKERRQ(ierr);
667   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
668   ierr = PetscOptionsList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);CHKERRQ(ierr);
669   if (flg) {
670     ierr = SNESSetType(snes,type);CHKERRQ(ierr);
671   } else if (!((PetscObject)snes)->type_name) {
672     ierr = SNESSetType(snes,deft);CHKERRQ(ierr);
673   }
674   /* not used here, but called so will go into help messaage */
675   ierr = PetscOptionsName("-snes_view","Print detailed information on solver used","SNESView",0);CHKERRQ(ierr);
676 
677   ierr = PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,0);CHKERRQ(ierr);
678   ierr = PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,0);CHKERRQ(ierr);
679 
680   ierr = PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,0);CHKERRQ(ierr);
681   ierr = PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,NULL);CHKERRQ(ierr);
682   ierr = PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,NULL);CHKERRQ(ierr);
683   ierr = PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,NULL);CHKERRQ(ierr);
684   ierr = PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,NULL);CHKERRQ(ierr);
685   ierr = PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,NULL);CHKERRQ(ierr);
686 
687   ierr = PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);CHKERRQ(ierr);
688   if (flg) {
689     ierr = SNESSetLagPreconditioner(snes,lag);CHKERRQ(ierr);
690   }
691   ierr = PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);CHKERRQ(ierr);
692   if (flg) {
693     ierr = SNESSetLagJacobian(snes,lag);CHKERRQ(ierr);
694   }
695   ierr = PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);CHKERRQ(ierr);
696   if (flg) {
697     ierr = SNESSetGridSequence(snes,grids);CHKERRQ(ierr);
698   }
699 
700   ierr = PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);CHKERRQ(ierr);
701   if (flg) {
702     switch (indx) {
703     case 0: ierr = SNESSetConvergenceTest(snes,SNESConvergedDefault,NULL,NULL);CHKERRQ(ierr); break;
704     case 1: ierr = SNESSetConvergenceTest(snes,SNESSkipConverged,NULL,NULL);CHKERRQ(ierr);    break;
705     }
706   }
707 
708   ierr = PetscOptionsBool("-snes_converged_reason","Print reason for converged or diverged","SNESSolve",snes->printreason,&snes->printreason,NULL);CHKERRQ(ierr);
709 
710   ierr = PetscOptionsEList("-snes_norm_type","SNES Norm type","SNESSetNormType",SNESNormTypes,5,"function",&indx,&flg);CHKERRQ(ierr);
711   if (flg) { ierr = SNESSetNormType(snes,(SNESNormType)indx);CHKERRQ(ierr); }
712 
713   kctx = (SNESKSPEW*)snes->kspconvctx;
714 
715   ierr = PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,NULL);CHKERRQ(ierr);
716 
717   ierr = PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,0);CHKERRQ(ierr);
718   ierr = PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,0);CHKERRQ(ierr);
719   ierr = PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,0);CHKERRQ(ierr);
720   ierr = PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,0);CHKERRQ(ierr);
721   ierr = PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,0);CHKERRQ(ierr);
722   ierr = PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,0);CHKERRQ(ierr);
723   ierr = PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,0);CHKERRQ(ierr);
724 
725   flg  = PETSC_FALSE;
726   ierr = PetscOptionsBool("-snes_check_jacobian","Check each Jacobian with a differenced one","SNESUpdateCheckJacobian",flg,&flg,NULL);CHKERRQ(ierr);
727   if (flg) {
728     ierr = SNESSetUpdate(snes,SNESUpdateCheckJacobian);CHKERRQ(ierr);
729   }
730 
731   flg  = PETSC_FALSE;
732   ierr = PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,NULL);CHKERRQ(ierr);
733   if (flg) {ierr = SNESMonitorCancel(snes);CHKERRQ(ierr);}
734 
735   ierr = PetscOptionsString("-snes_monitor","Monitor norm of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
736   if (flg) {
737     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
738     ierr = SNESMonitorSet(snes,SNESMonitorDefault,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
739   }
740 
741   ierr = PetscOptionsString("-snes_monitor_range","Monitor range of elements of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
742   if (flg) {
743     ierr = SNESMonitorSet(snes,SNESMonitorRange,0,0);CHKERRQ(ierr);
744   }
745 
746   ierr = PetscOptionsString("-snes_ratiomonitor","Monitor ratios of norms of function","SNESMonitorSetRatio","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
747   if (flg) {
748     ierr = PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);CHKERRQ(ierr);
749     ierr = SNESMonitorSetRatio(snes,monviewer);CHKERRQ(ierr);
750   }
751 
752   ierr = PetscOptionsString("-snes_monitor_short","Monitor norm of function (fewer digits)","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,SNESMonitorDefaultShort,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
756   }
757 
758   ierr = PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
759   if (flg) {ierr = PetscPythonMonitorSet((PetscObject)snes,monfilename);CHKERRQ(ierr);}
760 
761   flg  = PETSC_FALSE;
762   ierr = PetscOptionsBool("-snes_monitor_solution","Plot solution at each iteration","SNESMonitorSolution",flg,&flg,NULL);CHKERRQ(ierr);
763   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolution,0,0);CHKERRQ(ierr);}
764   flg  = PETSC_FALSE;
765   ierr = PetscOptionsBool("-snes_monitor_solution_update","Plot correction at each iteration","SNESMonitorSolutionUpdate",flg,&flg,NULL);CHKERRQ(ierr);
766   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorSolutionUpdate,0,0);CHKERRQ(ierr);}
767   flg  = PETSC_FALSE;
768   ierr = PetscOptionsBool("-snes_monitor_residual","Plot residual at each iteration","SNESMonitorResidual",flg,&flg,NULL);CHKERRQ(ierr);
769   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorResidual,0,0);CHKERRQ(ierr);}
770   flg  = PETSC_FALSE;
771   ierr = PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,NULL);CHKERRQ(ierr);
772   if (flg) {
773     PetscDrawLG ctx;
774 
775     ierr = SNESMonitorLGCreate(0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
776     ierr = SNESMonitorSet(snes,SNESMonitorLGResidualNorm,ctx,(PetscErrorCode (*)(void**))SNESMonitorLGDestroy);CHKERRQ(ierr);
777   }
778   flg  = PETSC_FALSE;
779   ierr = PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);CHKERRQ(ierr);
780   if (flg) {
781     PetscViewer ctx;
782 
783     ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);CHKERRQ(ierr);
784     ierr = SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
785   }
786 
787   flg  = PETSC_FALSE;
788   ierr = PetscOptionsBool("-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",flg,&flg,NULL);CHKERRQ(ierr);
789   if (flg) {ierr = SNESMonitorSet(snes,SNESMonitorJacUpdateSpectrum,0,0);CHKERRQ(ierr);}
790 
791   flg  = PETSC_FALSE;
792   ierr = PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);CHKERRQ(ierr);
793   if (flg) {
794     void *functx;
795     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
796     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);CHKERRQ(ierr);
797     ierr = PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");CHKERRQ(ierr);
798   }
799 
800   flg  = PETSC_FALSE;
801   ierr = PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);CHKERRQ(ierr);
802   if (flg) {
803     ierr = SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);CHKERRQ(ierr);
804   }
805 
806   flg  = PETSC_FALSE;
807   ierr = PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);CHKERRQ(ierr);
808   if (flg) {
809     void *functx;
810     ierr = SNESGetFunction(snes,NULL,NULL,&functx);CHKERRQ(ierr);
811     ierr = SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,0);CHKERRQ(ierr);
812     ierr = PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");CHKERRQ(ierr);
813   }
814 
815   flg  = PETSC_FALSE;
816   ierr = PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf_operator,&flg);CHKERRQ(ierr);
817   if (flg && snes->mf_operator) {
818     snes->mf_operator = PETSC_TRUE;
819     snes->mf          = PETSC_TRUE;
820   }
821   flg  = PETSC_FALSE;
822   ierr = PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf,&flg);CHKERRQ(ierr);
823   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
824   ierr = PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,0);CHKERRQ(ierr);
825 
826   flg  = PETSC_FALSE;
827   ierr = SNESGetPCSide(snes,&pcside);CHKERRQ(ierr);
828   ierr = PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);CHKERRQ(ierr);
829   if (flg) {ierr = SNESSetPCSide(snes,pcside);CHKERRQ(ierr);}
830 
831 #if defined(PETSC_HAVE_AMS)
832   {
833   PetscBool set;
834   flg  = PETSC_FALSE;
835   ierr = PetscOptionsBool("-snes_ams_block","Block for AMS memory snooper at end of SNESSolve","PetscObjectAMSBlock",((PetscObject)snes)->amspublishblock,&flg,&set);CHKERRQ(ierr);
836   if (set) {
837     ierr = PetscObjectAMSSetBlock((PetscObject)snes,flg);CHKERRQ(ierr);
838   }
839   }
840 #endif
841 
842   for (i = 0; i < numberofsetfromoptions; i++) {
843     ierr = (*othersetfromoptions[i])(snes);CHKERRQ(ierr);
844   }
845 
846   if (snes->ops->setfromoptions) {
847     ierr = (*snes->ops->setfromoptions)(snes);CHKERRQ(ierr);
848   }
849 
850   /* process any options handlers added with PetscObjectAddOptionsHandler() */
851   ierr = PetscObjectProcessOptionsHandlers((PetscObject)snes);CHKERRQ(ierr);
852   ierr = PetscOptionsEnd();CHKERRQ(ierr);
853 
854   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
855   ierr = KSPGetOperators(snes->ksp,NULL,NULL,&matflag);CHKERRQ(ierr);
856   ierr = KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre,matflag);CHKERRQ(ierr);
857   ierr = KSPSetFromOptions(snes->ksp);CHKERRQ(ierr);
858 
859   if (!snes->linesearch) {
860     ierr = SNESGetSNESLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
861   }
862   ierr = SNESLineSearchSetFromOptions(snes->linesearch);CHKERRQ(ierr);
863 
864   /* if someone has set the SNES PC type, create it. */
865   ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
866   ierr = PetscOptionsHasName(optionsprefix, "-npc_snes_type", &pcset);CHKERRQ(ierr);
867   if (pcset && (!snes->pc)) {
868     ierr = SNESGetPC(snes, &snes->pc);CHKERRQ(ierr);
869   }
870   PetscFunctionReturn(0);
871 }
872 
873 #undef __FUNCT__
874 #define __FUNCT__ "SNESSetComputeApplicationContext"
875 /*@
876    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
877    the nonlinear solvers.
878 
879    Logically Collective on SNES
880 
881    Input Parameters:
882 +  snes - the SNES context
883 .  compute - function to compute the context
884 -  destroy - function to destroy the context
885 
886    Level: intermediate
887 
888 .keywords: SNES, nonlinear, set, application, context
889 
890 .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
891 @*/
892 PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
893 {
894   PetscFunctionBegin;
895   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
896   snes->ops->usercompute = compute;
897   snes->ops->userdestroy = destroy;
898   PetscFunctionReturn(0);
899 }
900 
901 #undef __FUNCT__
902 #define __FUNCT__ "SNESSetApplicationContext"
903 /*@
904    SNESSetApplicationContext - Sets the optional user-defined context for
905    the nonlinear solvers.
906 
907    Logically Collective on SNES
908 
909    Input Parameters:
910 +  snes - the SNES context
911 -  usrP - optional user context
912 
913    Level: intermediate
914 
915 .keywords: SNES, nonlinear, set, application, context
916 
917 .seealso: SNESGetApplicationContext()
918 @*/
919 PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
920 {
921   PetscErrorCode ierr;
922   KSP            ksp;
923 
924   PetscFunctionBegin;
925   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
926   ierr       = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
927   ierr       = KSPSetApplicationContext(ksp,usrP);CHKERRQ(ierr);
928   snes->user = usrP;
929   PetscFunctionReturn(0);
930 }
931 
932 #undef __FUNCT__
933 #define __FUNCT__ "SNESGetApplicationContext"
934 /*@
935    SNESGetApplicationContext - Gets the user-defined context for the
936    nonlinear solvers.
937 
938    Not Collective
939 
940    Input Parameter:
941 .  snes - SNES context
942 
943    Output Parameter:
944 .  usrP - user context
945 
946    Level: intermediate
947 
948 .keywords: SNES, nonlinear, get, application, context
949 
950 .seealso: SNESSetApplicationContext()
951 @*/
952 PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
953 {
954   PetscFunctionBegin;
955   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
956   *(void**)usrP = snes->user;
957   PetscFunctionReturn(0);
958 }
959 
960 #undef __FUNCT__
961 #define __FUNCT__ "SNESGetIterationNumber"
962 /*@
963    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
964    at this time.
965 
966    Not Collective
967 
968    Input Parameter:
969 .  snes - SNES context
970 
971    Output Parameter:
972 .  iter - iteration number
973 
974    Notes:
975    For example, during the computation of iteration 2 this would return 1.
976 
977    This is useful for using lagged Jacobians (where one does not recompute the
978    Jacobian at each SNES iteration). For example, the code
979 .vb
980       ierr = SNESGetIterationNumber(snes,&it);
981       if (!(it % 2)) {
982         [compute Jacobian here]
983       }
984 .ve
985    can be used in your ComputeJacobian() function to cause the Jacobian to be
986    recomputed every second SNES iteration.
987 
988    Level: intermediate
989 
990 .keywords: SNES, nonlinear, get, iteration, number,
991 
992 .seealso:   SNESGetFunctionNorm(), SNESGetLinearSolveIterations()
993 @*/
994 PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
995 {
996   PetscFunctionBegin;
997   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
998   PetscValidIntPointer(iter,2);
999   *iter = snes->iter;
1000   PetscFunctionReturn(0);
1001 }
1002 
1003 #undef __FUNCT__
1004 #define __FUNCT__ "SNESSetIterationNumber"
1005 /*@
1006    SNESSetIterationNumber - Sets the current iteration number.
1007 
1008    Not Collective
1009 
1010    Input Parameter:
1011 .  snes - SNES context
1012 .  iter - iteration number
1013 
1014    Level: developer
1015 
1016 .keywords: SNES, nonlinear, set, iteration, number,
1017 
1018 .seealso:   SNESGetFunctionNorm(), SNESGetLinearSolveIterations()
1019 @*/
1020 PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
1021 {
1022   PetscErrorCode ierr;
1023 
1024   PetscFunctionBegin;
1025   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1026   ierr       = PetscObjectAMSTakeAccess((PetscObject)snes);CHKERRQ(ierr);
1027   snes->iter = iter;
1028   ierr       = PetscObjectAMSGrantAccess((PetscObject)snes);CHKERRQ(ierr);
1029   PetscFunctionReturn(0);
1030 }
1031 
1032 #undef __FUNCT__
1033 #define __FUNCT__ "SNESGetFunctionNorm"
1034 /*@
1035    SNESGetFunctionNorm - Gets the norm of the current function that was set
1036    with SNESSSetFunction().
1037 
1038    Collective on SNES
1039 
1040    Input Parameter:
1041 .  snes - SNES context
1042 
1043    Output Parameter:
1044 .  fnorm - 2-norm of function
1045 
1046    Level: intermediate
1047 
1048 .keywords: SNES, nonlinear, get, function, norm
1049 
1050 .seealso: SNESGetFunction(), SNESGetIterationNumber(), SNESGetLinearSolveIterations()
1051 @*/
1052 PetscErrorCode  SNESGetFunctionNorm(SNES snes,PetscReal *fnorm)
1053 {
1054   PetscFunctionBegin;
1055   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1056   PetscValidScalarPointer(fnorm,2);
1057   *fnorm = snes->norm;
1058   PetscFunctionReturn(0);
1059 }
1060 
1061 
1062 #undef __FUNCT__
1063 #define __FUNCT__ "SNESSetFunctionNorm"
1064 /*@
1065    SNESSetFunctionNorm - Sets the 2-norm of the current function computed using VecNorm().
1066 
1067    Collective on SNES
1068 
1069    Input Parameter:
1070 .  snes - SNES context
1071 .  fnorm - 2-norm of function
1072 
1073    Level: developer
1074 
1075 .keywords: SNES, nonlinear, set, function, norm
1076 
1077 .seealso: SNESSetFunction(), SNESSetIterationNumber(), VecNorm().
1078 @*/
1079 PetscErrorCode  SNESSetFunctionNorm(SNES snes,PetscReal fnorm)
1080 {
1081 
1082   PetscErrorCode ierr;
1083 
1084   PetscFunctionBegin;
1085   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1086   ierr       = PetscObjectAMSTakeAccess((PetscObject)snes);CHKERRQ(ierr);
1087   snes->norm = fnorm;
1088   ierr       = PetscObjectAMSGrantAccess((PetscObject)snes);CHKERRQ(ierr);
1089   PetscFunctionReturn(0);
1090 }
1091 
1092 #undef __FUNCT__
1093 #define __FUNCT__ "SNESGetNonlinearStepFailures"
1094 /*@
1095    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1096    attempted by the nonlinear solver.
1097 
1098    Not Collective
1099 
1100    Input Parameter:
1101 .  snes - SNES context
1102 
1103    Output Parameter:
1104 .  nfails - number of unsuccessful steps attempted
1105 
1106    Notes:
1107    This counter is reset to zero for each successive call to SNESSolve().
1108 
1109    Level: intermediate
1110 
1111 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1112 
1113 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1114           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
1115 @*/
1116 PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
1117 {
1118   PetscFunctionBegin;
1119   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1120   PetscValidIntPointer(nfails,2);
1121   *nfails = snes->numFailures;
1122   PetscFunctionReturn(0);
1123 }
1124 
1125 #undef __FUNCT__
1126 #define __FUNCT__ "SNESSetMaxNonlinearStepFailures"
1127 /*@
1128    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1129    attempted by the nonlinear solver before it gives up.
1130 
1131    Not Collective
1132 
1133    Input Parameters:
1134 +  snes     - SNES context
1135 -  maxFails - maximum of unsuccessful steps
1136 
1137    Level: intermediate
1138 
1139 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1140 
1141 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1142           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1143 @*/
1144 PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1145 {
1146   PetscFunctionBegin;
1147   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1148   snes->maxFailures = maxFails;
1149   PetscFunctionReturn(0);
1150 }
1151 
1152 #undef __FUNCT__
1153 #define __FUNCT__ "SNESGetMaxNonlinearStepFailures"
1154 /*@
1155    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1156    attempted by the nonlinear solver before it gives up.
1157 
1158    Not Collective
1159 
1160    Input Parameter:
1161 .  snes     - SNES context
1162 
1163    Output Parameter:
1164 .  maxFails - maximum of unsuccessful steps
1165 
1166    Level: intermediate
1167 
1168 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1169 
1170 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1171           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1172 
1173 @*/
1174 PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1175 {
1176   PetscFunctionBegin;
1177   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1178   PetscValidIntPointer(maxFails,2);
1179   *maxFails = snes->maxFailures;
1180   PetscFunctionReturn(0);
1181 }
1182 
1183 #undef __FUNCT__
1184 #define __FUNCT__ "SNESGetNumberFunctionEvals"
1185 /*@
1186    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1187      done by SNES.
1188 
1189    Not Collective
1190 
1191    Input Parameter:
1192 .  snes     - SNES context
1193 
1194    Output Parameter:
1195 .  nfuncs - number of evaluations
1196 
1197    Level: intermediate
1198 
1199 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1200 
1201 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures()
1202 @*/
1203 PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1204 {
1205   PetscFunctionBegin;
1206   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1207   PetscValidIntPointer(nfuncs,2);
1208   *nfuncs = snes->nfuncs;
1209   PetscFunctionReturn(0);
1210 }
1211 
1212 #undef __FUNCT__
1213 #define __FUNCT__ "SNESGetLinearSolveFailures"
1214 /*@
1215    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1216    linear solvers.
1217 
1218    Not Collective
1219 
1220    Input Parameter:
1221 .  snes - SNES context
1222 
1223    Output Parameter:
1224 .  nfails - number of failed solves
1225 
1226    Notes:
1227    This counter is reset to zero for each successive call to SNESSolve().
1228 
1229    Level: intermediate
1230 
1231 .keywords: SNES, nonlinear, get, number, unsuccessful, steps
1232 
1233 .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1234 @*/
1235 PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
1236 {
1237   PetscFunctionBegin;
1238   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1239   PetscValidIntPointer(nfails,2);
1240   *nfails = snes->numLinearSolveFailures;
1241   PetscFunctionReturn(0);
1242 }
1243 
1244 #undef __FUNCT__
1245 #define __FUNCT__ "SNESSetMaxLinearSolveFailures"
1246 /*@
1247    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1248    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE
1249 
1250    Logically Collective on SNES
1251 
1252    Input Parameters:
1253 +  snes     - SNES context
1254 -  maxFails - maximum allowed linear solve failures
1255 
1256    Level: intermediate
1257 
1258    Notes: By default this is 0; that is SNES returns on the first failed linear solve
1259 
1260 .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps
1261 
1262 .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1263 @*/
1264 PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1265 {
1266   PetscFunctionBegin;
1267   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1268   PetscValidLogicalCollectiveInt(snes,maxFails,2);
1269   snes->maxLinearSolveFailures = maxFails;
1270   PetscFunctionReturn(0);
1271 }
1272 
1273 #undef __FUNCT__
1274 #define __FUNCT__ "SNESGetMaxLinearSolveFailures"
1275 /*@
1276    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1277      are allowed before SNES terminates
1278 
1279    Not Collective
1280 
1281    Input Parameter:
1282 .  snes     - SNES context
1283 
1284    Output Parameter:
1285 .  maxFails - maximum of unsuccessful solves allowed
1286 
1287    Level: intermediate
1288 
1289    Notes: By default this is 1; that is SNES returns on the first failed linear solve
1290 
1291 .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps
1292 
1293 .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1294 @*/
1295 PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1296 {
1297   PetscFunctionBegin;
1298   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1299   PetscValidIntPointer(maxFails,2);
1300   *maxFails = snes->maxLinearSolveFailures;
1301   PetscFunctionReturn(0);
1302 }
1303 
1304 #undef __FUNCT__
1305 #define __FUNCT__ "SNESGetLinearSolveIterations"
1306 /*@
1307    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1308    used by the nonlinear solver.
1309 
1310    Not Collective
1311 
1312    Input Parameter:
1313 .  snes - SNES context
1314 
1315    Output Parameter:
1316 .  lits - number of linear iterations
1317 
1318    Notes:
1319    This counter is reset to zero for each successive call to SNESSolve().
1320 
1321    Level: intermediate
1322 
1323 .keywords: SNES, nonlinear, get, number, linear, iterations
1324 
1325 .seealso:  SNESGetIterationNumber(), SNESGetFunctionNorm(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures()
1326 @*/
1327 PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
1328 {
1329   PetscFunctionBegin;
1330   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1331   PetscValidIntPointer(lits,2);
1332   *lits = snes->linear_its;
1333   PetscFunctionReturn(0);
1334 }
1335 
1336 
1337 #undef __FUNCT__
1338 #define __FUNCT__ "SNESSetKSP"
1339 /*@
1340    SNESSetKSP - Sets a KSP context for the SNES object to use
1341 
1342    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm
1343 
1344    Input Parameters:
1345 +  snes - the SNES context
1346 -  ksp - the KSP context
1347 
1348    Notes:
1349    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1350    so this routine is rarely needed.
1351 
1352    The KSP object that is already in the SNES object has its reference count
1353    decreased by one.
1354 
1355    Level: developer
1356 
1357 .keywords: SNES, nonlinear, get, KSP, context
1358 
1359 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1360 @*/
1361 PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1362 {
1363   PetscErrorCode ierr;
1364 
1365   PetscFunctionBegin;
1366   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1367   PetscValidHeaderSpecific(ksp,KSP_CLASSID,2);
1368   PetscCheckSameComm(snes,1,ksp,2);
1369   ierr = PetscObjectReference((PetscObject)ksp);CHKERRQ(ierr);
1370   if (snes->ksp) {ierr = PetscObjectDereference((PetscObject)snes->ksp);CHKERRQ(ierr);}
1371   snes->ksp = ksp;
1372   PetscFunctionReturn(0);
1373 }
1374 
1375 /* -----------------------------------------------------------*/
1376 #undef __FUNCT__
1377 #define __FUNCT__ "SNESCreate"
1378 /*@
1379    SNESCreate - Creates a nonlinear solver context.
1380 
1381    Collective on MPI_Comm
1382 
1383    Input Parameters:
1384 .  comm - MPI communicator
1385 
1386    Output Parameter:
1387 .  outsnes - the new SNES context
1388 
1389    Options Database Keys:
1390 +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1391                and no preconditioning matrix
1392 .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1393                products, and a user-provided preconditioning matrix
1394                as set by SNESSetJacobian()
1395 -   -snes_fd - Uses (slow!) finite differences to compute Jacobian
1396 
1397    Level: beginner
1398 
1399 .keywords: SNES, nonlinear, create, context
1400 
1401 .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()
1402 
1403 @*/
1404 PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1405 {
1406   PetscErrorCode ierr;
1407   SNES           snes;
1408   SNESKSPEW      *kctx;
1409 
1410   PetscFunctionBegin;
1411   PetscValidPointer(outsnes,2);
1412   *outsnes = NULL;
1413 #if !defined(PETSC_USE_DYNAMIC_LIBRARIES)
1414   ierr = SNESInitializePackage(NULL);CHKERRQ(ierr);
1415 #endif
1416 
1417   ierr = PetscHeaderCreate(snes,_p_SNES,struct _SNESOps,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);CHKERRQ(ierr);
1418 
1419   snes->ops->converged    = SNESConvergedDefault;
1420   snes->usesksp           = PETSC_TRUE;
1421   snes->tolerancesset     = PETSC_FALSE;
1422   snes->max_its           = 50;
1423   snes->max_funcs         = 10000;
1424   snes->norm              = 0.0;
1425   snes->normtype          = SNES_NORM_FUNCTION;
1426   snes->rtol              = 1.e-8;
1427   snes->ttol              = 0.0;
1428   snes->abstol            = 1.e-50;
1429   snes->stol              = 1.e-8;
1430   snes->deltatol          = 1.e-12;
1431   snes->nfuncs            = 0;
1432   snes->numFailures       = 0;
1433   snes->maxFailures       = 1;
1434   snes->linear_its        = 0;
1435   snes->lagjacobian       = 1;
1436   snes->lagpreconditioner = 1;
1437   snes->numbermonitors    = 0;
1438   snes->data              = 0;
1439   snes->setupcalled       = PETSC_FALSE;
1440   snes->ksp_ewconv        = PETSC_FALSE;
1441   snes->nwork             = 0;
1442   snes->work              = 0;
1443   snes->nvwork            = 0;
1444   snes->vwork             = 0;
1445   snes->conv_hist_len     = 0;
1446   snes->conv_hist_max     = 0;
1447   snes->conv_hist         = NULL;
1448   snes->conv_hist_its     = NULL;
1449   snes->conv_hist_reset   = PETSC_TRUE;
1450   snes->vec_func_init_set = PETSC_FALSE;
1451   snes->norm_init         = 0.;
1452   snes->norm_init_set     = PETSC_FALSE;
1453   snes->reason            = SNES_CONVERGED_ITERATING;
1454   snes->pcside            = PC_RIGHT;
1455 
1456   snes->mf          = PETSC_FALSE;
1457   snes->mf_operator = PETSC_FALSE;
1458   snes->mf_version  = 1;
1459 
1460   snes->numLinearSolveFailures = 0;
1461   snes->maxLinearSolveFailures = 1;
1462 
1463   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1464   ierr = PetscNewLog(snes,SNESKSPEW,&kctx);CHKERRQ(ierr);
1465 
1466   snes->kspconvctx  = (void*)kctx;
1467   kctx->version     = 2;
1468   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1469                              this was too large for some test cases */
1470   kctx->rtol_last   = 0.0;
1471   kctx->rtol_max    = .9;
1472   kctx->gamma       = 1.0;
1473   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1474   kctx->alpha2      = kctx->alpha;
1475   kctx->threshold   = .1;
1476   kctx->lresid_last = 0.0;
1477   kctx->norm_last   = 0.0;
1478 
1479   *outsnes = snes;
1480   PetscFunctionReturn(0);
1481 }
1482 
1483 /*MC
1484     SNESFunction - functional form used to convey the nonlinear function to be solved by SNES
1485 
1486      Synopsis:
1487      #include "petscsnes.h"
1488      SNESFunction(SNES snes,Vec x,Vec f,void *ctx);
1489 
1490      Input Parameters:
1491 +     snes - the SNES context
1492 .     x    - state at which to evaluate residual
1493 -     ctx     - optional user-defined function context, passed in with SNESSetFunction()
1494 
1495      Output Parameter:
1496 .     f  - vector to put residual (function value)
1497 
1498    Level: intermediate
1499 
1500 .seealso:   SNESSetFunction(), SNESGetFunction()
1501 M*/
1502 
1503 #undef __FUNCT__
1504 #define __FUNCT__ "SNESSetFunction"
1505 /*@C
1506    SNESSetFunction - Sets the function evaluation routine and function
1507    vector for use by the SNES routines in solving systems of nonlinear
1508    equations.
1509 
1510    Logically Collective on SNES
1511 
1512    Input Parameters:
1513 +  snes - the SNES context
1514 .  r - vector to store function value
1515 .  SNESFunction - function evaluation routine
1516 -  ctx - [optional] user-defined context for private data for the
1517          function evaluation routine (may be NULL)
1518 
1519    Notes:
1520    The Newton-like methods typically solve linear systems of the form
1521 $      f'(x) x = -f(x),
1522    where f'(x) denotes the Jacobian matrix and f(x) is the function.
1523 
1524    Level: beginner
1525 
1526 .keywords: SNES, nonlinear, set, function
1527 
1528 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
1529 @*/
1530 PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*SNESFunction)(SNES,Vec,Vec,void*),void *ctx)
1531 {
1532   PetscErrorCode ierr;
1533   DM             dm;
1534 
1535   PetscFunctionBegin;
1536   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1537   if (r) {
1538     PetscValidHeaderSpecific(r,VEC_CLASSID,2);
1539     PetscCheckSameComm(snes,1,r,2);
1540     ierr = PetscObjectReference((PetscObject)r);CHKERRQ(ierr);
1541     ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
1542 
1543     snes->vec_func = r;
1544   }
1545   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1546   ierr = DMSNESSetFunction(dm,SNESFunction,ctx);CHKERRQ(ierr);
1547   PetscFunctionReturn(0);
1548 }
1549 
1550 
1551 #undef __FUNCT__
1552 #define __FUNCT__ "SNESSetInitialFunction"
1553 /*@C
1554    SNESSetInitialFunction - Sets the function vector to be used as the
1555    function norm at the initialization of the method.  In some
1556    instances, the user has precomputed the function before calling
1557    SNESSolve.  This function allows one to avoid a redundant call
1558    to SNESComputeFunction in that case.
1559 
1560    Logically Collective on SNES
1561 
1562    Input Parameters:
1563 +  snes - the SNES context
1564 -  f - vector to store function value
1565 
1566    Notes:
1567    This should not be modified during the solution procedure.
1568 
1569    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1570 
1571    Level: developer
1572 
1573 .keywords: SNES, nonlinear, set, function
1574 
1575 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1576 @*/
1577 PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1578 {
1579   PetscErrorCode ierr;
1580   Vec            vec_func;
1581 
1582   PetscFunctionBegin;
1583   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1584   PetscValidHeaderSpecific(f,VEC_CLASSID,2);
1585   PetscCheckSameComm(snes,1,f,2);
1586   ierr = SNESGetFunction(snes,&vec_func,NULL,NULL);CHKERRQ(ierr);
1587   ierr = VecCopy(f, vec_func);CHKERRQ(ierr);
1588 
1589   snes->vec_func_init_set = PETSC_TRUE;
1590   PetscFunctionReturn(0);
1591 }
1592 
1593 
1594 #undef __FUNCT__
1595 #define __FUNCT__ "SNESSetInitialFunctionNorm"
1596 /*@C
1597    SNESSetInitialFunctionNorm - Sets the function norm to be used as the function norm
1598    at the initialization of the  method.  In some instances, the user has precomputed
1599    the function and its norm before calling SNESSolve.  This function allows one to
1600    avoid a redundant call to SNESComputeFunction() and VecNorm() in that case.
1601 
1602    Logically Collective on SNES
1603 
1604    Input Parameters:
1605 +  snes - the SNES context
1606 -  fnorm - the norm of F as set by SNESSetInitialFunction()
1607 
1608    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.
1609 
1610    Level: developer
1611 
1612 .keywords: SNES, nonlinear, set, function, norm
1613 
1614 .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunction()
1615 @*/
1616 PetscErrorCode  SNESSetInitialFunctionNorm(SNES snes, PetscReal fnorm)
1617 {
1618   PetscFunctionBegin;
1619   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1620   snes->norm_init     = fnorm;
1621   snes->norm_init_set = PETSC_TRUE;
1622   PetscFunctionReturn(0);
1623 }
1624 
1625 #undef __FUNCT__
1626 #define __FUNCT__ "SNESSetNormType"
1627 /*@
1628    SNESSetNormType - Sets the SNESNormType used in covergence and monitoring
1629    of the SNES method.
1630 
1631    Logically Collective on SNES
1632 
1633    Input Parameters:
1634 +  snes - the SNES context
1635 -  normtype - the type of the norm used
1636 
1637    Notes:
1638    Only certain SNES methods support certain SNESNormTypes.  Most require evaluation
1639    of the nonlinear function and the taking of its norm at every iteration to
1640    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1641    (SNESGS) and the like do not require the norm of the function to be computed, and therfore
1642    may either be monitored for convergence or not.  As these are often used as nonlinear
1643    preconditioners, monitoring the norm of their error is not a useful enterprise within
1644    their solution.
1645 
1646    Level: developer
1647 
1648 .keywords: SNES, nonlinear, set, function, norm, type
1649 
1650 .seealso: SNESGetNormType(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormType
1651 @*/
1652 PetscErrorCode  SNESSetNormType(SNES snes, SNESNormType normtype)
1653 {
1654   PetscFunctionBegin;
1655   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1656   snes->normtype = normtype;
1657   PetscFunctionReturn(0);
1658 }
1659 
1660 
1661 #undef __FUNCT__
1662 #define __FUNCT__ "SNESGetNormType"
1663 /*@
1664    SNESGetNormType - Gets the SNESNormType used in covergence and monitoring
1665    of the SNES method.
1666 
1667    Logically Collective on SNES
1668 
1669    Input Parameters:
1670 +  snes - the SNES context
1671 -  normtype - the type of the norm used
1672 
1673    Level: advanced
1674 
1675 .keywords: SNES, nonlinear, set, function, norm, type
1676 
1677 .seealso: SNESSetNormType(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormType
1678 @*/
1679 PetscErrorCode  SNESGetNormType(SNES snes, SNESNormType *normtype)
1680 {
1681   PetscFunctionBegin;
1682   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1683   *normtype = snes->normtype;
1684   PetscFunctionReturn(0);
1685 }
1686 
1687 /*MC
1688     SNESGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function
1689 
1690      Synopsis:
1691      #include "petscsnes.h"
1692 $    SNESGSFunction(SNES snes,Vec x,Vec b,void *ctx);
1693 
1694 +  X   - solution vector
1695 .  B   - RHS vector
1696 -  ctx - optional user-defined Gauss-Seidel context
1697 
1698    Level: intermediate
1699 
1700 .seealso:   SNESSetGS(), SNESGetGS()
1701 M*/
1702 
1703 #undef __FUNCT__
1704 #define __FUNCT__ "SNESSetGS"
1705 /*@C
1706    SNESSetGS - Sets the user nonlinear Gauss-Seidel routine for
1707    use with composed nonlinear solvers.
1708 
1709    Input Parameters:
1710 +  snes   - the SNES context
1711 .  SNESGSFunction - function evaluation routine
1712 -  ctx    - [optional] user-defined context for private data for the
1713             smoother evaluation routine (may be NULL)
1714 
1715    Notes:
1716    The GS routines are used by the composed nonlinear solver to generate
1717     a problem appropriate update to the solution, particularly FAS.
1718 
1719    Level: intermediate
1720 
1721 .keywords: SNES, nonlinear, set, Gauss-Seidel
1722 
1723 .seealso: SNESGetFunction(), SNESComputeGS()
1724 @*/
1725 PetscErrorCode SNESSetGS(SNES snes,PetscErrorCode (*SNESGSFunction)(SNES,Vec,Vec,void*),void *ctx)
1726 {
1727   PetscErrorCode ierr;
1728   DM             dm;
1729 
1730   PetscFunctionBegin;
1731   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1732   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1733   ierr = DMSNESSetGS(dm,SNESGSFunction,ctx);CHKERRQ(ierr);
1734   PetscFunctionReturn(0);
1735 }
1736 
1737 #undef __FUNCT__
1738 #define __FUNCT__ "SNESPicardComputeFunction"
1739 PetscErrorCode  SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
1740 {
1741   PetscErrorCode ierr;
1742   DM             dm;
1743   DMSNES         sdm;
1744 
1745   PetscFunctionBegin;
1746   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1747   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
1748   /*  A(x)*x - b(x) */
1749   if (sdm->ops->computepfunction) {
1750     ierr = (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);CHKERRQ(ierr);
1751   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");
1752 
1753   if (sdm->ops->computepjacobian) {
1754     ierr = (*sdm->ops->computepjacobian)(snes,x,&snes->jacobian,&snes->jacobian_pre,&snes->matstruct,sdm->pctx);CHKERRQ(ierr);
1755   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard matrix.");
1756   ierr = VecScale(f,-1.0);CHKERRQ(ierr);
1757   ierr = MatMultAdd(snes->jacobian,x,f,f);CHKERRQ(ierr);
1758   PetscFunctionReturn(0);
1759 }
1760 
1761 #undef __FUNCT__
1762 #define __FUNCT__ "SNESPicardComputeJacobian"
1763 PetscErrorCode  SNESPicardComputeJacobian(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx)
1764 {
1765   PetscFunctionBegin;
1766   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
1767   *flag = snes->matstruct;
1768   PetscFunctionReturn(0);
1769 }
1770 
1771 #undef __FUNCT__
1772 #define __FUNCT__ "SNESSetPicard"
1773 /*@C
1774    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)
1775 
1776    Logically Collective on SNES
1777 
1778    Input Parameters:
1779 +  snes - the SNES context
1780 .  r - vector to store function value
1781 .  SNESFunction - function evaluation routine
1782 .  Amat - matrix with which A(x) x - b(x) is to be computed
1783 .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
1784 .  SNESJacobianFunction  - function to compute matrix value
1785 -  ctx - [optional] user-defined context for private data for the
1786          function evaluation routine (may be NULL)
1787 
1788    Notes:
1789     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
1790     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.
1791 
1792     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both
1793 
1794 $     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}
1795 $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.
1796 
1797      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.
1798 
1799    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
1800    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)
1801 
1802    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
1803    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
1804    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).
1805 
1806    Level: intermediate
1807 
1808 .keywords: SNES, nonlinear, set, function
1809 
1810 .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard()
1811 @*/
1812 PetscErrorCode  SNESSetPicard(SNES snes,Vec r,PetscErrorCode (*SNESFunction)(SNES,Vec,Vec,void*),Mat Amat, Mat Pmat, PetscErrorCode (*SNESJacobianFunction)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void *ctx)
1813 {
1814   PetscErrorCode ierr;
1815   DM             dm;
1816 
1817   PetscFunctionBegin;
1818   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1819   ierr = SNESGetDM(snes, &dm);CHKERRQ(ierr);
1820   ierr = DMSNESSetPicard(dm,SNESFunction,SNESJacobianFunction,ctx);CHKERRQ(ierr);
1821   ierr = SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);CHKERRQ(ierr);
1822   ierr = SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);CHKERRQ(ierr);
1823   PetscFunctionReturn(0);
1824 }
1825 
1826 #undef __FUNCT__
1827 #define __FUNCT__ "SNESGetPicard"
1828 /*@C
1829    SNESGetPicard - Returns the context for the Picard iteration
1830 
1831    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
1832 
1833    Input Parameter:
1834 .  snes - the SNES context
1835 
1836    Output Parameter:
1837 +  r - the function (or NULL)
1838 .  SNESFunction - the function (or NULL)
1839 .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
1840 .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
1841 .  SNESJacobianFunction - the function for matrix evaluation (or NULL)
1842 -  ctx - the function context (or NULL)
1843 
1844    Level: advanced
1845 
1846 .keywords: SNES, nonlinear, get, function
1847 
1848 .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
1849 @*/
1850 PetscErrorCode  SNESGetPicard(SNES snes,Vec *r,PetscErrorCode (**SNESFunction)(SNES,Vec,Vec,void*),Mat *Amat, Mat *Pmat, PetscErrorCode (**SNESJacobianFunction)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void **ctx)
1851 {
1852   PetscErrorCode ierr;
1853   DM             dm;
1854 
1855   PetscFunctionBegin;
1856   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1857   ierr = SNESGetFunction(snes,r,NULL,NULL);CHKERRQ(ierr);
1858   ierr = SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);CHKERRQ(ierr);
1859   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1860   ierr = DMSNESGetPicard(dm,SNESFunction,SNESJacobianFunction,ctx);CHKERRQ(ierr);
1861   PetscFunctionReturn(0);
1862 }
1863 
1864 #undef __FUNCT__
1865 #define __FUNCT__ "SNESSetComputeInitialGuess"
1866 /*@C
1867    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem
1868 
1869    Logically Collective on SNES
1870 
1871    Input Parameters:
1872 +  snes - the SNES context
1873 .  func - function evaluation routine
1874 -  ctx - [optional] user-defined context for private data for the
1875          function evaluation routine (may be NULL)
1876 
1877    Calling sequence of func:
1878 $    func (SNES snes,Vec x,void *ctx);
1879 
1880 .  f - function vector
1881 -  ctx - optional user-defined function context
1882 
1883    Level: intermediate
1884 
1885 .keywords: SNES, nonlinear, set, function
1886 
1887 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
1888 @*/
1889 PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
1890 {
1891   PetscFunctionBegin;
1892   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1893   if (func) snes->ops->computeinitialguess = func;
1894   if (ctx)  snes->initialguessP            = ctx;
1895   PetscFunctionReturn(0);
1896 }
1897 
1898 /* --------------------------------------------------------------- */
1899 #undef __FUNCT__
1900 #define __FUNCT__ "SNESGetRhs"
1901 /*@C
1902    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
1903    it assumes a zero right hand side.
1904 
1905    Logically Collective on SNES
1906 
1907    Input Parameter:
1908 .  snes - the SNES context
1909 
1910    Output Parameter:
1911 .  rhs - the right hand side vector or NULL if the right hand side vector is null
1912 
1913    Level: intermediate
1914 
1915 .keywords: SNES, nonlinear, get, function, right hand side
1916 
1917 .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
1918 @*/
1919 PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
1920 {
1921   PetscFunctionBegin;
1922   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1923   PetscValidPointer(rhs,2);
1924   *rhs = snes->vec_rhs;
1925   PetscFunctionReturn(0);
1926 }
1927 
1928 #undef __FUNCT__
1929 #define __FUNCT__ "SNESComputeFunction"
1930 /*@
1931    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().
1932 
1933    Collective on SNES
1934 
1935    Input Parameters:
1936 +  snes - the SNES context
1937 -  x - input vector
1938 
1939    Output Parameter:
1940 .  y - function vector, as set by SNESSetFunction()
1941 
1942    Notes:
1943    SNESComputeFunction() is typically used within nonlinear solvers
1944    implementations, so most users would not generally call this routine
1945    themselves.
1946 
1947    Level: developer
1948 
1949 .keywords: SNES, nonlinear, compute, function
1950 
1951 .seealso: SNESSetFunction(), SNESGetFunction()
1952 @*/
1953 PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
1954 {
1955   PetscErrorCode ierr;
1956   DM             dm;
1957   DMSNES         sdm;
1958 
1959   PetscFunctionBegin;
1960   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
1961   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
1962   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
1963   PetscCheckSameComm(snes,1,x,2);
1964   PetscCheckSameComm(snes,1,y,3);
1965   ierr = VecValidValues(x,2,PETSC_TRUE);CHKERRQ(ierr);
1966 
1967   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
1968   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
1969   if (snes->pc && snes->pcside == PC_LEFT) {
1970     ierr = VecCopy(x,y);CHKERRQ(ierr);
1971     ierr = PetscLogEventBegin(SNES_NPCSolve,snes->pc,x,y,0);CHKERRQ(ierr);
1972     ierr = SNESSolve(snes->pc,snes->vec_rhs,y);CHKERRQ(ierr);
1973     ierr = PetscLogEventEnd(SNES_NPCSolve,snes->pc,x,y,0);CHKERRQ(ierr);
1974     ierr = VecAYPX(y,-1.0,x);CHKERRQ(ierr);
1975   } else if (sdm->ops->computefunction) {
1976     ierr = PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
1977     PetscStackPush("SNES user function");
1978     ierr = (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);CHKERRQ(ierr);
1979     PetscStackPop;
1980     ierr = PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);CHKERRQ(ierr);
1981   } else if (snes->vec_rhs) {
1982     ierr = MatMult(snes->jacobian, x, y);CHKERRQ(ierr);
1983   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
1984   if (snes->vec_rhs) {
1985     ierr = VecAXPY(y,-1.0,snes->vec_rhs);CHKERRQ(ierr);
1986   }
1987   snes->nfuncs++;
1988   ierr = VecValidValues(y,3,PETSC_FALSE);CHKERRQ(ierr);
1989   PetscFunctionReturn(0);
1990 }
1991 
1992 #undef __FUNCT__
1993 #define __FUNCT__ "SNESComputeGS"
1994 /*@
1995    SNESComputeGS - Calls the Gauss-Seidel function that has been set with  SNESSetGS().
1996 
1997    Collective on SNES
1998 
1999    Input Parameters:
2000 +  snes - the SNES context
2001 .  x - input vector
2002 -  b - rhs vector
2003 
2004    Output Parameter:
2005 .  x - new solution vector
2006 
2007    Notes:
2008    SNESComputeGS() is typically used within composed nonlinear solver
2009    implementations, so most users would not generally call this routine
2010    themselves.
2011 
2012    Level: developer
2013 
2014 .keywords: SNES, nonlinear, compute, function
2015 
2016 .seealso: SNESSetGS(), SNESComputeFunction()
2017 @*/
2018 PetscErrorCode  SNESComputeGS(SNES snes,Vec b,Vec x)
2019 {
2020   PetscErrorCode ierr;
2021   DM             dm;
2022   DMSNES         sdm;
2023 
2024   PetscFunctionBegin;
2025   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2026   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
2027   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,3);
2028   PetscCheckSameComm(snes,1,x,2);
2029   if (b) PetscCheckSameComm(snes,1,b,3);
2030   if (b) {ierr = VecValidValues(b,2,PETSC_TRUE);CHKERRQ(ierr);}
2031   ierr = PetscLogEventBegin(SNES_GSEval,snes,x,b,0);CHKERRQ(ierr);
2032   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2033   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2034   if (sdm->ops->computegs) {
2035     PetscStackPush("SNES user GS");
2036     ierr = (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);CHKERRQ(ierr);
2037     PetscStackPop;
2038   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetGS() before SNESComputeGS(), likely called from SNESSolve().");
2039   ierr = PetscLogEventEnd(SNES_GSEval,snes,x,b,0);CHKERRQ(ierr);
2040   ierr = VecValidValues(x,3,PETSC_FALSE);CHKERRQ(ierr);
2041   PetscFunctionReturn(0);
2042 }
2043 
2044 #undef __FUNCT__
2045 #define __FUNCT__ "SNESComputeJacobian"
2046 /*@
2047    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().
2048 
2049    Collective on SNES and Mat
2050 
2051    Input Parameters:
2052 +  snes - the SNES context
2053 -  x - input vector
2054 
2055    Output Parameters:
2056 +  A - Jacobian matrix
2057 .  B - optional preconditioning matrix
2058 -  flag - flag indicating matrix structure (one of, SAME_NONZERO_PATTERN,DIFFERENT_NONZERO_PATTERN,SAME_PRECONDITIONER)
2059 
2060   Options Database Keys:
2061 +    -snes_lag_preconditioner <lag>
2062 .    -snes_lag_jacobian <lag>
2063 .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2064 .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2065 .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2066 .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2067 .    -snes_compare_coloring - Compute the finite differece Jacobian using coloring and display norms of difference
2068 .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
2069 .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2070 .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2071 .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2072 .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
2073 -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences
2074 
2075 
2076    Notes:
2077    Most users should not need to explicitly call this routine, as it
2078    is used internally within the nonlinear solvers.
2079 
2080    See KSPSetOperators() for important information about setting the
2081    flag parameter.
2082 
2083    Level: developer
2084 
2085 .keywords: SNES, compute, Jacobian, matrix
2086 
2087 .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2088 @*/
2089 PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat *A,Mat *B,MatStructure *flg)
2090 {
2091   PetscErrorCode ierr;
2092   PetscBool      flag;
2093   DM             dm;
2094   DMSNES         sdm;
2095 
2096   PetscFunctionBegin;
2097   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2098   PetscValidHeaderSpecific(X,VEC_CLASSID,2);
2099   PetscValidPointer(flg,5);
2100   PetscCheckSameComm(snes,1,X,2);
2101   ierr = VecValidValues(X,2,PETSC_TRUE);CHKERRQ(ierr);
2102   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2103   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2104 
2105   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");
2106 
2107   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */
2108 
2109   if (snes->lagjacobian == -2) {
2110     snes->lagjacobian = -1;
2111 
2112     ierr = PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");CHKERRQ(ierr);
2113   } else if (snes->lagjacobian == -1) {
2114     *flg = SAME_PRECONDITIONER;
2115     ierr = PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");CHKERRQ(ierr);
2116     ierr = PetscObjectTypeCompare((PetscObject)*A,MATMFFD,&flag);CHKERRQ(ierr);
2117     if (flag) {
2118       ierr = MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2119       ierr = MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2120     }
2121     PetscFunctionReturn(0);
2122   } else if (snes->lagjacobian > 1 && snes->iter % snes->lagjacobian) {
2123     *flg = SAME_PRECONDITIONER;
2124     ierr = PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);CHKERRQ(ierr);
2125     ierr = PetscObjectTypeCompare((PetscObject)*A,MATMFFD,&flag);CHKERRQ(ierr);
2126     if (flag) {
2127       ierr = MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2128       ierr = MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2129     }
2130     PetscFunctionReturn(0);
2131   }
2132   if (snes->pc && snes->pcside == PC_LEFT) {
2133       ierr = MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2134       ierr = MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2135       PetscFunctionReturn(0);
2136   }
2137 
2138   *flg = DIFFERENT_NONZERO_PATTERN;
2139   ierr = PetscLogEventBegin(SNES_JacobianEval,snes,X,*A,*B);CHKERRQ(ierr);
2140 
2141   PetscStackPush("SNES user Jacobian function");
2142   ierr = (*sdm->ops->computejacobian)(snes,X,A,B,flg,sdm->jacobianctx);CHKERRQ(ierr);
2143   PetscStackPop;
2144 
2145   ierr = PetscLogEventEnd(SNES_JacobianEval,snes,X,*A,*B);CHKERRQ(ierr);
2146 
2147   if (snes->lagpreconditioner == -2) {
2148     ierr = PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");CHKERRQ(ierr);
2149 
2150     snes->lagpreconditioner = -1;
2151   } else if (snes->lagpreconditioner == -1) {
2152     *flg = SAME_PRECONDITIONER;
2153     ierr = PetscInfo(snes,"Reusing preconditioner because lag is -1\n");CHKERRQ(ierr);
2154   } else if (snes->lagpreconditioner > 1 && snes->iter % snes->lagpreconditioner) {
2155     *flg = SAME_PRECONDITIONER;
2156     ierr = PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);CHKERRQ(ierr);
2157   }
2158 
2159   /* make sure user returned a correct Jacobian and preconditioner */
2160   /* PetscValidHeaderSpecific(*A,MAT_CLASSID,3);
2161     PetscValidHeaderSpecific(*B,MAT_CLASSID,4);   */
2162   {
2163     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2164     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit",&flag,NULL);CHKERRQ(ierr);
2165     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",&flag_draw,NULL);CHKERRQ(ierr);
2166     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2167     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_operator",&flag_operator,NULL);CHKERRQ(ierr);
2168     if (flag || flag_draw || flag_contour) {
2169       Mat          Bexp_mine = NULL,Bexp,FDexp;
2170       MatStructure mstruct;
2171       PetscViewer  vdraw,vstdout;
2172       PetscBool    flg;
2173       if (flag_operator) {
2174         ierr = MatComputeExplicitOperator(*A,&Bexp_mine);CHKERRQ(ierr);
2175         Bexp = Bexp_mine;
2176       } else {
2177         /* See if the preconditioning matrix can be viewed and added directly */
2178         ierr = PetscObjectTypeCompareAny((PetscObject)*B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");CHKERRQ(ierr);
2179         if (flg) Bexp = *B;
2180         else {
2181           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2182           ierr = MatComputeExplicitOperator(*B,&Bexp_mine);CHKERRQ(ierr);
2183           Bexp = Bexp_mine;
2184         }
2185       }
2186       ierr = MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);CHKERRQ(ierr);
2187       ierr = SNESComputeJacobianDefault(snes,X,&FDexp,&FDexp,&mstruct,NULL);CHKERRQ(ierr);
2188       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2189       if (flag_draw || flag_contour) {
2190         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2191         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2192       } else vdraw = NULL;
2193       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");CHKERRQ(ierr);
2194       if (flag) {ierr = MatView(Bexp,vstdout);CHKERRQ(ierr);}
2195       if (vdraw) {ierr = MatView(Bexp,vdraw);CHKERRQ(ierr);}
2196       ierr = PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");CHKERRQ(ierr);
2197       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2198       if (vdraw) {ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);}
2199       ierr = MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2200       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");CHKERRQ(ierr);
2201       if (flag) {ierr = MatView(FDexp,vstdout);CHKERRQ(ierr);}
2202       if (vdraw) {              /* Always use contour for the difference */
2203         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2204         ierr = MatView(FDexp,vdraw);CHKERRQ(ierr);
2205         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2206       }
2207       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2208       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2209       ierr = MatDestroy(&Bexp_mine);CHKERRQ(ierr);
2210       ierr = MatDestroy(&FDexp);CHKERRQ(ierr);
2211     }
2212   }
2213   {
2214     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2215     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2216     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring",&flag,NULL);CHKERRQ(ierr);
2217     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_display",&flag_display,NULL);CHKERRQ(ierr);
2218     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",&flag_draw,NULL);CHKERRQ(ierr);
2219     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",&flag_contour,NULL);CHKERRQ(ierr);
2220     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",&flag_threshold,NULL);CHKERRQ(ierr);
2221     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);CHKERRQ(ierr);
2222     ierr = PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);CHKERRQ(ierr);
2223     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2224       Mat            Bfd;
2225       MatStructure   mstruct;
2226       PetscViewer    vdraw,vstdout;
2227       ISColoring     iscoloring;
2228       MatFDColoring  matfdcoloring;
2229       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2230       void           *funcctx;
2231       PetscReal      norm1,norm2,normmax;
2232 
2233       ierr = MatDuplicate(*B,MAT_DO_NOT_COPY_VALUES,&Bfd);CHKERRQ(ierr);
2234       ierr = MatGetColoring(Bfd,MATCOLORINGSL,&iscoloring);CHKERRQ(ierr);
2235       ierr = MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);CHKERRQ(ierr);
2236       ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr);
2237 
2238       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2239       ierr = SNESGetFunction(snes,NULL,&func,&funcctx);CHKERRQ(ierr);
2240       ierr = MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);CHKERRQ(ierr);
2241       ierr = PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);CHKERRQ(ierr);
2242       ierr = PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");CHKERRQ(ierr);
2243       ierr = MatFDColoringSetFromOptions(matfdcoloring);CHKERRQ(ierr);
2244       ierr = MatFDColoringApply(Bfd,matfdcoloring,X,&mstruct,snes);CHKERRQ(ierr);
2245       ierr = MatFDColoringDestroy(&matfdcoloring);CHKERRQ(ierr);
2246 
2247       ierr = PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);CHKERRQ(ierr);
2248       if (flag_draw || flag_contour) {
2249         ierr = PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);CHKERRQ(ierr);
2250         if (flag_contour) {ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);}
2251       } else vdraw = NULL;
2252       ierr = PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");CHKERRQ(ierr);
2253       if (flag_display) {ierr = MatView(*B,vstdout);CHKERRQ(ierr);}
2254       if (vdraw) {ierr = MatView(*B,vdraw);CHKERRQ(ierr);}
2255       ierr = PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");CHKERRQ(ierr);
2256       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2257       if (vdraw) {ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);}
2258       ierr = MatAYPX(Bfd,-1.0,*B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
2259       ierr = MatNorm(Bfd,NORM_1,&norm1);CHKERRQ(ierr);
2260       ierr = MatNorm(Bfd,NORM_FROBENIUS,&norm2);CHKERRQ(ierr);
2261       ierr = MatNorm(Bfd,NORM_MAX,&normmax);CHKERRQ(ierr);
2262       ierr = PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%G normFrob=%G normmax=%G\n",norm1,norm2,normmax);CHKERRQ(ierr);
2263       if (flag_display) {ierr = MatView(Bfd,vstdout);CHKERRQ(ierr);}
2264       if (vdraw) {              /* Always use contour for the difference */
2265         ierr = PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);CHKERRQ(ierr);
2266         ierr = MatView(Bfd,vdraw);CHKERRQ(ierr);
2267         ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);
2268       }
2269       if (flag_contour) {ierr = PetscViewerPopFormat(vdraw);CHKERRQ(ierr);}
2270 
2271       if (flag_threshold) {
2272         PetscInt bs,rstart,rend,i;
2273         ierr = MatGetBlockSize(*B,&bs);CHKERRQ(ierr);
2274         ierr = MatGetOwnershipRange(*B,&rstart,&rend);CHKERRQ(ierr);
2275         for (i=rstart; i<rend; i++) {
2276           const PetscScalar *ba,*ca;
2277           const PetscInt    *bj,*cj;
2278           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2279           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2280           ierr = MatGetRow(*B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2281           ierr = MatGetRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2282           if (bn != cn) SETERRQ(((PetscObject)*A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2283           for (j=0; j<bn; j++) {
2284             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2285             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2286               maxentrycol = bj[j];
2287               maxentry    = PetscRealPart(ba[j]);
2288             }
2289             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2290               maxdiffcol = bj[j];
2291               maxdiff    = PetscRealPart(ca[j]);
2292             }
2293             if (rdiff > maxrdiff) {
2294               maxrdiffcol = bj[j];
2295               maxrdiff    = rdiff;
2296             }
2297           }
2298           if (maxrdiff > 1) {
2299             ierr = PetscViewerASCIIPrintf(vstdout,"row %D (maxentry=%G at %D, maxdiff=%G at %D, maxrdiff=%G at %D):",i,maxentry,maxentrycol,maxdiff,maxdiffcol,maxrdiff,maxrdiffcol);CHKERRQ(ierr);
2300             for (j=0; j<bn; j++) {
2301               PetscReal rdiff;
2302               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2303               if (rdiff > 1) {
2304                 ierr = PetscViewerASCIIPrintf(vstdout," (%D,%G:%G)",bj[j],PetscRealPart(ba[j]),PetscRealPart(ca[j]));CHKERRQ(ierr);
2305               }
2306             }
2307             ierr = PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);CHKERRQ(ierr);
2308           }
2309           ierr = MatRestoreRow(*B,i,&bn,&bj,&ba);CHKERRQ(ierr);
2310           ierr = MatRestoreRow(Bfd,i,&cn,&cj,&ca);CHKERRQ(ierr);
2311         }
2312       }
2313       ierr = PetscViewerDestroy(&vdraw);CHKERRQ(ierr);
2314       ierr = MatDestroy(&Bfd);CHKERRQ(ierr);
2315     }
2316   }
2317   PetscFunctionReturn(0);
2318 }
2319 
2320 /*MC
2321     SNESJacobianFunction - function used to convey the nonlinear Jacobian of the function to be solved by SNES
2322 
2323      Synopsis:
2324      #include "petscsnes.h"
2325 $     SNESJacobianFunction(SNES snes,Vec x,Mat *Amat,Mat *Pmat,int *flag,void *ctx);
2326 
2327 +  x - input vector
2328 .  Amat - the matrix that defines the (approximate) Jacobian
2329 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2330 .  flag - flag indicating information about the preconditioner matrix
2331    structure (same as flag in KSPSetOperators()), one of SAME_NONZERO_PATTERN,DIFFERENT_NONZERO_PATTERN,SAME_PRECONDITIONER
2332 -  ctx - [optional] user-defined Jacobian context
2333 
2334    Level: intermediate
2335 
2336 .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2337 M*/
2338 
2339 #undef __FUNCT__
2340 #define __FUNCT__ "SNESSetJacobian"
2341 /*@C
2342    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2343    location to store the matrix.
2344 
2345    Logically Collective on SNES and Mat
2346 
2347    Input Parameters:
2348 +  snes - the SNES context
2349 .  Amat - the matrix that defines the (approximate) Jacobian
2350 .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2351 .  SNESJacobianFunction - Jacobian evaluation routine (if NULL then SNES retains any previously set value)
2352 -  ctx - [optional] user-defined context for private data for the
2353          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)
2354 
2355    Notes:
2356    See KSPSetOperators() for important information about setting the flag
2357    output parameter in the routine func().  Be sure to read this information!
2358 
2359    The routine func() takes Mat * as the matrix arguments rather than Mat.
2360    This allows the Jacobian evaluation routine to replace A and/or B with a
2361    completely new new matrix structure (not just different matrix elements)
2362    when appropriate, for instance, if the nonzero structure is changing
2363    throughout the global iterations.
2364 
2365    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
2366    each matrix.
2367 
2368    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
2369    must be a MatFDColoring.
2370 
2371    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2372    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.
2373 
2374    Level: beginner
2375 
2376 .keywords: SNES, nonlinear, set, Jacobian, matrix
2377 
2378 .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, SNESJacobianFunction, SNESSetPicard()
2379 @*/
2380 PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*SNESJacobianFunction)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void *ctx)
2381 {
2382   PetscErrorCode ierr;
2383   DM             dm;
2384 
2385   PetscFunctionBegin;
2386   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2387   if (Amat) PetscValidHeaderSpecific(Amat,MAT_CLASSID,2);
2388   if (Pmat) PetscValidHeaderSpecific(Pmat,MAT_CLASSID,3);
2389   if (Amat) PetscCheckSameComm(snes,1,Amat,2);
2390   if (Pmat) PetscCheckSameComm(snes,1,Pmat,3);
2391   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2392   ierr = DMSNESSetJacobian(dm,SNESJacobianFunction,ctx);CHKERRQ(ierr);
2393   if (Amat) {
2394     ierr = PetscObjectReference((PetscObject)Amat);CHKERRQ(ierr);
2395     ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2396 
2397     snes->jacobian = Amat;
2398   }
2399   if (Pmat) {
2400     ierr = PetscObjectReference((PetscObject)Pmat);CHKERRQ(ierr);
2401     ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2402 
2403     snes->jacobian_pre = Pmat;
2404   }
2405   PetscFunctionReturn(0);
2406 }
2407 
2408 #undef __FUNCT__
2409 #define __FUNCT__ "SNESGetJacobian"
2410 /*@C
2411    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2412    provided context for evaluating the Jacobian.
2413 
2414    Not Collective, but Mat object will be parallel if SNES object is
2415 
2416    Input Parameter:
2417 .  snes - the nonlinear solver context
2418 
2419    Output Parameters:
2420 +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
2421 .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
2422 .  SNESJacobianFunction - location to put Jacobian function (or NULL)
2423 -  ctx - location to stash Jacobian ctx (or NULL)
2424 
2425    Level: advanced
2426 
2427 .seealso: SNESSetJacobian(), SNESComputeJacobian()
2428 @*/
2429 PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**SNESJacobianFunction)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void **ctx)
2430 {
2431   PetscErrorCode ierr;
2432   DM             dm;
2433   DMSNES         sdm;
2434 
2435   PetscFunctionBegin;
2436   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2437   if (Amat) *Amat = snes->jacobian;
2438   if (Pmat) *Pmat = snes->jacobian_pre;
2439   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2440   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2441   if (SNESJacobianFunction) *SNESJacobianFunction = sdm->ops->computejacobian;
2442   if (ctx) *ctx = sdm->jacobianctx;
2443   PetscFunctionReturn(0);
2444 }
2445 
2446 #undef __FUNCT__
2447 #define __FUNCT__ "SNESSetUp"
2448 /*@
2449    SNESSetUp - Sets up the internal data structures for the later use
2450    of a nonlinear solver.
2451 
2452    Collective on SNES
2453 
2454    Input Parameters:
2455 .  snes - the SNES context
2456 
2457    Notes:
2458    For basic use of the SNES solvers the user need not explicitly call
2459    SNESSetUp(), since these actions will automatically occur during
2460    the call to SNESSolve().  However, if one wishes to control this
2461    phase separately, SNESSetUp() should be called after SNESCreate()
2462    and optional routines of the form SNESSetXXX(), but before SNESSolve().
2463 
2464    Level: advanced
2465 
2466 .keywords: SNES, nonlinear, setup
2467 
2468 .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
2469 @*/
2470 PetscErrorCode  SNESSetUp(SNES snes)
2471 {
2472   PetscErrorCode ierr;
2473   DM             dm;
2474   DMSNES         sdm;
2475   SNESLineSearch linesearch, pclinesearch;
2476   void           *lsprectx,*lspostctx;
2477   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
2478   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
2479   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2480   Vec            f,fpc;
2481   void           *funcctx;
2482   PetscErrorCode (*jac)(SNES,Vec,Mat*,Mat*,MatStructure*,void*);
2483   void           *jacctx,*appctx;
2484   Mat            A,B;
2485 
2486   PetscFunctionBegin;
2487   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2488   if (snes->setupcalled) PetscFunctionReturn(0);
2489 
2490   if (!((PetscObject)snes)->type_name) {
2491     ierr = SNESSetType(snes,SNESNEWTONLS);CHKERRQ(ierr);
2492   }
2493 
2494   ierr = SNESGetFunction(snes,&snes->vec_func,NULL,NULL);CHKERRQ(ierr);
2495   if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
2496   if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
2497 
2498   if (!snes->vec_sol_update /* && snes->vec_sol */) {
2499     ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
2500     ierr = PetscLogObjectParent(snes,snes->vec_sol_update);CHKERRQ(ierr);
2501   }
2502 
2503   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2504   ierr = DMShellSetGlobalVector(snes->dm,snes->vec_sol);CHKERRQ(ierr);
2505   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
2506   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
2507   if (!sdm->ops->computejacobian) {
2508     ierr = DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);CHKERRQ(ierr);
2509   }
2510   if (!snes->vec_func) {
2511     ierr = DMCreateGlobalVector(dm,&snes->vec_func);CHKERRQ(ierr);
2512   }
2513 
2514   if (!snes->ksp) {
2515     ierr = SNESGetKSP(snes, &snes->ksp);CHKERRQ(ierr);
2516   }
2517 
2518   if (!snes->linesearch) {
2519     ierr = SNESGetSNESLineSearch(snes, &snes->linesearch);CHKERRQ(ierr);
2520   }
2521 
2522   if (snes->pc && (snes->pcside == PC_LEFT)) {
2523     snes->mf          = PETSC_TRUE;
2524     snes->mf_operator = PETSC_FALSE;
2525   }
2526 
2527   if (snes->mf) {
2528     ierr = SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);CHKERRQ(ierr);
2529   }
2530 
2531   if (snes->ops->usercompute && !snes->user) {
2532     ierr = (*snes->ops->usercompute)(snes,(void**)&snes->user);CHKERRQ(ierr);
2533   }
2534 
2535   if (snes->pc) {
2536     /* copy the DM over */
2537     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
2538     ierr = SNESSetDM(snes->pc,dm);CHKERRQ(ierr);
2539 
2540     ierr = SNESGetFunction(snes,&f,&func,&funcctx);CHKERRQ(ierr);
2541     ierr = VecDuplicate(f,&fpc);CHKERRQ(ierr);
2542     ierr = SNESSetFunction(snes->pc,fpc,func,funcctx);CHKERRQ(ierr);
2543     ierr = SNESGetJacobian(snes,&A,&B,&jac,&jacctx);CHKERRQ(ierr);
2544     ierr = SNESSetJacobian(snes->pc,A,B,jac,jacctx);CHKERRQ(ierr);
2545     ierr = SNESGetApplicationContext(snes,&appctx);CHKERRQ(ierr);
2546     ierr = SNESSetApplicationContext(snes->pc,appctx);CHKERRQ(ierr);
2547     ierr = VecDestroy(&fpc);CHKERRQ(ierr);
2548 
2549     /* copy the function pointers over */
2550     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);CHKERRQ(ierr);
2551 
2552     /* default to 1 iteration */
2553     ierr = SNESSetTolerances(snes->pc,0.0,0.0,0.0,1,snes->pc->max_funcs);CHKERRQ(ierr);
2554     if (snes->pcside==PC_RIGHT) {
2555       ierr = SNESSetNormType(snes->pc,SNES_NORM_FINAL_ONLY);CHKERRQ(ierr);
2556     } else {
2557       ierr = SNESSetNormType(snes->pc,SNES_NORM_NONE);CHKERRQ(ierr);
2558     }
2559     ierr = SNESSetFromOptions(snes->pc);CHKERRQ(ierr);
2560 
2561     /* copy the line search context over */
2562     ierr = SNESGetSNESLineSearch(snes,&linesearch);CHKERRQ(ierr);
2563     ierr = SNESGetSNESLineSearch(snes->pc,&pclinesearch);CHKERRQ(ierr);
2564     ierr = SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);CHKERRQ(ierr);
2565     ierr = SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);CHKERRQ(ierr);
2566     ierr = SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);CHKERRQ(ierr);
2567     ierr = SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);CHKERRQ(ierr);
2568     ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);CHKERRQ(ierr);
2569   }
2570 
2571   if (snes->ops->setup) {
2572     ierr = (*snes->ops->setup)(snes);CHKERRQ(ierr);
2573   }
2574 
2575   snes->setupcalled = PETSC_TRUE;
2576   PetscFunctionReturn(0);
2577 }
2578 
2579 #undef __FUNCT__
2580 #define __FUNCT__ "SNESReset"
2581 /*@
2582    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats
2583 
2584    Collective on SNES
2585 
2586    Input Parameter:
2587 .  snes - iterative context obtained from SNESCreate()
2588 
2589    Level: intermediate
2590 
2591    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()
2592 
2593 .keywords: SNES, destroy
2594 
2595 .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
2596 @*/
2597 PetscErrorCode  SNESReset(SNES snes)
2598 {
2599   PetscErrorCode ierr;
2600 
2601   PetscFunctionBegin;
2602   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2603   if (snes->ops->userdestroy && snes->user) {
2604     ierr       = (*snes->ops->userdestroy)((void**)&snes->user);CHKERRQ(ierr);
2605     snes->user = NULL;
2606   }
2607   if (snes->pc) {
2608     ierr = SNESReset(snes->pc);CHKERRQ(ierr);
2609   }
2610 
2611   if (snes->ops->reset) {
2612     ierr = (*snes->ops->reset)(snes);CHKERRQ(ierr);
2613   }
2614   if (snes->ksp) {
2615     ierr = KSPReset(snes->ksp);CHKERRQ(ierr);
2616   }
2617 
2618   if (snes->linesearch) {
2619     ierr = SNESLineSearchReset(snes->linesearch);CHKERRQ(ierr);
2620   }
2621 
2622   ierr = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
2623   ierr = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
2624   ierr = VecDestroy(&snes->vec_sol_update);CHKERRQ(ierr);
2625   ierr = VecDestroy(&snes->vec_func);CHKERRQ(ierr);
2626   ierr = MatDestroy(&snes->jacobian);CHKERRQ(ierr);
2627   ierr = MatDestroy(&snes->jacobian_pre);CHKERRQ(ierr);
2628   ierr = VecDestroyVecs(snes->nwork,&snes->work);CHKERRQ(ierr);
2629   ierr = VecDestroyVecs(snes->nvwork,&snes->vwork);CHKERRQ(ierr);
2630 
2631   snes->nwork       = snes->nvwork = 0;
2632   snes->setupcalled = PETSC_FALSE;
2633   PetscFunctionReturn(0);
2634 }
2635 
2636 #undef __FUNCT__
2637 #define __FUNCT__ "SNESDestroy"
2638 /*@
2639    SNESDestroy - Destroys the nonlinear solver context that was created
2640    with SNESCreate().
2641 
2642    Collective on SNES
2643 
2644    Input Parameter:
2645 .  snes - the SNES context
2646 
2647    Level: beginner
2648 
2649 .keywords: SNES, nonlinear, destroy
2650 
2651 .seealso: SNESCreate(), SNESSolve()
2652 @*/
2653 PetscErrorCode  SNESDestroy(SNES *snes)
2654 {
2655   PetscErrorCode ierr;
2656 
2657   PetscFunctionBegin;
2658   if (!*snes) PetscFunctionReturn(0);
2659   PetscValidHeaderSpecific((*snes),SNES_CLASSID,1);
2660   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; PetscFunctionReturn(0);}
2661 
2662   ierr = SNESReset((*snes));CHKERRQ(ierr);
2663   ierr = SNESDestroy(&(*snes)->pc);CHKERRQ(ierr);
2664 
2665   /* if memory was published with AMS then destroy it */
2666   ierr = PetscObjectAMSViewOff((PetscObject)*snes);CHKERRQ(ierr);
2667   if ((*snes)->ops->destroy) {ierr = (*((*snes))->ops->destroy)((*snes));CHKERRQ(ierr);}
2668 
2669   ierr = DMDestroy(&(*snes)->dm);CHKERRQ(ierr);
2670   ierr = KSPDestroy(&(*snes)->ksp);CHKERRQ(ierr);
2671   ierr = SNESLineSearchDestroy(&(*snes)->linesearch);CHKERRQ(ierr);
2672 
2673   ierr = PetscFree((*snes)->kspconvctx);CHKERRQ(ierr);
2674   if ((*snes)->ops->convergeddestroy) {
2675     ierr = (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);CHKERRQ(ierr);
2676   }
2677   if ((*snes)->conv_malloc) {
2678     ierr = PetscFree((*snes)->conv_hist);CHKERRQ(ierr);
2679     ierr = PetscFree((*snes)->conv_hist_its);CHKERRQ(ierr);
2680   }
2681   ierr = SNESMonitorCancel((*snes));CHKERRQ(ierr);
2682   ierr = PetscHeaderDestroy(snes);CHKERRQ(ierr);
2683   PetscFunctionReturn(0);
2684 }
2685 
2686 /* ----------- Routines to set solver parameters ---------- */
2687 
2688 #undef __FUNCT__
2689 #define __FUNCT__ "SNESSetLagPreconditioner"
2690 /*@
2691    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.
2692 
2693    Logically Collective on SNES
2694 
2695    Input Parameters:
2696 +  snes - the SNES context
2697 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2698          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2699 
2700    Options Database Keys:
2701 .    -snes_lag_preconditioner <lag>
2702 
2703    Notes:
2704    The default is 1
2705    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2706    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use
2707 
2708    Level: intermediate
2709 
2710 .keywords: SNES, nonlinear, set, convergence, tolerances
2711 
2712 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2713 
2714 @*/
2715 PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
2716 {
2717   PetscFunctionBegin;
2718   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2719   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2720   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2721   PetscValidLogicalCollectiveInt(snes,lag,2);
2722   snes->lagpreconditioner = lag;
2723   PetscFunctionReturn(0);
2724 }
2725 
2726 #undef __FUNCT__
2727 #define __FUNCT__ "SNESSetGridSequence"
2728 /*@
2729    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does
2730 
2731    Logically Collective on SNES
2732 
2733    Input Parameters:
2734 +  snes - the SNES context
2735 -  steps - the number of refinements to do, defaults to 0
2736 
2737    Options Database Keys:
2738 .    -snes_grid_sequence <steps>
2739 
2740    Level: intermediate
2741 
2742    Notes:
2743    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.
2744 
2745 .keywords: SNES, nonlinear, set, convergence, tolerances
2746 
2747 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()
2748 
2749 @*/
2750 PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
2751 {
2752   PetscFunctionBegin;
2753   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2754   PetscValidLogicalCollectiveInt(snes,steps,2);
2755   snes->gridsequence = steps;
2756   PetscFunctionReturn(0);
2757 }
2758 
2759 #undef __FUNCT__
2760 #define __FUNCT__ "SNESGetLagPreconditioner"
2761 /*@
2762    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt
2763 
2764    Not Collective
2765 
2766    Input Parameter:
2767 .  snes - the SNES context
2768 
2769    Output Parameter:
2770 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2771          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that
2772 
2773    Options Database Keys:
2774 .    -snes_lag_preconditioner <lag>
2775 
2776    Notes:
2777    The default is 1
2778    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2779 
2780    Level: intermediate
2781 
2782 .keywords: SNES, nonlinear, set, convergence, tolerances
2783 
2784 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()
2785 
2786 @*/
2787 PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
2788 {
2789   PetscFunctionBegin;
2790   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2791   *lag = snes->lagpreconditioner;
2792   PetscFunctionReturn(0);
2793 }
2794 
2795 #undef __FUNCT__
2796 #define __FUNCT__ "SNESSetLagJacobian"
2797 /*@
2798    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
2799      often the preconditioner is rebuilt.
2800 
2801    Logically Collective on SNES
2802 
2803    Input Parameters:
2804 +  snes - the SNES context
2805 -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2806          the Jacobian is built etc. -2 means rebuild at next chance but then never again
2807 
2808    Options Database Keys:
2809 .    -snes_lag_jacobian <lag>
2810 
2811    Notes:
2812    The default is 1
2813    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2814    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
2815    at the next Newton step but never again (unless it is reset to another value)
2816 
2817    Level: intermediate
2818 
2819 .keywords: SNES, nonlinear, set, convergence, tolerances
2820 
2821 .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()
2822 
2823 @*/
2824 PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
2825 {
2826   PetscFunctionBegin;
2827   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2828   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
2829   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
2830   PetscValidLogicalCollectiveInt(snes,lag,2);
2831   snes->lagjacobian = lag;
2832   PetscFunctionReturn(0);
2833 }
2834 
2835 #undef __FUNCT__
2836 #define __FUNCT__ "SNESGetLagJacobian"
2837 /*@
2838    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt
2839 
2840    Not Collective
2841 
2842    Input Parameter:
2843 .  snes - the SNES context
2844 
2845    Output Parameter:
2846 .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
2847          the Jacobian is built etc.
2848 
2849    Options Database Keys:
2850 .    -snes_lag_jacobian <lag>
2851 
2852    Notes:
2853    The default is 1
2854    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
2855 
2856    Level: intermediate
2857 
2858 .keywords: SNES, nonlinear, set, convergence, tolerances
2859 
2860 .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()
2861 
2862 @*/
2863 PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
2864 {
2865   PetscFunctionBegin;
2866   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2867   *lag = snes->lagjacobian;
2868   PetscFunctionReturn(0);
2869 }
2870 
2871 #undef __FUNCT__
2872 #define __FUNCT__ "SNESSetTolerances"
2873 /*@
2874    SNESSetTolerances - Sets various parameters used in convergence tests.
2875 
2876    Logically Collective on SNES
2877 
2878    Input Parameters:
2879 +  snes - the SNES context
2880 .  abstol - absolute convergence tolerance
2881 .  rtol - relative convergence tolerance
2882 .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
2883 .  maxit - maximum number of iterations
2884 -  maxf - maximum number of function evaluations
2885 
2886    Options Database Keys:
2887 +    -snes_atol <abstol> - Sets abstol
2888 .    -snes_rtol <rtol> - Sets rtol
2889 .    -snes_stol <stol> - Sets stol
2890 .    -snes_max_it <maxit> - Sets maxit
2891 -    -snes_max_funcs <maxf> - Sets maxf
2892 
2893    Notes:
2894    The default maximum number of iterations is 50.
2895    The default maximum number of function evaluations is 1000.
2896 
2897    Level: intermediate
2898 
2899 .keywords: SNES, nonlinear, set, convergence, tolerances
2900 
2901 .seealso: SNESSetTrustRegionTolerance()
2902 @*/
2903 PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
2904 {
2905   PetscFunctionBegin;
2906   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2907   PetscValidLogicalCollectiveReal(snes,abstol,2);
2908   PetscValidLogicalCollectiveReal(snes,rtol,3);
2909   PetscValidLogicalCollectiveReal(snes,stol,4);
2910   PetscValidLogicalCollectiveInt(snes,maxit,5);
2911   PetscValidLogicalCollectiveInt(snes,maxf,6);
2912 
2913   if (abstol != PETSC_DEFAULT) {
2914     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %G must be non-negative",abstol);
2915     snes->abstol = abstol;
2916   }
2917   if (rtol != PETSC_DEFAULT) {
2918     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",rtol);
2919     snes->rtol = rtol;
2920   }
2921   if (stol != PETSC_DEFAULT) {
2922     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %G must be non-negative",stol);
2923     snes->stol = stol;
2924   }
2925   if (maxit != PETSC_DEFAULT) {
2926     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
2927     snes->max_its = maxit;
2928   }
2929   if (maxf != PETSC_DEFAULT) {
2930     if (maxf < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
2931     snes->max_funcs = maxf;
2932   }
2933   snes->tolerancesset = PETSC_TRUE;
2934   PetscFunctionReturn(0);
2935 }
2936 
2937 #undef __FUNCT__
2938 #define __FUNCT__ "SNESGetTolerances"
2939 /*@
2940    SNESGetTolerances - Gets various parameters used in convergence tests.
2941 
2942    Not Collective
2943 
2944    Input Parameters:
2945 +  snes - the SNES context
2946 .  atol - absolute convergence tolerance
2947 .  rtol - relative convergence tolerance
2948 .  stol -  convergence tolerance in terms of the norm
2949            of the change in the solution between steps
2950 .  maxit - maximum number of iterations
2951 -  maxf - maximum number of function evaluations
2952 
2953    Notes:
2954    The user can specify NULL for any parameter that is not needed.
2955 
2956    Level: intermediate
2957 
2958 .keywords: SNES, nonlinear, get, convergence, tolerances
2959 
2960 .seealso: SNESSetTolerances()
2961 @*/
2962 PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
2963 {
2964   PetscFunctionBegin;
2965   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2966   if (atol)  *atol  = snes->abstol;
2967   if (rtol)  *rtol  = snes->rtol;
2968   if (stol)  *stol  = snes->stol;
2969   if (maxit) *maxit = snes->max_its;
2970   if (maxf)  *maxf  = snes->max_funcs;
2971   PetscFunctionReturn(0);
2972 }
2973 
2974 #undef __FUNCT__
2975 #define __FUNCT__ "SNESSetTrustRegionTolerance"
2976 /*@
2977    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.
2978 
2979    Logically Collective on SNES
2980 
2981    Input Parameters:
2982 +  snes - the SNES context
2983 -  tol - tolerance
2984 
2985    Options Database Key:
2986 .  -snes_trtol <tol> - Sets tol
2987 
2988    Level: intermediate
2989 
2990 .keywords: SNES, nonlinear, set, trust region, tolerance
2991 
2992 .seealso: SNESSetTolerances()
2993 @*/
2994 PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
2995 {
2996   PetscFunctionBegin;
2997   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
2998   PetscValidLogicalCollectiveReal(snes,tol,2);
2999   snes->deltatol = tol;
3000   PetscFunctionReturn(0);
3001 }
3002 
3003 /*
3004    Duplicate the lg monitors for SNES from KSP; for some reason with
3005    dynamic libraries things don't work under Sun4 if we just use
3006    macros instead of functions
3007 */
3008 #undef __FUNCT__
3009 #define __FUNCT__ "SNESMonitorLGResidualNorm"
3010 PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,void *ctx)
3011 {
3012   PetscErrorCode ierr;
3013 
3014   PetscFunctionBegin;
3015   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3016   ierr = KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);CHKERRQ(ierr);
3017   PetscFunctionReturn(0);
3018 }
3019 
3020 #undef __FUNCT__
3021 #define __FUNCT__ "SNESMonitorLGCreate"
3022 PetscErrorCode  SNESMonitorLGCreate(const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *draw)
3023 {
3024   PetscErrorCode ierr;
3025 
3026   PetscFunctionBegin;
3027   ierr = KSPMonitorLGResidualNormCreate(host,label,x,y,m,n,draw);CHKERRQ(ierr);
3028   PetscFunctionReturn(0);
3029 }
3030 
3031 #undef __FUNCT__
3032 #define __FUNCT__ "SNESMonitorLGDestroy"
3033 PetscErrorCode  SNESMonitorLGDestroy(PetscDrawLG *draw)
3034 {
3035   PetscErrorCode ierr;
3036 
3037   PetscFunctionBegin;
3038   ierr = KSPMonitorLGResidualNormDestroy(draw);CHKERRQ(ierr);
3039   PetscFunctionReturn(0);
3040 }
3041 
3042 extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
3043 #undef __FUNCT__
3044 #define __FUNCT__ "SNESMonitorLGRange"
3045 PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3046 {
3047   PetscDrawLG      lg;
3048   PetscErrorCode   ierr;
3049   PetscReal        x,y,per;
3050   PetscViewer      v = (PetscViewer)monctx;
3051   static PetscReal prev; /* should be in the context */
3052   PetscDraw        draw;
3053 
3054   PetscFunctionBegin;
3055   ierr = PetscViewerDrawGetDrawLG(v,0,&lg);CHKERRQ(ierr);
3056   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3057   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3058   ierr = PetscDrawSetTitle(draw,"Residual norm");CHKERRQ(ierr);
3059   x    = (PetscReal)n;
3060   if (rnorm > 0.0) y = log10(rnorm);
3061   else y = -15.0;
3062   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3063   if (n < 20 || !(n % 5)) {
3064     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3065   }
3066 
3067   ierr = PetscViewerDrawGetDrawLG(v,1,&lg);CHKERRQ(ierr);
3068   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3069   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3070   ierr = PetscDrawSetTitle(draw,"% elemts > .2*max elemt");CHKERRQ(ierr);
3071   ierr =  SNESMonitorRange_Private(snes,n,&per);CHKERRQ(ierr);
3072   x    = (PetscReal)n;
3073   y    = 100.0*per;
3074   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3075   if (n < 20 || !(n % 5)) {
3076     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3077   }
3078 
3079   ierr = PetscViewerDrawGetDrawLG(v,2,&lg);CHKERRQ(ierr);
3080   if (!n) {prev = rnorm;ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3081   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3082   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");CHKERRQ(ierr);
3083   x    = (PetscReal)n;
3084   y    = (prev - rnorm)/prev;
3085   ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3086   if (n < 20 || !(n % 5)) {
3087     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3088   }
3089 
3090   ierr = PetscViewerDrawGetDrawLG(v,3,&lg);CHKERRQ(ierr);
3091   if (!n) {ierr = PetscDrawLGReset(lg);CHKERRQ(ierr);}
3092   ierr = PetscDrawLGGetDraw(lg,&draw);CHKERRQ(ierr);
3093   ierr = PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");CHKERRQ(ierr);
3094   x    = (PetscReal)n;
3095   y    = (prev - rnorm)/(prev*per);
3096   if (n > 2) { /*skip initial crazy value */
3097     ierr = PetscDrawLGAddPoint(lg,&x,&y);CHKERRQ(ierr);
3098   }
3099   if (n < 20 || !(n % 5)) {
3100     ierr = PetscDrawLGDraw(lg);CHKERRQ(ierr);
3101   }
3102   prev = rnorm;
3103   PetscFunctionReturn(0);
3104 }
3105 
3106 #undef __FUNCT__
3107 #define __FUNCT__ "SNESMonitor"
3108 /*@
3109    SNESMonitor - runs the user provided monitor routines, if they exist
3110 
3111    Collective on SNES
3112 
3113    Input Parameters:
3114 +  snes - nonlinear solver context obtained from SNESCreate()
3115 .  iter - iteration number
3116 -  rnorm - relative norm of the residual
3117 
3118    Notes:
3119    This routine is called by the SNES implementations.
3120    It does not typically need to be called by the user.
3121 
3122    Level: developer
3123 
3124 .seealso: SNESMonitorSet()
3125 @*/
3126 PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3127 {
3128   PetscErrorCode ierr;
3129   PetscInt       i,n = snes->numbermonitors;
3130 
3131   PetscFunctionBegin;
3132   for (i=0; i<n; i++) {
3133     ierr = (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);CHKERRQ(ierr);
3134   }
3135   PetscFunctionReturn(0);
3136 }
3137 
3138 /* ------------ Routines to set performance monitoring options ----------- */
3139 
3140 /*MC
3141     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver
3142 
3143      Synopsis:
3144      #include "petscsnes.h"
3145 $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)
3146 
3147 +    snes - the SNES context
3148 .    its - iteration number
3149 .    norm - 2-norm function value (may be estimated)
3150 -    mctx - [optional] monitoring context
3151 
3152    Level: advanced
3153 
3154 .seealso:   SNESMonitorSet(), SNESMonitorGet()
3155 M*/
3156 
3157 #undef __FUNCT__
3158 #define __FUNCT__ "SNESMonitorSet"
3159 /*@C
3160    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3161    iteration of the nonlinear solver to display the iteration's
3162    progress.
3163 
3164    Logically Collective on SNES
3165 
3166    Input Parameters:
3167 +  snes - the SNES context
3168 .  SNESMonitorFunction - monitoring routine
3169 .  mctx - [optional] user-defined context for private data for the
3170           monitor routine (use NULL if no context is desired)
3171 -  monitordestroy - [optional] routine that frees monitor context
3172           (may be NULL)
3173 
3174    Options Database Keys:
3175 +    -snes_monitor        - sets SNESMonitorDefault()
3176 .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3177                             uses SNESMonitorLGCreate()
3178 -    -snes_monitor_cancel - cancels all monitors that have
3179                             been hardwired into a code by
3180                             calls to SNESMonitorSet(), but
3181                             does not cancel those set via
3182                             the options database.
3183 
3184    Notes:
3185    Several different monitoring routines may be set by calling
3186    SNESMonitorSet() multiple times; all will be called in the
3187    order in which they were set.
3188 
3189    Fortran notes: Only a single monitor function can be set for each SNES object
3190 
3191    Level: intermediate
3192 
3193 .keywords: SNES, nonlinear, set, monitor
3194 
3195 .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
3196 @*/
3197 PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*SNESMonitorFunction)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3198 {
3199   PetscInt       i;
3200   PetscErrorCode ierr;
3201 
3202   PetscFunctionBegin;
3203   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3204   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3205   for (i=0; i<snes->numbermonitors;i++) {
3206     if (SNESMonitorFunction == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
3207       if (monitordestroy) {
3208         ierr = (*monitordestroy)(&mctx);CHKERRQ(ierr);
3209       }
3210       PetscFunctionReturn(0);
3211     }
3212   }
3213   snes->monitor[snes->numbermonitors]          = SNESMonitorFunction;
3214   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
3215   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
3216   PetscFunctionReturn(0);
3217 }
3218 
3219 #undef __FUNCT__
3220 #define __FUNCT__ "SNESMonitorCancel"
3221 /*@C
3222    SNESMonitorCancel - Clears all the monitor functions for a SNES object.
3223 
3224    Logically Collective on SNES
3225 
3226    Input Parameters:
3227 .  snes - the SNES context
3228 
3229    Options Database Key:
3230 .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3231     into a code by calls to SNESMonitorSet(), but does not cancel those
3232     set via the options database
3233 
3234    Notes:
3235    There is no way to clear one specific monitor from a SNES object.
3236 
3237    Level: intermediate
3238 
3239 .keywords: SNES, nonlinear, set, monitor
3240 
3241 .seealso: SNESMonitorDefault(), SNESMonitorSet()
3242 @*/
3243 PetscErrorCode  SNESMonitorCancel(SNES snes)
3244 {
3245   PetscErrorCode ierr;
3246   PetscInt       i;
3247 
3248   PetscFunctionBegin;
3249   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3250   for (i=0; i<snes->numbermonitors; i++) {
3251     if (snes->monitordestroy[i]) {
3252       ierr = (*snes->monitordestroy[i])(&snes->monitorcontext[i]);CHKERRQ(ierr);
3253     }
3254   }
3255   snes->numbermonitors = 0;
3256   PetscFunctionReturn(0);
3257 }
3258 
3259 /*MC
3260     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver
3261 
3262      Synopsis:
3263      #include "petscsnes.h"
3264 $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)
3265 
3266 +    snes - the SNES context
3267 .    it - current iteration (0 is the first and is before any Newton step)
3268 .    cctx - [optional] convergence context
3269 .    reason - reason for convergence/divergence
3270 .    xnorm - 2-norm of current iterate
3271 .    gnorm - 2-norm of current step
3272 -    f - 2-norm of function
3273 
3274    Level: intermediate
3275 
3276 .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
3277 M*/
3278 
3279 #undef __FUNCT__
3280 #define __FUNCT__ "SNESSetConvergenceTest"
3281 /*@C
3282    SNESSetConvergenceTest - Sets the function that is to be used
3283    to test for convergence of the nonlinear iterative solution.
3284 
3285    Logically Collective on SNES
3286 
3287    Input Parameters:
3288 +  snes - the SNES context
3289 .  SNESConvergenceTestFunction - routine to test for convergence
3290 .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
3291 -  destroy - [optional] destructor for the context (may be NULL; NULL_FUNCTION in Fortran)
3292 
3293    Level: advanced
3294 
3295 .keywords: SNES, nonlinear, set, convergence, test
3296 
3297 .seealso: SNESConvergedDefault(), SNESSkipConverged(), SNESConvergenceTestFunction
3298 @*/
3299 PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
3300 {
3301   PetscErrorCode ierr;
3302 
3303   PetscFunctionBegin;
3304   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3305   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESSkipConverged;
3306   if (snes->ops->convergeddestroy) {
3307     ierr = (*snes->ops->convergeddestroy)(snes->cnvP);CHKERRQ(ierr);
3308   }
3309   snes->ops->converged        = SNESConvergenceTestFunction;
3310   snes->ops->convergeddestroy = destroy;
3311   snes->cnvP                  = cctx;
3312   PetscFunctionReturn(0);
3313 }
3314 
3315 #undef __FUNCT__
3316 #define __FUNCT__ "SNESGetConvergedReason"
3317 /*@
3318    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.
3319 
3320    Not Collective
3321 
3322    Input Parameter:
3323 .  snes - the SNES context
3324 
3325    Output Parameter:
3326 .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
3327             manual pages for the individual convergence tests for complete lists
3328 
3329    Level: intermediate
3330 
3331    Notes: Can only be called after the call the SNESSolve() is complete.
3332 
3333 .keywords: SNES, nonlinear, set, convergence, test
3334 
3335 .seealso: SNESSetConvergenceTest(), SNESConvergedReason
3336 @*/
3337 PetscErrorCode  SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
3338 {
3339   PetscFunctionBegin;
3340   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3341   PetscValidPointer(reason,2);
3342   *reason = snes->reason;
3343   PetscFunctionReturn(0);
3344 }
3345 
3346 #undef __FUNCT__
3347 #define __FUNCT__ "SNESSetConvergenceHistory"
3348 /*@
3349    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.
3350 
3351    Logically Collective on SNES
3352 
3353    Input Parameters:
3354 +  snes - iterative context obtained from SNESCreate()
3355 .  a   - array to hold history, this array will contain the function norms computed at each step
3356 .  its - integer array holds the number of linear iterations for each solve.
3357 .  na  - size of a and its
3358 -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
3359            else it continues storing new values for new nonlinear solves after the old ones
3360 
3361    Notes:
3362    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
3363    default array of length 10000 is allocated.
3364 
3365    This routine is useful, e.g., when running a code for purposes
3366    of accurate performance monitoring, when no I/O should be done
3367    during the section of code that is being timed.
3368 
3369    Level: intermediate
3370 
3371 .keywords: SNES, set, convergence, history
3372 
3373 .seealso: SNESGetConvergenceHistory()
3374 
3375 @*/
3376 PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
3377 {
3378   PetscErrorCode ierr;
3379 
3380   PetscFunctionBegin;
3381   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3382   if (a) PetscValidScalarPointer(a,2);
3383   if (its) PetscValidIntPointer(its,3);
3384   if (!a) {
3385     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
3386     ierr = PetscMalloc(na*sizeof(PetscReal),&a);CHKERRQ(ierr);
3387     ierr = PetscMalloc(na*sizeof(PetscInt),&its);CHKERRQ(ierr);
3388 
3389     snes->conv_malloc = PETSC_TRUE;
3390   }
3391   snes->conv_hist       = a;
3392   snes->conv_hist_its   = its;
3393   snes->conv_hist_max   = na;
3394   snes->conv_hist_len   = 0;
3395   snes->conv_hist_reset = reset;
3396   PetscFunctionReturn(0);
3397 }
3398 
3399 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3400 #include <engine.h>   /* MATLAB include file */
3401 #include <mex.h>      /* MATLAB include file */
3402 
3403 #undef __FUNCT__
3404 #define __FUNCT__ "SNESGetConvergenceHistoryMatlab"
3405 PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
3406 {
3407   mxArray   *mat;
3408   PetscInt  i;
3409   PetscReal *ar;
3410 
3411   PetscFunctionBegin;
3412   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
3413   ar  = (PetscReal*) mxGetData(mat);
3414   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
3415   PetscFunctionReturn(mat);
3416 }
3417 #endif
3418 
3419 #undef __FUNCT__
3420 #define __FUNCT__ "SNESGetConvergenceHistory"
3421 /*@C
3422    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.
3423 
3424    Not Collective
3425 
3426    Input Parameter:
3427 .  snes - iterative context obtained from SNESCreate()
3428 
3429    Output Parameters:
3430 .  a   - array to hold history
3431 .  its - integer array holds the number of linear iterations (or
3432          negative if not converged) for each solve.
3433 -  na  - size of a and its
3434 
3435    Notes:
3436     The calling sequence for this routine in Fortran is
3437 $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
3438 
3439    This routine is useful, e.g., when running a code for purposes
3440    of accurate performance monitoring, when no I/O should be done
3441    during the section of code that is being timed.
3442 
3443    Level: intermediate
3444 
3445 .keywords: SNES, get, convergence, history
3446 
3447 .seealso: SNESSetConvergencHistory()
3448 
3449 @*/
3450 PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
3451 {
3452   PetscFunctionBegin;
3453   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3454   if (a)   *a   = snes->conv_hist;
3455   if (its) *its = snes->conv_hist_its;
3456   if (na)  *na  = snes->conv_hist_len;
3457   PetscFunctionReturn(0);
3458 }
3459 
3460 #undef __FUNCT__
3461 #define __FUNCT__ "SNESSetUpdate"
3462 /*@C
3463   SNESSetUpdate - Sets the general-purpose update function called
3464   at the beginning of every iteration of the nonlinear solve. Specifically
3465   it is called just before the Jacobian is "evaluated".
3466 
3467   Logically Collective on SNES
3468 
3469   Input Parameters:
3470 . snes - The nonlinear solver context
3471 . func - The function
3472 
3473   Calling sequence of func:
3474 . func (SNES snes, PetscInt step);
3475 
3476 . step - The current step of the iteration
3477 
3478   Level: advanced
3479 
3480   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()
3481         This is not used by most users.
3482 
3483 .keywords: SNES, update
3484 
3485 .seealso SNESSetJacobian(), SNESSolve()
3486 @*/
3487 PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
3488 {
3489   PetscFunctionBegin;
3490   PetscValidHeaderSpecific(snes, SNES_CLASSID,1);
3491   snes->ops->update = func;
3492   PetscFunctionReturn(0);
3493 }
3494 
3495 #undef __FUNCT__
3496 #define __FUNCT__ "SNESScaleStep_Private"
3497 /*
3498    SNESScaleStep_Private - Scales a step so that its length is less than the
3499    positive parameter delta.
3500 
3501     Input Parameters:
3502 +   snes - the SNES context
3503 .   y - approximate solution of linear system
3504 .   fnorm - 2-norm of current function
3505 -   delta - trust region size
3506 
3507     Output Parameters:
3508 +   gpnorm - predicted function norm at the new point, assuming local
3509     linearization.  The value is zero if the step lies within the trust
3510     region, and exceeds zero otherwise.
3511 -   ynorm - 2-norm of the step
3512 
3513     Note:
3514     For non-trust region methods such as SNESNEWTONLS, the parameter delta
3515     is set to be the maximum allowable step size.
3516 
3517 .keywords: SNES, nonlinear, scale, step
3518 */
3519 PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
3520 {
3521   PetscReal      nrm;
3522   PetscScalar    cnorm;
3523   PetscErrorCode ierr;
3524 
3525   PetscFunctionBegin;
3526   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3527   PetscValidHeaderSpecific(y,VEC_CLASSID,2);
3528   PetscCheckSameComm(snes,1,y,2);
3529 
3530   ierr = VecNorm(y,NORM_2,&nrm);CHKERRQ(ierr);
3531   if (nrm > *delta) {
3532     nrm     = *delta/nrm;
3533     *gpnorm = (1.0 - nrm)*(*fnorm);
3534     cnorm   = nrm;
3535     ierr    = VecScale(y,cnorm);CHKERRQ(ierr);
3536     *ynorm  = *delta;
3537   } else {
3538     *gpnorm = 0.0;
3539     *ynorm  = nrm;
3540   }
3541   PetscFunctionReturn(0);
3542 }
3543 
3544 #undef __FUNCT__
3545 #define __FUNCT__ "SNESSolve"
3546 /*@C
3547    SNESSolve - Solves a nonlinear system F(x) = b.
3548    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().
3549 
3550    Collective on SNES
3551 
3552    Input Parameters:
3553 +  snes - the SNES context
3554 .  b - the constant part of the equation F(x) = b, or NULL to use zero.
3555 -  x - the solution vector.
3556 
3557    Notes:
3558    The user should initialize the vector,x, with the initial guess
3559    for the nonlinear solve prior to calling SNESSolve.  In particular,
3560    to employ an initial guess of zero, the user should explicitly set
3561    this vector to zero by calling VecSet().
3562 
3563    Level: beginner
3564 
3565 .keywords: SNES, nonlinear, solve
3566 
3567 .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
3568 @*/
3569 PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
3570 {
3571   PetscErrorCode    ierr;
3572   PetscBool         flg;
3573   PetscViewer       viewer;
3574   PetscInt          grid;
3575   Vec               xcreated = NULL;
3576   DM                dm;
3577   PetscViewerFormat format;
3578 
3579   PetscFunctionBegin;
3580   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3581   if (x) PetscValidHeaderSpecific(x,VEC_CLASSID,3);
3582   if (x) PetscCheckSameComm(snes,1,x,3);
3583   if (b) PetscValidHeaderSpecific(b,VEC_CLASSID,2);
3584   if (b) PetscCheckSameComm(snes,1,b,2);
3585 
3586   if (!x) {
3587     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3588     ierr = DMCreateGlobalVector(dm,&xcreated);CHKERRQ(ierr);
3589     x    = xcreated;
3590   }
3591 
3592   ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_view_pre",&viewer,&format,&flg);CHKERRQ(ierr);
3593   if (flg && !PetscPreLoadingOn) {
3594     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
3595     ierr = SNESView(snes,viewer);CHKERRQ(ierr);
3596     ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
3597     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3598   }
3599 
3600   for (grid=0; grid<snes->gridsequence; grid++) {ierr = PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);}
3601   for (grid=0; grid<snes->gridsequence+1; grid++) {
3602 
3603     /* set solution vector */
3604     if (!grid) {ierr = PetscObjectReference((PetscObject)x);CHKERRQ(ierr);}
3605     ierr          = VecDestroy(&snes->vec_sol);CHKERRQ(ierr);
3606     snes->vec_sol = x;
3607     ierr          = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3608 
3609     /* set affine vector if provided */
3610     if (b) { ierr = PetscObjectReference((PetscObject)b);CHKERRQ(ierr); }
3611     ierr          = VecDestroy(&snes->vec_rhs);CHKERRQ(ierr);
3612     snes->vec_rhs = b;
3613 
3614     ierr = SNESSetUp(snes);CHKERRQ(ierr);
3615 
3616     if (!grid) {
3617       if (snes->ops->computeinitialguess) {
3618         ierr = (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);CHKERRQ(ierr);
3619       }
3620     }
3621 
3622     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
3623     snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;
3624 
3625     ierr = PetscLogEventBegin(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3626     ierr = (*snes->ops->solve)(snes);CHKERRQ(ierr);
3627     ierr = PetscLogEventEnd(SNES_Solve,snes,0,0,0);CHKERRQ(ierr);
3628     if (snes->domainerror) {
3629       snes->reason      = SNES_DIVERGED_FUNCTION_DOMAIN;
3630       snes->domainerror = PETSC_FALSE;
3631     }
3632     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
3633 
3634     flg  = PETSC_FALSE;
3635     ierr = PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,NULL);CHKERRQ(ierr);
3636     if (flg && !PetscPreLoadingOn) { ierr = SNESTestLocalMin(snes);CHKERRQ(ierr); }
3637     if (snes->printreason) {
3638       ierr = PetscViewerASCIIAddTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3639       if (snes->reason > 0) {
3640         ierr = PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);CHKERRQ(ierr);
3641       } else {
3642         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);
3643       }
3644       ierr = PetscViewerASCIISubtractTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),((PetscObject)snes)->tablevel);CHKERRQ(ierr);
3645     }
3646 
3647     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
3648     if (grid <  snes->gridsequence) {
3649       DM  fine;
3650       Vec xnew;
3651       Mat interp;
3652 
3653       ierr = DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);CHKERRQ(ierr);
3654       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
3655       ierr = DMCreateInterpolation(snes->dm,fine,&interp,NULL);CHKERRQ(ierr);
3656       ierr = DMCreateGlobalVector(fine,&xnew);CHKERRQ(ierr);
3657       ierr = MatInterpolate(interp,x,xnew);CHKERRQ(ierr);
3658       ierr = DMInterpolate(snes->dm,interp,fine);CHKERRQ(ierr);
3659       ierr = MatDestroy(&interp);CHKERRQ(ierr);
3660       x    = xnew;
3661 
3662       ierr = SNESReset(snes);CHKERRQ(ierr);
3663       ierr = SNESSetDM(snes,fine);CHKERRQ(ierr);
3664       ierr = DMDestroy(&fine);CHKERRQ(ierr);
3665       ierr = PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));CHKERRQ(ierr);
3666     }
3667   }
3668   /* monitoring and viewing */
3669   ierr = PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_view",&viewer,&format,&flg);CHKERRQ(ierr);
3670   if (flg && !PetscPreLoadingOn) {
3671     ierr = PetscViewerPushFormat(viewer,format);CHKERRQ(ierr);
3672     ierr = SNESView(snes,viewer);CHKERRQ(ierr);
3673     ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
3674     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3675   }
3676   ierr = VecViewFromOptions(snes->vec_sol,"-snes_view_solution");CHKERRQ(ierr);
3677 
3678   ierr = VecDestroy(&xcreated);CHKERRQ(ierr);
3679   ierr = PetscObjectAMSBlock((PetscObject)snes);CHKERRQ(ierr);
3680   PetscFunctionReturn(0);
3681 }
3682 
3683 /* --------- Internal routines for SNES Package --------- */
3684 
3685 #undef __FUNCT__
3686 #define __FUNCT__ "SNESSetType"
3687 /*@C
3688    SNESSetType - Sets the method for the nonlinear solver.
3689 
3690    Collective on SNES
3691 
3692    Input Parameters:
3693 +  snes - the SNES context
3694 -  type - a known method
3695 
3696    Options Database Key:
3697 .  -snes_type <type> - Sets the method; use -help for a list
3698    of available methods (for instance, newtonls or newtontr)
3699 
3700    Notes:
3701    See "petsc/include/petscsnes.h" for available methods (for instance)
3702 +    SNESNEWTONLS - Newton's method with line search
3703      (systems of nonlinear equations)
3704 .    SNESNEWTONTR - Newton's method with trust region
3705      (systems of nonlinear equations)
3706 
3707   Normally, it is best to use the SNESSetFromOptions() command and then
3708   set the SNES solver type from the options database rather than by using
3709   this routine.  Using the options database provides the user with
3710   maximum flexibility in evaluating the many nonlinear solvers.
3711   The SNESSetType() routine is provided for those situations where it
3712   is necessary to set the nonlinear solver independently of the command
3713   line or options database.  This might be the case, for example, when
3714   the choice of solver changes during the execution of the program,
3715   and the user's application is taking responsibility for choosing the
3716   appropriate method.
3717 
3718   Level: intermediate
3719 
3720 .keywords: SNES, set, type
3721 
3722 .seealso: SNESType, SNESCreate()
3723 
3724 @*/
3725 PetscErrorCode  SNESSetType(SNES snes,SNESType type)
3726 {
3727   PetscErrorCode ierr,(*r)(SNES);
3728   PetscBool      match;
3729 
3730   PetscFunctionBegin;
3731   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3732   PetscValidCharPointer(type,2);
3733 
3734   ierr = PetscObjectTypeCompare((PetscObject)snes,type,&match);CHKERRQ(ierr);
3735   if (match) PetscFunctionReturn(0);
3736 
3737   ierr =  PetscFunctionListFind(PetscObjectComm((PetscObject)snes),SNESList,type,PETSC_TRUE,(void (**)(void)) &r);CHKERRQ(ierr);
3738   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
3739   /* Destroy the previous private SNES context */
3740   if (snes->ops->destroy) {
3741     ierr               = (*(snes)->ops->destroy)(snes);CHKERRQ(ierr);
3742     snes->ops->destroy = NULL;
3743   }
3744   /* Reinitialize function pointers in SNESOps structure */
3745   snes->ops->setup          = 0;
3746   snes->ops->solve          = 0;
3747   snes->ops->view           = 0;
3748   snes->ops->setfromoptions = 0;
3749   snes->ops->destroy        = 0;
3750   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
3751   snes->setupcalled = PETSC_FALSE;
3752 
3753   ierr = PetscObjectChangeTypeName((PetscObject)snes,type);CHKERRQ(ierr);
3754   ierr = (*r)(snes);CHKERRQ(ierr);
3755   PetscFunctionReturn(0);
3756 }
3757 
3758 /* --------------------------------------------------------------------- */
3759 #undef __FUNCT__
3760 #define __FUNCT__ "SNESRegisterDestroy"
3761 /*@
3762    SNESRegisterDestroy - Frees the list of nonlinear solvers that were
3763    registered by SNESRegisterDynamic().
3764 
3765    Not Collective
3766 
3767    Level: advanced
3768 
3769 .keywords: SNES, nonlinear, register, destroy
3770 
3771 .seealso: SNESRegisterAll()
3772 @*/
3773 PetscErrorCode  SNESRegisterDestroy(void)
3774 {
3775   PetscErrorCode ierr;
3776 
3777   PetscFunctionBegin;
3778   ierr = PetscFunctionListDestroy(&SNESList);CHKERRQ(ierr);
3779 
3780   SNESRegisterAllCalled = PETSC_FALSE;
3781   PetscFunctionReturn(0);
3782 }
3783 
3784 #undef __FUNCT__
3785 #define __FUNCT__ "SNESGetType"
3786 /*@C
3787    SNESGetType - Gets the SNES method type and name (as a string).
3788 
3789    Not Collective
3790 
3791    Input Parameter:
3792 .  snes - nonlinear solver context
3793 
3794    Output Parameter:
3795 .  type - SNES method (a character string)
3796 
3797    Level: intermediate
3798 
3799 .keywords: SNES, nonlinear, get, type, name
3800 @*/
3801 PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
3802 {
3803   PetscFunctionBegin;
3804   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3805   PetscValidPointer(type,2);
3806   *type = ((PetscObject)snes)->type_name;
3807   PetscFunctionReturn(0);
3808 }
3809 
3810 #undef __FUNCT__
3811 #define __FUNCT__ "SNESGetSolution"
3812 /*@
3813    SNESGetSolution - Returns the vector where the approximate solution is
3814    stored. This is the fine grid solution when using SNESSetGridSequence().
3815 
3816    Not Collective, but Vec is parallel if SNES is parallel
3817 
3818    Input Parameter:
3819 .  snes - the SNES context
3820 
3821    Output Parameter:
3822 .  x - the solution
3823 
3824    Level: intermediate
3825 
3826 .keywords: SNES, nonlinear, get, solution
3827 
3828 .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
3829 @*/
3830 PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
3831 {
3832   PetscFunctionBegin;
3833   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3834   PetscValidPointer(x,2);
3835   *x = snes->vec_sol;
3836   PetscFunctionReturn(0);
3837 }
3838 
3839 #undef __FUNCT__
3840 #define __FUNCT__ "SNESGetSolutionUpdate"
3841 /*@
3842    SNESGetSolutionUpdate - Returns the vector where the solution update is
3843    stored.
3844 
3845    Not Collective, but Vec is parallel if SNES is parallel
3846 
3847    Input Parameter:
3848 .  snes - the SNES context
3849 
3850    Output Parameter:
3851 .  x - the solution update
3852 
3853    Level: advanced
3854 
3855 .keywords: SNES, nonlinear, get, solution, update
3856 
3857 .seealso: SNESGetSolution(), SNESGetFunction()
3858 @*/
3859 PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
3860 {
3861   PetscFunctionBegin;
3862   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3863   PetscValidPointer(x,2);
3864   *x = snes->vec_sol_update;
3865   PetscFunctionReturn(0);
3866 }
3867 
3868 #undef __FUNCT__
3869 #define __FUNCT__ "SNESGetFunction"
3870 /*@C
3871    SNESGetFunction - Returns the vector where the function is stored.
3872 
3873    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
3874 
3875    Input Parameter:
3876 .  snes - the SNES context
3877 
3878    Output Parameter:
3879 +  r - the vector that is used to store residuals (or NULL if you don't want it)
3880 .  SNESFunction- the function (or NULL if you don't want it)
3881 -  ctx - the function context (or NULL if you don't want it)
3882 
3883    Level: advanced
3884 
3885 .keywords: SNES, nonlinear, get, function
3886 
3887 .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
3888 @*/
3889 PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**SNESFunction)(SNES,Vec,Vec,void*),void **ctx)
3890 {
3891   PetscErrorCode ierr;
3892   DM             dm;
3893 
3894   PetscFunctionBegin;
3895   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3896   if (r) {
3897     if (!snes->vec_func) {
3898       if (snes->vec_rhs) {
3899         ierr = VecDuplicate(snes->vec_rhs,&snes->vec_func);CHKERRQ(ierr);
3900       } else if (snes->vec_sol) {
3901         ierr = VecDuplicate(snes->vec_sol,&snes->vec_func);CHKERRQ(ierr);
3902       } else if (snes->dm) {
3903         ierr = DMCreateGlobalVector(snes->dm,&snes->vec_func);CHKERRQ(ierr);
3904       }
3905     }
3906     *r = snes->vec_func;
3907   }
3908   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3909   ierr = DMSNESGetFunction(dm,SNESFunction,ctx);CHKERRQ(ierr);
3910   PetscFunctionReturn(0);
3911 }
3912 
3913 /*@C
3914    SNESGetGS - Returns the GS function and context.
3915 
3916    Input Parameter:
3917 .  snes - the SNES context
3918 
3919    Output Parameter:
3920 +  SNESGSFunction - the function (or NULL)
3921 -  ctx    - the function context (or NULL)
3922 
3923    Level: advanced
3924 
3925 .keywords: SNES, nonlinear, get, function
3926 
3927 .seealso: SNESSetGS(), SNESGetFunction()
3928 @*/
3929 
3930 #undef __FUNCT__
3931 #define __FUNCT__ "SNESGetGS"
3932 PetscErrorCode SNESGetGS (SNES snes, PetscErrorCode (**SNESGSFunction)(SNES, Vec, Vec, void*), void ** ctx)
3933 {
3934   PetscErrorCode ierr;
3935   DM             dm;
3936 
3937   PetscFunctionBegin;
3938   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3939   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
3940   ierr = DMSNESGetGS(dm,SNESGSFunction,ctx);CHKERRQ(ierr);
3941   PetscFunctionReturn(0);
3942 }
3943 
3944 #undef __FUNCT__
3945 #define __FUNCT__ "SNESSetOptionsPrefix"
3946 /*@C
3947    SNESSetOptionsPrefix - Sets the prefix used for searching for all
3948    SNES options in the database.
3949 
3950    Logically Collective on SNES
3951 
3952    Input Parameter:
3953 +  snes - the SNES context
3954 -  prefix - the prefix to prepend to all option names
3955 
3956    Notes:
3957    A hyphen (-) must NOT be given at the beginning of the prefix name.
3958    The first character of all runtime options is AUTOMATICALLY the hyphen.
3959 
3960    Level: advanced
3961 
3962 .keywords: SNES, set, options, prefix, database
3963 
3964 .seealso: SNESSetFromOptions()
3965 @*/
3966 PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
3967 {
3968   PetscErrorCode ierr;
3969 
3970   PetscFunctionBegin;
3971   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3972   ierr = PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
3973   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
3974   if (snes->linesearch) {
3975     ierr = SNESGetSNESLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
3976     ierr = PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
3977   }
3978   ierr = KSPSetOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
3979   PetscFunctionReturn(0);
3980 }
3981 
3982 #undef __FUNCT__
3983 #define __FUNCT__ "SNESAppendOptionsPrefix"
3984 /*@C
3985    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
3986    SNES options in the database.
3987 
3988    Logically Collective on SNES
3989 
3990    Input Parameters:
3991 +  snes - the SNES context
3992 -  prefix - the prefix to prepend to all option names
3993 
3994    Notes:
3995    A hyphen (-) must NOT be given at the beginning of the prefix name.
3996    The first character of all runtime options is AUTOMATICALLY the hyphen.
3997 
3998    Level: advanced
3999 
4000 .keywords: SNES, append, options, prefix, database
4001 
4002 .seealso: SNESGetOptionsPrefix()
4003 @*/
4004 PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4005 {
4006   PetscErrorCode ierr;
4007 
4008   PetscFunctionBegin;
4009   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4010   ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4011   if (!snes->ksp) {ierr = SNESGetKSP(snes,&snes->ksp);CHKERRQ(ierr);}
4012   if (snes->linesearch) {
4013     ierr = SNESGetSNESLineSearch(snes,&snes->linesearch);CHKERRQ(ierr);
4014     ierr = PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);CHKERRQ(ierr);
4015   }
4016   ierr = KSPAppendOptionsPrefix(snes->ksp,prefix);CHKERRQ(ierr);
4017   PetscFunctionReturn(0);
4018 }
4019 
4020 #undef __FUNCT__
4021 #define __FUNCT__ "SNESGetOptionsPrefix"
4022 /*@C
4023    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4024    SNES options in the database.
4025 
4026    Not Collective
4027 
4028    Input Parameter:
4029 .  snes - the SNES context
4030 
4031    Output Parameter:
4032 .  prefix - pointer to the prefix string used
4033 
4034    Notes: On the fortran side, the user should pass in a string 'prefix' of
4035    sufficient length to hold the prefix.
4036 
4037    Level: advanced
4038 
4039 .keywords: SNES, get, options, prefix, database
4040 
4041 .seealso: SNESAppendOptionsPrefix()
4042 @*/
4043 PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4044 {
4045   PetscErrorCode ierr;
4046 
4047   PetscFunctionBegin;
4048   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4049   ierr = PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);CHKERRQ(ierr);
4050   PetscFunctionReturn(0);
4051 }
4052 
4053 
4054 #undef __FUNCT__
4055 #define __FUNCT__ "SNESRegister"
4056 /*@C
4057   SNESRegister - See SNESRegisterDynamic()
4058 
4059   Level: advanced
4060 @*/
4061 PetscErrorCode  SNESRegister(const char sname[],const char path[],const char name[],PetscErrorCode (*function)(SNES))
4062 {
4063   char           fullname[PETSC_MAX_PATH_LEN];
4064   PetscErrorCode ierr;
4065 
4066   PetscFunctionBegin;
4067   ierr = PetscFunctionListConcat(path,name,fullname);CHKERRQ(ierr);
4068   ierr = PetscFunctionListAdd(PETSC_COMM_WORLD,&SNESList,sname,fullname,(void (*)(void))function);CHKERRQ(ierr);
4069   PetscFunctionReturn(0);
4070 }
4071 
4072 #undef __FUNCT__
4073 #define __FUNCT__ "SNESTestLocalMin"
4074 PetscErrorCode  SNESTestLocalMin(SNES snes)
4075 {
4076   PetscErrorCode ierr;
4077   PetscInt       N,i,j;
4078   Vec            u,uh,fh;
4079   PetscScalar    value;
4080   PetscReal      norm;
4081 
4082   PetscFunctionBegin;
4083   ierr = SNESGetSolution(snes,&u);CHKERRQ(ierr);
4084   ierr = VecDuplicate(u,&uh);CHKERRQ(ierr);
4085   ierr = VecDuplicate(u,&fh);CHKERRQ(ierr);
4086 
4087   /* currently only works for sequential */
4088   ierr = PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");CHKERRQ(ierr);
4089   ierr = VecGetSize(u,&N);CHKERRQ(ierr);
4090   for (i=0; i<N; i++) {
4091     ierr = VecCopy(u,uh);CHKERRQ(ierr);
4092     ierr = PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);CHKERRQ(ierr);
4093     for (j=-10; j<11; j++) {
4094       value = PetscSign(j)*exp(PetscAbs(j)-10.0);
4095       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4096       ierr  = SNESComputeFunction(snes,uh,fh);CHKERRQ(ierr);
4097       ierr  = VecNorm(fh,NORM_2,&norm);CHKERRQ(ierr);
4098       ierr  = PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);CHKERRQ(ierr);
4099       value = -value;
4100       ierr  = VecSetValue(uh,i,value,ADD_VALUES);CHKERRQ(ierr);
4101     }
4102   }
4103   ierr = VecDestroy(&uh);CHKERRQ(ierr);
4104   ierr = VecDestroy(&fh);CHKERRQ(ierr);
4105   PetscFunctionReturn(0);
4106 }
4107 
4108 #undef __FUNCT__
4109 #define __FUNCT__ "SNESKSPSetUseEW"
4110 /*@
4111    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4112    computing relative tolerance for linear solvers within an inexact
4113    Newton method.
4114 
4115    Logically Collective on SNES
4116 
4117    Input Parameters:
4118 +  snes - SNES context
4119 -  flag - PETSC_TRUE or PETSC_FALSE
4120 
4121     Options Database:
4122 +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
4123 .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
4124 .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
4125 .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
4126 .  -snes_ksp_ew_gamma <gamma> - Sets gamma
4127 .  -snes_ksp_ew_alpha <alpha> - Sets alpha
4128 .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
4129 -  -snes_ksp_ew_threshold <threshold> - Sets threshold
4130 
4131    Notes:
4132    Currently, the default is to use a constant relative tolerance for
4133    the inner linear solvers.  Alternatively, one can use the
4134    Eisenstat-Walker method, where the relative convergence tolerance
4135    is reset at each Newton iteration according progress of the nonlinear
4136    solver.
4137 
4138    Level: advanced
4139 
4140    Reference:
4141    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4142    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4143 
4144 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4145 
4146 .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4147 @*/
4148 PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
4149 {
4150   PetscFunctionBegin;
4151   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4152   PetscValidLogicalCollectiveBool(snes,flag,2);
4153   snes->ksp_ewconv = flag;
4154   PetscFunctionReturn(0);
4155 }
4156 
4157 #undef __FUNCT__
4158 #define __FUNCT__ "SNESKSPGetUseEW"
4159 /*@
4160    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
4161    for computing relative tolerance for linear solvers within an
4162    inexact Newton method.
4163 
4164    Not Collective
4165 
4166    Input Parameter:
4167 .  snes - SNES context
4168 
4169    Output Parameter:
4170 .  flag - PETSC_TRUE or PETSC_FALSE
4171 
4172    Notes:
4173    Currently, the default is to use a constant relative tolerance for
4174    the inner linear solvers.  Alternatively, one can use the
4175    Eisenstat-Walker method, where the relative convergence tolerance
4176    is reset at each Newton iteration according progress of the nonlinear
4177    solver.
4178 
4179    Level: advanced
4180 
4181    Reference:
4182    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4183    inexact Newton method", SISC 17 (1), pp.16-32, 1996.
4184 
4185 .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton
4186 
4187 .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
4188 @*/
4189 PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
4190 {
4191   PetscFunctionBegin;
4192   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4193   PetscValidPointer(flag,2);
4194   *flag = snes->ksp_ewconv;
4195   PetscFunctionReturn(0);
4196 }
4197 
4198 #undef __FUNCT__
4199 #define __FUNCT__ "SNESKSPSetParametersEW"
4200 /*@
4201    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
4202    convergence criteria for the linear solvers within an inexact
4203    Newton method.
4204 
4205    Logically Collective on SNES
4206 
4207    Input Parameters:
4208 +    snes - SNES context
4209 .    version - version 1, 2 (default is 2) or 3
4210 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4211 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4212 .    gamma - multiplicative factor for version 2 rtol computation
4213              (0 <= gamma2 <= 1)
4214 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4215 .    alpha2 - power for safeguard
4216 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4217 
4218    Note:
4219    Version 3 was contributed by Luis Chacon, June 2006.
4220 
4221    Use PETSC_DEFAULT to retain the default for any of the parameters.
4222 
4223    Level: advanced
4224 
4225    Reference:
4226    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
4227    inexact Newton method", Utah State University Math. Stat. Dept. Res.
4228    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.
4229 
4230 .keywords: SNES, KSP, Eisenstat, Walker, set, parameters
4231 
4232 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
4233 @*/
4234 PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
4235 {
4236   SNESKSPEW *kctx;
4237 
4238   PetscFunctionBegin;
4239   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4240   kctx = (SNESKSPEW*)snes->kspconvctx;
4241   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4242   PetscValidLogicalCollectiveInt(snes,version,2);
4243   PetscValidLogicalCollectiveReal(snes,rtol_0,3);
4244   PetscValidLogicalCollectiveReal(snes,rtol_max,4);
4245   PetscValidLogicalCollectiveReal(snes,gamma,5);
4246   PetscValidLogicalCollectiveReal(snes,alpha,6);
4247   PetscValidLogicalCollectiveReal(snes,alpha2,7);
4248   PetscValidLogicalCollectiveReal(snes,threshold,8);
4249 
4250   if (version != PETSC_DEFAULT)   kctx->version   = version;
4251   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
4252   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
4253   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
4254   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
4255   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
4256   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;
4257 
4258   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);
4259   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",kctx->rtol_0);
4260   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",kctx->rtol_max);
4261   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%G) <= 1.0\n",kctx->gamma);
4262   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%G) <= 2.0\n",kctx->alpha);
4263   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%G) < 1.0\n",kctx->threshold);
4264   PetscFunctionReturn(0);
4265 }
4266 
4267 #undef __FUNCT__
4268 #define __FUNCT__ "SNESKSPGetParametersEW"
4269 /*@
4270    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
4271    convergence criteria for the linear solvers within an inexact
4272    Newton method.
4273 
4274    Not Collective
4275 
4276    Input Parameters:
4277      snes - SNES context
4278 
4279    Output Parameters:
4280 +    version - version 1, 2 (default is 2) or 3
4281 .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
4282 .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
4283 .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
4284 .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
4285 .    alpha2 - power for safeguard
4286 -    threshold - threshold for imposing safeguard (0 < threshold < 1)
4287 
4288    Level: advanced
4289 
4290 .keywords: SNES, KSP, Eisenstat, Walker, get, parameters
4291 
4292 .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
4293 @*/
4294 PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
4295 {
4296   SNESKSPEW *kctx;
4297 
4298   PetscFunctionBegin;
4299   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4300   kctx = (SNESKSPEW*)snes->kspconvctx;
4301   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
4302   if (version)   *version   = kctx->version;
4303   if (rtol_0)    *rtol_0    = kctx->rtol_0;
4304   if (rtol_max)  *rtol_max  = kctx->rtol_max;
4305   if (gamma)     *gamma     = kctx->gamma;
4306   if (alpha)     *alpha     = kctx->alpha;
4307   if (alpha2)    *alpha2    = kctx->alpha2;
4308   if (threshold) *threshold = kctx->threshold;
4309   PetscFunctionReturn(0);
4310 }
4311 
4312 #undef __FUNCT__
4313 #define __FUNCT__ "SNESKSPEW_PreSolve"
4314  PetscErrorCode SNESKSPEW_PreSolve(KSP ksp, Vec b, Vec x, SNES snes)
4315 {
4316   PetscErrorCode ierr;
4317   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4318   PetscReal      rtol  = PETSC_DEFAULT,stol;
4319 
4320   PetscFunctionBegin;
4321   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4322   if (!snes->iter) rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
4323   else {
4324     if (kctx->version == 1) {
4325       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
4326       if (rtol < 0.0) rtol = -rtol;
4327       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
4328       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4329     } else if (kctx->version == 2) {
4330       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4331       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
4332       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
4333     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
4334       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
4335       /* safeguard: avoid sharp decrease of rtol */
4336       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
4337       stol = PetscMax(rtol,stol);
4338       rtol = PetscMin(kctx->rtol_0,stol);
4339       /* safeguard: avoid oversolving */
4340       stol = kctx->gamma*(snes->ttol)/snes->norm;
4341       stol = PetscMax(rtol,stol);
4342       rtol = PetscMin(kctx->rtol_0,stol);
4343     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
4344   }
4345   /* safeguard: avoid rtol greater than one */
4346   rtol = PetscMin(rtol,kctx->rtol_max);
4347   ierr = KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
4348   ierr = PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%G\n",snes->iter,kctx->version,rtol);CHKERRQ(ierr);
4349   PetscFunctionReturn(0);
4350 }
4351 
4352 #undef __FUNCT__
4353 #define __FUNCT__ "SNESKSPEW_PostSolve"
4354 PetscErrorCode SNESKSPEW_PostSolve(KSP ksp, Vec b, Vec x, SNES snes)
4355 {
4356   PetscErrorCode ierr;
4357   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
4358   PCSide         pcside;
4359   Vec            lres;
4360 
4361   PetscFunctionBegin;
4362   if (!snes->ksp_ewconv) PetscFunctionReturn(0);
4363   ierr = KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);CHKERRQ(ierr);
4364   ierr = SNESGetFunctionNorm(snes,&kctx->norm_last);CHKERRQ(ierr);
4365   if (kctx->version == 1) {
4366     ierr = KSPGetPCSide(ksp,&pcside);CHKERRQ(ierr);
4367     if (pcside == PC_RIGHT) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
4368       /* KSP residual is true linear residual */
4369       ierr = KSPGetResidualNorm(ksp,&kctx->lresid_last);CHKERRQ(ierr);
4370     } else {
4371       /* KSP residual is preconditioned residual */
4372       /* compute true linear residual norm */
4373       ierr = VecDuplicate(b,&lres);CHKERRQ(ierr);
4374       ierr = MatMult(snes->jacobian,x,lres);CHKERRQ(ierr);
4375       ierr = VecAYPX(lres,-1.0,b);CHKERRQ(ierr);
4376       ierr = VecNorm(lres,NORM_2,&kctx->lresid_last);CHKERRQ(ierr);
4377       ierr = VecDestroy(&lres);CHKERRQ(ierr);
4378     }
4379   }
4380   PetscFunctionReturn(0);
4381 }
4382 
4383 #undef __FUNCT__
4384 #define __FUNCT__ "SNESGetKSP"
4385 /*@
4386    SNESGetKSP - Returns the KSP context for a SNES solver.
4387 
4388    Not Collective, but if SNES object is parallel, then KSP object is parallel
4389 
4390    Input Parameter:
4391 .  snes - the SNES context
4392 
4393    Output Parameter:
4394 .  ksp - the KSP context
4395 
4396    Notes:
4397    The user can then directly manipulate the KSP context to set various
4398    options, etc.  Likewise, the user can then extract and manipulate the
4399    PC contexts as well.
4400 
4401    Level: beginner
4402 
4403 .keywords: SNES, nonlinear, get, KSP, context
4404 
4405 .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
4406 @*/
4407 PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
4408 {
4409   PetscErrorCode ierr;
4410 
4411   PetscFunctionBegin;
4412   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4413   PetscValidPointer(ksp,2);
4414 
4415   if (!snes->ksp) {
4416     ierr = KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);CHKERRQ(ierr);
4417     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);CHKERRQ(ierr);
4418     ierr = PetscLogObjectParent(snes,snes->ksp);CHKERRQ(ierr);
4419 
4420     ierr = KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))SNESKSPEW_PreSolve,snes);CHKERRQ(ierr);
4421     ierr = KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))SNESKSPEW_PostSolve,snes);CHKERRQ(ierr);
4422   }
4423   *ksp = snes->ksp;
4424   PetscFunctionReturn(0);
4425 }
4426 
4427 
4428 #include <petsc-private/dmimpl.h>
4429 #undef __FUNCT__
4430 #define __FUNCT__ "SNESSetDM"
4431 /*@
4432    SNESSetDM - Sets the DM that may be used by some preconditioners
4433 
4434    Logically Collective on SNES
4435 
4436    Input Parameters:
4437 +  snes - the preconditioner context
4438 -  dm - the dm
4439 
4440    Level: intermediate
4441 
4442 .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
4443 @*/
4444 PetscErrorCode  SNESSetDM(SNES snes,DM dm)
4445 {
4446   PetscErrorCode ierr;
4447   KSP            ksp;
4448   DMSNES         sdm;
4449 
4450   PetscFunctionBegin;
4451   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4452   if (dm) {ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);}
4453   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
4454     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
4455       ierr = DMCopyDMSNES(snes->dm,dm);CHKERRQ(ierr);
4456       ierr = DMGetDMSNES(snes->dm,&sdm);CHKERRQ(ierr);
4457       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
4458     }
4459     ierr = DMDestroy(&snes->dm);CHKERRQ(ierr);
4460   }
4461   snes->dm     = dm;
4462   snes->dmAuto = PETSC_FALSE;
4463 
4464   ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr);
4465   ierr = KSPSetDM(ksp,dm);CHKERRQ(ierr);
4466   ierr = KSPSetDMActive(ksp,PETSC_FALSE);CHKERRQ(ierr);
4467   if (snes->pc) {
4468     ierr = SNESSetDM(snes->pc, snes->dm);CHKERRQ(ierr);
4469     ierr = SNESSetPCSide(snes,snes->pcside);CHKERRQ(ierr);
4470   }
4471   PetscFunctionReturn(0);
4472 }
4473 
4474 #undef __FUNCT__
4475 #define __FUNCT__ "SNESGetDM"
4476 /*@
4477    SNESGetDM - Gets the DM that may be used by some preconditioners
4478 
4479    Not Collective but DM obtained is parallel on SNES
4480 
4481    Input Parameter:
4482 . snes - the preconditioner context
4483 
4484    Output Parameter:
4485 .  dm - the dm
4486 
4487    Level: intermediate
4488 
4489 .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
4490 @*/
4491 PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
4492 {
4493   PetscErrorCode ierr;
4494 
4495   PetscFunctionBegin;
4496   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4497   if (!snes->dm) {
4498     ierr         = DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);CHKERRQ(ierr);
4499     snes->dmAuto = PETSC_TRUE;
4500   }
4501   *dm = snes->dm;
4502   PetscFunctionReturn(0);
4503 }
4504 
4505 #undef __FUNCT__
4506 #define __FUNCT__ "SNESSetPC"
4507 /*@
4508   SNESSetPC - Sets the nonlinear preconditioner to be used.
4509 
4510   Collective on SNES
4511 
4512   Input Parameters:
4513 + snes - iterative context obtained from SNESCreate()
4514 - pc   - the preconditioner object
4515 
4516   Notes:
4517   Use SNESGetPC() to retrieve the preconditioner context (for example,
4518   to configure it using the API).
4519 
4520   Level: developer
4521 
4522 .keywords: SNES, set, precondition
4523 .seealso: SNESGetPC()
4524 @*/
4525 PetscErrorCode SNESSetPC(SNES snes, SNES pc)
4526 {
4527   PetscErrorCode ierr;
4528 
4529   PetscFunctionBegin;
4530   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4531   PetscValidHeaderSpecific(pc, SNES_CLASSID, 2);
4532   PetscCheckSameComm(snes, 1, pc, 2);
4533   ierr     = PetscObjectReference((PetscObject) pc);CHKERRQ(ierr);
4534   ierr     = SNESDestroy(&snes->pc);CHKERRQ(ierr);
4535   snes->pc = pc;
4536   ierr     = PetscLogObjectParent(snes, snes->pc);CHKERRQ(ierr);
4537   PetscFunctionReturn(0);
4538 }
4539 
4540 #undef __FUNCT__
4541 #define __FUNCT__ "SNESGetPC"
4542 /*@
4543   SNESGetPC - Returns a pointer to the nonlinear preconditioning context set with SNESSetPC().
4544 
4545   Not Collective
4546 
4547   Input Parameter:
4548 . snes - iterative context obtained from SNESCreate()
4549 
4550   Output Parameter:
4551 . pc - preconditioner context
4552 
4553   Level: developer
4554 
4555 .keywords: SNES, get, preconditioner
4556 .seealso: SNESSetPC()
4557 @*/
4558 PetscErrorCode SNESGetPC(SNES snes, SNES *pc)
4559 {
4560   PetscErrorCode ierr;
4561   const char     *optionsprefix;
4562 
4563   PetscFunctionBegin;
4564   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4565   PetscValidPointer(pc, 2);
4566   if (!snes->pc) {
4567     ierr = SNESCreate(PetscObjectComm((PetscObject)snes),&snes->pc);CHKERRQ(ierr);
4568     ierr = PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);CHKERRQ(ierr);
4569     ierr = PetscLogObjectParent(snes,snes->pc);CHKERRQ(ierr);
4570     ierr = SNESGetOptionsPrefix(snes,&optionsprefix);CHKERRQ(ierr);
4571     ierr = SNESSetOptionsPrefix(snes->pc,optionsprefix);CHKERRQ(ierr);
4572     ierr = SNESAppendOptionsPrefix(snes->pc,"npc_");CHKERRQ(ierr);
4573   }
4574   *pc = snes->pc;
4575   PetscFunctionReturn(0);
4576 }
4577 
4578 #undef __FUNCT__
4579 #define __FUNCT__ "SNESSetPCSide"
4580 /*@
4581     SNESSetPCSide - Sets the preconditioning side.
4582 
4583     Logically Collective on SNES
4584 
4585     Input Parameter:
4586 .   snes - iterative context obtained from SNESCreate()
4587 
4588     Output Parameter:
4589 .   side - the preconditioning side, where side is one of
4590 .vb
4591       PC_LEFT - left preconditioning (default)
4592       PC_RIGHT - right preconditioning
4593 .ve
4594 
4595     Options Database Keys:
4596 .   -snes_pc_side <right,left>
4597 
4598     Level: intermediate
4599 
4600 .keywords: SNES, set, right, left, side, preconditioner, flag
4601 
4602 .seealso: SNESGetPCSide(), KSPSetPCSide()
4603 @*/
4604 PetscErrorCode  SNESSetPCSide(SNES snes,PCSide side)
4605 {
4606   PetscFunctionBegin;
4607   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4608   PetscValidLogicalCollectiveEnum(snes,side,2);
4609   snes->pcside = side;
4610   PetscFunctionReturn(0);
4611 }
4612 
4613 #undef __FUNCT__
4614 #define __FUNCT__ "SNESGetPCSide"
4615 /*@
4616     SNESGetPCSide - Gets the preconditioning side.
4617 
4618     Not Collective
4619 
4620     Input Parameter:
4621 .   snes - iterative context obtained from SNESCreate()
4622 
4623     Output Parameter:
4624 .   side - the preconditioning side, where side is one of
4625 .vb
4626       PC_LEFT - left preconditioning (default)
4627       PC_RIGHT - right preconditioning
4628 .ve
4629 
4630     Level: intermediate
4631 
4632 .keywords: SNES, get, right, left, side, preconditioner, flag
4633 
4634 .seealso: SNESSetPCSide(), KSPGetPCSide()
4635 @*/
4636 PetscErrorCode  SNESGetPCSide(SNES snes,PCSide *side)
4637 {
4638   PetscFunctionBegin;
4639   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4640   PetscValidPointer(side,2);
4641   *side = snes->pcside;
4642   PetscFunctionReturn(0);
4643 }
4644 
4645 #undef __FUNCT__
4646 #define __FUNCT__ "SNESSetSNESLineSearch"
4647 /*@
4648   SNESSetSNESLineSearch - Sets the linesearch on the SNES instance.
4649 
4650   Collective on SNES
4651 
4652   Input Parameters:
4653 + snes - iterative context obtained from SNESCreate()
4654 - linesearch   - the linesearch object
4655 
4656   Notes:
4657   Use SNESGetSNESLineSearch() to retrieve the preconditioner context (for example,
4658   to configure it using the API).
4659 
4660   Level: developer
4661 
4662 .keywords: SNES, set, linesearch
4663 .seealso: SNESGetSNESLineSearch()
4664 @*/
4665 PetscErrorCode SNESSetSNESLineSearch(SNES snes, SNESLineSearch linesearch)
4666 {
4667   PetscErrorCode ierr;
4668 
4669   PetscFunctionBegin;
4670   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4671   PetscValidHeaderSpecific(linesearch, SNESLINESEARCH_CLASSID, 2);
4672   PetscCheckSameComm(snes, 1, linesearch, 2);
4673   ierr = PetscObjectReference((PetscObject) linesearch);CHKERRQ(ierr);
4674   ierr = SNESLineSearchDestroy(&snes->linesearch);CHKERRQ(ierr);
4675 
4676   snes->linesearch = linesearch;
4677 
4678   ierr = PetscLogObjectParent(snes, snes->linesearch);CHKERRQ(ierr);
4679   PetscFunctionReturn(0);
4680 }
4681 
4682 #undef __FUNCT__
4683 #define __FUNCT__ "SNESGetSNESLineSearch"
4684 /*@C
4685   SNESGetSNESLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
4686   or creates a default line search instance associated with the SNES and returns it.
4687 
4688   Not Collective
4689 
4690   Input Parameter:
4691 . snes - iterative context obtained from SNESCreate()
4692 
4693   Output Parameter:
4694 . linesearch - linesearch context
4695 
4696   Level: developer
4697 
4698 .keywords: SNES, get, linesearch
4699 .seealso: SNESSetSNESLineSearch()
4700 @*/
4701 PetscErrorCode SNESGetSNESLineSearch(SNES snes, SNESLineSearch *linesearch)
4702 {
4703   PetscErrorCode ierr;
4704   const char     *optionsprefix;
4705 
4706   PetscFunctionBegin;
4707   PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
4708   PetscValidPointer(linesearch, 2);
4709   if (!snes->linesearch) {
4710     ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
4711     ierr = SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);CHKERRQ(ierr);
4712     ierr = SNESLineSearchSetSNES(snes->linesearch, snes);CHKERRQ(ierr);
4713     ierr = SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);CHKERRQ(ierr);
4714     ierr = PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);CHKERRQ(ierr);
4715     ierr = PetscLogObjectParent(snes, snes->linesearch);CHKERRQ(ierr);
4716   }
4717   *linesearch = snes->linesearch;
4718   PetscFunctionReturn(0);
4719 }
4720 
4721 #if defined(PETSC_HAVE_MATLAB_ENGINE)
4722 #include <mex.h>
4723 
4724 typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;
4725 
4726 #undef __FUNCT__
4727 #define __FUNCT__ "SNESComputeFunction_Matlab"
4728 /*
4729    SNESComputeFunction_Matlab - Calls the function that has been set with SNESSetFunctionMatlab().
4730 
4731    Collective on SNES
4732 
4733    Input Parameters:
4734 +  snes - the SNES context
4735 -  x - input vector
4736 
4737    Output Parameter:
4738 .  y - function vector, as set by SNESSetFunction()
4739 
4740    Notes:
4741    SNESComputeFunction() is typically used within nonlinear solvers
4742    implementations, so most users would not generally call this routine
4743    themselves.
4744 
4745    Level: developer
4746 
4747 .keywords: SNES, nonlinear, compute, function
4748 
4749 .seealso: SNESSetFunction(), SNESGetFunction()
4750 */
4751 PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
4752 {
4753   PetscErrorCode    ierr;
4754   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
4755   int               nlhs  = 1,nrhs = 5;
4756   mxArray           *plhs[1],*prhs[5];
4757   long long int     lx = 0,ly = 0,ls = 0;
4758 
4759   PetscFunctionBegin;
4760   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4761   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4762   PetscValidHeaderSpecific(y,VEC_CLASSID,3);
4763   PetscCheckSameComm(snes,1,x,2);
4764   PetscCheckSameComm(snes,1,y,3);
4765 
4766   /* call Matlab function in ctx with arguments x and y */
4767 
4768   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4769   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4770   ierr    = PetscMemcpy(&ly,&y,sizeof(x));CHKERRQ(ierr);
4771   prhs[0] = mxCreateDoubleScalar((double)ls);
4772   prhs[1] = mxCreateDoubleScalar((double)lx);
4773   prhs[2] = mxCreateDoubleScalar((double)ly);
4774   prhs[3] = mxCreateString(sctx->funcname);
4775   prhs[4] = sctx->ctx;
4776   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");CHKERRQ(ierr);
4777   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
4778   mxDestroyArray(prhs[0]);
4779   mxDestroyArray(prhs[1]);
4780   mxDestroyArray(prhs[2]);
4781   mxDestroyArray(prhs[3]);
4782   mxDestroyArray(plhs[0]);
4783   PetscFunctionReturn(0);
4784 }
4785 
4786 #undef __FUNCT__
4787 #define __FUNCT__ "SNESSetFunctionMatlab"
4788 /*
4789    SNESSetFunctionMatlab - Sets the function evaluation routine and function
4790    vector for use by the SNES routines in solving systems of nonlinear
4791    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4792 
4793    Logically Collective on SNES
4794 
4795    Input Parameters:
4796 +  snes - the SNES context
4797 .  r - vector to store function value
4798 -  SNESFunction - function evaluation routine
4799 
4800    Notes:
4801    The Newton-like methods typically solve linear systems of the form
4802 $      f'(x) x = -f(x),
4803    where f'(x) denotes the Jacobian matrix and f(x) is the function.
4804 
4805    Level: beginner
4806 
4807 .keywords: SNES, nonlinear, set, function
4808 
4809 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4810 */
4811 PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *SNESFunction,mxArray *ctx)
4812 {
4813   PetscErrorCode    ierr;
4814   SNESMatlabContext *sctx;
4815 
4816   PetscFunctionBegin;
4817   /* currently sctx is memory bleed */
4818   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4819   ierr = PetscStrallocpy(SNESFunction,&sctx->funcname);CHKERRQ(ierr);
4820   /*
4821      This should work, but it doesn't
4822   sctx->ctx = ctx;
4823   mexMakeArrayPersistent(sctx->ctx);
4824   */
4825   sctx->ctx = mxDuplicateArray(ctx);
4826   ierr      = SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);CHKERRQ(ierr);
4827   PetscFunctionReturn(0);
4828 }
4829 
4830 #undef __FUNCT__
4831 #define __FUNCT__ "SNESComputeJacobian_Matlab"
4832 /*
4833    SNESComputeJacobian_Matlab - Calls the function that has been set with SNESSetJacobianMatlab().
4834 
4835    Collective on SNES
4836 
4837    Input Parameters:
4838 +  snes - the SNES context
4839 .  x - input vector
4840 .  A, B - the matrices
4841 -  ctx - user context
4842 
4843    Output Parameter:
4844 .  flag - structure of the matrix
4845 
4846    Level: developer
4847 
4848 .keywords: SNES, nonlinear, compute, function
4849 
4850 .seealso: SNESSetFunction(), SNESGetFunction()
4851 @*/
4852 PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat *A,Mat *B,MatStructure *flag, void *ctx)
4853 {
4854   PetscErrorCode    ierr;
4855   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
4856   int               nlhs  = 2,nrhs = 6;
4857   mxArray           *plhs[2],*prhs[6];
4858   long long int     lx = 0,lA = 0,ls = 0, lB = 0;
4859 
4860   PetscFunctionBegin;
4861   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4862   PetscValidHeaderSpecific(x,VEC_CLASSID,2);
4863 
4864   /* call Matlab function in ctx with arguments x and y */
4865 
4866   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4867   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4868   ierr    = PetscMemcpy(&lA,A,sizeof(x));CHKERRQ(ierr);
4869   ierr    = PetscMemcpy(&lB,B,sizeof(x));CHKERRQ(ierr);
4870   prhs[0] = mxCreateDoubleScalar((double)ls);
4871   prhs[1] = mxCreateDoubleScalar((double)lx);
4872   prhs[2] = mxCreateDoubleScalar((double)lA);
4873   prhs[3] = mxCreateDoubleScalar((double)lB);
4874   prhs[4] = mxCreateString(sctx->funcname);
4875   prhs[5] = sctx->ctx;
4876   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");CHKERRQ(ierr);
4877   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
4878   *flag   = (MatStructure) mxGetScalar(plhs[1]);CHKERRQ(ierr);
4879   mxDestroyArray(prhs[0]);
4880   mxDestroyArray(prhs[1]);
4881   mxDestroyArray(prhs[2]);
4882   mxDestroyArray(prhs[3]);
4883   mxDestroyArray(prhs[4]);
4884   mxDestroyArray(plhs[0]);
4885   mxDestroyArray(plhs[1]);
4886   PetscFunctionReturn(0);
4887 }
4888 
4889 #undef __FUNCT__
4890 #define __FUNCT__ "SNESSetJacobianMatlab"
4891 /*
4892    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
4893    vector for use by the SNES routines in solving systems of nonlinear
4894    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
4895 
4896    Logically Collective on SNES
4897 
4898    Input Parameters:
4899 +  snes - the SNES context
4900 .  A,B - Jacobian matrices
4901 .  SNESJacobianFunction - function evaluation routine
4902 -  ctx - user context
4903 
4904    Level: developer
4905 
4906 .keywords: SNES, nonlinear, set, function
4907 
4908 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction(), SNESJacobianFunction
4909 */
4910 PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *SNESJacobianFunction,mxArray *ctx)
4911 {
4912   PetscErrorCode    ierr;
4913   SNESMatlabContext *sctx;
4914 
4915   PetscFunctionBegin;
4916   /* currently sctx is memory bleed */
4917   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4918   ierr = PetscStrallocpy(SNESJacobianFunction,&sctx->funcname);CHKERRQ(ierr);
4919   /*
4920      This should work, but it doesn't
4921   sctx->ctx = ctx;
4922   mexMakeArrayPersistent(sctx->ctx);
4923   */
4924   sctx->ctx = mxDuplicateArray(ctx);
4925   ierr      = SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
4926   PetscFunctionReturn(0);
4927 }
4928 
4929 #undef __FUNCT__
4930 #define __FUNCT__ "SNESMonitor_Matlab"
4931 /*
4932    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().
4933 
4934    Collective on SNES
4935 
4936 .seealso: SNESSetFunction(), SNESGetFunction()
4937 @*/
4938 PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
4939 {
4940   PetscErrorCode    ierr;
4941   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
4942   int               nlhs  = 1,nrhs = 6;
4943   mxArray           *plhs[1],*prhs[6];
4944   long long int     lx = 0,ls = 0;
4945   Vec               x  = snes->vec_sol;
4946 
4947   PetscFunctionBegin;
4948   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
4949 
4950   ierr    = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
4951   ierr    = PetscMemcpy(&lx,&x,sizeof(x));CHKERRQ(ierr);
4952   prhs[0] = mxCreateDoubleScalar((double)ls);
4953   prhs[1] = mxCreateDoubleScalar((double)it);
4954   prhs[2] = mxCreateDoubleScalar((double)fnorm);
4955   prhs[3] = mxCreateDoubleScalar((double)lx);
4956   prhs[4] = mxCreateString(sctx->funcname);
4957   prhs[5] = sctx->ctx;
4958   ierr    = mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");CHKERRQ(ierr);
4959   ierr    = mxGetScalar(plhs[0]);CHKERRQ(ierr);
4960   mxDestroyArray(prhs[0]);
4961   mxDestroyArray(prhs[1]);
4962   mxDestroyArray(prhs[2]);
4963   mxDestroyArray(prhs[3]);
4964   mxDestroyArray(prhs[4]);
4965   mxDestroyArray(plhs[0]);
4966   PetscFunctionReturn(0);
4967 }
4968 
4969 #undef __FUNCT__
4970 #define __FUNCT__ "SNESMonitorSetMatlab"
4971 /*
4972    SNESMonitorSetMatlab - Sets the monitor function from MATLAB
4973 
4974    Level: developer
4975 
4976 .keywords: SNES, nonlinear, set, function
4977 
4978 .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
4979 */
4980 PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *SNESMonitorFunction,mxArray *ctx)
4981 {
4982   PetscErrorCode    ierr;
4983   SNESMatlabContext *sctx;
4984 
4985   PetscFunctionBegin;
4986   /* currently sctx is memory bleed */
4987   ierr = PetscMalloc(sizeof(SNESMatlabContext),&sctx);CHKERRQ(ierr);
4988   ierr = PetscStrallocpy(SNESMonitorFunction,&sctx->funcname);CHKERRQ(ierr);
4989   /*
4990      This should work, but it doesn't
4991   sctx->ctx = ctx;
4992   mexMakeArrayPersistent(sctx->ctx);
4993   */
4994   sctx->ctx = mxDuplicateArray(ctx);
4995   ierr      = SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,NULL);CHKERRQ(ierr);
4996   PetscFunctionReturn(0);
4997 }
4998 
4999 #endif
5000