xref: /petsc/src/snes/impls/nasm/nasm.c (revision a71f0d7d9375a154061b6b52b45db4a1fedb0dea)
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,ddm;
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) {
103         ierr = DMCreateDomainDecompositionDM(dm,"default",&ddm);CHKERRQ(ierr);
104         if (!ddm) SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_ARG_WRONGSTATE,"DM has no default decomposition defined.  Set subsolves manually with SNESNASMSetSubdomains().");
105         ierr = SNESSetDM(snes,ddm);CHKERRQ(ierr);
106         ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
107         ierr = DMCreateDomainDecomposition(dm,&nasm->n,NULL,NULL,NULL,&subdms);CHKERRQ(ierr);
108       }
109       if (!subdms) SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_ARG_WRONGSTATE,"DM has no default decomposition defined.  Set subsolves manually with SNESNASMSetSubdomains().");
110       ierr = DMCreateDomainDecompositionScatters(dm,nasm->n,subdms,&nasm->iscatter,&nasm->oscatter,&nasm->gscatter);CHKERRQ(ierr);
111 
112       ierr = SNESGetOptionsPrefix(snes, &optionsprefix);CHKERRQ(ierr);
113       ierr = PetscMalloc(nasm->n*sizeof(SNES),&nasm->subsnes);CHKERRQ(ierr);
114 
115       for (i=0; i<nasm->n; i++) {
116         ierr = SNESCreate(PETSC_COMM_SELF,&nasm->subsnes[i]);CHKERRQ(ierr);
117         ierr = SNESAppendOptionsPrefix(nasm->subsnes[i],optionsprefix);CHKERRQ(ierr);
118         ierr = SNESAppendOptionsPrefix(nasm->subsnes[i],"sub_");CHKERRQ(ierr);
119         ierr = SNESSetDM(nasm->subsnes[i],subdms[i]);CHKERRQ(ierr);
120         ierr = SNESSetFromOptions(nasm->subsnes[i]);CHKERRQ(ierr);
121         ierr = DMDestroy(&subdms[i]);CHKERRQ(ierr);
122       }
123       ierr = PetscFree(subdms);CHKERRQ(ierr);
124     } else SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Cannot construct local problems automatically without a DM!");
125   } else SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Must set subproblems manually if there is no DM!");
126   /* allocate the global vectors */
127   ierr = PetscMalloc(nasm->n*sizeof(Vec),&nasm->x);CHKERRQ(ierr);
128   ierr = PetscMalloc(nasm->n*sizeof(Vec),&nasm->xl);CHKERRQ(ierr);
129   ierr = PetscMalloc(nasm->n*sizeof(Vec),&nasm->y);CHKERRQ(ierr);
130   ierr = PetscMalloc(nasm->n*sizeof(Vec),&nasm->b);CHKERRQ(ierr);
131 
132   for (i=0; i<nasm->n; i++) {
133     DM subdm;
134     ierr = SNESGetFunction(nasm->subsnes[i],&F,NULL,NULL);CHKERRQ(ierr);
135     ierr = VecDuplicate(F,&nasm->x[i]);CHKERRQ(ierr);
136     ierr = VecDuplicate(F,&nasm->y[i]);CHKERRQ(ierr);
137     ierr = VecDuplicate(F,&nasm->b[i]);CHKERRQ(ierr);
138     ierr = SNESGetDM(nasm->subsnes[i],&subdm);CHKERRQ(ierr);
139     ierr = DMCreateLocalVector(subdm,&nasm->xl[i]);CHKERRQ(ierr);
140     ierr = DMGlobalToLocalHookAdd(subdm,DMGlobalToLocalSubDomainDirichletHook_Private,NULL,nasm->xl[i]);CHKERRQ(ierr);
141   }
142   PetscFunctionReturn(0);
143 }
144 
145 #undef __FUNCT__
146 #define __FUNCT__ "SNESSetFromOptions_NASM"
147 PetscErrorCode SNESSetFromOptions_NASM(SNES snes)
148 {
149   PetscErrorCode    ierr;
150   DM                dm,ddm;
151   char              ddm_name[1024];
152   PCASMType         asmtype;
153   PetscBool         flg,monflg;
154   SNES_NASM         *nasm = (SNES_NASM*)snes->data;
155 
156   PetscFunctionBegin;
157   ierr = PetscOptionsHead("Nonlinear Additive Schwartz options");CHKERRQ(ierr);
158   ierr = PetscOptionsEnum("-snes_nasm_type","Type of restriction/extension","",SNESNASMTypes,(PetscEnum)nasm->type,(PetscEnum*)&asmtype,&flg);CHKERRQ(ierr);
159   if (flg) nasm->type = asmtype;
160   flg    = PETSC_FALSE;
161   monflg = PETSC_TRUE;
162   ierr   = PetscOptionsBool("-snes_nasm_log","Log times for subSNES solves and restriction","",monflg,&monflg,&flg);CHKERRQ(ierr);
163   if (flg) {
164     ierr = PetscLogEventRegister("SNESNASMSubSolve",((PetscObject)snes)->classid,&nasm->eventsubsolve);CHKERRQ(ierr);
165     ierr = PetscLogEventRegister("SNESNASMRestrict",((PetscObject)snes)->classid,&nasm->eventrestrictinterp);CHKERRQ(ierr);
166   }
167   ierr = PetscOptionsString("-snes_nasm_decomposition", "Name of the DM defining the composition", "SNESSetDM", ddm_name, ddm_name,1024,&flg);CHKERRQ(ierr);
168   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
169   if (flg) {
170     if (dm) {
171       ierr = DMCreateDomainDecompositionDM(dm, ddm_name, &ddm);CHKERRQ(ierr);
172       if (!ddm) SETERRQ1(((PetscObject)snes)->comm, PETSC_ERR_ARG_WRONGSTATE, "Unknown DM decomposition name %s", ddm_name);
173       ierr = PetscInfo(snes,"Using domain decomposition DM defined using options database\n");CHKERRQ(ierr);
174       ierr = SNESSetDM(snes,ddm);CHKERRQ(ierr);
175     } else SETERRQ(((PetscObject)snes)->comm, PETSC_ERR_ARG_WRONGSTATE, "No DM to decompose");
176   }
177   ierr = PetscOptionsTail();CHKERRQ(ierr);
178   PetscFunctionReturn(0);
179 }
180 
181 #undef __FUNCT__
182 #define __FUNCT__ "SNESView_NASM"
183 PetscErrorCode SNESView_NASM(SNES snes, PetscViewer viewer)
184 {
185   PetscFunctionBegin;
186   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
187   PetscErrorCode ierr;
188   PetscMPIInt    rank;
189   PetscInt       i,N;
190   PetscBool      iascii,isstring;
191   PetscViewer    sviewer;
192   MPI_Comm       comm = ((PetscObject)snes)->comm;
193 
194   PetscFunctionBegin;
195   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
196   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
197   ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
198   ierr = MPI_Reduce(&nasm->n,&N,1,MPIU_INT,MPIU_SUM,0,comm);CHKERRQ(ierr);
199   if (iascii) {
200     ierr = PetscViewerASCIIPrintf(viewer, "  Nonlinear Additive Schwarz: total subdomain blocks = %D\n",N);CHKERRQ(ierr);
201     ierr = PetscViewerASCIIPrintf(viewer,"  Nonlinear Additive Schwarz: restriction/interpolation type - %s\n",SNESNASMTypes[nasm->type]);CHKERRQ(ierr);
202     ierr = PetscViewerASCIIPrintf(viewer,"  Nonlinear Additive Schwarz: subSNES iterations: %D subKSP iterations: %D\n",SNESNASMTypes[nasm->type]);CHKERRQ(ierr);
203     ierr = PetscViewerASCIISynchronizedAllow(viewer,PETSC_TRUE);CHKERRQ(ierr);
204     ierr = PetscViewerASCIISynchronizedPrintf(viewer,"  [%d] number of local blocks = %D\n",(int)rank,nasm->n);CHKERRQ(ierr);
205     ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
206     ierr = PetscViewerASCIIPrintf(viewer,"  Local SNES objects:\n");CHKERRQ(ierr);
207     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
208     if (!rank) {
209       for (i=0; i<nasm->n; i++) {
210         ierr = PetscViewerGetSingleton(viewer,&sviewer);CHKERRQ(ierr);
211         ierr = SNESView(nasm->subsnes[i],sviewer);CHKERRQ(ierr);
212         ierr = PetscViewerRestoreSingleton(viewer,&sviewer);CHKERRQ(ierr);
213       }
214     }
215     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
216     ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
217     ierr = PetscViewerASCIISynchronizedAllow(viewer,PETSC_FALSE);CHKERRQ(ierr);
218   } else if (isstring) {
219     ierr = PetscViewerStringSPrintf(viewer," blocks=%D,type=%s",N,SNESNASMTypes[nasm->type]);CHKERRQ(ierr);
220     ierr = PetscViewerGetSingleton(viewer,&sviewer);CHKERRQ(ierr);
221     if (nasm->subsnes && !rank) {ierr = SNESView(nasm->subsnes[0],sviewer);CHKERRQ(ierr);}
222     ierr = PetscViewerRestoreSingleton(viewer,&sviewer);CHKERRQ(ierr);
223   }
224   PetscFunctionReturn(0);
225 }
226 
227 #undef __FUNCT__
228 #define __FUNCT__ "SNESNASMSetSubdomains"
229 PetscErrorCode SNESNASMSetSubdomains(SNES snes,PetscInt n,SNES subsnes[],VecScatter iscatter[],VecScatter oscatter[],VecScatter gscatter[])
230 {
231   PetscErrorCode ierr;
232   PetscErrorCode (*f)(SNES,PetscInt,SNES*,VecScatter*,VecScatter*,VecScatter*);
233 
234   PetscFunctionBegin;
235   ierr = PetscObjectQueryFunction((PetscObject)snes,"SNESNASMSetSubdomains_C",(void (**)(void))&f);CHKERRQ(ierr);
236   ierr = (f)(snes,n,subsnes,iscatter,oscatter,gscatter);CHKERRQ(ierr);
237   PetscFunctionReturn(0);
238 }
239 
240 EXTERN_C_BEGIN
241 #undef __FUNCT__
242 #define __FUNCT__ "SNESNASMSetSubdomains_NASM"
243 PetscErrorCode SNESNASMSetSubdomains_NASM(SNES snes,PetscInt n,SNES subsnes[],VecScatter iscatter[],VecScatter oscatter[],VecScatter gscatter[])
244 {
245   PetscInt       i;
246   PetscErrorCode ierr;
247   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
248 
249   PetscFunctionBegin;
250   if (snes->setupcalled) SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"SNESNASMSetSubdomains() should be called before calling SNESSetUp().");
251 
252   /* tear down the previously set things */
253   ierr = SNESReset(snes);CHKERRQ(ierr);
254 
255   nasm->n = n;
256   if (oscatter) {
257     for (i=0; i<n; i++) {ierr = PetscObjectReference((PetscObject)oscatter[i]);CHKERRQ(ierr);}
258   }
259   if (iscatter) {
260     for (i=0; i<n; i++) {ierr = PetscObjectReference((PetscObject)iscatter[i]);CHKERRQ(ierr);}
261   }
262   if (gscatter) {
263     for (i=0; i<n; i++) {ierr = PetscObjectReference((PetscObject)gscatter[i]);CHKERRQ(ierr);}
264   }
265   if (oscatter) {
266     ierr = PetscMalloc(n*sizeof(IS),&nasm->oscatter);CHKERRQ(ierr);
267     for (i=0; i<n; i++) {
268       nasm->oscatter[i] = oscatter[i];
269     }
270   }
271   if (iscatter) {
272     ierr = PetscMalloc(n*sizeof(IS),&nasm->iscatter);CHKERRQ(ierr);
273     for (i=0; i<n; i++) {
274       nasm->iscatter[i] = iscatter[i];
275     }
276   }
277   if (gscatter) {
278     ierr = PetscMalloc(n*sizeof(IS),&nasm->gscatter);CHKERRQ(ierr);
279     for (i=0; i<n; i++) {
280       nasm->gscatter[i] = gscatter[i];
281     }
282   }
283 
284   if (subsnes) {
285     ierr = PetscMalloc(n*sizeof(SNES),&nasm->subsnes);CHKERRQ(ierr);
286     for (i=0; i<n; i++) {
287       nasm->subsnes[i] = subsnes[i];
288     }
289   }
290   PetscFunctionReturn(0);
291 }
292 EXTERN_C_END
293 
294 #undef __FUNCT__
295 #define __FUNCT__ "SNESNASMSolveLocal_Private"
296 PetscErrorCode SNESNASMSolveLocal_Private(SNES snes,Vec B,Vec Y,Vec X)
297 {
298   SNES_NASM      *nasm = (SNES_NASM*)snes->data;
299   SNES           subsnes;
300   PetscInt       i;
301   PetscErrorCode ierr;
302   Vec            Xlloc,Xl,Bl,Yl;
303   VecScatter     iscat,oscat,gscat;
304   DM             dm,subdm;
305 
306   PetscFunctionBegin;
307   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
308   ierr = VecSet(Y,0);CHKERRQ(ierr);
309 
310   if (nasm->eventrestrictinterp) {ierr = PetscLogEventBegin(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
311   for (i=0; i<nasm->n; i++) {
312     /* scatter the solution to the local solution */
313     Xlloc = nasm->xl[i];
314     gscat   = nasm->gscatter[i];
315     oscat   = nasm->oscatter[i];
316     ierr = VecScatterBegin(gscat,X,Xlloc,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
317     if (B) {
318       /* scatter the RHS to the local RHS */
319       Bl   = nasm->b[i];
320       ierr = VecScatterBegin(oscat,B,Bl,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
321     } else {
322       Bl = NULL;
323     }
324   }
325   if (nasm->eventrestrictinterp) {ierr = PetscLogEventEnd(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
326 
327   for (i=0; i<nasm->n; i++) {
328     Xlloc = nasm->xl[i];
329     ierr = VecScatterEnd(gscat,X,Xlloc,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
330     if (B) {
331       ierr = VecScatterEnd(oscat,B,Bl,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
332     }
333   }
334 
335   if (nasm->eventsubsolve) {ierr = PetscLogEventBegin(nasm->eventsubsolve,snes,0,0,0);CHKERRQ(ierr);}
336   for (i=0; i<nasm->n; i++) {
337     Xl    = nasm->x[i];
338     Xlloc = nasm->xl[i];
339     Yl    = nasm->y[i];
340     subsnes = nasm->subsnes[i];
341     ierr    = SNESGetDM(subsnes,&subdm);CHKERRQ(ierr);
342     iscat   = nasm->iscatter[i];
343     oscat   = nasm->oscatter[i];
344     gscat   = nasm->gscatter[i];
345     ierr    = DMSubDomainRestrict(dm,oscat,gscat,subdm);CHKERRQ(ierr);
346 
347     ierr = DMLocalToGlobalBegin(subdm,Xlloc,INSERT_VALUES,Xl);CHKERRQ(ierr);
348     ierr = DMLocalToGlobalEnd(subdm,Xlloc,INSERT_VALUES,Xl);CHKERRQ(ierr);
349     ierr = VecCopy(Xl,Yl);CHKERRQ(ierr);
350     ierr = SNESSolve(subsnes,Bl,Yl);CHKERRQ(ierr);
351     ierr = VecAXPY(Yl,-1.0,Xl);CHKERRQ(ierr);
352   }
353   if (nasm->eventsubsolve) {ierr = PetscLogEventEnd(nasm->eventsubsolve,snes,0,0,0);CHKERRQ(ierr);}
354 
355   ierr = MPI_Barrier(((PetscObject)snes)->comm);CHKERRQ(ierr);
356 
357   if (nasm->eventrestrictinterp) {ierr = PetscLogEventBegin(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
358   for (i=0; i<nasm->n; i++) {
359     Yl    = nasm->y[i];
360     iscat   = nasm->iscatter[i];
361     oscat   = nasm->oscatter[i];
362     if (nasm->type == PC_ASM_BASIC) {
363       ierr = VecScatterBegin(oscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
364     } else if (nasm->type == PC_ASM_RESTRICT) {
365       ierr = VecScatterBegin(iscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
366     } else SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Only basic and restrict types are supported for SNESNASM");
367   }
368 
369   for (i=0; i<nasm->n; i++) {
370     Yl    = nasm->y[i];
371     iscat   = nasm->iscatter[i];
372     oscat   = nasm->oscatter[i];
373     if (nasm->type == PC_ASM_BASIC) {
374       ierr = VecScatterEnd(oscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
375     } else if (nasm->type == PC_ASM_RESTRICT) {
376       ierr = VecScatterEnd(iscat,Yl,Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
377     } else SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Only basic and restrict types are supported for SNESNASM");
378   }
379   if (nasm->eventrestrictinterp) {ierr = PetscLogEventEnd(nasm->eventrestrictinterp,snes,0,0,0);CHKERRQ(ierr);}
380 
381   ierr = MPI_Barrier(((PetscObject)snes)->comm);CHKERRQ(ierr);
382 
383   ierr = VecAXPY(X,1.0,Y);CHKERRQ(ierr);
384   PetscFunctionReturn(0);
385 }
386 
387 #undef __FUNCT__
388 #define __FUNCT__ "SNESSolve_NASM"
389 PetscErrorCode SNESSolve_NASM(SNES snes)
390 {
391   Vec            F;
392   Vec            X;
393   Vec            B;
394   Vec            Y;
395   PetscInt       i;
396   PetscReal      fnorm;
397   PetscErrorCode ierr;
398   SNESNormType   normtype;
399 
400   PetscFunctionBegin;
401   X = snes->vec_sol;
402   Y = snes->vec_sol_update;
403   F = snes->vec_func;
404   B = snes->vec_rhs;
405 
406   ierr         = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
407   snes->iter   = 0;
408   snes->norm   = 0.;
409   ierr         = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
410   snes->reason = SNES_CONVERGED_ITERATING;
411   ierr         = SNESGetNormType(snes, &normtype);CHKERRQ(ierr);
412   if (normtype == SNES_NORM_FUNCTION || normtype == SNES_NORM_INITIAL_ONLY || normtype == SNES_NORM_INITIAL_FINAL_ONLY) {
413     /* compute the initial function and preconditioned update delX */
414     if (!snes->vec_func_init_set) {
415       ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr);
416       if (snes->domainerror) {
417         snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN;
418         PetscFunctionReturn(0);
419       }
420     } else snes->vec_func_init_set = PETSC_FALSE;
421 
422     /* convergence test */
423     if (!snes->norm_init_set) {
424       ierr = VecNorm(F, NORM_2, &fnorm);CHKERRQ(ierr); /* fnorm <- ||F||  */
425       if (PetscIsInfOrNanReal(fnorm)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_FP,"Infinite or not-a-number generated in norm");
426     } else {
427       fnorm               = snes->norm_init;
428       snes->norm_init_set = PETSC_FALSE;
429     }
430     ierr       = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
431     snes->iter = 0;
432     snes->norm = fnorm;
433     ierr       = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
434     ierr       = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
435     ierr       = SNESMonitor(snes,0,snes->norm);CHKERRQ(ierr);
436 
437     /* set parameter for default relative tolerance convergence test */
438     snes->ttol = fnorm*snes->rtol;
439 
440     /* test convergence */
441     ierr = (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr);
442     if (snes->reason) PetscFunctionReturn(0);
443   } else {
444     ierr = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
445     ierr = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
446     ierr = SNESMonitor(snes,0,snes->norm);CHKERRQ(ierr);
447   }
448 
449   /* Call general purpose update function */
450   if (snes->ops->update) {
451     ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr);
452   }
453 
454   for (i = 0; i < snes->max_its; i++) {
455     ierr = SNESNASMSolveLocal_Private(snes,B,Y,X);CHKERRQ(ierr);
456     if (normtype == SNES_NORM_FUNCTION || ((i == snes->max_its - 1) && (normtype == SNES_NORM_INITIAL_FINAL_ONLY || normtype == SNES_NORM_FINAL_ONLY))) {
457       ierr = SNESComputeFunction(snes,X,F);CHKERRQ(ierr);
458       if (snes->domainerror) {
459         snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN;
460         PetscFunctionReturn(0);
461       }
462       ierr = VecNorm(F, NORM_2, &fnorm);CHKERRQ(ierr); /* fnorm <- ||F||  */
463       if (PetscIsInfOrNanReal(fnorm)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_FP,"Infinite or not-a-number generated in norm");
464     }
465     /* Monitor convergence */
466     ierr       = PetscObjectTakeAccess(snes);CHKERRQ(ierr);
467     snes->iter = i+1;
468     snes->norm = fnorm;
469     ierr       = PetscObjectGrantAccess(snes);CHKERRQ(ierr);
470     ierr       = SNESLogConvergenceHistory(snes,snes->norm,0);CHKERRQ(ierr);
471     ierr       = SNESMonitor(snes,snes->iter,snes->norm);CHKERRQ(ierr);
472     /* Test for convergence */
473     if (normtype == SNES_NORM_FUNCTION) ierr = (*snes->ops->converged)(snes,snes->iter,0.0,0.0,fnorm,&snes->reason,snes->cnvP);CHKERRQ(ierr);
474     if (snes->reason) PetscFunctionReturn(0);
475     /* Call general purpose update function */
476     if (snes->ops->update) {
477       ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr);
478     }
479   }
480   if (normtype == SNES_NORM_FUNCTION) {
481     if (i == snes->max_its) {
482       ierr = PetscInfo1(snes,"Maximum number of iterations has been reached: %D\n",snes->max_its);CHKERRQ(ierr);
483       if (!snes->reason) snes->reason = SNES_DIVERGED_MAX_IT;
484     }
485   } else if (!snes->reason) snes->reason = SNES_CONVERGED_ITS; /* NASM is meant to be used as a preconditioner */
486   PetscFunctionReturn(0);
487 }
488 
489 /*MC
490   SNESNASM - Nonlinear Additive Schwartz
491 
492    Level: advanced
493 
494 .seealso: SNESCreate(), SNES, SNESSetType(), SNESType (for list of available types)
495 M*/
496 
497 EXTERN_C_BEGIN
498 #undef __FUNCT__
499 #define __FUNCT__ "SNESCreate_NASM"
500 PetscErrorCode SNESCreate_NASM(SNES snes)
501 {
502   SNES_NASM      *nasm;
503   PetscErrorCode ierr;
504 
505   PetscFunctionBegin;
506   ierr       = PetscNewLog(snes, SNES_NASM, &nasm);CHKERRQ(ierr);
507   snes->data = (void*)nasm;
508 
509   nasm->n        = PETSC_DECIDE;
510   nasm->subsnes  = 0;
511   nasm->x        = 0;
512   nasm->xl       = 0;
513   nasm->y        = 0;
514   nasm->b        = 0;
515   nasm->oscatter = 0;
516   nasm->iscatter = 0;
517   nasm->gscatter = 0;
518 
519   nasm->type = PC_ASM_BASIC;
520 
521   snes->ops->destroy        = SNESDestroy_NASM;
522   snes->ops->setup          = SNESSetUp_NASM;
523   snes->ops->setfromoptions = SNESSetFromOptions_NASM;
524   snes->ops->view           = SNESView_NASM;
525   snes->ops->solve          = SNESSolve_NASM;
526   snes->ops->reset          = SNESReset_NASM;
527 
528   snes->usesksp = PETSC_FALSE;
529   snes->usespc  = PETSC_FALSE;
530 
531   nasm->eventrestrictinterp = 0;
532   nasm->eventsubsolve       = 0;
533 
534   if (!snes->tolerancesset) {
535     snes->max_its   = 10000;
536     snes->max_funcs = 10000;
537   }
538 
539   ierr = PetscObjectComposeFunctionDynamic((PetscObject)snes,"SNESNASMSetSubdomains_C","SNESNASMSetSubdomains_NASM",
540                                            SNESNASMSetSubdomains_NASM);CHKERRQ(ierr);
541   PetscFunctionReturn(0);
542 }
543 EXTERN_C_END
544