xref: /petsc/src/snes/impls/nasm/nasm.c (revision 76857b2a031448ee0adc73ac5a39b8ed69ad1175)
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,subdm;
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(PetscObjectComm((PetscObject)dm),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(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"Cannot construct local problems automatically without a DM!");
118   } else SETERRQ(PetscObjectComm((PetscObject)snes),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     ierr = SNESGetFunction(nasm->subsnes[i],&F,NULL,NULL);CHKERRQ(ierr);
127     if (!nasm->x[i]) {ierr = VecDuplicate(F,&nasm->x[i]);CHKERRQ(ierr);}
128     if (!nasm->y[i]) {ierr = VecDuplicate(F,&nasm->y[i]);CHKERRQ(ierr);}
129     if (!nasm->b[i]) {ierr = VecDuplicate(F,&nasm->b[i]);CHKERRQ(ierr);}
130     if (!nasm->xl[i]) {
131       ierr = SNESGetDM(nasm->subsnes[i],&subdm);CHKERRQ(ierr);
132       ierr = DMCreateLocalVector(subdm,&nasm->xl[i]);CHKERRQ(ierr);
133     }
134     ierr = DMGlobalToLocalHookAdd(subdm,DMGlobalToLocalSubDomainDirichletHook_Private,NULL,nasm->xl[i]);CHKERRQ(ierr);
135   }
136   PetscFunctionReturn(0);
137 }
138 
139 #undef __FUNCT__
140 #define __FUNCT__ "SNESSetFromOptions_NASM"
141 PetscErrorCode SNESSetFromOptions_NASM(SNES snes)
142 {
143   PetscErrorCode    ierr;
144   PCASMType         asmtype;
145   PetscBool         flg,monflg;
146   SNES_NASM         *nasm = (SNES_NASM*)snes->data;
147 
148   PetscFunctionBegin;
149   ierr = PetscOptionsHead("Nonlinear Additive Schwartz options");CHKERRQ(ierr);
150   ierr = PetscOptionsEnum("-snes_nasm_type","Type of restriction/extension","",SNESNASMTypes,(PetscEnum)nasm->type,(PetscEnum*)&asmtype,&flg);CHKERRQ(ierr);
151   if (flg) nasm->type = asmtype;
152   flg    = PETSC_FALSE;
153   monflg = PETSC_TRUE;
154   ierr   = PetscOptionsBool("-snes_nasm_log","Log times for subSNES solves and restriction","",monflg,&monflg,&flg);CHKERRQ(ierr);
155   if (flg) {
156     ierr = PetscLogEventRegister("SNESNASMSubSolve",((PetscObject)snes)->classid,&nasm->eventsubsolve);CHKERRQ(ierr);
157     ierr = PetscLogEventRegister("SNESNASMRestrict",((PetscObject)snes)->classid,&nasm->eventrestrictinterp);CHKERRQ(ierr);
158   }
159   ierr = PetscOptionsTail();CHKERRQ(ierr);
160   PetscFunctionReturn(0);
161 }
162 
163 #undef __FUNCT__
164 #define __FUNCT__ "SNESView_NASM"
165 PetscErrorCode SNESView_NASM(SNES snes, PetscViewer viewer)
166 {
167   PetscFunctionBegin;
168   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
169   PetscErrorCode ierr;
170   PetscMPIInt    rank;
171   PetscInt       i,N;
172   PetscBool      iascii,isstring;
173   PetscViewer    sviewer;
174   MPI_Comm       comm;
175 
176   PetscFunctionBegin;
177   ierr = PetscObjectGetComm((PetscObject)snes,&comm);CHKERRQ(ierr);
178   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
179   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
180   ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
181   ierr = MPI_Reduce(&nasm->n,&N,1,MPIU_INT,MPIU_SUM,0,comm);CHKERRQ(ierr);
182   if (iascii) {
183     ierr = PetscViewerASCIIPrintf(viewer, "  Nonlinear Additive Schwarz: total subdomain blocks = %D\n",N);CHKERRQ(ierr);
184     ierr = PetscViewerASCIIPrintf(viewer,"  Nonlinear Additive Schwarz: restriction/interpolation type - %s\n",SNESNASMTypes[nasm->type]);CHKERRQ(ierr);
185     ierr = PetscViewerASCIIPrintf(viewer,"  Nonlinear Additive Schwarz: subSNES iterations: %D subKSP iterations: %D\n",SNESNASMTypes[nasm->type]);CHKERRQ(ierr);
186     ierr = PetscViewerASCIISynchronizedAllow(viewer,PETSC_TRUE);CHKERRQ(ierr);
187     ierr = PetscViewerASCIISynchronizedPrintf(viewer,"  [%d] number of local blocks = %D\n",(int)rank,nasm->n);CHKERRQ(ierr);
188     ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
189     ierr = PetscViewerASCIIPrintf(viewer,"  Local SNES objects:\n");CHKERRQ(ierr);
190     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
191     if (!rank) {
192       for (i=0; i<nasm->n; i++) {
193         ierr = PetscViewerGetSingleton(viewer,&sviewer);CHKERRQ(ierr);
194         ierr = SNESView(nasm->subsnes[i],sviewer);CHKERRQ(ierr);
195         ierr = PetscViewerRestoreSingleton(viewer,&sviewer);CHKERRQ(ierr);
196       }
197     }
198     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
199     ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
200     ierr = PetscViewerASCIISynchronizedAllow(viewer,PETSC_FALSE);CHKERRQ(ierr);
201   } else if (isstring) {
202     ierr = PetscViewerStringSPrintf(viewer," blocks=%D,type=%s",N,SNESNASMTypes[nasm->type]);CHKERRQ(ierr);
203     ierr = PetscViewerGetSingleton(viewer,&sviewer);CHKERRQ(ierr);
204     if (nasm->subsnes && !rank) {ierr = SNESView(nasm->subsnes[0],sviewer);CHKERRQ(ierr);}
205     ierr = PetscViewerRestoreSingleton(viewer,&sviewer);CHKERRQ(ierr);
206   }
207   PetscFunctionReturn(0);
208 }
209 
210 #undef __FUNCT__
211 #define __FUNCT__ "SNESNASMSetSubdomains"
212 /*@
213    SNESNASMSetSubdomains - Manually Set the context required to restrict and solve subdomain problems.
214 
215    Not Collective
216 
217    Input Parameters:
218 +  SNES - the SNES context
219 .  n - the number of local subdomains
220 .  subsnes - solvers defined on the local subdomains
221 .  iscatter - scatters into the nonoverlapping portions of the local subdomains
222 .  oscatter - scatters into the overlapping portions of the local subdomains
223 -  gscatter - scatters into the (ghosted) local vector of the local subdomain
224 
225    Level: intermediate
226 
227 .keywords: SNES, NASM
228 
229 .seealso: SNESNASM, SNESNASMGetSubdomains()
230 @*/
231 PetscErrorCode SNESNASMSetSubdomains(SNES snes,PetscInt n,SNES subsnes[],VecScatter iscatter[],VecScatter oscatter[],VecScatter gscatter[])
232 {
233   PetscErrorCode ierr;
234   PetscErrorCode (*f)(SNES,PetscInt,SNES*,VecScatter*,VecScatter*,VecScatter*);
235 
236   PetscFunctionBegin;
237   ierr = PetscObjectQueryFunction((PetscObject)snes,"SNESNASMSetSubdomains_C",(void (**)(void))&f);CHKERRQ(ierr);
238   ierr = (f)(snes,n,subsnes,iscatter,oscatter,gscatter);CHKERRQ(ierr);
239   PetscFunctionReturn(0);
240 }
241 
242 EXTERN_C_BEGIN
243 #undef __FUNCT__
244 #define __FUNCT__ "SNESNASMSetSubdomains_NASM"
245 PetscErrorCode SNESNASMSetSubdomains_NASM(SNES snes,PetscInt n,SNES subsnes[],VecScatter iscatter[],VecScatter oscatter[],VecScatter gscatter[])
246 {
247   PetscInt       i;
248   PetscErrorCode ierr;
249   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
250 
251   PetscFunctionBegin;
252   if (snes->setupcalled) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"SNESNASMSetSubdomains() should be called before calling SNESSetUp().");
253 
254   /* tear down the previously set things */
255   ierr = SNESReset(snes);CHKERRQ(ierr);
256 
257   nasm->n = n;
258   if (oscatter) {
259     for (i=0; i<n; i++) {ierr = PetscObjectReference((PetscObject)oscatter[i]);CHKERRQ(ierr);}
260   }
261   if (iscatter) {
262     for (i=0; i<n; i++) {ierr = PetscObjectReference((PetscObject)iscatter[i]);CHKERRQ(ierr);}
263   }
264   if (gscatter) {
265     for (i=0; i<n; i++) {ierr = PetscObjectReference((PetscObject)gscatter[i]);CHKERRQ(ierr);}
266   }
267   if (oscatter) {
268     ierr = PetscMalloc(n*sizeof(IS),&nasm->oscatter);CHKERRQ(ierr);
269     for (i=0; i<n; i++) {
270       nasm->oscatter[i] = oscatter[i];
271     }
272   }
273   if (iscatter) {
274     ierr = PetscMalloc(n*sizeof(IS),&nasm->iscatter);CHKERRQ(ierr);
275     for (i=0; i<n; i++) {
276       nasm->iscatter[i] = iscatter[i];
277     }
278   }
279   if (gscatter) {
280     ierr = PetscMalloc(n*sizeof(IS),&nasm->gscatter);CHKERRQ(ierr);
281     for (i=0; i<n; i++) {
282       nasm->gscatter[i] = gscatter[i];
283     }
284   }
285 
286   if (subsnes) {
287     ierr = PetscMalloc(n*sizeof(SNES),&nasm->subsnes);CHKERRQ(ierr);
288     for (i=0; i<n; i++) {
289       nasm->subsnes[i] = subsnes[i];
290     }
291   }
292   PetscFunctionReturn(0);
293 }
294 EXTERN_C_END
295 
296 #undef __FUNCT__
297 #define __FUNCT__ "SNESNASMGetSubdomains"
298 /*@
299    SNESNASMGetSubdomains - Get the local subdomain context.
300 
301    Not Collective
302 
303    Input Parameters:
304 .  SNES - the SNES context
305 
306    Output Parameters:
307 +  n - the number of local subdomains
308 .  subsnes - solvers defined on the local subdomains
309 .  iscatter - scatters into the nonoverlapping portions of the local subdomains
310 .  oscatter - scatters into the overlapping portions of the local subdomains
311 -  gscatter - scatters into the (ghosted) local vector of the local subdomain
312 
313    Level: intermediate
314 
315 .keywords: SNES, NASM
316 
317 .seealso: SNESNASM, SNESNASMSetSubdomains()
318 @*/
319 PetscErrorCode SNESNASMGetSubdomains(SNES snes,PetscInt *n,SNES *subsnes[],VecScatter *iscatter[],VecScatter *oscatter[],VecScatter *gscatter[])
320 {
321   PetscErrorCode ierr;
322   PetscErrorCode (*f)(SNES,PetscInt*,SNES**,VecScatter**,VecScatter**,VecScatter**);
323 
324   PetscFunctionBegin;
325   ierr = PetscObjectQueryFunction((PetscObject)snes,"SNESNASMGetSubdomains_C",(void (**)(void))&f);CHKERRQ(ierr);
326   ierr = (f)(snes,n,subsnes,iscatter,oscatter,gscatter);CHKERRQ(ierr);
327   PetscFunctionReturn(0);
328 }
329 
330 EXTERN_C_BEGIN
331 #undef __FUNCT__
332 #define __FUNCT__ "SNESNASMGetSubdomains_NASM"
333 PetscErrorCode SNESNASMGetSubdomains_NASM(SNES snes,PetscInt *n,SNES *subsnes[],VecScatter *iscatter[],VecScatter *oscatter[],VecScatter *gscatter[])
334 {
335   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
336 
337   PetscFunctionBegin;
338   if (n) *n = nasm->n;
339   if (oscatter) *oscatter = nasm->oscatter;
340   if (iscatter) *iscatter = nasm->iscatter;
341   if (gscatter) *gscatter = nasm->gscatter;
342   if (subsnes)  *subsnes  = nasm->subsnes;
343   PetscFunctionReturn(0);
344 }
345 EXTERN_C_END
346 
347 #undef __FUNCT__
348 #define __FUNCT__ "SNESNASMGetSubdomainVecs"
349 /*@
350    SNESNASMGetSubdomainVecs - Get the processor-local subdomain vectors
351 
352    Not Collective
353 
354    Input Parameters:
355 .  SNES - the SNES context
356 
357    Output Parameters:
358 +  n - the number of local subdomains
359 .  x - The subdomain solution vector
360 .  y - The subdomain step vector
361 .  b - The subdomain RHS vector
362 -  xl - The subdomain local vectors (ghosted)
363 
364    Level: developer
365 
366 .keywords: SNES, NASM
367 
368 .seealso: SNESNASM, SNESNASMGetSubdomains()
369 @*/
370 PetscErrorCode SNESNASMGetSubdomainVecs(SNES snes,PetscInt *n,Vec **x,Vec **y,Vec **b, Vec **xl)
371 {
372   PetscErrorCode ierr;
373   PetscErrorCode (*f)(SNES,PetscInt*,Vec**,Vec**,Vec**,Vec**);
374 
375   PetscFunctionBegin;
376   ierr = PetscObjectQueryFunction((PetscObject)snes,"SNESNASMGetSubdomainVecs_C",(void (**)(void))&f);CHKERRQ(ierr);
377   ierr = (f)(snes,n,x,y,b,xl);CHKERRQ(ierr);
378   PetscFunctionReturn(0);
379 }
380 
381 EXTERN_C_BEGIN
382 #undef __FUNCT__
383 #define __FUNCT__ "SNESNASMGetSubdomainVecs_NASM"
384 PetscErrorCode SNESNASMGetSubdomainVecs_NASM(SNES snes,PetscInt *n,Vec **x,Vec **y,Vec **b,Vec **xl)
385 {
386   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
387 
388   PetscFunctionBegin;
389   if (n)  *n  = nasm->n;
390   if (x)  *x  = nasm->x;
391   if (y)  *y  = nasm->y;
392   if (b)  *b  = nasm->b;
393   if (xl) *xl = nasm->xl;
394   PetscFunctionReturn(0);
395 }
396 EXTERN_C_END
397 
398 
399 #undef __FUNCT__
400 #define __FUNCT__ "SNESNASMSolveLocal_Private"
401 PetscErrorCode SNESNASMSolveLocal_Private(SNES snes,Vec B,Vec Y,Vec X)
402 {
403   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
404   SNES           subsnes;
405   PetscInt       i;
406   PetscErrorCode ierr;
407   Vec            Xlloc,Xl,Bl,Yl;
408   VecScatter     iscat,oscat,gscat;
409   DM             dm,subdm;
410 
411   PetscFunctionBegin;
412   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
413   ierr = VecSet(Y,0);CHKERRQ(ierr);
414 
415   if (nasm->eventrestrictinterp) {ierr = PetscLogEventBegin(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
416   for (i=0; i<nasm->n; i++) {
417     /* scatter the solution to the local solution */
418     Xlloc = nasm->xl[i];
419     gscat   = nasm->gscatter[i];
420     oscat   = nasm->oscatter[i];
421     ierr = VecScatterBegin(gscat,X,Xlloc,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
422     if (B) {
423       /* scatter the RHS to the local RHS */
424       Bl   = nasm->b[i];
425       ierr = VecScatterBegin(oscat,B,Bl,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
426     }
427   }
428   if (nasm->eventrestrictinterp) {ierr = PetscLogEventEnd(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
429 
430   for (i=0; i<nasm->n; i++) {
431     Xlloc = nasm->xl[i];
432     gscat   = nasm->gscatter[i];
433     oscat   = nasm->oscatter[i];
434     ierr = VecScatterEnd(gscat,X,Xlloc,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
435     if (B) {
436       Bl   = nasm->b[i];
437       ierr = VecScatterEnd(oscat,B,Bl,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
438     }
439   }
440 
441   if (nasm->eventsubsolve) {ierr = PetscLogEventBegin(nasm->eventsubsolve,snes,0,0,0);CHKERRQ(ierr);}
442   for (i=0; i<nasm->n; i++) {
443     Xl    = nasm->x[i];
444     Xlloc = nasm->xl[i];
445     Yl    = nasm->y[i];
446     subsnes = nasm->subsnes[i];
447     ierr    = SNESGetDM(subsnes,&subdm);CHKERRQ(ierr);
448     iscat   = nasm->iscatter[i];
449     oscat   = nasm->oscatter[i];
450     gscat   = nasm->gscatter[i];
451     ierr    = DMSubDomainRestrict(dm,oscat,gscat,subdm);CHKERRQ(ierr);
452     if (B) {
453       Bl = nasm->b[i];
454     } else {
455       Bl = NULL;
456     }
457     ierr = DMLocalToGlobalBegin(subdm,Xlloc,INSERT_VALUES,Xl);CHKERRQ(ierr);
458     ierr = DMLocalToGlobalEnd(subdm,Xlloc,INSERT_VALUES,Xl);CHKERRQ(ierr);
459     ierr = VecCopy(Xl,Yl);CHKERRQ(ierr);
460     ierr = SNESSolve(subsnes,Bl,Yl);CHKERRQ(ierr);
461     ierr = VecAXPY(Yl,-1.0,Xl);CHKERRQ(ierr);
462   }
463   if (nasm->eventsubsolve) {ierr = PetscLogEventEnd(nasm->eventsubsolve,snes,0,0,0);CHKERRQ(ierr);}
464 
465   ierr = MPI_Barrier(PetscObjectComm((PetscObject)snes));CHKERRQ(ierr);
466 
467   if (nasm->eventrestrictinterp) {ierr = PetscLogEventBegin(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
468   for (i=0; i<nasm->n; i++) {
469     Yl    = nasm->y[i];
470     iscat   = nasm->iscatter[i];
471     oscat   = nasm->oscatter[i];
472     if (nasm->type == PC_ASM_BASIC) {
473       ierr = VecScatterBegin(oscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
474     } else if (nasm->type == PC_ASM_RESTRICT) {
475       ierr = VecScatterBegin(iscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
476     } else SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"Only basic and restrict types are supported for SNESNASM");
477   }
478 
479   for (i=0; i<nasm->n; i++) {
480     Yl    = nasm->y[i];
481     iscat   = nasm->iscatter[i];
482     oscat   = nasm->oscatter[i];
483     if (nasm->type == PC_ASM_BASIC) {
484       ierr = VecScatterEnd(oscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
485     } else if (nasm->type == PC_ASM_RESTRICT) {
486       ierr = VecScatterEnd(iscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
487     } else SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"Only basic and restrict types are supported for SNESNASM");
488   }
489   if (nasm->eventrestrictinterp) {ierr = PetscLogEventEnd(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
490 
491   ierr = MPI_Barrier(PetscObjectComm((PetscObject)snes));CHKERRQ(ierr);
492 
493   ierr = VecAXPY(X,1.0,Y);CHKERRQ(ierr);
494   PetscFunctionReturn(0);
495 }
496 
497 #undef __FUNCT__
498 #define __FUNCT__ "SNESSolve_NASM"
499 PetscErrorCode SNESSolve_NASM(SNES snes)
500 {
501   Vec            F;
502   Vec            X;
503   Vec            B;
504   Vec            Y;
505   PetscInt       i;
506   PetscReal      fnorm;
507   PetscErrorCode ierr;
508   SNESNormType   normtype;
509 
510   PetscFunctionBegin;
511   X = snes->vec_sol;
512   Y = snes->vec_sol_update;
513   F = snes->vec_func;
514   B = snes->vec_rhs;
515 
516   ierr         = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
517   snes->iter   = 0;
518   snes->norm   = 0.;
519   ierr         = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
520   snes->reason = SNES_CONVERGED_ITERATING;
521   ierr         = SNESGetNormType(snes, &normtype);CHKERRQ(ierr);
522   if (normtype == SNES_NORM_FUNCTION || normtype == SNES_NORM_INITIAL_ONLY || normtype == SNES_NORM_INITIAL_FINAL_ONLY) {
523     /* compute the initial function and preconditioned update delX */
524     if (!snes->vec_func_init_set) {
525       ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr);
526       if (snes->domainerror) {
527         snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN;
528         PetscFunctionReturn(0);
529       }
530     } else snes->vec_func_init_set = PETSC_FALSE;
531 
532     /* convergence test */
533     if (!snes->norm_init_set) {
534       ierr = VecNorm(F, NORM_2, &fnorm);CHKERRQ(ierr); /* fnorm <- ||F||  */
535       if (PetscIsInfOrNanReal(fnorm)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_FP,"Infinite or not-a-number generated in norm");
536     } else {
537       fnorm               = snes->norm_init;
538       snes->norm_init_set = PETSC_FALSE;
539     }
540     ierr       = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
541     snes->iter = 0;
542     snes->norm = fnorm;
543     ierr       = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
544     ierr       = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
545     ierr       = SNESMonitor(snes,0,snes->norm);CHKERRQ(ierr);
546 
547     /* set parameter for default relative tolerance convergence test */
548     snes->ttol = fnorm*snes->rtol;
549 
550     /* test convergence */
551     ierr = (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr);
552     if (snes->reason) PetscFunctionReturn(0);
553   } else {
554     ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
555     ierr = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
556     ierr = SNESMonitor(snes,0,snes->norm);CHKERRQ(ierr);
557   }
558 
559   /* Call general purpose update function */
560   if (snes->ops->update) {
561     ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr);
562   }
563 
564   for (i = 0; i < snes->max_its; i++) {
565     ierr = SNESNASMSolveLocal_Private(snes,B,Y,X);CHKERRQ(ierr);
566     if (normtype == SNES_NORM_FUNCTION || ((i == snes->max_its - 1) && (normtype == SNES_NORM_INITIAL_FINAL_ONLY || normtype == SNES_NORM_FINAL_ONLY))) {
567       ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr);
568       if (snes->domainerror) {
569         snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN;
570         PetscFunctionReturn(0);
571       }
572       ierr = VecNorm(F, NORM_2, &fnorm);CHKERRQ(ierr); /* fnorm <- ||F||  */
573       if (PetscIsInfOrNanReal(fnorm)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_FP,"Infinite or not-a-number generated in norm");
574     }
575     /* Monitor convergence */
576     ierr       = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
577     snes->iter = i+1;
578     snes->norm = fnorm;
579     ierr       = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
580     ierr       = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
581     ierr       = SNESMonitor(snes,snes->iter,snes->norm);CHKERRQ(ierr);
582     /* Test for convergence */
583     if (normtype == SNES_NORM_FUNCTION) ierr = (*snes->ops->converged)(snes,snes->iter,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr);
584     if (snes->reason) PetscFunctionReturn(0);
585     /* Call general purpose update function */
586     if (snes->ops->update) {
587       ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr);
588     }
589   }
590   if (normtype == SNES_NORM_FUNCTION) {
591     if (i == snes->max_its) {
592       ierr = PetscInfo1(snes,"Maximum number of iterations has been reached: %D\n",snes->max_its);CHKERRQ(ierr);
593       if (!snes->reason) snes->reason = SNES_DIVERGED_MAX_IT;
594     }
595   } else if (!snes->reason) snes->reason = SNES_CONVERGED_ITS; /* NASM is meant to be used as a preconditioner */
596   PetscFunctionReturn(0);
597 }
598 
599 /*MC
600   SNESNASM - Nonlinear Additive Schwartz
601 
602    Level: advanced
603 
604 .seealso: SNESCreate(), SNES, SNESSetType(), SNESType (for list of available types)
605 M*/
606 
607 EXTERN_C_BEGIN
608 #undef __FUNCT__
609 #define __FUNCT__ "SNESCreate_NASM"
610 PetscErrorCode SNESCreate_NASM(SNES snes)
611 {
612   SNES_NASM      *nasm;
613   PetscErrorCode ierr;
614 
615   PetscFunctionBegin;
616   ierr       = PetscNewLog(snes, SNES_NASM, &nasm);CHKERRQ(ierr);
617   snes->data = (void*)nasm;
618 
619   nasm->n        = PETSC_DECIDE;
620   nasm->subsnes  = 0;
621   nasm->x        = 0;
622   nasm->xl       = 0;
623   nasm->y        = 0;
624   nasm->b        = 0;
625   nasm->oscatter = 0;
626   nasm->iscatter = 0;
627   nasm->gscatter = 0;
628 
629   nasm->type = PC_ASM_BASIC;
630 
631   snes->ops->destroy        = SNESDestroy_NASM;
632   snes->ops->setup          = SNESSetUp_NASM;
633   snes->ops->setfromoptions = SNESSetFromOptions_NASM;
634   snes->ops->view           = SNESView_NASM;
635   snes->ops->solve          = SNESSolve_NASM;
636   snes->ops->reset          = SNESReset_NASM;
637 
638   snes->usesksp = PETSC_FALSE;
639   snes->usespc  = PETSC_FALSE;
640 
641   nasm->eventrestrictinterp = 0;
642   nasm->eventsubsolve       = 0;
643 
644   if (!snes->tolerancesset) {
645     snes->max_its   = 10000;
646     snes->max_funcs = 10000;
647   }
648 
649   ierr = PetscObjectComposeFunctionDynamic((PetscObject)snes,"SNESNASMSetSubdomains_C","SNESNASMSetSubdomains_NASM",
650                                            SNESNASMSetSubdomains_NASM);CHKERRQ(ierr);
651   ierr = PetscObjectComposeFunctionDynamic((PetscObject)snes,"SNESNASMGetSubdomains_C","SNESNASMGetSubdomains_NASM",
652                                            SNESNASMGetSubdomains_NASM);CHKERRQ(ierr);
653   ierr = PetscObjectComposeFunctionDynamic((PetscObject)snes,"SNESNASMGetSubdomainVecs_C","SNESNASMGetSubdomainVecs_NASM",
654                                            SNESNASMGetSubdomainVecs_NASM);CHKERRQ(ierr);
655   PetscFunctionReturn(0);
656 }
657 EXTERN_C_END
658