xref: /petsc/src/snes/impls/nasm/nasm.c (revision 67c2884ef72a42a4f3a1babc25bcfa28f347172e)
1 #include <petsc-private/snesimpl.h>             /*I   "petscsnes.h"   I*/
2 #include <petscdm.h>
3 
4 typedef struct {
5   PetscInt   n;                   /* local subdomains */
6   SNES       *subsnes;            /* nonlinear solvers for each subdomain */
7   Vec        *x;                  /* solution vectors */
8   Vec        *xl;                 /* solution local vectors */
9   Vec        *y;                  /* step vectors */
10   Vec        *b;                  /* rhs vectors */
11   VecScatter *oscatter;           /* scatter from global space to the subdomain global space */
12   VecScatter *iscatter;           /* scatter from global space to the nonoverlapping subdomain space */
13   VecScatter *gscatter;           /* scatter from global space to the subdomain local space */
14   PCASMType  type;                /* ASM type */
15   PetscBool  usesdm;              /* use the DM for setting up the subproblems */
16 
17   /* logging events */
18   PetscLogEvent eventrestrictinterp;
19   PetscLogEvent eventsubsolve;
20 } SNES_NASM;
21 
22 const char *const SNESNASMTypes[] = {"NONE","RESTRICT","INTERPOLATE","BASIC","PCASMType","PC_ASM_",0};
23 
24 #undef __FUNCT__
25 #define __FUNCT__ "SNESReset_NASM"
26 PetscErrorCode SNESReset_NASM(SNES snes)
27 {
28   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
29   PetscErrorCode ierr;
30   PetscInt       i;
31 
32   PetscFunctionBegin;
33   for (i=0; i<nasm->n; i++) {
34     if (nasm->xl) { ierr = VecDestroy(&nasm->xl[i]);CHKERRQ(ierr); }
35     if (nasm->x) { ierr = VecDestroy(&nasm->x[i]);CHKERRQ(ierr); }
36     if (nasm->y) { ierr = VecDestroy(&nasm->y[i]);CHKERRQ(ierr); }
37     if (nasm->b) { ierr = VecDestroy(&nasm->b[i]);CHKERRQ(ierr); }
38 
39     if (nasm->subsnes) { ierr = SNESDestroy(&nasm->subsnes[i]);CHKERRQ(ierr); }
40     if (nasm->oscatter) { ierr = VecScatterDestroy(&nasm->oscatter[i]);CHKERRQ(ierr); }
41     if (nasm->iscatter) { ierr = VecScatterDestroy(&nasm->iscatter[i]);CHKERRQ(ierr); }
42     if (nasm->gscatter) { ierr = VecScatterDestroy(&nasm->gscatter[i]);CHKERRQ(ierr); }
43   }
44 
45   if (nasm->x) {ierr = PetscFree(nasm->x);CHKERRQ(ierr);}
46   if (nasm->xl) {ierr = PetscFree(nasm->xl);CHKERRQ(ierr);}
47   if (nasm->y) {ierr = PetscFree(nasm->y);CHKERRQ(ierr);}
48   if (nasm->b) {ierr = PetscFree(nasm->b);CHKERRQ(ierr);}
49 
50   if (nasm->subsnes) {ierr = PetscFree(nasm->subsnes);CHKERRQ(ierr);}
51   if (nasm->oscatter) {ierr = PetscFree(nasm->oscatter);CHKERRQ(ierr);}
52   if (nasm->iscatter) {ierr = PetscFree(nasm->iscatter);CHKERRQ(ierr);}
53   if (nasm->gscatter) {ierr = PetscFree(nasm->gscatter);CHKERRQ(ierr);}
54 
55   nasm->eventrestrictinterp = 0;
56   nasm->eventsubsolve = 0;
57   PetscFunctionReturn(0);
58 }
59 
60 #undef __FUNCT__
61 #define __FUNCT__ "SNESDestroy_NASM"
62 PetscErrorCode SNESDestroy_NASM(SNES snes)
63 {
64   PetscErrorCode ierr;
65 
66   PetscFunctionBegin;
67   ierr = SNESReset_NASM(snes);CHKERRQ(ierr);
68   ierr = PetscFree(snes->data);CHKERRQ(ierr);
69   PetscFunctionReturn(0);
70 }
71 
72 #undef __FUNCT__
73 #define __FUNCT__ "DMGlobalToLocalSubDomainDirichletHook_Private"
74 PetscErrorCode DMGlobalToLocalSubDomainDirichletHook_Private(DM dm,Vec g,InsertMode mode,Vec l,void *ctx)
75 {
76   PetscErrorCode ierr;
77   Vec            bcs = (Vec)ctx;
78 
79   PetscFunctionBegin;
80   ierr = VecCopy(bcs,l);CHKERRQ(ierr);
81   PetscFunctionReturn(0);
82 }
83 
84 #undef __FUNCT__
85 #define __FUNCT__ "SNESSetUp_NASM"
86 PetscErrorCode SNESSetUp_NASM(SNES snes)
87 {
88   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
89   PetscErrorCode ierr;
90   DM             dm;
91   DM             *subdms;
92   PetscInt       i;
93   const char     *optionsprefix;
94   Vec            F;
95 
96   PetscFunctionBegin;
97   if (!nasm->subsnes) {
98     ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
99     if (dm) {
100       nasm->usesdm = PETSC_TRUE;
101       ierr         = DMCreateDomainDecomposition(dm,&nasm->n,NULL,NULL,NULL,&subdms);CHKERRQ(ierr);
102       if (!subdms) SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_ARG_WRONGSTATE,"DM has no default decomposition defined.  Set subsolves manually with SNESNASMSetSubdomains().");
103       ierr = DMCreateDomainDecompositionScatters(dm,nasm->n,subdms,&nasm->iscatter,&nasm->oscatter,&nasm->gscatter);CHKERRQ(ierr);
104 
105       ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
106       ierr = PetscMalloc(nasm->n*sizeof(SNES),&nasm->subsnes);CHKERRQ(ierr);
107 
108       for (i=0; i<nasm->n; i++) {
109         ierr = SNESCreate(PETSC_COMM_SELF,&nasm->subsnes[i]);CHKERRQ(ierr);
110         ierr = SNESAppendOptionsPrefix(nasm->subsnes[i],optionsprefix);CHKERRQ(ierr);
111         ierr = SNESAppendOptionsPrefix(nasm->subsnes[i],"sub_");CHKERRQ(ierr);
112         ierr = SNESSetDM(nasm->subsnes[i],subdms[i]);CHKERRQ(ierr);
113         ierr = SNESSetFromOptions(nasm->subsnes[i]);CHKERRQ(ierr);
114         ierr = DMDestroy(&subdms[i]);CHKERRQ(ierr);
115       }
116       ierr = PetscFree(subdms);CHKERRQ(ierr);
117     } else SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Cannot construct local problems automatically without a DM!");
118   } else SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Must set subproblems manually if there is no DM!");
119   /* allocate the global vectors */
120   ierr = PetscMalloc(nasm->n*sizeof(Vec),&nasm->x);CHKERRQ(ierr);
121   ierr = PetscMalloc(nasm->n*sizeof(Vec),&nasm->xl);CHKERRQ(ierr);
122   ierr = PetscMalloc(nasm->n*sizeof(Vec),&nasm->y);CHKERRQ(ierr);
123   ierr = PetscMalloc(nasm->n*sizeof(Vec),&nasm->b);CHKERRQ(ierr);
124 
125   for (i=0; i<nasm->n; i++) {
126     DM subdm;
127     ierr = SNESGetFunction(nasm->subsnes[i],&F,NULL,NULL);CHKERRQ(ierr);
128     ierr = VecDuplicate(F,&nasm->x[i]);CHKERRQ(ierr);
129     ierr = VecDuplicate(F,&nasm->y[i]);CHKERRQ(ierr);
130     ierr = VecDuplicate(F,&nasm->b[i]);CHKERRQ(ierr);
131     ierr = SNESGetDM(nasm->subsnes[i],&subdm);CHKERRQ(ierr);
132     ierr = DMCreateLocalVector(subdm,&nasm->xl[i]);CHKERRQ(ierr);
133     ierr = DMGlobalToLocalHookAdd(subdm,DMGlobalToLocalSubDomainDirichletHook_Private,NULL,nasm->xl[i]);CHKERRQ(ierr);
134   }
135   PetscFunctionReturn(0);
136 }
137 
138 #undef __FUNCT__
139 #define __FUNCT__ "SNESSetFromOptions_NASM"
140 PetscErrorCode SNESSetFromOptions_NASM(SNES snes)
141 {
142   PetscErrorCode    ierr;
143   PCASMType         asmtype;
144   PetscBool         flg,monflg;
145   SNES_NASM         *nasm = (SNES_NASM*)snes->data;
146 
147   PetscFunctionBegin;
148   ierr = PetscOptionsHead("Nonlinear Additive Schwartz options");CHKERRQ(ierr);
149   ierr = PetscOptionsEnum("-snes_nasm_type","Type of restriction/extension","",SNESNASMTypes,(PetscEnum)nasm->type,(PetscEnum*)&asmtype,&flg);CHKERRQ(ierr);
150   if (flg) nasm->type = asmtype;
151   flg    = PETSC_FALSE;
152   monflg = PETSC_TRUE;
153   ierr   = PetscOptionsBool("-snes_nasm_log","Log times for subSNES solves and restriction","",monflg,&monflg,&flg);CHKERRQ(ierr);
154   if (flg) {
155     ierr = PetscLogEventRegister("SNESNASMSubSolve",((PetscObject)snes)->classid,&nasm->eventsubsolve);CHKERRQ(ierr);
156     ierr = PetscLogEventRegister("SNESNASMRestrict",((PetscObject)snes)->classid,&nasm->eventrestrictinterp);CHKERRQ(ierr);
157   }
158   ierr = PetscOptionsTail();CHKERRQ(ierr);
159   PetscFunctionReturn(0);
160 }
161 
162 #undef __FUNCT__
163 #define __FUNCT__ "SNESView_NASM"
164 PetscErrorCode SNESView_NASM(SNES snes, PetscViewer viewer)
165 {
166   PetscFunctionBegin;
167   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
168   PetscErrorCode ierr;
169   PetscMPIInt    rank;
170   PetscInt       i,N;
171   PetscBool      iascii,isstring;
172   PetscViewer    sviewer;
173   MPI_Comm       comm = ((PetscObject)snes)->comm;
174 
175   PetscFunctionBegin;
176   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
177   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
178   ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
179   ierr = MPI_Reduce(&nasm->n,&N,1,MPIU_INT,MPIU_SUM,0,comm);CHKERRQ(ierr);
180   if (iascii) {
181     ierr = PetscViewerASCIIPrintf(viewer, "  Nonlinear Additive Schwarz: total subdomain blocks = %D\n",N);CHKERRQ(ierr);
182     ierr = PetscViewerASCIIPrintf(viewer,"  Nonlinear Additive Schwarz: restriction/interpolation type - %s\n",SNESNASMTypes[nasm->type]);CHKERRQ(ierr);
183     ierr = PetscViewerASCIIPrintf(viewer,"  Nonlinear Additive Schwarz: subSNES iterations: %D subKSP iterations: %D\n",SNESNASMTypes[nasm->type]);CHKERRQ(ierr);
184     ierr = PetscViewerASCIISynchronizedAllow(viewer,PETSC_TRUE);CHKERRQ(ierr);
185     ierr = PetscViewerASCIISynchronizedPrintf(viewer,"  [%d] number of local blocks = %D\n",(int)rank,nasm->n);CHKERRQ(ierr);
186     ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
187     ierr = PetscViewerASCIIPrintf(viewer,"  Local SNES objects:\n");CHKERRQ(ierr);
188     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
189     if (!rank) {
190       for (i=0; i<nasm->n; i++) {
191         ierr = PetscViewerGetSingleton(viewer,&sviewer);CHKERRQ(ierr);
192         ierr = SNESView(nasm->subsnes[i],sviewer);CHKERRQ(ierr);
193         ierr = PetscViewerRestoreSingleton(viewer,&sviewer);CHKERRQ(ierr);
194       }
195     }
196     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
197     ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
198     ierr = PetscViewerASCIISynchronizedAllow(viewer,PETSC_FALSE);CHKERRQ(ierr);
199   } else if (isstring) {
200     ierr = PetscViewerStringSPrintf(viewer," blocks=%D,type=%s",N,SNESNASMTypes[nasm->type]);CHKERRQ(ierr);
201     ierr = PetscViewerGetSingleton(viewer,&sviewer);CHKERRQ(ierr);
202     if (nasm->subsnes && !rank) {ierr = SNESView(nasm->subsnes[0],sviewer);CHKERRQ(ierr);}
203     ierr = PetscViewerRestoreSingleton(viewer,&sviewer);CHKERRQ(ierr);
204   }
205   PetscFunctionReturn(0);
206 }
207 
208 #undef __FUNCT__
209 #define __FUNCT__ "SNESNASMSetSubdomains"
210 PetscErrorCode SNESNASMSetSubdomains(SNES snes,PetscInt n,SNES subsnes[],VecScatter iscatter[],VecScatter oscatter[],VecScatter gscatter[])
211 {
212   PetscErrorCode ierr;
213   PetscErrorCode (*f)(SNES,PetscInt,SNES*,VecScatter*,VecScatter*,VecScatter*);
214 
215   PetscFunctionBegin;
216   ierr = PetscObjectQueryFunction((PetscObject)snes,"SNESNASMSetSubdomains_C",(void (**)(void))&f);CHKERRQ(ierr);
217   ierr = (f)(snes,n,subsnes,iscatter,oscatter,gscatter);CHKERRQ(ierr);
218   PetscFunctionReturn(0);
219 }
220 
221 EXTERN_C_BEGIN
222 #undef __FUNCT__
223 #define __FUNCT__ "SNESNASMSetSubdomains_NASM"
224 PetscErrorCode SNESNASMSetSubdomains_NASM(SNES snes,PetscInt n,SNES subsnes[],VecScatter iscatter[],VecScatter oscatter[],VecScatter gscatter[])
225 {
226   PetscInt       i;
227   PetscErrorCode ierr;
228   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
229 
230   PetscFunctionBegin;
231   if (snes->setupcalled) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"SNESNASMSetSubdomains() should be called before calling SNESSetUp().");
232 
233   /* tear down the previously set things */
234   ierr = SNESReset(snes);CHKERRQ(ierr);
235 
236   nasm->n = n;
237   if (oscatter) {
238     for (i=0; i<n; i++) {ierr = PetscObjectReference((PetscObject)oscatter[i]);CHKERRQ(ierr);}
239   }
240   if (iscatter) {
241     for (i=0; i<n; i++) {ierr = PetscObjectReference((PetscObject)iscatter[i]);CHKERRQ(ierr);}
242   }
243   if (gscatter) {
244     for (i=0; i<n; i++) {ierr = PetscObjectReference((PetscObject)gscatter[i]);CHKERRQ(ierr);}
245   }
246   if (oscatter) {
247     ierr = PetscMalloc(n*sizeof(IS),&nasm->oscatter);CHKERRQ(ierr);
248     for (i=0; i<n; i++) {
249       nasm->oscatter[i] = oscatter[i];
250     }
251   }
252   if (iscatter) {
253     ierr = PetscMalloc(n*sizeof(IS),&nasm->iscatter);CHKERRQ(ierr);
254     for (i=0; i<n; i++) {
255       nasm->iscatter[i] = iscatter[i];
256     }
257   }
258   if (gscatter) {
259     ierr = PetscMalloc(n*sizeof(IS),&nasm->gscatter);CHKERRQ(ierr);
260     for (i=0; i<n; i++) {
261       nasm->gscatter[i] = gscatter[i];
262     }
263   }
264 
265   if (subsnes) {
266     ierr = PetscMalloc(n*sizeof(SNES),&nasm->subsnes);CHKERRQ(ierr);
267     for (i=0; i<n; i++) {
268       nasm->subsnes[i] = subsnes[i];
269     }
270   }
271   PetscFunctionReturn(0);
272 }
273 EXTERN_C_END
274 
275 #undef __FUNCT__
276 #define __FUNCT__ "SNESNASMSolveLocal_Private"
277 PetscErrorCode SNESNASMSolveLocal_Private(SNES snes,Vec B,Vec Y,Vec X)
278 {
279   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
280   SNES           subsnes;
281   PetscInt       i;
282   PetscErrorCode ierr;
283   Vec            Xlloc,Xl,Bl,Yl;
284   VecScatter     iscat,oscat,gscat;
285   DM             dm,subdm;
286 
287   PetscFunctionBegin;
288   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
289   ierr = VecSet(Y,0);CHKERRQ(ierr);
290 
291   if (nasm->eventrestrictinterp) {ierr = PetscLogEventBegin(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
292   for (i=0; i<nasm->n; i++) {
293     /* scatter the solution to the local solution */
294     Xlloc = nasm->xl[i];
295     gscat   = nasm->gscatter[i];
296     oscat   = nasm->oscatter[i];
297     ierr = VecScatterBegin(gscat,X,Xlloc,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
298     if (B) {
299       /* scatter the RHS to the local RHS */
300       Bl   = nasm->b[i];
301       ierr = VecScatterBegin(oscat,B,Bl,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
302     }
303   }
304   if (nasm->eventrestrictinterp) {ierr = PetscLogEventEnd(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
305 
306   for (i=0; i<nasm->n; i++) {
307     Xlloc = nasm->xl[i];
308     gscat   = nasm->gscatter[i];
309     oscat   = nasm->oscatter[i];
310     ierr = VecScatterEnd(gscat,X,Xlloc,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
311     if (B) {
312       Bl   = nasm->b[i];
313       ierr = VecScatterEnd(oscat,B,Bl,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
314     }
315   }
316 
317   if (nasm->eventsubsolve) {ierr = PetscLogEventBegin(nasm->eventsubsolve,snes,0,0,0);CHKERRQ(ierr);}
318   for (i=0; i<nasm->n; i++) {
319     Xl    = nasm->x[i];
320     Xlloc = nasm->xl[i];
321     Yl    = nasm->y[i];
322     subsnes = nasm->subsnes[i];
323     ierr    = SNESGetDM(subsnes,&subdm);CHKERRQ(ierr);
324     iscat   = nasm->iscatter[i];
325     oscat   = nasm->oscatter[i];
326     gscat   = nasm->gscatter[i];
327     ierr    = DMSubDomainRestrict(dm,oscat,gscat,subdm);CHKERRQ(ierr);
328     if (B) {
329       Bl = nasm->b[i];
330     } else {
331       Bl = NULL;
332     }
333     ierr = DMLocalToGlobalBegin(subdm,Xlloc,INSERT_VALUES,Xl);CHKERRQ(ierr);
334     ierr = DMLocalToGlobalEnd(subdm,Xlloc,INSERT_VALUES,Xl);CHKERRQ(ierr);
335     ierr = VecCopy(Xl,Yl);CHKERRQ(ierr);
336     ierr = SNESSolve(subsnes,Bl,Yl);CHKERRQ(ierr);
337     ierr = VecAXPY(Yl,-1.0,Xl);CHKERRQ(ierr);
338   }
339   if (nasm->eventsubsolve) {ierr = PetscLogEventEnd(nasm->eventsubsolve,snes,0,0,0);CHKERRQ(ierr);}
340 
341   ierr = MPI_Barrier(((PetscObject)snes)->comm);CHKERRQ(ierr);
342 
343   if (nasm->eventrestrictinterp) {ierr = PetscLogEventBegin(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
344   for (i=0; i<nasm->n; i++) {
345     Yl    = nasm->y[i];
346     iscat   = nasm->iscatter[i];
347     oscat   = nasm->oscatter[i];
348     if (nasm->type == PC_ASM_BASIC) {
349       ierr = VecScatterBegin(oscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
350     } else if (nasm->type == PC_ASM_RESTRICT) {
351       ierr = VecScatterBegin(iscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
352     } else SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Only basic and restrict types are supported for SNESNASM");
353   }
354 
355   for (i=0; i<nasm->n; i++) {
356     Yl    = nasm->y[i];
357     iscat   = nasm->iscatter[i];
358     oscat   = nasm->oscatter[i];
359     if (nasm->type == PC_ASM_BASIC) {
360       ierr = VecScatterEnd(oscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
361     } else if (nasm->type == PC_ASM_RESTRICT) {
362       ierr = VecScatterEnd(iscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
363     } else SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Only basic and restrict types are supported for SNESNASM");
364   }
365   if (nasm->eventrestrictinterp) {ierr = PetscLogEventEnd(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
366 
367   ierr = MPI_Barrier(((PetscObject)snes)->comm);CHKERRQ(ierr);
368 
369   ierr = VecAXPY(X,1.0,Y);CHKERRQ(ierr);
370   PetscFunctionReturn(0);
371 }
372 
373 #undef __FUNCT__
374 #define __FUNCT__ "SNESSolve_NASM"
375 PetscErrorCode SNESSolve_NASM(SNES snes)
376 {
377   Vec            F;
378   Vec            X;
379   Vec            B;
380   Vec            Y;
381   PetscInt       i;
382   PetscReal      fnorm;
383   PetscErrorCode ierr;
384   SNESNormType   normtype;
385 
386   PetscFunctionBegin;
387   X = snes->vec_sol;
388   Y = snes->vec_sol_update;
389   F = snes->vec_func;
390   B = snes->vec_rhs;
391 
392   ierr         = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
393   snes->iter   = 0;
394   snes->norm   = 0.;
395   ierr         = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
396   snes->reason = SNES_CONVERGED_ITERATING;
397   ierr         = SNESGetNormType(snes, &normtype);CHKERRQ(ierr);
398   if (normtype == SNES_NORM_FUNCTION || normtype == SNES_NORM_INITIAL_ONLY || normtype == SNES_NORM_INITIAL_FINAL_ONLY) {
399     /* compute the initial function and preconditioned update delX */
400     if (!snes->vec_func_init_set) {
401       ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr);
402       if (snes->domainerror) {
403         snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN;
404         PetscFunctionReturn(0);
405       }
406     } else snes->vec_func_init_set = PETSC_FALSE;
407 
408     /* convergence test */
409     if (!snes->norm_init_set) {
410       ierr = VecNorm(F, NORM_2, &fnorm);CHKERRQ(ierr); /* fnorm <- ||F||  */
411       if (PetscIsInfOrNanReal(fnorm)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_FP,"Infinite or not-a-number generated in norm");
412     } else {
413       fnorm               = snes->norm_init;
414       snes->norm_init_set = PETSC_FALSE;
415     }
416     ierr       = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
417     snes->iter = 0;
418     snes->norm = fnorm;
419     ierr       = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
420     ierr       = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
421     ierr       = SNESMonitor(snes,0,snes->norm);CHKERRQ(ierr);
422 
423     /* set parameter for default relative tolerance convergence test */
424     snes->ttol = fnorm*snes->rtol;
425 
426     /* test convergence */
427     ierr = (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr);
428     if (snes->reason) PetscFunctionReturn(0);
429   } else {
430     ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
431     ierr = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
432     ierr = SNESMonitor(snes,0,snes->norm);CHKERRQ(ierr);
433   }
434 
435   /* Call general purpose update function */
436   if (snes->ops->update) {
437     ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr);
438   }
439 
440   for (i = 0; i < snes->max_its; i++) {
441     ierr = SNESNASMSolveLocal_Private(snes,B,Y,X);CHKERRQ(ierr);
442     if (normtype == SNES_NORM_FUNCTION || ((i == snes->max_its - 1) && (normtype == SNES_NORM_INITIAL_FINAL_ONLY || normtype == SNES_NORM_FINAL_ONLY))) {
443       ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr);
444       if (snes->domainerror) {
445         snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN;
446         PetscFunctionReturn(0);
447       }
448       ierr = VecNorm(F, NORM_2, &fnorm);CHKERRQ(ierr); /* fnorm <- ||F||  */
449       if (PetscIsInfOrNanReal(fnorm)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_FP,"Infinite or not-a-number generated in norm");
450     }
451     /* Monitor convergence */
452     ierr       = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
453     snes->iter = i+1;
454     snes->norm = fnorm;
455     ierr       = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
456     ierr       = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
457     ierr       = SNESMonitor(snes,snes->iter,snes->norm);CHKERRQ(ierr);
458     /* Test for convergence */
459     if (normtype == SNES_NORM_FUNCTION) ierr = (*snes->ops->converged)(snes,snes->iter,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr);
460     if (snes->reason) PetscFunctionReturn(0);
461     /* Call general purpose update function */
462     if (snes->ops->update) {
463       ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr);
464     }
465   }
466   if (normtype == SNES_NORM_FUNCTION) {
467     if (i == snes->max_its) {
468       ierr = PetscInfo1(snes,"Maximum number of iterations has been reached: %D\n",snes->max_its);CHKERRQ(ierr);
469       if (!snes->reason) snes->reason = SNES_DIVERGED_MAX_IT;
470     }
471   } else if (!snes->reason) snes->reason = SNES_CONVERGED_ITS; /* NASM is meant to be used as a preconditioner */
472   PetscFunctionReturn(0);
473 }
474 
475 /*MC
476   SNESNASM - Nonlinear Additive Schwartz
477 
478    Level: advanced
479 
480 .seealso: SNESCreate(), SNES, SNESSetType(), SNESType (for list of available types)
481 M*/
482 
483 EXTERN_C_BEGIN
484 #undef __FUNCT__
485 #define __FUNCT__ "SNESCreate_NASM"
486 PetscErrorCode SNESCreate_NASM(SNES snes)
487 {
488   SNES_NASM      *nasm;
489   PetscErrorCode ierr;
490 
491   PetscFunctionBegin;
492   ierr       = PetscNewLog(snes, SNES_NASM, &nasm);CHKERRQ(ierr);
493   snes->data = (void*)nasm;
494 
495   nasm->n        = PETSC_DECIDE;
496   nasm->subsnes  = 0;
497   nasm->x        = 0;
498   nasm->xl       = 0;
499   nasm->y        = 0;
500   nasm->b        = 0;
501   nasm->oscatter = 0;
502   nasm->iscatter = 0;
503   nasm->gscatter = 0;
504 
505   nasm->type = PC_ASM_BASIC;
506 
507   snes->ops->destroy        = SNESDestroy_NASM;
508   snes->ops->setup          = SNESSetUp_NASM;
509   snes->ops->setfromoptions = SNESSetFromOptions_NASM;
510   snes->ops->view           = SNESView_NASM;
511   snes->ops->solve          = SNESSolve_NASM;
512   snes->ops->reset          = SNESReset_NASM;
513 
514   snes->usesksp = PETSC_FALSE;
515   snes->usespc  = PETSC_FALSE;
516 
517   nasm->eventrestrictinterp = 0;
518   nasm->eventsubsolve       = 0;
519 
520   if (!snes->tolerancesset) {
521     snes->max_its   = 10000;
522     snes->max_funcs = 10000;
523   }
524 
525   ierr = PetscObjectComposeFunctionDynamic((PetscObject)snes,"SNESNASMSetSubdomains_C","SNESNASMSetSubdomains_NASM",
526                                            SNESNASMSetSubdomains_NASM);CHKERRQ(ierr);
527   PetscFunctionReturn(0);
528 }
529 EXTERN_C_END
530