xref: /petsc/src/snes/impls/nasm/nasm.c (revision bb74729cafbfcb6265ea097979a2a2cac4d11507)
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     } else {
303       Bl = NULL;
304     }
305   }
306   if (nasm->eventrestrictinterp) {ierr = PetscLogEventEnd(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
307 
308   for (i=0; i<nasm->n; i++) {
309     Xlloc = nasm->xl[i];
310     ierr = VecScatterEnd(gscat,X,Xlloc,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
311     if (B) {
312       ierr = VecScatterEnd(oscat,B,Bl,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
313     }
314   }
315 
316   if (nasm->eventsubsolve) {ierr = PetscLogEventBegin(nasm->eventsubsolve,snes,0,0,0);CHKERRQ(ierr);}
317   for (i=0; i<nasm->n; i++) {
318     Xl    = nasm->x[i];
319     Xlloc = nasm->xl[i];
320     Yl    = nasm->y[i];
321     subsnes = nasm->subsnes[i];
322     ierr    = SNESGetDM(subsnes,&subdm);CHKERRQ(ierr);
323     iscat   = nasm->iscatter[i];
324     oscat   = nasm->oscatter[i];
325     gscat   = nasm->gscatter[i];
326     ierr    = DMSubDomainRestrict(dm,oscat,gscat,subdm);CHKERRQ(ierr);
327 
328     ierr = DMLocalToGlobalBegin(subdm,Xlloc,INSERT_VALUES,Xl);CHKERRQ(ierr);
329     ierr = DMLocalToGlobalEnd(subdm,Xlloc,INSERT_VALUES,Xl);CHKERRQ(ierr);
330     ierr = VecCopy(Xl,Yl);CHKERRQ(ierr);
331     ierr = SNESSolve(subsnes,Bl,Yl);CHKERRQ(ierr);
332     ierr = VecAXPY(Yl,-1.0,Xl);CHKERRQ(ierr);
333   }
334   if (nasm->eventsubsolve) {ierr = PetscLogEventEnd(nasm->eventsubsolve,snes,0,0,0);CHKERRQ(ierr);}
335 
336   ierr = MPI_Barrier(((PetscObject)snes)->comm);CHKERRQ(ierr);
337 
338   if (nasm->eventrestrictinterp) {ierr = PetscLogEventBegin(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
339   for (i=0; i<nasm->n; i++) {
340     Yl    = nasm->y[i];
341     iscat   = nasm->iscatter[i];
342     oscat   = nasm->oscatter[i];
343     if (nasm->type == PC_ASM_BASIC) {
344       ierr = VecScatterBegin(oscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
345     } else if (nasm->type == PC_ASM_RESTRICT) {
346       ierr = VecScatterBegin(iscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
347     } else SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Only basic and restrict types are supported for SNESNASM");
348   }
349 
350   for (i=0; i<nasm->n; i++) {
351     Yl    = nasm->y[i];
352     iscat   = nasm->iscatter[i];
353     oscat   = nasm->oscatter[i];
354     if (nasm->type == PC_ASM_BASIC) {
355       ierr = VecScatterEnd(oscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
356     } else if (nasm->type == PC_ASM_RESTRICT) {
357       ierr = VecScatterEnd(iscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
358     } else SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Only basic and restrict types are supported for SNESNASM");
359   }
360   if (nasm->eventrestrictinterp) {ierr = PetscLogEventEnd(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
361 
362   ierr = MPI_Barrier(((PetscObject)snes)->comm);CHKERRQ(ierr);
363 
364   ierr = VecAXPY(X,1.0,Y);CHKERRQ(ierr);
365   PetscFunctionReturn(0);
366 }
367 
368 #undef __FUNCT__
369 #define __FUNCT__ "SNESSolve_NASM"
370 PetscErrorCode SNESSolve_NASM(SNES snes)
371 {
372   Vec            F;
373   Vec            X;
374   Vec            B;
375   Vec            Y;
376   PetscInt       i;
377   PetscReal      fnorm;
378   PetscErrorCode ierr;
379   SNESNormType   normtype;
380 
381   PetscFunctionBegin;
382   X = snes->vec_sol;
383   Y = snes->vec_sol_update;
384   F = snes->vec_func;
385   B = snes->vec_rhs;
386 
387   ierr         = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
388   snes->iter   = 0;
389   snes->norm   = 0.;
390   ierr         = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
391   snes->reason = SNES_CONVERGED_ITERATING;
392   ierr         = SNESGetNormType(snes, &normtype);CHKERRQ(ierr);
393   if (normtype == SNES_NORM_FUNCTION || normtype == SNES_NORM_INITIAL_ONLY || normtype == SNES_NORM_INITIAL_FINAL_ONLY) {
394     /* compute the initial function and preconditioned update delX */
395     if (!snes->vec_func_init_set) {
396       ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr);
397       if (snes->domainerror) {
398         snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN;
399         PetscFunctionReturn(0);
400       }
401     } else snes->vec_func_init_set = PETSC_FALSE;
402 
403     /* convergence test */
404     if (!snes->norm_init_set) {
405       ierr = VecNorm(F, NORM_2, &fnorm);CHKERRQ(ierr); /* fnorm <- ||F||  */
406       if (PetscIsInfOrNanReal(fnorm)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_FP,"Infinite or not-a-number generated in norm");
407     } else {
408       fnorm               = snes->norm_init;
409       snes->norm_init_set = PETSC_FALSE;
410     }
411     ierr       = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
412     snes->iter = 0;
413     snes->norm = fnorm;
414     ierr       = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
415     ierr       = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
416     ierr       = SNESMonitor(snes,0,snes->norm);CHKERRQ(ierr);
417 
418     /* set parameter for default relative tolerance convergence test */
419     snes->ttol = fnorm*snes->rtol;
420 
421     /* test convergence */
422     ierr = (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr);
423     if (snes->reason) PetscFunctionReturn(0);
424   } else {
425     ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
426     ierr = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
427     ierr = SNESMonitor(snes,0,snes->norm);CHKERRQ(ierr);
428   }
429 
430   /* Call general purpose update function */
431   if (snes->ops->update) {
432     ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr);
433   }
434 
435   for (i = 0; i < snes->max_its; i++) {
436     ierr = SNESNASMSolveLocal_Private(snes,B,Y,X);CHKERRQ(ierr);
437     if (normtype == SNES_NORM_FUNCTION || ((i == snes->max_its - 1) && (normtype == SNES_NORM_INITIAL_FINAL_ONLY || normtype == SNES_NORM_FINAL_ONLY))) {
438       ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr);
439       if (snes->domainerror) {
440         snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN;
441         PetscFunctionReturn(0);
442       }
443       ierr = VecNorm(F, NORM_2, &fnorm);CHKERRQ(ierr); /* fnorm <- ||F||  */
444       if (PetscIsInfOrNanReal(fnorm)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_FP,"Infinite or not-a-number generated in norm");
445     }
446     /* Monitor convergence */
447     ierr       = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
448     snes->iter = i+1;
449     snes->norm = fnorm;
450     ierr       = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
451     ierr       = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
452     ierr       = SNESMonitor(snes,snes->iter,snes->norm);CHKERRQ(ierr);
453     /* Test for convergence */
454     if (normtype == SNES_NORM_FUNCTION) ierr = (*snes->ops->converged)(snes,snes->iter,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr);
455     if (snes->reason) PetscFunctionReturn(0);
456     /* Call general purpose update function */
457     if (snes->ops->update) {
458       ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr);
459     }
460   }
461   if (normtype == SNES_NORM_FUNCTION) {
462     if (i == snes->max_its) {
463       ierr = PetscInfo1(snes,"Maximum number of iterations has been reached: %D\n",snes->max_its);CHKERRQ(ierr);
464       if (!snes->reason) snes->reason = SNES_DIVERGED_MAX_IT;
465     }
466   } else if (!snes->reason) snes->reason = SNES_CONVERGED_ITS; /* NASM is meant to be used as a preconditioner */
467   PetscFunctionReturn(0);
468 }
469 
470 /*MC
471   SNESNASM - Nonlinear Additive Schwartz
472 
473    Level: advanced
474 
475 .seealso: SNESCreate(), SNES, SNESSetType(), SNESType (for list of available types)
476 M*/
477 
478 EXTERN_C_BEGIN
479 #undef __FUNCT__
480 #define __FUNCT__ "SNESCreate_NASM"
481 PetscErrorCode SNESCreate_NASM(SNES snes)
482 {
483   SNES_NASM      *nasm;
484   PetscErrorCode ierr;
485 
486   PetscFunctionBegin;
487   ierr       = PetscNewLog(snes, SNES_NASM, &nasm);CHKERRQ(ierr);
488   snes->data = (void*)nasm;
489 
490   nasm->n        = PETSC_DECIDE;
491   nasm->subsnes  = 0;
492   nasm->x        = 0;
493   nasm->xl       = 0;
494   nasm->y        = 0;
495   nasm->b        = 0;
496   nasm->oscatter = 0;
497   nasm->iscatter = 0;
498   nasm->gscatter = 0;
499 
500   nasm->type = PC_ASM_BASIC;
501 
502   snes->ops->destroy        = SNESDestroy_NASM;
503   snes->ops->setup          = SNESSetUp_NASM;
504   snes->ops->setfromoptions = SNESSetFromOptions_NASM;
505   snes->ops->view           = SNESView_NASM;
506   snes->ops->solve          = SNESSolve_NASM;
507   snes->ops->reset          = SNESReset_NASM;
508 
509   snes->usesksp = PETSC_FALSE;
510   snes->usespc  = PETSC_FALSE;
511 
512   nasm->eventrestrictinterp = 0;
513   nasm->eventsubsolve       = 0;
514 
515   if (!snes->tolerancesset) {
516     snes->max_its   = 10000;
517     snes->max_funcs = 10000;
518   }
519 
520   ierr = PetscObjectComposeFunctionDynamic((PetscObject)snes,"SNESNASMSetSubdomains_C","SNESNASMSetSubdomains_NASM",
521                                            SNESNASMSetSubdomains_NASM);CHKERRQ(ierr);
522   PetscFunctionReturn(0);
523 }
524 EXTERN_C_END
525