Actual source code: fieldsplit.c
petsc-3.6.0 2015-06-09
2: #include <petsc/private/pcimpl.h> /*I "petscpc.h" I*/
3: #include <petscdm.h>
6: const char *const PCFieldSplitSchurPreTypes[] = {"SELF","SELFP","A11","USER","FULL","PCFieldSplitSchurPreType","PC_FIELDSPLIT_SCHUR_PRE_",0};
7: const char *const PCFieldSplitSchurFactTypes[] = {"DIAG","LOWER","UPPER","FULL","PCFieldSplitSchurFactType","PC_FIELDSPLIT_SCHUR_FACT_",0};
9: typedef struct _PC_FieldSplitLink *PC_FieldSplitLink;
10: struct _PC_FieldSplitLink {
11: KSP ksp;
12: Vec x,y,z;
13: char *splitname;
14: PetscInt nfields;
15: PetscInt *fields,*fields_col;
16: VecScatter sctx;
17: IS is,is_col;
18: PC_FieldSplitLink next,previous;
19: };
21: typedef struct {
22: PCCompositeType type;
23: PetscBool defaultsplit; /* Flag for a system with a set of 'k' scalar fields with the same layout (and bs = k) */
24: PetscBool splitdefined; /* Flag is set after the splits have been defined, to prevent more splits from being added */
25: PetscInt bs; /* Block size for IS and Mat structures */
26: PetscInt nsplits; /* Number of field divisions defined */
27: Vec *x,*y,w1,w2;
28: Mat *mat; /* The diagonal block for each split */
29: Mat *pmat; /* The preconditioning diagonal block for each split */
30: Mat *Afield; /* The rows of the matrix associated with each split */
31: PetscBool issetup;
33: /* Only used when Schur complement preconditioning is used */
34: Mat B; /* The (0,1) block */
35: Mat C; /* The (1,0) block */
36: Mat schur; /* The Schur complement S = A11 - A10 A00^{-1} A01, the KSP here, kspinner, is H_1 in [El08] */
37: Mat schurp; /* Assembled approximation to S built by MatSchurComplement to be used as a preconditioning matrix when solving with S */
38: Mat schur_user; /* User-provided preconditioning matrix for the Schur complement */
39: PCFieldSplitSchurPreType schurpre; /* Determines which preconditioning matrix is used for the Schur complement */
40: PCFieldSplitSchurFactType schurfactorization;
41: KSP kspschur; /* The solver for S */
42: KSP kspupper; /* The solver for A in the upper diagonal part of the factorization (H_2 in [El08]) */
43: PC_FieldSplitLink head;
44: PetscBool reset; /* indicates PCReset() has been last called on this object, hack */
45: PetscBool suboptionsset; /* Indicates that the KSPSetFromOptions() has been called on the sub-KSPs */
46: PetscBool dm_splits; /* Whether to use DMCreateFieldDecomposition() whenever possible */
47: PetscBool diag_use_amat; /* Whether to extract diagonal matrix blocks from Amat, rather than Pmat (weaker than -pc_use_amat) */
48: PetscBool offdiag_use_amat; /* Whether to extract off-diagonal matrix blocks from Amat, rather than Pmat (weaker than -pc_use_amat) */
49: } PC_FieldSplit;
51: /*
52: Notes: there is no particular reason that pmat, x, and y are stored as arrays in PC_FieldSplit instead of
53: inside PC_FieldSplitLink, just historical. If you want to be able to add new fields after already using the
54: PC you could change this.
55: */
57: /* This helper is so that setting a user-provided preconditioning matrix is orthogonal to choosing to use it. This way the
58: * application-provided FormJacobian can provide this matrix without interfering with the user's (command-line) choices. */
59: static Mat FieldSplitSchurPre(PC_FieldSplit *jac)
60: {
61: switch (jac->schurpre) {
62: case PC_FIELDSPLIT_SCHUR_PRE_SELF: return jac->schur;
63: case PC_FIELDSPLIT_SCHUR_PRE_SELFP: return jac->schurp;
64: case PC_FIELDSPLIT_SCHUR_PRE_A11: return jac->pmat[1];
65: case PC_FIELDSPLIT_SCHUR_PRE_FULL: /* We calculate this and store it in schur_user */
66: case PC_FIELDSPLIT_SCHUR_PRE_USER: /* Use a user-provided matrix if it is given, otherwise diagonal block */
67: default:
68: return jac->schur_user ? jac->schur_user : jac->pmat[1];
69: }
70: }
73: #include <petscdraw.h>
76: static PetscErrorCode PCView_FieldSplit(PC pc,PetscViewer viewer)
77: {
78: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
79: PetscErrorCode ierr;
80: PetscBool iascii,isdraw;
81: PetscInt i,j;
82: PC_FieldSplitLink ilink = jac->head;
85: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
86: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
87: if (iascii) {
88: if (jac->bs > 0) {
89: PetscViewerASCIIPrintf(viewer," FieldSplit with %s composition: total splits = %D, blocksize = %D\n",PCCompositeTypes[jac->type],jac->nsplits,jac->bs);
90: } else {
91: PetscViewerASCIIPrintf(viewer," FieldSplit with %s composition: total splits = %D\n",PCCompositeTypes[jac->type],jac->nsplits);
92: }
93: if (pc->useAmat) {
94: PetscViewerASCIIPrintf(viewer," using Amat (not Pmat) as operator for blocks\n");
95: }
96: if (jac->diag_use_amat) {
97: PetscViewerASCIIPrintf(viewer," using Amat (not Pmat) as operator for diagonal blocks\n");
98: }
99: if (jac->offdiag_use_amat) {
100: PetscViewerASCIIPrintf(viewer," using Amat (not Pmat) as operator for off-diagonal blocks\n");
101: }
102: PetscViewerASCIIPrintf(viewer," Solver info for each split is in the following KSP objects:\n");
103: PetscViewerASCIIPushTab(viewer);
104: for (i=0; i<jac->nsplits; i++) {
105: if (ilink->fields) {
106: PetscViewerASCIIPrintf(viewer,"Split number %D Fields ",i);
107: PetscViewerASCIIUseTabs(viewer,PETSC_FALSE);
108: for (j=0; j<ilink->nfields; j++) {
109: if (j > 0) {
110: PetscViewerASCIIPrintf(viewer,",");
111: }
112: PetscViewerASCIIPrintf(viewer," %D",ilink->fields[j]);
113: }
114: PetscViewerASCIIPrintf(viewer,"\n");
115: PetscViewerASCIIUseTabs(viewer,PETSC_TRUE);
116: } else {
117: PetscViewerASCIIPrintf(viewer,"Split number %D Defined by IS\n",i);
118: }
119: KSPView(ilink->ksp,viewer);
120: ilink = ilink->next;
121: }
122: PetscViewerASCIIPopTab(viewer);
123: }
125: if (isdraw) {
126: PetscDraw draw;
127: PetscReal x,y,w,wd;
129: PetscViewerDrawGetDraw(viewer,0,&draw);
130: PetscDrawGetCurrentPoint(draw,&x,&y);
131: w = 2*PetscMin(1.0 - x,x);
132: wd = w/(jac->nsplits + 1);
133: x = x - wd*(jac->nsplits-1)/2.0;
134: for (i=0; i<jac->nsplits; i++) {
135: PetscDrawPushCurrentPoint(draw,x,y);
136: KSPView(ilink->ksp,viewer);
137: PetscDrawPopCurrentPoint(draw);
138: x += wd;
139: ilink = ilink->next;
140: }
141: }
142: return(0);
143: }
147: static PetscErrorCode PCView_FieldSplit_Schur(PC pc,PetscViewer viewer)
148: {
149: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
150: PetscErrorCode ierr;
151: PetscBool iascii,isdraw;
152: PetscInt i,j;
153: PC_FieldSplitLink ilink = jac->head;
156: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
157: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
158: if (iascii) {
159: if (jac->bs > 0) {
160: PetscViewerASCIIPrintf(viewer," FieldSplit with Schur preconditioner, blocksize = %D, factorization %s\n",jac->bs,PCFieldSplitSchurFactTypes[jac->schurfactorization]);
161: } else {
162: PetscViewerASCIIPrintf(viewer," FieldSplit with Schur preconditioner, factorization %s\n",PCFieldSplitSchurFactTypes[jac->schurfactorization]);
163: }
164: if (pc->useAmat) {
165: PetscViewerASCIIPrintf(viewer," using Amat (not Pmat) as operator for blocks\n");
166: }
167: switch (jac->schurpre) {
168: case PC_FIELDSPLIT_SCHUR_PRE_SELF:
169: PetscViewerASCIIPrintf(viewer," Preconditioner for the Schur complement formed from S itself\n");break;
170: case PC_FIELDSPLIT_SCHUR_PRE_SELFP:
171: PetscViewerASCIIPrintf(viewer," Preconditioner for the Schur complement formed from Sp, an assembled approximation to S, which uses (lumped, if requested) A00's diagonal's inverse\n");break;
172: case PC_FIELDSPLIT_SCHUR_PRE_A11:
173: PetscViewerASCIIPrintf(viewer," Preconditioner for the Schur complement formed from A11\n");break;
174: case PC_FIELDSPLIT_SCHUR_PRE_FULL:
175: PetscViewerASCIIPrintf(viewer," Preconditioner for the Schur complement formed from the exact Schur complement\n");break;
176: case PC_FIELDSPLIT_SCHUR_PRE_USER:
177: if (jac->schur_user) {
178: PetscViewerASCIIPrintf(viewer," Preconditioner for the Schur complement formed from user provided matrix\n");
179: } else {
180: PetscViewerASCIIPrintf(viewer," Preconditioner for the Schur complement formed from A11\n");
181: }
182: break;
183: default:
184: SETERRQ1(PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_OUTOFRANGE, "Invalid Schur preconditioning type: %d", jac->schurpre);
185: }
186: PetscViewerASCIIPrintf(viewer," Split info:\n");
187: PetscViewerASCIIPushTab(viewer);
188: for (i=0; i<jac->nsplits; i++) {
189: if (ilink->fields) {
190: PetscViewerASCIIPrintf(viewer,"Split number %D Fields ",i);
191: PetscViewerASCIIUseTabs(viewer,PETSC_FALSE);
192: for (j=0; j<ilink->nfields; j++) {
193: if (j > 0) {
194: PetscViewerASCIIPrintf(viewer,",");
195: }
196: PetscViewerASCIIPrintf(viewer," %D",ilink->fields[j]);
197: }
198: PetscViewerASCIIPrintf(viewer,"\n");
199: PetscViewerASCIIUseTabs(viewer,PETSC_TRUE);
200: } else {
201: PetscViewerASCIIPrintf(viewer,"Split number %D Defined by IS\n",i);
202: }
203: ilink = ilink->next;
204: }
205: PetscViewerASCIIPrintf(viewer,"KSP solver for A00 block\n");
206: PetscViewerASCIIPushTab(viewer);
207: if (jac->head) {
208: KSPView(jac->head->ksp,viewer);
209: } else {PetscViewerASCIIPrintf(viewer," not yet available\n");}
210: PetscViewerASCIIPopTab(viewer);
211: if (jac->head && jac->kspupper != jac->head->ksp) {
212: PetscViewerASCIIPrintf(viewer,"KSP solver for upper A00 in upper triangular factor \n");
213: PetscViewerASCIIPushTab(viewer);
214: if (jac->kspupper) {KSPView(jac->kspupper,viewer);}
215: else {PetscViewerASCIIPrintf(viewer," not yet available\n");}
216: PetscViewerASCIIPopTab(viewer);
217: }
218: PetscViewerASCIIPrintf(viewer,"KSP solver for S = A11 - A10 inv(A00) A01 \n");
219: PetscViewerASCIIPushTab(viewer);
220: if (jac->kspschur) {
221: KSPView(jac->kspschur,viewer);
222: } else {
223: PetscViewerASCIIPrintf(viewer," not yet available\n");
224: }
225: PetscViewerASCIIPopTab(viewer);
226: PetscViewerASCIIPopTab(viewer);
227: } else if (isdraw && jac->head) {
228: PetscDraw draw;
229: PetscReal x,y,w,wd,h;
230: PetscInt cnt = 2;
231: char str[32];
233: PetscViewerDrawGetDraw(viewer,0,&draw);
234: PetscDrawGetCurrentPoint(draw,&x,&y);
235: if (jac->kspupper != jac->head->ksp) cnt++;
236: w = 2*PetscMin(1.0 - x,x);
237: wd = w/(cnt + 1);
239: PetscSNPrintf(str,32,"Schur fact. %s",PCFieldSplitSchurFactTypes[jac->schurfactorization]);
240: PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_RED,PETSC_DRAW_BLACK,str,NULL,&h);
241: y -= h;
242: if (jac->schurpre == PC_FIELDSPLIT_SCHUR_PRE_USER && !jac->schur_user) {
243: PetscSNPrintf(str,32,"Prec. for Schur from %s",PCFieldSplitSchurPreTypes[PC_FIELDSPLIT_SCHUR_PRE_A11]);
244: } else {
245: PetscSNPrintf(str,32,"Prec. for Schur from %s",PCFieldSplitSchurPreTypes[jac->schurpre]);
246: }
247: PetscDrawStringBoxed(draw,x+wd*(cnt-1)/2.0,y,PETSC_DRAW_RED,PETSC_DRAW_BLACK,str,NULL,&h);
248: y -= h;
249: x = x - wd*(cnt-1)/2.0;
251: PetscDrawPushCurrentPoint(draw,x,y);
252: KSPView(jac->head->ksp,viewer);
253: PetscDrawPopCurrentPoint(draw);
254: if (jac->kspupper != jac->head->ksp) {
255: x += wd;
256: PetscDrawPushCurrentPoint(draw,x,y);
257: KSPView(jac->kspupper,viewer);
258: PetscDrawPopCurrentPoint(draw);
259: }
260: x += wd;
261: PetscDrawPushCurrentPoint(draw,x,y);
262: KSPView(jac->kspschur,viewer);
263: PetscDrawPopCurrentPoint(draw);
264: }
265: return(0);
266: }
270: /* Precondition: jac->bs is set to a meaningful value */
271: static PetscErrorCode PCFieldSplitSetRuntimeSplits_Private(PC pc)
272: {
274: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
275: PetscInt i,nfields,*ifields,nfields_col,*ifields_col;
276: PetscBool flg,flg_col;
277: char optionname[128],splitname[8],optionname_col[128];
280: PetscMalloc1(jac->bs,&ifields);
281: PetscMalloc1(jac->bs,&ifields_col);
282: for (i=0,flg=PETSC_TRUE;; i++) {
283: PetscSNPrintf(splitname,sizeof(splitname),"%D",i);
284: PetscSNPrintf(optionname,sizeof(optionname),"-pc_fieldsplit_%D_fields",i);
285: PetscSNPrintf(optionname_col,sizeof(optionname_col),"-pc_fieldsplit_%D_fields_col",i);
286: nfields = jac->bs;
287: nfields_col = jac->bs;
288: PetscOptionsGetIntArray(((PetscObject)pc)->prefix,optionname,ifields,&nfields,&flg);
289: PetscOptionsGetIntArray(((PetscObject)pc)->prefix,optionname_col,ifields_col,&nfields_col,&flg_col);
290: if (!flg) break;
291: else if (flg && !flg_col) {
292: if (!nfields) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"Cannot list zero fields");
293: PCFieldSplitSetFields(pc,splitname,nfields,ifields,ifields);
294: } else {
295: if (!nfields || !nfields_col) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"Cannot list zero fields");
296: if (nfields != nfields_col) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"Number of row and column fields must match");
297: PCFieldSplitSetFields(pc,splitname,nfields,ifields,ifields_col);
298: }
299: }
300: if (i > 0) {
301: /* Makes command-line setting of splits take precedence over setting them in code.
302: Otherwise subsequent calls to PCFieldSplitSetIS() or PCFieldSplitSetFields() would
303: create new splits, which would probably not be what the user wanted. */
304: jac->splitdefined = PETSC_TRUE;
305: }
306: PetscFree(ifields);
307: PetscFree(ifields_col);
308: return(0);
309: }
313: static PetscErrorCode PCFieldSplitSetDefaults(PC pc)
314: {
315: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
316: PetscErrorCode ierr;
317: PC_FieldSplitLink ilink = jac->head;
318: PetscBool fieldsplit_default = PETSC_FALSE,stokes = PETSC_FALSE,coupling = PETSC_FALSE;
319: PetscInt i;
322: /*
323: Kinda messy, but at least this now uses DMCreateFieldDecomposition() even with jac->reset.
324: Should probably be rewritten.
325: */
326: if (!ilink || jac->reset) {
327: PetscOptionsGetBool(((PetscObject)pc)->prefix,"-pc_fieldsplit_detect_saddle_point",&stokes,NULL);
328: PetscOptionsGetBool(((PetscObject)pc)->prefix,"-pc_fieldsplit_detect_coupling",&coupling,NULL);
329: if (pc->dm && jac->dm_splits && !stokes && !coupling) {
330: PetscInt numFields, f, i, j;
331: char **fieldNames;
332: IS *fields;
333: DM *dms;
334: DM subdm[128];
335: PetscBool flg;
337: DMCreateFieldDecomposition(pc->dm, &numFields, &fieldNames, &fields, &dms);
338: /* Allow the user to prescribe the splits */
339: for (i = 0, flg = PETSC_TRUE;; i++) {
340: PetscInt ifields[128];
341: IS compField;
342: char optionname[128], splitname[8];
343: PetscInt nfields = numFields;
345: PetscSNPrintf(optionname, sizeof(optionname), "-pc_fieldsplit_%D_fields", i);
346: PetscOptionsGetIntArray(((PetscObject) pc)->prefix, optionname, ifields, &nfields, &flg);
347: if (!flg) break;
348: if (numFields > 128) SETERRQ1(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Cannot currently support %d > 128 fields", numFields);
349: DMCreateSubDM(pc->dm, nfields, ifields, &compField, &subdm[i]);
350: if (nfields == 1) {
351: PCFieldSplitSetIS(pc, fieldNames[ifields[0]], compField);
352: /* PetscPrintf(PetscObjectComm((PetscObject)pc), "%s Field Indices:", fieldNames[ifields[0]]);
353: ISView(compField, NULL); */
354: } else {
355: PetscSNPrintf(splitname, sizeof(splitname), "%D", i);
356: PCFieldSplitSetIS(pc, splitname, compField);
357: /* PetscPrintf(PetscObjectComm((PetscObject)pc), "%s Field Indices:", splitname);
358: ISView(compField, NULL); */
359: }
360: ISDestroy(&compField);
361: for (j = 0; j < nfields; ++j) {
362: f = ifields[j];
363: PetscFree(fieldNames[f]);
364: ISDestroy(&fields[f]);
365: }
366: }
367: if (i == 0) {
368: for (f = 0; f < numFields; ++f) {
369: PCFieldSplitSetIS(pc, fieldNames[f], fields[f]);
370: PetscFree(fieldNames[f]);
371: ISDestroy(&fields[f]);
372: }
373: } else {
374: for (j=0; j<numFields; j++) {
375: DMDestroy(dms+j);
376: }
377: PetscFree(dms);
378: PetscMalloc1(i, &dms);
379: for (j = 0; j < i; ++j) dms[j] = subdm[j];
380: }
381: PetscFree(fieldNames);
382: PetscFree(fields);
383: if (dms) {
384: PetscInfo(pc, "Setting up physics based fieldsplit preconditioner using the embedded DM\n");
385: for (ilink = jac->head, i = 0; ilink; ilink = ilink->next, ++i) {
386: const char *prefix;
387: PetscObjectGetOptionsPrefix((PetscObject)(ilink->ksp),&prefix);
388: PetscObjectSetOptionsPrefix((PetscObject)(dms[i]), prefix);
389: KSPSetDM(ilink->ksp, dms[i]);
390: KSPSetDMActive(ilink->ksp, PETSC_FALSE);
391: PetscObjectIncrementTabLevel((PetscObject)dms[i],(PetscObject)ilink->ksp,0);
392: DMDestroy(&dms[i]);
393: }
394: PetscFree(dms);
395: }
396: } else {
397: if (jac->bs <= 0) {
398: if (pc->pmat) {
399: MatGetBlockSize(pc->pmat,&jac->bs);
400: } else jac->bs = 1;
401: }
403: if (stokes) {
404: IS zerodiags,rest;
405: PetscInt nmin,nmax;
407: MatGetOwnershipRange(pc->mat,&nmin,&nmax);
408: MatFindZeroDiagonals(pc->mat,&zerodiags);
409: ISComplement(zerodiags,nmin,nmax,&rest);
410: if (jac->reset) {
411: jac->head->is = rest;
412: jac->head->next->is = zerodiags;
413: } else {
414: PCFieldSplitSetIS(pc,"0",rest);
415: PCFieldSplitSetIS(pc,"1",zerodiags);
416: }
417: ISDestroy(&zerodiags);
418: ISDestroy(&rest);
419: } else if (coupling) {
420: IS coupling,rest;
421: PetscInt nmin,nmax;
423: MatGetOwnershipRange(pc->mat,&nmin,&nmax);
424: MatFindOffBlockDiagonalEntries(pc->mat,&coupling);
425: ISCreateStride(PetscObjectComm((PetscObject)pc->mat),nmax-nmin,nmin,1,&rest);
426: ISSetIdentity(rest);
427: if (jac->reset) {
428: jac->head->is = coupling;
429: jac->head->next->is = rest;
430: } else {
431: PCFieldSplitSetIS(pc,"0",coupling);
432: PCFieldSplitSetIS(pc,"1",rest);
433: }
434: ISDestroy(&coupling);
435: ISDestroy(&rest);
436: } else {
437: if (jac->reset) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Cases not yet handled when PCReset() was used");
438: PetscOptionsGetBool(((PetscObject)pc)->prefix,"-pc_fieldsplit_default",&fieldsplit_default,NULL);
439: if (!fieldsplit_default) {
440: /* Allow user to set fields from command line, if bs was known at the time of PCSetFromOptions_FieldSplit()
441: then it is set there. This is not ideal because we should only have options set in XXSetFromOptions(). */
442: PCFieldSplitSetRuntimeSplits_Private(pc);
443: if (jac->splitdefined) {PetscInfo(pc,"Splits defined using the options database\n");}
444: }
445: if (fieldsplit_default || !jac->splitdefined) {
446: PetscInfo(pc,"Using default splitting of fields\n");
447: for (i=0; i<jac->bs; i++) {
448: char splitname[8];
449: PetscSNPrintf(splitname,sizeof(splitname),"%D",i);
450: PCFieldSplitSetFields(pc,splitname,1,&i,&i);
451: }
452: jac->defaultsplit = PETSC_TRUE;
453: }
454: }
455: }
456: } else if (jac->nsplits == 1) {
457: if (ilink->is) {
458: IS is2;
459: PetscInt nmin,nmax;
461: MatGetOwnershipRange(pc->mat,&nmin,&nmax);
462: ISComplement(ilink->is,nmin,nmax,&is2);
463: PCFieldSplitSetIS(pc,"1",is2);
464: ISDestroy(&is2);
465: } else SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Must provide at least two sets of fields to PCFieldSplit()");
466: }
469: if (jac->nsplits < 2) SETERRQ1(PetscObjectComm((PetscObject)pc),PETSC_ERR_PLIB,"Unhandled case, must have at least two fields, not %d", jac->nsplits);
470: return(0);
471: }
473: PETSC_EXTERN PetscErrorCode PetscOptionsFindPairPrefix_Private(const char pre[], const char name[], char *value[], PetscBool *flg);
477: static PetscErrorCode PCSetUp_FieldSplit(PC pc)
478: {
479: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
480: PetscErrorCode ierr;
481: PC_FieldSplitLink ilink;
482: PetscInt i,nsplit;
483: PetscBool sorted, sorted_col;
486: PCFieldSplitSetDefaults(pc);
487: nsplit = jac->nsplits;
488: ilink = jac->head;
490: /* get the matrices for each split */
491: if (!jac->issetup) {
492: PetscInt rstart,rend,nslots,bs;
494: jac->issetup = PETSC_TRUE;
496: /* This is done here instead of in PCFieldSplitSetFields() because may not have matrix at that point */
497: if (jac->defaultsplit || !ilink->is) {
498: if (jac->bs <= 0) jac->bs = nsplit;
499: }
500: bs = jac->bs;
501: MatGetOwnershipRange(pc->pmat,&rstart,&rend);
502: nslots = (rend - rstart)/bs;
503: for (i=0; i<nsplit; i++) {
504: if (jac->defaultsplit) {
505: ISCreateStride(PetscObjectComm((PetscObject)pc),nslots,rstart+i,nsplit,&ilink->is);
506: ISDuplicate(ilink->is,&ilink->is_col);
507: } else if (!ilink->is) {
508: if (ilink->nfields > 1) {
509: PetscInt *ii,*jj,j,k,nfields = ilink->nfields,*fields = ilink->fields,*fields_col = ilink->fields_col;
510: PetscMalloc1(ilink->nfields*nslots,&ii);
511: PetscMalloc1(ilink->nfields*nslots,&jj);
512: for (j=0; j<nslots; j++) {
513: for (k=0; k<nfields; k++) {
514: ii[nfields*j + k] = rstart + bs*j + fields[k];
515: jj[nfields*j + k] = rstart + bs*j + fields_col[k];
516: }
517: }
518: ISCreateGeneral(PetscObjectComm((PetscObject)pc),nslots*nfields,ii,PETSC_OWN_POINTER,&ilink->is);
519: ISCreateGeneral(PetscObjectComm((PetscObject)pc),nslots*nfields,jj,PETSC_OWN_POINTER,&ilink->is_col);
520: ISSetBlockSize(ilink->is, nfields);
521: ISSetBlockSize(ilink->is_col, nfields);
522: } else {
523: ISCreateStride(PetscObjectComm((PetscObject)pc),nslots,rstart+ilink->fields[0],bs,&ilink->is);
524: ISCreateStride(PetscObjectComm((PetscObject)pc),nslots,rstart+ilink->fields_col[0],bs,&ilink->is_col);
525: }
526: }
527: ISSorted(ilink->is,&sorted);
528: if (ilink->is_col) { ISSorted(ilink->is_col,&sorted_col); }
529: if (!sorted || !sorted_col) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"Fields must be sorted when creating split");
530: ilink = ilink->next;
531: }
532: }
534: ilink = jac->head;
535: if (!jac->pmat) {
536: Vec xtmp;
538: MatCreateVecs(pc->pmat,&xtmp,NULL);
539: PetscMalloc1(nsplit,&jac->pmat);
540: PetscMalloc2(nsplit,&jac->x,nsplit,&jac->y);
541: for (i=0; i<nsplit; i++) {
542: MatNullSpace sp;
544: /* Check for preconditioning matrix attached to IS */
545: PetscObjectQuery((PetscObject) ilink->is, "pmat", (PetscObject*) &jac->pmat[i]);
546: if (jac->pmat[i]) {
547: PetscObjectReference((PetscObject) jac->pmat[i]);
548: if (jac->type == PC_COMPOSITE_SCHUR) {
549: jac->schur_user = jac->pmat[i];
551: PetscObjectReference((PetscObject) jac->schur_user);
552: }
553: } else {
554: const char *prefix;
555: MatGetSubMatrix(pc->pmat,ilink->is,ilink->is_col,MAT_INITIAL_MATRIX,&jac->pmat[i]);
556: KSPGetOptionsPrefix(ilink->ksp,&prefix);
557: MatSetOptionsPrefix(jac->pmat[i],prefix);
558: MatViewFromOptions(jac->pmat[i],NULL,"-mat_view");
559: }
560: /* create work vectors for each split */
561: MatCreateVecs(jac->pmat[i],&jac->x[i],&jac->y[i]);
562: ilink->x = jac->x[i]; ilink->y = jac->y[i]; ilink->z = NULL;
563: /* compute scatter contexts needed by multiplicative versions and non-default splits */
564: VecScatterCreate(xtmp,ilink->is,jac->x[i],NULL,&ilink->sctx);
565: /* Check for null space attached to IS */
566: PetscObjectQuery((PetscObject) ilink->is, "nullspace", (PetscObject*) &sp);
567: if (sp) {
568: MatSetNullSpace(jac->pmat[i], sp);
569: }
570: PetscObjectQuery((PetscObject) ilink->is, "nearnullspace", (PetscObject*) &sp);
571: if (sp) {
572: MatSetNearNullSpace(jac->pmat[i], sp);
573: }
574: ilink = ilink->next;
575: }
576: VecDestroy(&xtmp);
577: } else {
578: for (i=0; i<nsplit; i++) {
579: Mat pmat;
581: /* Check for preconditioning matrix attached to IS */
582: PetscObjectQuery((PetscObject) ilink->is, "pmat", (PetscObject*) &pmat);
583: if (!pmat) {
584: MatGetSubMatrix(pc->pmat,ilink->is,ilink->is_col,MAT_REUSE_MATRIX,&jac->pmat[i]);
585: }
586: ilink = ilink->next;
587: }
588: }
589: if (jac->diag_use_amat) {
590: ilink = jac->head;
591: if (!jac->mat) {
592: PetscMalloc1(nsplit,&jac->mat);
593: for (i=0; i<nsplit; i++) {
594: MatGetSubMatrix(pc->mat,ilink->is,ilink->is_col,MAT_INITIAL_MATRIX,&jac->mat[i]);
595: ilink = ilink->next;
596: }
597: } else {
598: for (i=0; i<nsplit; i++) {
599: if (jac->mat[i]) {MatGetSubMatrix(pc->mat,ilink->is,ilink->is_col,MAT_REUSE_MATRIX,&jac->mat[i]);}
600: ilink = ilink->next;
601: }
602: }
603: } else {
604: jac->mat = jac->pmat;
605: }
607: if (jac->type != PC_COMPOSITE_ADDITIVE && jac->type != PC_COMPOSITE_SCHUR) {
608: /* extract the rows of the matrix associated with each field: used for efficient computation of residual inside algorithm */
609: /* FIXME: Can/should we reuse jac->mat whenever (jac->diag_use_amat) is true? */
610: ilink = jac->head;
611: if (nsplit == 2 && jac->type == PC_COMPOSITE_MULTIPLICATIVE) {
612: /* special case need where Afield[0] is not needed and only certain columns of Afield[1] are needed since update is only on those rows of the solution */
613: if (!jac->Afield) {
614: PetscCalloc1(nsplit,&jac->Afield);
615: MatGetSubMatrix(pc->mat,ilink->next->is,ilink->is,MAT_INITIAL_MATRIX,&jac->Afield[1]);
616: } else {
617: MatGetSubMatrix(pc->mat,ilink->next->is,ilink->is,MAT_REUSE_MATRIX,&jac->Afield[1]);
618: }
619: } else {
620: if (!jac->Afield) {
621: PetscMalloc1(nsplit,&jac->Afield);
622: for (i=0; i<nsplit; i++) {
623: MatGetSubMatrix(pc->mat,ilink->is,NULL,MAT_INITIAL_MATRIX,&jac->Afield[i]);
624: ilink = ilink->next;
625: }
626: } else {
627: for (i=0; i<nsplit; i++) {
628: MatGetSubMatrix(pc->mat,ilink->is,NULL,MAT_REUSE_MATRIX,&jac->Afield[i]);
629: ilink = ilink->next;
630: }
631: }
632: }
633: }
635: if (jac->type == PC_COMPOSITE_SCHUR) {
636: IS ccis;
637: PetscInt rstart,rend;
638: char lscname[256];
639: PetscObject LSC_L;
641: if (nsplit != 2) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_INCOMP,"To use Schur complement preconditioner you must have exactly 2 fields");
643: /* When extracting off-diagonal submatrices, we take complements from this range */
644: MatGetOwnershipRangeColumn(pc->mat,&rstart,&rend);
646: /* need to handle case when one is resetting up the preconditioner */
647: if (jac->schur) {
648: KSP kspA = jac->head->ksp, kspInner = NULL, kspUpper = jac->kspupper;
650: MatSchurComplementGetKSP(jac->schur, &kspInner);
651: ilink = jac->head;
652: ISComplement(ilink->is_col,rstart,rend,&ccis);
653: if (jac->offdiag_use_amat) {
654: MatGetSubMatrix(pc->mat,ilink->is,ccis,MAT_REUSE_MATRIX,&jac->B);
655: } else {
656: MatGetSubMatrix(pc->pmat,ilink->is,ccis,MAT_REUSE_MATRIX,&jac->B);
657: }
658: ISDestroy(&ccis);
659: ilink = ilink->next;
660: ISComplement(ilink->is_col,rstart,rend,&ccis);
661: if (jac->offdiag_use_amat) {
662: MatGetSubMatrix(pc->mat,ilink->is,ccis,MAT_REUSE_MATRIX,&jac->C);
663: } else {
664: MatGetSubMatrix(pc->pmat,ilink->is,ccis,MAT_REUSE_MATRIX,&jac->C);
665: }
666: ISDestroy(&ccis);
667: MatSchurComplementUpdateSubMatrices(jac->schur,jac->mat[0],jac->pmat[0],jac->B,jac->C,jac->mat[1]);
668: if (jac->schurpre == PC_FIELDSPLIT_SCHUR_PRE_SELFP) {
669: MatDestroy(&jac->schurp);
670: MatSchurComplementGetPmat(jac->schur,MAT_INITIAL_MATRIX,&jac->schurp);
671: }
672: if (kspA != kspInner) {
673: KSPSetOperators(kspA,jac->mat[0],jac->pmat[0]);
674: }
675: if (kspUpper != kspA) {
676: KSPSetOperators(kspUpper,jac->mat[0],jac->pmat[0]);
677: }
678: KSPSetOperators(jac->kspschur,jac->schur,FieldSplitSchurPre(jac));
679: } else {
680: const char *Dprefix;
681: char schurprefix[256], schurmatprefix[256];
682: char schurtestoption[256];
683: MatNullSpace sp;
684: PetscBool flg;
686: /* extract the A01 and A10 matrices */
687: ilink = jac->head;
688: ISComplement(ilink->is_col,rstart,rend,&ccis);
689: if (jac->offdiag_use_amat) {
690: MatGetSubMatrix(pc->mat,ilink->is,ccis,MAT_INITIAL_MATRIX,&jac->B);
691: } else {
692: MatGetSubMatrix(pc->pmat,ilink->is,ccis,MAT_INITIAL_MATRIX,&jac->B);
693: }
694: ISDestroy(&ccis);
695: ilink = ilink->next;
696: ISComplement(ilink->is_col,rstart,rend,&ccis);
697: if (jac->offdiag_use_amat) {
698: MatGetSubMatrix(pc->mat,ilink->is,ccis,MAT_INITIAL_MATRIX,&jac->C);
699: } else {
700: MatGetSubMatrix(pc->pmat,ilink->is,ccis,MAT_INITIAL_MATRIX,&jac->C);
701: }
702: ISDestroy(&ccis);
704: /* Use mat[0] (diagonal block of Amat) preconditioned by pmat[0] to define Schur complement */
705: MatCreate(((PetscObject)jac->mat[0])->comm,&jac->schur);
706: MatSetType(jac->schur,MATSCHURCOMPLEMENT);
707: MatSchurComplementSetSubMatrices(jac->schur,jac->mat[0],jac->pmat[0],jac->B,jac->C,jac->mat[1]);
708: PetscSNPrintf(schurmatprefix, sizeof(schurmatprefix), "%sfieldsplit_%s_", ((PetscObject)pc)->prefix ? ((PetscObject)pc)->prefix : "", ilink->splitname);
709: /* Note that the inner KSP is NOT going to inherit this prefix, and if it did, it would be reset just below. Is that what we want? */
710: MatSetOptionsPrefix(jac->schur,schurmatprefix);
711: MatSetFromOptions(jac->schur);
712: MatGetNullSpace(jac->pmat[1], &sp);
713: if (sp) {
714: MatSetNullSpace(jac->schur, sp);
715: }
717: PetscSNPrintf(schurtestoption, sizeof(schurtestoption), "-fieldsplit_%s_inner_", ilink->splitname);
718: PetscOptionsFindPairPrefix_Private(((PetscObject)pc)->prefix, schurtestoption, NULL, &flg);
719: if (flg) {
720: DM dmInner;
721: KSP kspInner;
723: MatSchurComplementGetKSP(jac->schur, &kspInner);
724: PetscSNPrintf(schurprefix, sizeof(schurprefix), "%sfieldsplit_%s_inner_", ((PetscObject)pc)->prefix ? ((PetscObject)pc)->prefix : "", ilink->splitname);
725: /* Indent this deeper to emphasize the "inner" nature of this solver. */
726: PetscObjectIncrementTabLevel((PetscObject)kspInner, (PetscObject) pc, 2);
727: KSPSetOptionsPrefix(kspInner, schurprefix);
729: /* Set DM for new solver */
730: KSPGetDM(jac->head->ksp, &dmInner);
731: KSPSetDM(kspInner, dmInner);
732: KSPSetDMActive(kspInner, PETSC_FALSE);
733: } else {
734: /* Use the outer solver for the inner solve, but revert the KSPPREONLY from PCFieldSplitSetFields_FieldSplit or
735: * PCFieldSplitSetIS_FieldSplit. We don't want KSPPREONLY because it makes the Schur complement inexact,
736: * preventing Schur complement reduction to be an accurate solve. Usually when an iterative solver is used for
737: * S = D - C A_inner^{-1} B, we expect S to be defined using an accurate definition of A_inner^{-1}, so we make
738: * GMRES the default. Note that it is also common to use PREONLY for S, in which case S may not be used
739: * directly, and the user is responsible for setting an inexact method for fieldsplit's A^{-1}. */
740: KSPSetType(jac->head->ksp,KSPGMRES);
741: MatSchurComplementSetKSP(jac->schur,jac->head->ksp);
742: }
743: KSPSetOperators(jac->head->ksp,jac->mat[0],jac->pmat[0]);
744: KSPSetFromOptions(jac->head->ksp);
745: MatSetFromOptions(jac->schur);
747: PetscSNPrintf(schurtestoption, sizeof(schurtestoption), "-fieldsplit_%s_upper_", ilink->splitname);
748: PetscOptionsFindPairPrefix_Private(((PetscObject)pc)->prefix, schurtestoption, NULL, &flg);
749: if (flg) {
750: DM dmInner;
752: PetscSNPrintf(schurprefix, sizeof(schurprefix), "%sfieldsplit_%s_upper_", ((PetscObject)pc)->prefix ? ((PetscObject)pc)->prefix : "", ilink->splitname);
753: KSPCreate(PetscObjectComm((PetscObject)pc), &jac->kspupper);
754: KSPSetErrorIfNotConverged(jac->kspupper,pc->erroriffailure);
755: KSPSetOptionsPrefix(jac->kspupper, schurprefix);
756: KSPGetDM(jac->head->ksp, &dmInner);
757: KSPSetDM(jac->kspupper, dmInner);
758: KSPSetDMActive(jac->kspupper, PETSC_FALSE);
759: KSPSetFromOptions(jac->kspupper);
760: KSPSetOperators(jac->kspupper,jac->mat[0],jac->pmat[0]);
761: VecDuplicate(jac->head->x, &jac->head->z);
762: } else {
763: jac->kspupper = jac->head->ksp;
764: PetscObjectReference((PetscObject) jac->head->ksp);
765: }
767: if (jac->schurpre == PC_FIELDSPLIT_SCHUR_PRE_SELFP) {
768: MatSchurComplementGetPmat(jac->schur,MAT_INITIAL_MATRIX,&jac->schurp);
769: }
770: KSPCreate(PetscObjectComm((PetscObject)pc),&jac->kspschur);
771: KSPSetErrorIfNotConverged(jac->kspschur,pc->erroriffailure);
772: PetscLogObjectParent((PetscObject)pc,(PetscObject)jac->kspschur);
773: PetscObjectIncrementTabLevel((PetscObject)jac->kspschur,(PetscObject)pc,1);
774: if (jac->schurpre == PC_FIELDSPLIT_SCHUR_PRE_SELF) {
775: PC pcschur;
776: KSPGetPC(jac->kspschur,&pcschur);
777: PCSetType(pcschur,PCNONE);
778: /* Note: This is bad if there exist preconditioners for MATSCHURCOMPLEMENT */
779: } else if (jac->schurpre == PC_FIELDSPLIT_SCHUR_PRE_FULL) {
780: MatSchurComplementComputeExplicitOperator(jac->schur, &jac->schur_user);
781: }
782: KSPSetOperators(jac->kspschur,jac->schur,FieldSplitSchurPre(jac));
783: KSPGetOptionsPrefix(jac->head->next->ksp, &Dprefix);
784: KSPSetOptionsPrefix(jac->kspschur, Dprefix);
785: /* propogate DM */
786: {
787: DM sdm;
788: KSPGetDM(jac->head->next->ksp, &sdm);
789: if (sdm) {
790: KSPSetDM(jac->kspschur, sdm);
791: KSPSetDMActive(jac->kspschur, PETSC_FALSE);
792: }
793: }
794: /* really want setfromoptions called in PCSetFromOptions_FieldSplit(), but it is not ready yet */
795: /* need to call this every time, since the jac->kspschur is freshly created, otherwise its options never get set */
796: KSPSetFromOptions(jac->kspschur);
797: }
799: /* HACK: special support to forward L and Lp matrices that might be used by PCLSC */
800: PetscSNPrintf(lscname,sizeof(lscname),"%s_LSC_L",ilink->splitname);
801: PetscObjectQuery((PetscObject)pc->mat,lscname,(PetscObject*)&LSC_L);
802: if (!LSC_L) {PetscObjectQuery((PetscObject)pc->pmat,lscname,(PetscObject*)&LSC_L);}
803: if (LSC_L) {PetscObjectCompose((PetscObject)jac->schur,"LSC_L",(PetscObject)LSC_L);}
804: PetscSNPrintf(lscname,sizeof(lscname),"%s_LSC_Lp",ilink->splitname);
805: PetscObjectQuery((PetscObject)pc->pmat,lscname,(PetscObject*)&LSC_L);
806: if (!LSC_L) {PetscObjectQuery((PetscObject)pc->mat,lscname,(PetscObject*)&LSC_L);}
807: if (LSC_L) {PetscObjectCompose((PetscObject)jac->schur,"LSC_Lp",(PetscObject)LSC_L);}
808: } else {
809: /* set up the individual splits' PCs */
810: i = 0;
811: ilink = jac->head;
812: while (ilink) {
813: KSPSetOperators(ilink->ksp,jac->mat[i],jac->pmat[i]);
814: /* really want setfromoptions called in PCSetFromOptions_FieldSplit(), but it is not ready yet */
815: if (!jac->suboptionsset) {KSPSetFromOptions(ilink->ksp);}
816: i++;
817: ilink = ilink->next;
818: }
819: }
821: jac->suboptionsset = PETSC_TRUE;
822: return(0);
823: }
825: #define FieldSplitSplitSolveAdd(ilink,xx,yy) \
826: (VecScatterBegin(ilink->sctx,xx,ilink->x,INSERT_VALUES,SCATTER_FORWARD) || \
827: VecScatterEnd(ilink->sctx,xx,ilink->x,INSERT_VALUES,SCATTER_FORWARD) || \
828: KSPSolve(ilink->ksp,ilink->x,ilink->y) || \
829: VecScatterBegin(ilink->sctx,ilink->y,yy,ADD_VALUES,SCATTER_REVERSE) || \
830: VecScatterEnd(ilink->sctx,ilink->y,yy,ADD_VALUES,SCATTER_REVERSE))
834: static PetscErrorCode PCApply_FieldSplit_Schur(PC pc,Vec x,Vec y)
835: {
836: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
837: PetscErrorCode ierr;
838: PC_FieldSplitLink ilinkA = jac->head, ilinkD = ilinkA->next;
839: KSP kspA = ilinkA->ksp, kspLower = kspA, kspUpper = jac->kspupper;
842: switch (jac->schurfactorization) {
843: case PC_FIELDSPLIT_SCHUR_FACT_DIAG:
844: /* [A00 0; 0 -S], positive definite, suitable for MINRES */
845: VecScatterBegin(ilinkA->sctx,x,ilinkA->x,INSERT_VALUES,SCATTER_FORWARD);
846: VecScatterBegin(ilinkD->sctx,x,ilinkD->x,INSERT_VALUES,SCATTER_FORWARD);
847: VecScatterEnd(ilinkA->sctx,x,ilinkA->x,INSERT_VALUES,SCATTER_FORWARD);
848: KSPSolve(kspA,ilinkA->x,ilinkA->y);
849: VecScatterBegin(ilinkA->sctx,ilinkA->y,y,INSERT_VALUES,SCATTER_REVERSE);
850: VecScatterEnd(ilinkD->sctx,x,ilinkD->x,INSERT_VALUES,SCATTER_FORWARD);
851: KSPSolve(jac->kspschur,ilinkD->x,ilinkD->y);
852: VecScale(ilinkD->y,-1.);
853: VecScatterBegin(ilinkD->sctx,ilinkD->y,y,INSERT_VALUES,SCATTER_REVERSE);
854: VecScatterEnd(ilinkA->sctx,ilinkA->y,y,INSERT_VALUES,SCATTER_REVERSE);
855: VecScatterEnd(ilinkD->sctx,ilinkD->y,y,INSERT_VALUES,SCATTER_REVERSE);
856: break;
857: case PC_FIELDSPLIT_SCHUR_FACT_LOWER:
858: /* [A00 0; A10 S], suitable for left preconditioning */
859: VecScatterBegin(ilinkA->sctx,x,ilinkA->x,INSERT_VALUES,SCATTER_FORWARD);
860: VecScatterEnd(ilinkA->sctx,x,ilinkA->x,INSERT_VALUES,SCATTER_FORWARD);
861: KSPSolve(kspA,ilinkA->x,ilinkA->y);
862: MatMult(jac->C,ilinkA->y,ilinkD->x);
863: VecScale(ilinkD->x,-1.);
864: VecScatterBegin(ilinkD->sctx,x,ilinkD->x,ADD_VALUES,SCATTER_FORWARD);
865: VecScatterBegin(ilinkA->sctx,ilinkA->y,y,INSERT_VALUES,SCATTER_REVERSE);
866: VecScatterEnd(ilinkD->sctx,x,ilinkD->x,ADD_VALUES,SCATTER_FORWARD);
867: KSPSolve(jac->kspschur,ilinkD->x,ilinkD->y);
868: VecScatterBegin(ilinkD->sctx,ilinkD->y,y,INSERT_VALUES,SCATTER_REVERSE);
869: VecScatterEnd(ilinkA->sctx,ilinkA->y,y,INSERT_VALUES,SCATTER_REVERSE);
870: VecScatterEnd(ilinkD->sctx,ilinkD->y,y,INSERT_VALUES,SCATTER_REVERSE);
871: break;
872: case PC_FIELDSPLIT_SCHUR_FACT_UPPER:
873: /* [A00 A01; 0 S], suitable for right preconditioning */
874: VecScatterBegin(ilinkD->sctx,x,ilinkD->x,INSERT_VALUES,SCATTER_FORWARD);
875: VecScatterEnd(ilinkD->sctx,x,ilinkD->x,INSERT_VALUES,SCATTER_FORWARD);
876: KSPSolve(jac->kspschur,ilinkD->x,ilinkD->y);
877: MatMult(jac->B,ilinkD->y,ilinkA->x);
878: VecScale(ilinkA->x,-1.);
879: VecScatterBegin(ilinkA->sctx,x,ilinkA->x,ADD_VALUES,SCATTER_FORWARD);
880: VecScatterBegin(ilinkD->sctx,ilinkD->y,y,INSERT_VALUES,SCATTER_REVERSE);
881: VecScatterEnd(ilinkA->sctx,x,ilinkA->x,ADD_VALUES,SCATTER_FORWARD);
882: KSPSolve(kspA,ilinkA->x,ilinkA->y);
883: VecScatterBegin(ilinkA->sctx,ilinkA->y,y,INSERT_VALUES,SCATTER_REVERSE);
884: VecScatterEnd(ilinkD->sctx,ilinkD->y,y,INSERT_VALUES,SCATTER_REVERSE);
885: VecScatterEnd(ilinkA->sctx,ilinkA->y,y,INSERT_VALUES,SCATTER_REVERSE);
886: break;
887: case PC_FIELDSPLIT_SCHUR_FACT_FULL:
888: /* [1 0; A10 A00^{-1} 1] [A00 0; 0 S] [1 A00^{-1}A01; 0 1], an exact solve if applied exactly, needs one extra solve with A */
889: VecScatterBegin(ilinkA->sctx,x,ilinkA->x,INSERT_VALUES,SCATTER_FORWARD);
890: VecScatterEnd(ilinkA->sctx,x,ilinkA->x,INSERT_VALUES,SCATTER_FORWARD);
891: KSPSolve(kspLower,ilinkA->x,ilinkA->y);
892: MatMult(jac->C,ilinkA->y,ilinkD->x);
893: VecScale(ilinkD->x,-1.0);
894: VecScatterBegin(ilinkD->sctx,x,ilinkD->x,ADD_VALUES,SCATTER_FORWARD);
895: VecScatterEnd(ilinkD->sctx,x,ilinkD->x,ADD_VALUES,SCATTER_FORWARD);
897: KSPSolve(jac->kspschur,ilinkD->x,ilinkD->y);
898: VecScatterBegin(ilinkD->sctx,ilinkD->y,y,INSERT_VALUES,SCATTER_REVERSE);
899: VecScatterEnd(ilinkD->sctx,ilinkD->y,y,INSERT_VALUES,SCATTER_REVERSE);
901: if (kspUpper == kspA) {
902: MatMult(jac->B,ilinkD->y,ilinkA->y);
903: VecAXPY(ilinkA->x,-1.0,ilinkA->y);
904: KSPSolve(kspA,ilinkA->x,ilinkA->y);
905: } else {
906: KSPSolve(kspA,ilinkA->x,ilinkA->y);
907: MatMult(jac->B,ilinkD->y,ilinkA->x);
908: KSPSolve(kspUpper,ilinkA->x,ilinkA->z);
909: VecAXPY(ilinkA->y,-1.0,ilinkA->z);
910: }
911: VecScatterBegin(ilinkA->sctx,ilinkA->y,y,INSERT_VALUES,SCATTER_REVERSE);
912: VecScatterEnd(ilinkA->sctx,ilinkA->y,y,INSERT_VALUES,SCATTER_REVERSE);
913: }
914: return(0);
915: }
919: static PetscErrorCode PCApply_FieldSplit(PC pc,Vec x,Vec y)
920: {
921: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
922: PetscErrorCode ierr;
923: PC_FieldSplitLink ilink = jac->head;
924: PetscInt cnt,bs;
927: if (jac->type == PC_COMPOSITE_ADDITIVE) {
928: if (jac->defaultsplit) {
929: VecGetBlockSize(x,&bs);
930: if (jac->bs > 0 && bs != jac->bs) SETERRQ2(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Blocksize of x vector %D does not match fieldsplit blocksize %D",bs,jac->bs);
931: VecGetBlockSize(y,&bs);
932: if (jac->bs > 0 && bs != jac->bs) SETERRQ2(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Blocksize of y vector %D does not match fieldsplit blocksize %D",bs,jac->bs);
933: VecStrideGatherAll(x,jac->x,INSERT_VALUES);
934: while (ilink) {
935: KSPSolve(ilink->ksp,ilink->x,ilink->y);
936: ilink = ilink->next;
937: }
938: VecStrideScatterAll(jac->y,y,INSERT_VALUES);
939: } else {
940: VecSet(y,0.0);
941: while (ilink) {
942: FieldSplitSplitSolveAdd(ilink,x,y);
943: ilink = ilink->next;
944: }
945: }
946: } else if (jac->type == PC_COMPOSITE_MULTIPLICATIVE && jac->nsplits == 2) {
947: VecSet(y,0.0);
948: /* solve on first block for first block variables */
949: VecScatterBegin(ilink->sctx,x,ilink->x,INSERT_VALUES,SCATTER_FORWARD);
950: VecScatterEnd(ilink->sctx,x,ilink->x,INSERT_VALUES,SCATTER_FORWARD);
951: KSPSolve(ilink->ksp,ilink->x,ilink->y);
952: VecScatterBegin(ilink->sctx,ilink->y,y,ADD_VALUES,SCATTER_REVERSE);
953: VecScatterEnd(ilink->sctx,ilink->y,y,ADD_VALUES,SCATTER_REVERSE);
955: /* compute the residual only onto second block variables using first block variables */
956: MatMult(jac->Afield[1],ilink->y,ilink->next->x);
957: ilink = ilink->next;
958: VecScale(ilink->x,-1.0);
959: VecScatterBegin(ilink->sctx,x,ilink->x,ADD_VALUES,SCATTER_FORWARD);
960: VecScatterEnd(ilink->sctx,x,ilink->x,ADD_VALUES,SCATTER_FORWARD);
962: /* solve on second block variables */
963: KSPSolve(ilink->ksp,ilink->x,ilink->y);
964: VecScatterBegin(ilink->sctx,ilink->y,y,ADD_VALUES,SCATTER_REVERSE);
965: VecScatterEnd(ilink->sctx,ilink->y,y,ADD_VALUES,SCATTER_REVERSE);
966: } else if (jac->type == PC_COMPOSITE_MULTIPLICATIVE || jac->type == PC_COMPOSITE_SYMMETRIC_MULTIPLICATIVE) {
967: if (!jac->w1) {
968: VecDuplicate(x,&jac->w1);
969: VecDuplicate(x,&jac->w2);
970: }
971: VecSet(y,0.0);
972: FieldSplitSplitSolveAdd(ilink,x,y);
973: cnt = 1;
974: while (ilink->next) {
975: ilink = ilink->next;
976: /* compute the residual only over the part of the vector needed */
977: MatMult(jac->Afield[cnt++],y,ilink->x);
978: VecScale(ilink->x,-1.0);
979: VecScatterBegin(ilink->sctx,x,ilink->x,ADD_VALUES,SCATTER_FORWARD);
980: VecScatterEnd(ilink->sctx,x,ilink->x,ADD_VALUES,SCATTER_FORWARD);
981: KSPSolve(ilink->ksp,ilink->x,ilink->y);
982: VecScatterBegin(ilink->sctx,ilink->y,y,ADD_VALUES,SCATTER_REVERSE);
983: VecScatterEnd(ilink->sctx,ilink->y,y,ADD_VALUES,SCATTER_REVERSE);
984: }
985: if (jac->type == PC_COMPOSITE_SYMMETRIC_MULTIPLICATIVE) {
986: cnt -= 2;
987: while (ilink->previous) {
988: ilink = ilink->previous;
989: /* compute the residual only over the part of the vector needed */
990: MatMult(jac->Afield[cnt--],y,ilink->x);
991: VecScale(ilink->x,-1.0);
992: VecScatterBegin(ilink->sctx,x,ilink->x,ADD_VALUES,SCATTER_FORWARD);
993: VecScatterEnd(ilink->sctx,x,ilink->x,ADD_VALUES,SCATTER_FORWARD);
994: KSPSolve(ilink->ksp,ilink->x,ilink->y);
995: VecScatterBegin(ilink->sctx,ilink->y,y,ADD_VALUES,SCATTER_REVERSE);
996: VecScatterEnd(ilink->sctx,ilink->y,y,ADD_VALUES,SCATTER_REVERSE);
997: }
998: }
999: } else SETERRQ1(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Unsupported or unknown composition",(int) jac->type);
1000: return(0);
1001: }
1003: #define FieldSplitSplitSolveAddTranspose(ilink,xx,yy) \
1004: (VecScatterBegin(ilink->sctx,xx,ilink->y,INSERT_VALUES,SCATTER_FORWARD) || \
1005: VecScatterEnd(ilink->sctx,xx,ilink->y,INSERT_VALUES,SCATTER_FORWARD) || \
1006: KSPSolveTranspose(ilink->ksp,ilink->y,ilink->x) || \
1007: VecScatterBegin(ilink->sctx,ilink->x,yy,ADD_VALUES,SCATTER_REVERSE) || \
1008: VecScatterEnd(ilink->sctx,ilink->x,yy,ADD_VALUES,SCATTER_REVERSE))
1012: static PetscErrorCode PCApplyTranspose_FieldSplit(PC pc,Vec x,Vec y)
1013: {
1014: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1015: PetscErrorCode ierr;
1016: PC_FieldSplitLink ilink = jac->head;
1017: PetscInt bs;
1020: if (jac->type == PC_COMPOSITE_ADDITIVE) {
1021: if (jac->defaultsplit) {
1022: VecGetBlockSize(x,&bs);
1023: if (jac->bs > 0 && bs != jac->bs) SETERRQ2(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Blocksize of x vector %D does not match fieldsplit blocksize %D",bs,jac->bs);
1024: VecGetBlockSize(y,&bs);
1025: if (jac->bs > 0 && bs != jac->bs) SETERRQ2(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Blocksize of y vector %D does not match fieldsplit blocksize %D",bs,jac->bs);
1026: VecStrideGatherAll(x,jac->x,INSERT_VALUES);
1027: while (ilink) {
1028: KSPSolveTranspose(ilink->ksp,ilink->x,ilink->y);
1029: ilink = ilink->next;
1030: }
1031: VecStrideScatterAll(jac->y,y,INSERT_VALUES);
1032: } else {
1033: VecSet(y,0.0);
1034: while (ilink) {
1035: FieldSplitSplitSolveAddTranspose(ilink,x,y);
1036: ilink = ilink->next;
1037: }
1038: }
1039: } else {
1040: if (!jac->w1) {
1041: VecDuplicate(x,&jac->w1);
1042: VecDuplicate(x,&jac->w2);
1043: }
1044: VecSet(y,0.0);
1045: if (jac->type == PC_COMPOSITE_SYMMETRIC_MULTIPLICATIVE) {
1046: FieldSplitSplitSolveAddTranspose(ilink,x,y);
1047: while (ilink->next) {
1048: ilink = ilink->next;
1049: MatMultTranspose(pc->mat,y,jac->w1);
1050: VecWAXPY(jac->w2,-1.0,jac->w1,x);
1051: FieldSplitSplitSolveAddTranspose(ilink,jac->w2,y);
1052: }
1053: while (ilink->previous) {
1054: ilink = ilink->previous;
1055: MatMultTranspose(pc->mat,y,jac->w1);
1056: VecWAXPY(jac->w2,-1.0,jac->w1,x);
1057: FieldSplitSplitSolveAddTranspose(ilink,jac->w2,y);
1058: }
1059: } else {
1060: while (ilink->next) { /* get to last entry in linked list */
1061: ilink = ilink->next;
1062: }
1063: FieldSplitSplitSolveAddTranspose(ilink,x,y);
1064: while (ilink->previous) {
1065: ilink = ilink->previous;
1066: MatMultTranspose(pc->mat,y,jac->w1);
1067: VecWAXPY(jac->w2,-1.0,jac->w1,x);
1068: FieldSplitSplitSolveAddTranspose(ilink,jac->w2,y);
1069: }
1070: }
1071: }
1072: return(0);
1073: }
1077: static PetscErrorCode PCReset_FieldSplit(PC pc)
1078: {
1079: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1080: PetscErrorCode ierr;
1081: PC_FieldSplitLink ilink = jac->head,next;
1084: while (ilink) {
1085: KSPReset(ilink->ksp);
1086: VecDestroy(&ilink->x);
1087: VecDestroy(&ilink->y);
1088: VecDestroy(&ilink->z);
1089: VecScatterDestroy(&ilink->sctx);
1090: ISDestroy(&ilink->is);
1091: ISDestroy(&ilink->is_col);
1092: next = ilink->next;
1093: ilink = next;
1094: }
1095: PetscFree2(jac->x,jac->y);
1096: if (jac->mat && jac->mat != jac->pmat) {
1097: MatDestroyMatrices(jac->nsplits,&jac->mat);
1098: } else if (jac->mat) {
1099: jac->mat = NULL;
1100: }
1101: if (jac->pmat) {MatDestroyMatrices(jac->nsplits,&jac->pmat);}
1102: if (jac->Afield) {MatDestroyMatrices(jac->nsplits,&jac->Afield);}
1103: VecDestroy(&jac->w1);
1104: VecDestroy(&jac->w2);
1105: MatDestroy(&jac->schur);
1106: MatDestroy(&jac->schurp);
1107: MatDestroy(&jac->schur_user);
1108: KSPDestroy(&jac->kspschur);
1109: KSPDestroy(&jac->kspupper);
1110: MatDestroy(&jac->B);
1111: MatDestroy(&jac->C);
1112: jac->reset = PETSC_TRUE;
1113: return(0);
1114: }
1118: static PetscErrorCode PCDestroy_FieldSplit(PC pc)
1119: {
1120: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1121: PetscErrorCode ierr;
1122: PC_FieldSplitLink ilink = jac->head,next;
1125: PCReset_FieldSplit(pc);
1126: while (ilink) {
1127: KSPDestroy(&ilink->ksp);
1128: next = ilink->next;
1129: PetscFree(ilink->splitname);
1130: PetscFree(ilink->fields);
1131: PetscFree(ilink->fields_col);
1132: PetscFree(ilink);
1133: ilink = next;
1134: }
1135: PetscFree2(jac->x,jac->y);
1136: PetscFree(pc->data);
1137: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitGetSubKSP_C",NULL);
1138: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetFields_C",NULL);
1139: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetIS_C",NULL);
1140: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetType_C",NULL);
1141: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetBlockSize_C",NULL);
1142: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetSchurPre_C",NULL);
1143: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitGetSchurPre_C",NULL);
1144: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetSchurFactType_C",NULL);
1145: return(0);
1146: }
1150: static PetscErrorCode PCSetFromOptions_FieldSplit(PetscOptions *PetscOptionsObject,PC pc)
1151: {
1152: PetscErrorCode ierr;
1153: PetscInt bs;
1154: PetscBool flg,stokes = PETSC_FALSE;
1155: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1156: PCCompositeType ctype;
1159: PetscOptionsHead(PetscOptionsObject,"FieldSplit options");
1160: PetscOptionsBool("-pc_fieldsplit_dm_splits","Whether to use DMCreateFieldDecomposition() for splits","PCFieldSplitSetDMSplits",jac->dm_splits,&jac->dm_splits,NULL);
1161: PetscOptionsInt("-pc_fieldsplit_block_size","Blocksize that defines number of fields","PCFieldSplitSetBlockSize",jac->bs,&bs,&flg);
1162: if (flg) {
1163: PCFieldSplitSetBlockSize(pc,bs);
1164: }
1165: jac->diag_use_amat = pc->useAmat;
1166: PetscOptionsBool("-pc_fieldsplit_diag_use_amat","Use Amat (not Pmat) to extract diagonal fieldsplit blocks", "PCFieldSplitSetDiagUseAmat",jac->diag_use_amat,&jac->diag_use_amat,NULL);
1167: jac->offdiag_use_amat = pc->useAmat;
1168: PetscOptionsBool("-pc_fieldsplit_off_diag_use_amat","Use Amat (not Pmat) to extract off-diagonal fieldsplit blocks", "PCFieldSplitSetOffDiagUseAmat",jac->offdiag_use_amat,&jac->offdiag_use_amat,NULL);
1169: /* FIXME: No programmatic equivalent to the following. */
1170: PetscOptionsGetBool(((PetscObject)pc)->prefix,"-pc_fieldsplit_detect_saddle_point",&stokes,NULL);
1171: if (stokes) {
1172: PCFieldSplitSetType(pc,PC_COMPOSITE_SCHUR);
1173: jac->schurpre = PC_FIELDSPLIT_SCHUR_PRE_SELF;
1174: }
1176: PetscOptionsEnum("-pc_fieldsplit_type","Type of composition","PCFieldSplitSetType",PCCompositeTypes,(PetscEnum)jac->type,(PetscEnum*)&ctype,&flg);
1177: if (flg) {
1178: PCFieldSplitSetType(pc,ctype);
1179: }
1180: /* Only setup fields once */
1181: if ((jac->bs > 0) && (jac->nsplits == 0)) {
1182: /* only allow user to set fields from command line if bs is already known.
1183: otherwise user can set them in PCFieldSplitSetDefaults() */
1184: PCFieldSplitSetRuntimeSplits_Private(pc);
1185: if (jac->splitdefined) {PetscInfo(pc,"Splits defined using the options database\n");}
1186: }
1187: if (jac->type == PC_COMPOSITE_SCHUR) {
1188: PetscOptionsGetEnum(((PetscObject)pc)->prefix,"-pc_fieldsplit_schur_factorization_type",PCFieldSplitSchurFactTypes,(PetscEnum*)&jac->schurfactorization,&flg);
1189: if (flg) {PetscInfo(pc,"Deprecated use of -pc_fieldsplit_schur_factorization_type\n");}
1190: PetscOptionsEnum("-pc_fieldsplit_schur_fact_type","Which off-diagonal parts of the block factorization to use","PCFieldSplitSetSchurFactType",PCFieldSplitSchurFactTypes,(PetscEnum)jac->schurfactorization,(PetscEnum*)&jac->schurfactorization,NULL);
1191: PetscOptionsEnum("-pc_fieldsplit_schur_precondition","How to build preconditioner for Schur complement","PCFieldSplitSetSchurPre",PCFieldSplitSchurPreTypes,(PetscEnum)jac->schurpre,(PetscEnum*)&jac->schurpre,NULL);
1192: }
1193: PetscOptionsTail();
1194: return(0);
1195: }
1197: /*------------------------------------------------------------------------------------*/
1201: static PetscErrorCode PCFieldSplitSetFields_FieldSplit(PC pc,const char splitname[],PetscInt n,const PetscInt *fields,const PetscInt *fields_col)
1202: {
1203: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1204: PetscErrorCode ierr;
1205: PC_FieldSplitLink ilink,next = jac->head;
1206: char prefix[128];
1207: PetscInt i;
1210: if (jac->splitdefined) {
1211: PetscInfo1(pc,"Ignoring new split \"%s\" because the splits have already been defined\n",splitname);
1212: return(0);
1213: }
1214: for (i=0; i<n; i++) {
1215: if (fields[i] >= jac->bs) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Field %D requested but only %D exist",fields[i],jac->bs);
1216: if (fields[i] < 0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Negative field %D requested",fields[i]);
1217: }
1218: PetscNew(&ilink);
1219: if (splitname) {
1220: PetscStrallocpy(splitname,&ilink->splitname);
1221: } else {
1222: PetscMalloc1(3,&ilink->splitname);
1223: PetscSNPrintf(ilink->splitname,2,"%s",jac->nsplits);
1224: }
1225: PetscMalloc1(n,&ilink->fields);
1226: PetscMemcpy(ilink->fields,fields,n*sizeof(PetscInt));
1227: PetscMalloc1(n,&ilink->fields_col);
1228: PetscMemcpy(ilink->fields_col,fields_col,n*sizeof(PetscInt));
1230: ilink->nfields = n;
1231: ilink->next = NULL;
1232: KSPCreate(PetscObjectComm((PetscObject)pc),&ilink->ksp);
1233: KSPSetErrorIfNotConverged(ilink->ksp,pc->erroriffailure);
1234: PetscObjectIncrementTabLevel((PetscObject)ilink->ksp,(PetscObject)pc,1);
1235: KSPSetType(ilink->ksp,KSPPREONLY);
1236: PetscLogObjectParent((PetscObject)pc,(PetscObject)ilink->ksp);
1238: PetscSNPrintf(prefix,sizeof(prefix),"%sfieldsplit_%s_",((PetscObject)pc)->prefix ? ((PetscObject)pc)->prefix : "",ilink->splitname);
1239: KSPSetOptionsPrefix(ilink->ksp,prefix);
1241: if (!next) {
1242: jac->head = ilink;
1243: ilink->previous = NULL;
1244: } else {
1245: while (next->next) {
1246: next = next->next;
1247: }
1248: next->next = ilink;
1249: ilink->previous = next;
1250: }
1251: jac->nsplits++;
1252: return(0);
1253: }
1257: static PetscErrorCode PCFieldSplitGetSubKSP_FieldSplit_Schur(PC pc,PetscInt *n,KSP **subksp)
1258: {
1259: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1263: PetscMalloc1(jac->nsplits,subksp);
1264: MatSchurComplementGetKSP(jac->schur,*subksp);
1266: (*subksp)[1] = jac->kspschur;
1267: if (n) *n = jac->nsplits;
1268: return(0);
1269: }
1273: static PetscErrorCode PCFieldSplitGetSubKSP_FieldSplit(PC pc,PetscInt *n,KSP **subksp)
1274: {
1275: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1276: PetscErrorCode ierr;
1277: PetscInt cnt = 0;
1278: PC_FieldSplitLink ilink = jac->head;
1281: PetscMalloc1(jac->nsplits,subksp);
1282: while (ilink) {
1283: (*subksp)[cnt++] = ilink->ksp;
1284: ilink = ilink->next;
1285: }
1286: if (cnt != jac->nsplits) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Corrupt PCFIELDSPLIT object: number of splits in linked list %D does not match number in object %D",cnt,jac->nsplits);
1287: if (n) *n = jac->nsplits;
1288: return(0);
1289: }
1293: static PetscErrorCode PCFieldSplitSetIS_FieldSplit(PC pc,const char splitname[],IS is)
1294: {
1295: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1296: PetscErrorCode ierr;
1297: PC_FieldSplitLink ilink, next = jac->head;
1298: char prefix[128];
1301: if (jac->splitdefined) {
1302: PetscInfo1(pc,"Ignoring new split \"%s\" because the splits have already been defined\n",splitname);
1303: return(0);
1304: }
1305: PetscNew(&ilink);
1306: if (splitname) {
1307: PetscStrallocpy(splitname,&ilink->splitname);
1308: } else {
1309: PetscMalloc1(8,&ilink->splitname);
1310: PetscSNPrintf(ilink->splitname,7,"%D",jac->nsplits);
1311: }
1312: PetscObjectReference((PetscObject)is);
1313: ISDestroy(&ilink->is);
1314: ilink->is = is;
1315: PetscObjectReference((PetscObject)is);
1316: ISDestroy(&ilink->is_col);
1317: ilink->is_col = is;
1318: ilink->next = NULL;
1319: KSPCreate(PetscObjectComm((PetscObject)pc),&ilink->ksp);
1320: KSPSetErrorIfNotConverged(ilink->ksp,pc->erroriffailure);
1321: PetscObjectIncrementTabLevel((PetscObject)ilink->ksp,(PetscObject)pc,1);
1322: KSPSetType(ilink->ksp,KSPPREONLY);
1323: PetscLogObjectParent((PetscObject)pc,(PetscObject)ilink->ksp);
1325: PetscSNPrintf(prefix,sizeof(prefix),"%sfieldsplit_%s_",((PetscObject)pc)->prefix ? ((PetscObject)pc)->prefix : "",ilink->splitname);
1326: KSPSetOptionsPrefix(ilink->ksp,prefix);
1328: if (!next) {
1329: jac->head = ilink;
1330: ilink->previous = NULL;
1331: } else {
1332: while (next->next) {
1333: next = next->next;
1334: }
1335: next->next = ilink;
1336: ilink->previous = next;
1337: }
1338: jac->nsplits++;
1339: return(0);
1340: }
1344: /*@
1345: PCFieldSplitSetFields - Sets the fields for one particular split in the field split preconditioner
1347: Logically Collective on PC
1349: Input Parameters:
1350: + pc - the preconditioner context
1351: . splitname - name of this split, if NULL the number of the split is used
1352: . n - the number of fields in this split
1353: - fields - the fields in this split
1355: Level: intermediate
1357: Notes: Use PCFieldSplitSetIS() to set a completely general set of indices as a field.
1359: The PCFieldSplitSetFields() is for defining fields as strided blocks. For example, if the block
1360: size is three then one can define a field as 0, or 1 or 2 or 0,1 or 0,2 or 1,2 which mean
1361: 0xx3xx6xx9xx12 ... x1xx4xx7xx ... xx2xx5xx8xx.. 01x34x67x... 0x1x3x5x7.. x12x45x78x....
1362: where the numbered entries indicate what is in the field.
1364: This function is called once per split (it creates a new split each time). Solve options
1365: for this split will be available under the prefix -fieldsplit_SPLITNAME_.
1367: Developer Note: This routine does not actually create the IS representing the split, that is delayed
1368: until PCSetUp_FieldSplit(), because information about the vector/matrix layouts may not be
1369: available when this routine is called.
1371: .seealso: PCFieldSplitGetSubKSP(), PCFIELDSPLIT, PCFieldSplitSetBlockSize(), PCFieldSplitSetIS()
1373: @*/
1374: PetscErrorCode PCFieldSplitSetFields(PC pc,const char splitname[],PetscInt n,const PetscInt *fields,const PetscInt *fields_col)
1375: {
1381: if (n < 1) SETERRQ2(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_OUTOFRANGE,"Provided number of fields %D in split \"%s\" not positive",n,splitname);
1383: PetscTryMethod(pc,"PCFieldSplitSetFields_C",(PC,const char[],PetscInt,const PetscInt*,const PetscInt*),(pc,splitname,n,fields,fields_col));
1384: return(0);
1385: }
1389: /*@
1390: PCFieldSplitSetDiagUseAmat - set flag indicating whether to extract diagonal blocks from Amat (rather than Pmat)
1392: Logically Collective on PC
1394: Input Parameters:
1395: + pc - the preconditioner object
1396: - flg - boolean flag indicating whether or not to use Amat to extract the diagonal blocks from
1398: Options Database:
1399: . -pc_fieldsplit_diag_use_amat
1401: Level: intermediate
1403: .seealso: PCFieldSplitGetDiagUseAmat(), PCFieldSplitSetOffDiagUseAmat(), PCFIELDSPLIT
1405: @*/
1406: PetscErrorCode PCFieldSplitSetDiagUseAmat(PC pc,PetscBool flg)
1407: {
1408: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1409: PetscBool isfs;
1414: PetscObjectTypeCompare((PetscObject)pc,PCFIELDSPLIT,&isfs);
1415: if (!isfs) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"PC not of type %s",PCFIELDSPLIT);
1416: jac->diag_use_amat = flg;
1417: return(0);
1418: }
1422: /*@
1423: PCFieldSplitGetDiagUseAmat - get the flag indicating whether to extract diagonal blocks from Amat (rather than Pmat)
1425: Logically Collective on PC
1427: Input Parameters:
1428: . pc - the preconditioner object
1430: Output Parameters:
1431: . flg - boolean flag indicating whether or not to use Amat to extract the diagonal blocks from
1434: Level: intermediate
1436: .seealso: PCFieldSplitSetDiagUseAmat(), PCFieldSplitGetOffDiagUseAmat(), PCFIELDSPLIT
1438: @*/
1439: PetscErrorCode PCFieldSplitGetDiagUseAmat(PC pc,PetscBool *flg)
1440: {
1441: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1442: PetscBool isfs;
1448: PetscObjectTypeCompare((PetscObject)pc,PCFIELDSPLIT,&isfs);
1449: if (!isfs) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"PC not of type %s",PCFIELDSPLIT);
1450: *flg = jac->diag_use_amat;
1451: return(0);
1452: }
1456: /*@
1457: PCFieldSplitSetOffDiagUseAmat - set flag indicating whether to extract off-diagonal blocks from Amat (rather than Pmat)
1459: Logically Collective on PC
1461: Input Parameters:
1462: + pc - the preconditioner object
1463: - flg - boolean flag indicating whether or not to use Amat to extract the off-diagonal blocks from
1465: Options Database:
1466: . -pc_fieldsplit_off_diag_use_amat
1468: Level: intermediate
1470: .seealso: PCFieldSplitGetOffDiagUseAmat(), PCFieldSplitSetDiagUseAmat(), PCFIELDSPLIT
1472: @*/
1473: PetscErrorCode PCFieldSplitSetOffDiagUseAmat(PC pc,PetscBool flg)
1474: {
1475: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1476: PetscBool isfs;
1481: PetscObjectTypeCompare((PetscObject)pc,PCFIELDSPLIT,&isfs);
1482: if (!isfs) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"PC not of type %s",PCFIELDSPLIT);
1483: jac->offdiag_use_amat = flg;
1484: return(0);
1485: }
1489: /*@
1490: PCFieldSplitGetOffDiagUseAmat - get the flag indicating whether to extract off-diagonal blocks from Amat (rather than Pmat)
1492: Logically Collective on PC
1494: Input Parameters:
1495: . pc - the preconditioner object
1497: Output Parameters:
1498: . flg - boolean flag indicating whether or not to use Amat to extract the off-diagonal blocks from
1501: Level: intermediate
1503: .seealso: PCFieldSplitSetOffDiagUseAmat(), PCFieldSplitGetDiagUseAmat(), PCFIELDSPLIT
1505: @*/
1506: PetscErrorCode PCFieldSplitGetOffDiagUseAmat(PC pc,PetscBool *flg)
1507: {
1508: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1509: PetscBool isfs;
1515: PetscObjectTypeCompare((PetscObject)pc,PCFIELDSPLIT,&isfs);
1516: if (!isfs) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"PC not of type %s",PCFIELDSPLIT);
1517: *flg = jac->offdiag_use_amat;
1518: return(0);
1519: }
1525: /*@C
1526: PCFieldSplitSetIS - Sets the exact elements for field
1528: Logically Collective on PC
1530: Input Parameters:
1531: + pc - the preconditioner context
1532: . splitname - name of this split, if NULL the number of the split is used
1533: - is - the index set that defines the vector elements in this field
1536: Notes:
1537: Use PCFieldSplitSetFields(), for fields defined by strided types.
1539: This function is called once per split (it creates a new split each time). Solve options
1540: for this split will be available under the prefix -fieldsplit_SPLITNAME_.
1542: Level: intermediate
1544: .seealso: PCFieldSplitGetSubKSP(), PCFIELDSPLIT, PCFieldSplitSetBlockSize()
1546: @*/
1547: PetscErrorCode PCFieldSplitSetIS(PC pc,const char splitname[],IS is)
1548: {
1555: PetscTryMethod(pc,"PCFieldSplitSetIS_C",(PC,const char[],IS),(pc,splitname,is));
1556: return(0);
1557: }
1561: /*@
1562: PCFieldSplitGetIS - Retrieves the elements for a field as an IS
1564: Logically Collective on PC
1566: Input Parameters:
1567: + pc - the preconditioner context
1568: - splitname - name of this split
1570: Output Parameter:
1571: - is - the index set that defines the vector elements in this field, or NULL if the field is not found
1573: Level: intermediate
1575: .seealso: PCFieldSplitGetSubKSP(), PCFIELDSPLIT, PCFieldSplitSetIS()
1577: @*/
1578: PetscErrorCode PCFieldSplitGetIS(PC pc,const char splitname[],IS *is)
1579: {
1586: {
1587: PC_FieldSplit *jac = (PC_FieldSplit*) pc->data;
1588: PC_FieldSplitLink ilink = jac->head;
1589: PetscBool found;
1591: *is = NULL;
1592: while (ilink) {
1593: PetscStrcmp(ilink->splitname, splitname, &found);
1594: if (found) {
1595: *is = ilink->is;
1596: break;
1597: }
1598: ilink = ilink->next;
1599: }
1600: }
1601: return(0);
1602: }
1606: /*@
1607: PCFieldSplitSetBlockSize - Sets the block size for defining where fields start in the
1608: fieldsplit preconditioner. If not set the matrix block size is used.
1610: Logically Collective on PC
1612: Input Parameters:
1613: + pc - the preconditioner context
1614: - bs - the block size
1616: Level: intermediate
1618: .seealso: PCFieldSplitGetSubKSP(), PCFIELDSPLIT, PCFieldSplitSetFields()
1620: @*/
1621: PetscErrorCode PCFieldSplitSetBlockSize(PC pc,PetscInt bs)
1622: {
1628: PetscTryMethod(pc,"PCFieldSplitSetBlockSize_C",(PC,PetscInt),(pc,bs));
1629: return(0);
1630: }
1634: /*@C
1635: PCFieldSplitGetSubKSP - Gets the KSP contexts for all splits
1637: Collective on KSP
1639: Input Parameter:
1640: . pc - the preconditioner context
1642: Output Parameters:
1643: + n - the number of splits
1644: - pc - the array of KSP contexts
1646: Note:
1647: After PCFieldSplitGetSubKSP() the array of KSPs IS to be freed by the user
1648: (not the KSP just the array that contains them).
1650: You must call KSPSetUp() before calling PCFieldSplitGetSubKSP().
1652: Fortran Usage: You must pass in a KSP array that is large enough to contain all the local KSPs.
1653: You can call PCFieldSplitGetSubKSP(pc,n,NULL_OBJECT,ierr) to determine how large the
1654: KSP array must be.
1657: Level: advanced
1659: .seealso: PCFIELDSPLIT
1660: @*/
1661: PetscErrorCode PCFieldSplitGetSubKSP(PC pc,PetscInt *n,KSP *subksp[])
1662: {
1668: PetscUseMethod(pc,"PCFieldSplitGetSubKSP_C",(PC,PetscInt*,KSP **),(pc,n,subksp));
1669: return(0);
1670: }
1674: /*@
1675: PCFieldSplitSetSchurPre - Indicates if the Schur complement is preconditioned by a preconditioner constructed by the
1676: A11 matrix. Otherwise no preconditioner is used.
1678: Collective on PC
1680: Input Parameters:
1681: + pc - the preconditioner context
1682: . ptype - which matrix to use for preconditioning the Schur complement: PC_FIELDSPLIT_SCHUR_PRE_A11 (default), PC_FIELDSPLIT_SCHUR_PRE_SELF, PC_FIELDSPLIT_PRE_USER
1683: - userpre - matrix to use for preconditioning, or NULL
1685: Options Database:
1686: . -pc_fieldsplit_schur_precondition <self,selfp,user,a11,full> default is a11
1688: Notes:
1689: $ If ptype is
1690: $ user then the preconditioner for the Schur complement is generated by the provided matrix (pre argument
1691: $ to this function).
1692: $ a11 then the preconditioner for the Schur complement is generated by the block diagonal part of the preconditioner
1693: $ matrix associated with the Schur complement (i.e. A11), not he Schur complement matrix
1694: $ full then the preconditioner uses the exact Schur complement (this is expensive)
1695: $ self the preconditioner for the Schur complement is generated from the Schur complement matrix itself:
1696: $ The only preconditioner that currently works directly with the Schur complement matrix object is the PCLSC
1697: $ preconditioner
1698: $ selfp then the preconditioning matrix is an explicitly-assembled approximation Sp = A11 - A10 inv(diag(A00)) A01
1699: $ This is only a good preconditioner when diag(A00) is a good preconditioner for A00. Optionally, A00 can be
1700: $ lumped before extracting the diagonal: -fieldsplit_1_mat_schur_complement_ainv_type lump; diag is the default.
1702: When solving a saddle point problem, where the A11 block is identically zero, using a11 as the ptype only makes sense
1703: with the additional option -fieldsplit_1_pc_type none. Usually for saddle point problems one would use a ptype of self and
1704: -fieldsplit_1_pc_type lsc which uses the least squares commutator to compute a preconditioner for the Schur complement.
1706: Level: intermediate
1708: .seealso: PCFieldSplitGetSchurPre(), PCFieldSplitGetSubKSP(), PCFIELDSPLIT, PCFieldSplitSetFields(), PCFieldSplitSchurPreType,
1709: MatSchurComplementSetAinvType(), PCLSC
1711: @*/
1712: PetscErrorCode PCFieldSplitSetSchurPre(PC pc,PCFieldSplitSchurPreType ptype,Mat pre)
1713: {
1718: PetscTryMethod(pc,"PCFieldSplitSetSchurPre_C",(PC,PCFieldSplitSchurPreType,Mat),(pc,ptype,pre));
1719: return(0);
1720: }
1721: PetscErrorCode PCFieldSplitSchurPrecondition(PC pc,PCFieldSplitSchurPreType ptype,Mat pre) {return PCFieldSplitSetSchurPre(pc,ptype,pre);} /* Deprecated name */
1725: /*@
1726: PCFieldSplitGetSchurPre - For Schur complement fieldsplit, determine how the Schur complement will be
1727: preconditioned. See PCFieldSplitSetSchurPre() for details.
1729: Logically Collective on PC
1731: Input Parameters:
1732: . pc - the preconditioner context
1734: Output Parameters:
1735: + ptype - which matrix to use for preconditioning the Schur complement: PC_FIELDSPLIT_SCHUR_PRE_A11, PC_FIELDSPLIT_SCHUR_PRE_SELF, PC_FIELDSPLIT_PRE_USER
1736: - userpre - matrix to use for preconditioning (with PC_FIELDSPLIT_PRE_USER), or NULL
1738: Level: intermediate
1740: .seealso: PCFieldSplitSetSchurPre(), PCFieldSplitGetSubKSP(), PCFIELDSPLIT, PCFieldSplitSetFields(), PCFieldSplitSchurPreType, PCLSC
1742: @*/
1743: PetscErrorCode PCFieldSplitGetSchurPre(PC pc,PCFieldSplitSchurPreType *ptype,Mat *pre)
1744: {
1749: PetscUseMethod(pc,"PCFieldSplitGetSchurPre_C",(PC,PCFieldSplitSchurPreType*,Mat*),(pc,ptype,pre));
1750: return(0);
1751: }
1755: /*@
1756: PCFieldSplitSchurGetS - extract the MatSchurComplement object used by this PC in case it needs to be configured separately
1758: Not collective
1760: Input Parameter:
1761: . pc - the preconditioner context
1763: Output Parameter:
1764: . S - the Schur complement matrix
1766: Notes:
1767: This matrix should not be destroyed using MatDestroy(); rather, use PCFieldSplitSchurRestoreS().
1769: Level: advanced
1771: .seealso: PCFieldSplitGetSubKSP(), PCFIELDSPLIT, PCFieldSplitSchurPreType, PCFieldSplitSetSchurPre(), MatSchurComplement, PCFieldSplitSchurRestoreS()
1773: @*/
1774: PetscErrorCode PCFieldSplitSchurGetS(PC pc,Mat *S)
1775: {
1777: const char* t;
1778: PetscBool isfs;
1779: PC_FieldSplit *jac;
1783: PetscObjectGetType((PetscObject)pc,&t);
1784: PetscStrcmp(t,PCFIELDSPLIT,&isfs);
1785: if (!isfs) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Expected PC of type PCFIELDSPLIT, got %s instead",t);
1786: jac = (PC_FieldSplit*)pc->data;
1787: if (jac->type != PC_COMPOSITE_SCHUR) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Expected PCFIELDSPLIT of type SCHUR, got %D instead",jac->type);
1788: if (S) *S = jac->schur;
1789: return(0);
1790: }
1794: /*@
1795: PCFieldSplitSchurRestoreS - restores the MatSchurComplement object used by this PC
1797: Not collective
1799: Input Parameters:
1800: + pc - the preconditioner context
1801: . S - the Schur complement matrix
1803: Level: advanced
1805: .seealso: PCFieldSplitGetSubKSP(), PCFIELDSPLIT, PCFieldSplitSchurPreType, PCFieldSplitSetSchurPre(), MatSchurComplement, PCFieldSplitSchurGetS()
1807: @*/
1808: PetscErrorCode PCFieldSplitSchurRestoreS(PC pc,Mat *S)
1809: {
1811: const char* t;
1812: PetscBool isfs;
1813: PC_FieldSplit *jac;
1817: PetscObjectGetType((PetscObject)pc,&t);
1818: PetscStrcmp(t,PCFIELDSPLIT,&isfs);
1819: if (!isfs) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Expected PC of type PCFIELDSPLIT, got %s instead",t);
1820: jac = (PC_FieldSplit*)pc->data;
1821: if (jac->type != PC_COMPOSITE_SCHUR) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Expected PCFIELDSPLIT of type SCHUR, got %D instead",jac->type);
1822: if (!S || *S != jac->schur) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"MatSchurComplement restored is not the same as gotten");
1823: return(0);
1824: }
1829: static PetscErrorCode PCFieldSplitSetSchurPre_FieldSplit(PC pc,PCFieldSplitSchurPreType ptype,Mat pre)
1830: {
1831: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1835: jac->schurpre = ptype;
1836: if (ptype == PC_FIELDSPLIT_SCHUR_PRE_USER && pre) {
1837: MatDestroy(&jac->schur_user);
1838: jac->schur_user = pre;
1839: PetscObjectReference((PetscObject)jac->schur_user);
1840: }
1841: return(0);
1842: }
1846: static PetscErrorCode PCFieldSplitGetSchurPre_FieldSplit(PC pc,PCFieldSplitSchurPreType *ptype,Mat *pre)
1847: {
1848: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1851: *ptype = jac->schurpre;
1852: *pre = jac->schur_user;
1853: return(0);
1854: }
1858: /*@
1859: PCFieldSplitSetSchurFactType - sets which blocks of the approximate block factorization to retain
1861: Collective on PC
1863: Input Parameters:
1864: + pc - the preconditioner context
1865: - ftype - which blocks of factorization to retain, PC_FIELDSPLIT_SCHUR_FACT_FULL is default
1867: Options Database:
1868: . -pc_fieldsplit_schur_fact_type <diag,lower,upper,full> default is full
1871: Level: intermediate
1873: Notes:
1874: The FULL factorization is
1876: $ (A B) = (1 0) (A 0) (1 Ainv*B)
1877: $ (C D) (C*Ainv 1) (0 S) (0 1 )
1879: where S = D - C*Ainv*B. In practice, the full factorization is applied via block triangular solves with the grouping L*(D*U). UPPER uses D*U, LOWER uses L*D,
1880: and DIAG is the diagonal part with the sign of S flipped (because this makes the preconditioner positive definite for many formulations, thus allowing the use of KSPMINRES).
1882: If applied exactly, FULL factorization is a direct solver. The preconditioned operator with LOWER or UPPER has all eigenvalues equal to 1 and minimal polynomial
1883: of degree 2, so KSPGMRES converges in 2 iterations. If the iteration count is very low, consider using KSPFGMRES or KSPGCR which can use one less preconditioner
1884: application in this case. Note that the preconditioned operator may be highly non-normal, so such fast convergence may not be observed in practice. With DIAG,
1885: the preconditioned operator has three distinct nonzero eigenvalues and minimal polynomial of degree at most 4, so KSPGMRES converges in at most 4 iterations.
1887: For symmetric problems in which A is positive definite and S is negative definite, DIAG can be used with KSPMINRES. Note that a flexible method like KSPFGMRES
1888: or KSPGCR must be used if the fieldsplit preconditioner is nonlinear (e.g. a few iterations of a Krylov method is used inside a split).
1890: References:
1891: Murphy, Golub, and Wathen, A note on preconditioning indefinite linear systems, SIAM J. Sci. Comput., 21 (2000) pp. 1969-1972.
1893: Ipsen, A note on preconditioning nonsymmetric matrices, SIAM J. Sci. Comput., 23 (2001), pp. 1050-1051.
1895: .seealso: PCFieldSplitGetSubKSP(), PCFIELDSPLIT, PCFieldSplitSetFields(), PCFieldSplitSchurPreType
1896: @*/
1897: PetscErrorCode PCFieldSplitSetSchurFactType(PC pc,PCFieldSplitSchurFactType ftype)
1898: {
1903: PetscTryMethod(pc,"PCFieldSplitSetSchurFactType_C",(PC,PCFieldSplitSchurFactType),(pc,ftype));
1904: return(0);
1905: }
1909: static PetscErrorCode PCFieldSplitSetSchurFactType_FieldSplit(PC pc,PCFieldSplitSchurFactType ftype)
1910: {
1911: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1914: jac->schurfactorization = ftype;
1915: return(0);
1916: }
1920: /*@C
1921: PCFieldSplitGetSchurBlocks - Gets all matrix blocks for the Schur complement
1923: Collective on KSP
1925: Input Parameter:
1926: . pc - the preconditioner context
1928: Output Parameters:
1929: + A00 - the (0,0) block
1930: . A01 - the (0,1) block
1931: . A10 - the (1,0) block
1932: - A11 - the (1,1) block
1934: Level: advanced
1936: .seealso: PCFIELDSPLIT
1937: @*/
1938: PetscErrorCode PCFieldSplitGetSchurBlocks(PC pc,Mat *A00,Mat *A01,Mat *A10, Mat *A11)
1939: {
1940: PC_FieldSplit *jac = (PC_FieldSplit*) pc->data;
1944: if (jac->type != PC_COMPOSITE_SCHUR) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONG, "FieldSplit is not using a Schur complement approach.");
1945: if (A00) *A00 = jac->pmat[0];
1946: if (A01) *A01 = jac->B;
1947: if (A10) *A10 = jac->C;
1948: if (A11) *A11 = jac->pmat[1];
1949: return(0);
1950: }
1954: static PetscErrorCode PCFieldSplitSetType_FieldSplit(PC pc,PCCompositeType type)
1955: {
1956: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1960: jac->type = type;
1961: if (type == PC_COMPOSITE_SCHUR) {
1962: pc->ops->apply = PCApply_FieldSplit_Schur;
1963: pc->ops->view = PCView_FieldSplit_Schur;
1965: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitGetSubKSP_C",PCFieldSplitGetSubKSP_FieldSplit_Schur);
1966: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetSchurPre_C",PCFieldSplitSetSchurPre_FieldSplit);
1967: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitGetSchurPre_C",PCFieldSplitGetSchurPre_FieldSplit);
1968: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetSchurFactType_C",PCFieldSplitSetSchurFactType_FieldSplit);
1970: } else {
1971: pc->ops->apply = PCApply_FieldSplit;
1972: pc->ops->view = PCView_FieldSplit;
1974: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitGetSubKSP_C",PCFieldSplitGetSubKSP_FieldSplit);
1975: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetSchurPre_C",0);
1976: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitGetSchurPre_C",0);
1977: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetSchurFactType_C",0);
1978: }
1979: return(0);
1980: }
1984: static PetscErrorCode PCFieldSplitSetBlockSize_FieldSplit(PC pc,PetscInt bs)
1985: {
1986: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
1989: if (bs < 1) SETERRQ1(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_OUTOFRANGE,"Blocksize must be positive, you gave %D",bs);
1990: if (jac->bs > 0 && jac->bs != bs) SETERRQ2(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Cannot change fieldsplit blocksize from %D to %D after it has been set",jac->bs,bs);
1991: jac->bs = bs;
1992: return(0);
1993: }
1997: /*@
1998: PCFieldSplitSetType - Sets the type of fieldsplit preconditioner.
2000: Collective on PC
2002: Input Parameter:
2003: . pc - the preconditioner context
2004: . type - PC_COMPOSITE_ADDITIVE, PC_COMPOSITE_MULTIPLICATIVE (default), PC_COMPOSITE_SYMMETRIC_MULTIPLICATIVE, PC_COMPOSITE_SPECIAL, PC_COMPOSITE_SCHUR
2006: Options Database Key:
2007: . -pc_fieldsplit_type <type: one of multiplicative, additive, symmetric_multiplicative, special, schur> - Sets fieldsplit preconditioner type
2009: Level: Intermediate
2011: .keywords: PC, set, type, composite preconditioner, additive, multiplicative
2013: .seealso: PCCompositeSetType()
2015: @*/
2016: PetscErrorCode PCFieldSplitSetType(PC pc,PCCompositeType type)
2017: {
2022: PetscTryMethod(pc,"PCFieldSplitSetType_C",(PC,PCCompositeType),(pc,type));
2023: return(0);
2024: }
2028: /*@
2029: PCFieldSplitGetType - Gets the type of fieldsplit preconditioner.
2031: Not collective
2033: Input Parameter:
2034: . pc - the preconditioner context
2036: Output Parameter:
2037: . type - PC_COMPOSITE_ADDITIVE, PC_COMPOSITE_MULTIPLICATIVE (default), PC_COMPOSITE_SYMMETRIC_MULTIPLICATIVE, PC_COMPOSITE_SPECIAL, PC_COMPOSITE_SCHUR
2039: Level: Intermediate
2041: .keywords: PC, set, type, composite preconditioner, additive, multiplicative
2042: .seealso: PCCompositeSetType()
2043: @*/
2044: PetscErrorCode PCFieldSplitGetType(PC pc, PCCompositeType *type)
2045: {
2046: PC_FieldSplit *jac = (PC_FieldSplit*) pc->data;
2051: *type = jac->type;
2052: return(0);
2053: }
2057: /*@
2058: PCFieldSplitSetDMSplits - Flags whether DMCreateFieldDecomposition() should be used to define the splits, whenever possible.
2060: Logically Collective
2062: Input Parameters:
2063: + pc - the preconditioner context
2064: - flg - boolean indicating whether to use field splits defined by the DM
2066: Options Database Key:
2067: . -pc_fieldsplit_dm_splits
2069: Level: Intermediate
2071: .keywords: PC, DM, composite preconditioner, additive, multiplicative
2073: .seealso: PCFieldSplitGetDMSplits()
2075: @*/
2076: PetscErrorCode PCFieldSplitSetDMSplits(PC pc,PetscBool flg)
2077: {
2078: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
2079: PetscBool isfs;
2085: PetscObjectTypeCompare((PetscObject)pc,PCFIELDSPLIT,&isfs);
2086: if (isfs) {
2087: jac->dm_splits = flg;
2088: }
2089: return(0);
2090: }
2095: /*@
2096: PCFieldSplitGetDMSplits - Returns flag indicating whether DMCreateFieldDecomposition() should be used to define the splits, whenever possible.
2098: Logically Collective
2100: Input Parameter:
2101: . pc - the preconditioner context
2103: Output Parameter:
2104: . flg - boolean indicating whether to use field splits defined by the DM
2106: Level: Intermediate
2108: .keywords: PC, DM, composite preconditioner, additive, multiplicative
2110: .seealso: PCFieldSplitSetDMSplits()
2112: @*/
2113: PetscErrorCode PCFieldSplitGetDMSplits(PC pc,PetscBool* flg)
2114: {
2115: PC_FieldSplit *jac = (PC_FieldSplit*)pc->data;
2116: PetscBool isfs;
2122: PetscObjectTypeCompare((PetscObject)pc,PCFIELDSPLIT,&isfs);
2123: if (isfs) {
2124: if(flg) *flg = jac->dm_splits;
2125: }
2126: return(0);
2127: }
2129: /* -------------------------------------------------------------------------------------*/
2130: /*MC
2131: PCFIELDSPLIT - Preconditioner created by combining separate preconditioners for individual
2132: fields or groups of fields. See the users manual section "Solving Block Matrices" for more details.
2134: To set options on the solvers for each block append -fieldsplit_ to all the PC
2135: options database keys. For example, -fieldsplit_pc_type ilu -fieldsplit_pc_factor_levels 1
2137: To set the options on the solvers separate for each block call PCFieldSplitGetSubKSP()
2138: and set the options directly on the resulting KSP object
2140: Level: intermediate
2142: Options Database Keys:
2143: + -pc_fieldsplit_%d_fields <a,b,..> - indicates the fields to be used in the %d'th split
2144: . -pc_fieldsplit_default - automatically add any fields to additional splits that have not
2145: been supplied explicitly by -pc_fieldsplit_%d_fields
2146: . -pc_fieldsplit_block_size <bs> - size of block that defines fields (i.e. there are bs fields)
2147: . -pc_fieldsplit_type <additive,multiplicative,symmetric_multiplicative,schur> - type of relaxation or factorization splitting
2148: . -pc_fieldsplit_schur_precondition <self,selfp,user,a11,full> - default is a11
2149: . -pc_fieldsplit_detect_saddle_point - automatically finds rows with zero or negative diagonal and uses Schur complement with no preconditioner as the solver
2151: - Options prefix for inner solvers when using Schur complement preconditioner are -fieldsplit_0_ and -fieldsplit_1_
2152: for all other solvers they are -fieldsplit_%d_ for the dth field, use -fieldsplit_ for all fields
2154: Notes:
2155: Use PCFieldSplitSetFields() to set fields defined by "strided" entries and PCFieldSplitSetIS()
2156: to define a field by an arbitrary collection of entries.
2158: If no fields are set the default is used. The fields are defined by entries strided by bs,
2159: beginning at 0 then 1, etc to bs-1. The block size can be set with PCFieldSplitSetBlockSize(),
2160: if this is not called the block size defaults to the blocksize of the second matrix passed
2161: to KSPSetOperators()/PCSetOperators().
2163: $ For the Schur complement preconditioner if J = ( A00 A01 )
2164: $ ( A10 A11 )
2165: $ the preconditioner using full factorization is
2166: $ ( I -ksp(A00) A01 ) ( inv(A00) 0 ) ( I 0 )
2167: $ ( 0 I ) ( 0 ksp(S) ) ( -A10 ksp(A00) I )
2168: where the action of inv(A00) is applied using the KSP solver with prefix -fieldsplit_0_. S is the Schur complement
2169: $ S = A11 - A10 ksp(A00) A01
2170: which is usually dense and not stored explicitly. The action of ksp(S) is computed using the KSP solver with prefix -fieldsplit_splitname_ (where splitname was given
2171: in providing the SECOND split or 1 if not give). For PCFieldSplitGetKSP() when field number is 0,
2172: it returns the KSP associated with -fieldsplit_0_ while field number 1 gives -fieldsplit_1_ KSP. By default
2173: A11 is used to construct a preconditioner for S, use PCFieldSplitSetSchurPre() to turn on or off this
2174: option. You can use the preconditioner PCLSC to precondition the Schur complement with -fieldsplit_1_pc_type lsc.
2175: When option -fieldsplit_schur_precondition selfp is given, an approximation to S is assembled --
2176: Sp = A11 - A10 inv(diag(A00)) A01, which has type AIJ and can be used with a variety of preconditioners
2177: (e.g., -fieldsplit_1_pc_type asm). Optionally, A00 can be lumped before extracting the diagonal:
2178: -fieldsplit_1_mat_schur_complement_ainv_type lump; diag is the default.
2180: The factorization type is set using -pc_fieldsplit_schur_fact_type <diag, lower, upper, full>. The full is shown above,
2181: diag gives
2182: $ ( inv(A00) 0 )
2183: $ ( 0 -ksp(S) )
2184: note that slightly counter intuitively there is a negative in front of the ksp(S) so that the preconditioner is positive definite. The lower factorization is the inverse of
2185: $ ( A00 0 )
2186: $ ( A10 S )
2187: where the inverses of A00 and S are applied using KSPs. The upper factorization is the inverse of
2188: $ ( A00 A01 )
2189: $ ( 0 S )
2190: where again the inverses of A00 and S are applied using KSPs.
2192: If only one set of indices (one IS) is provided with PCFieldSplitSetIS() then the complement of that IS
2193: is used automatically for a second block.
2195: The fieldsplit preconditioner cannot currently be used with the BAIJ or SBAIJ data formats if the blocksize is larger than 1.
2196: Generally it should be used with the AIJ format.
2198: The forms of these preconditioners are closely related if not identical to forms derived as "Distributive Iterations", see,
2199: for example, page 294 in "Principles of Computational Fluid Dynamics" by Pieter Wesseling. Note that one can also use PCFIELDSPLIT
2200: inside a smoother resulting in "Distributive Smoothers".
2202: Concepts: physics based preconditioners, block preconditioners
2204: There is a nice discussion of block preconditioners in
2206: [El08] A taxonomy and comparison of parallel block multi-level preconditioners for the incompressible Navier-Stokes equations
2207: Howard Elman, V.E. Howle, John Shadid, Robert Shuttleworth, Ray Tuminaro, Journal of Computational Physics 227 (2008) 1790--1808
2208: http://chess.cs.umd.edu/~elman/papers/tax.pdf
2210: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PC, Block_Preconditioners, PCLSC,
2211: PCFieldSplitGetSubKSP(), PCFieldSplitSetFields(), PCFieldSplitSetType(), PCFieldSplitSetIS(), PCFieldSplitSetSchurPre(),
2212: MatSchurComplementSetAinvType()
2213: M*/
2217: PETSC_EXTERN PetscErrorCode PCCreate_FieldSplit(PC pc)
2218: {
2220: PC_FieldSplit *jac;
2223: PetscNewLog(pc,&jac);
2225: jac->bs = -1;
2226: jac->nsplits = 0;
2227: jac->type = PC_COMPOSITE_MULTIPLICATIVE;
2228: jac->schurpre = PC_FIELDSPLIT_SCHUR_PRE_USER; /* Try user preconditioner first, fall back on diagonal */
2229: jac->schurfactorization = PC_FIELDSPLIT_SCHUR_FACT_FULL;
2230: jac->dm_splits = PETSC_TRUE;
2232: pc->data = (void*)jac;
2234: pc->ops->apply = PCApply_FieldSplit;
2235: pc->ops->applytranspose = PCApplyTranspose_FieldSplit;
2236: pc->ops->setup = PCSetUp_FieldSplit;
2237: pc->ops->reset = PCReset_FieldSplit;
2238: pc->ops->destroy = PCDestroy_FieldSplit;
2239: pc->ops->setfromoptions = PCSetFromOptions_FieldSplit;
2240: pc->ops->view = PCView_FieldSplit;
2241: pc->ops->applyrichardson = 0;
2243: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitGetSubKSP_C",PCFieldSplitGetSubKSP_FieldSplit);
2244: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetFields_C",PCFieldSplitSetFields_FieldSplit);
2245: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetIS_C",PCFieldSplitSetIS_FieldSplit);
2246: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetType_C",PCFieldSplitSetType_FieldSplit);
2247: PetscObjectComposeFunction((PetscObject)pc,"PCFieldSplitSetBlockSize_C",PCFieldSplitSetBlockSize_FieldSplit);
2248: return(0);
2249: }