Actual source code: galerkin.c

petsc-3.10.4 2019-02-26
Report Typos and Errors

  2: /*
  3:       Defines a preconditioner defined by R^T S R
  4: */
  5:  #include <petsc/private/pcimpl.h>
  6:  #include <petscksp.h>

  8: typedef struct {
  9:   KSP            ksp;
 10:   Mat            R,P;
 11:   Vec            b,x;
 12:   PetscErrorCode (*computeasub)(PC,Mat,Mat,Mat*,void*);
 13:   void           *computeasub_ctx;
 14: } PC_Galerkin;

 16: static PetscErrorCode PCApply_Galerkin(PC pc,Vec x,Vec y)
 17: {
 19:   PC_Galerkin    *jac = (PC_Galerkin*)pc->data;

 22:   if (jac->R) {
 23:     MatRestrict(jac->R,x,jac->b);
 24:   } else {
 25:     MatRestrict(jac->P,x,jac->b);
 26:   }
 27:   KSPSolve(jac->ksp,jac->b,jac->x);
 28:   if (jac->P) {
 29:     MatInterpolate(jac->P,jac->x,y);
 30:   } else {
 31:     MatInterpolate(jac->R,jac->x,y);
 32:   }
 33:   return(0);
 34: }

 36: static PetscErrorCode PCSetUp_Galerkin(PC pc)
 37: {
 39:   PC_Galerkin    *jac = (PC_Galerkin*)pc->data;
 40:   PetscBool      a;
 41:   Vec            *xx,*yy;

 44:   if (jac->computeasub) {
 45:     Mat Ap;
 46:     if (!pc->setupcalled) {
 47:       (*jac->computeasub)(pc,pc->pmat,NULL,&Ap,jac->computeasub_ctx);
 48:       KSPSetOperators(jac->ksp,Ap,Ap);
 49:       MatDestroy(&Ap);
 50:     } else {
 51:       KSPGetOperators(jac->ksp,NULL,&Ap);
 52:       (*jac->computeasub)(pc,pc->pmat,Ap,NULL,jac->computeasub_ctx);
 53:     }
 54:   }

 56:   if (!jac->x) {
 57:     KSPGetOperatorsSet(jac->ksp,&a,NULL);
 58:     if (!a) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Must set operator of PCGALERKIN KSP with PCGalerkinGetKSP()/KSPSetOperators()");
 59:     KSPCreateVecs(jac->ksp,1,&xx,1,&yy);
 60:     jac->x = *xx;
 61:     jac->b = *yy;
 62:     PetscFree(xx);
 63:     PetscFree(yy);
 64:   }
 65:   if (!jac->R && !jac->P) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Must set restriction or interpolation of PCGALERKIN with PCGalerkinSetRestriction()/Interpolation()");
 66:   /* should check here that sizes of R/P match size of a */

 68:   return(0);
 69: }

 71: static PetscErrorCode PCReset_Galerkin(PC pc)
 72: {
 73:   PC_Galerkin    *jac = (PC_Galerkin*)pc->data;

 77:   MatDestroy(&jac->R);
 78:   MatDestroy(&jac->P);
 79:   VecDestroy(&jac->x);
 80:   VecDestroy(&jac->b);
 81:   KSPReset(jac->ksp);
 82:   return(0);
 83: }

 85: static PetscErrorCode PCDestroy_Galerkin(PC pc)
 86: {
 87:   PC_Galerkin    *jac = (PC_Galerkin*)pc->data;

 91:   PCReset_Galerkin(pc);
 92:   KSPDestroy(&jac->ksp);
 93:   PetscFree(pc->data);
 94:   return(0);
 95: }

 97: static PetscErrorCode PCView_Galerkin(PC pc,PetscViewer viewer)
 98: {
 99:   PC_Galerkin    *jac = (PC_Galerkin*)pc->data;
101:   PetscBool      iascii;

104:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
105:   if (iascii) {
106:     PetscViewerASCIIPrintf(viewer,"  KSP on Galerkin follow\n");
107:     PetscViewerASCIIPrintf(viewer,"  ---------------------------------\n");
108:   }
109:   KSPView(jac->ksp,viewer);
110:   return(0);
111: }

113: static PetscErrorCode  PCGalerkinGetKSP_Galerkin(PC pc,KSP *ksp)
114: {
115:   PC_Galerkin *jac = (PC_Galerkin*)pc->data;

118:   *ksp = jac->ksp;
119:   return(0);
120: }

122: static PetscErrorCode  PCGalerkinSetRestriction_Galerkin(PC pc,Mat R)
123: {
124:   PC_Galerkin    *jac = (PC_Galerkin*)pc->data;

128:   PetscObjectReference((PetscObject)R);
129:   MatDestroy(&jac->R);
130:   jac->R = R;
131:   return(0);
132: }

134: static PetscErrorCode  PCGalerkinSetInterpolation_Galerkin(PC pc,Mat P)
135: {
136:   PC_Galerkin    *jac = (PC_Galerkin*)pc->data;

140:   PetscObjectReference((PetscObject)P);
141:   MatDestroy(&jac->P);
142:   jac->P = P;
143:   return(0);
144: }

146: static PetscErrorCode  PCGalerkinSetComputeSubmatrix_Galerkin(PC pc,PetscErrorCode (*computeAsub)(PC,Mat,Mat,Mat*,void*),void *ctx)
147: {
148:   PC_Galerkin    *jac = (PC_Galerkin*)pc->data;

151:   jac->computeasub     = computeAsub;
152:   jac->computeasub_ctx = ctx;
153:   return(0);
154: }

156: /* -------------------------------------------------------------------------------- */
157: /*@
158:    PCGalerkinSetRestriction - Sets the restriction operator for the "Galerkin-type" preconditioner

160:    Logically Collective on PC

162:    Input Parameter:
163: +  pc - the preconditioner context
164: -  R - the restriction operator

166:    Notes:
167:     Either this or PCGalerkinSetInterpolation() or both must be called

169:    Level: Intermediate

171: .keywords: PC, set, Galerkin preconditioner

173: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PCGALERKIN,
174:            PCGalerkinSetInterpolation(), PCGalerkinGetKSP()

176: @*/
177: PetscErrorCode  PCGalerkinSetRestriction(PC pc,Mat R)
178: {

183:   PetscTryMethod(pc,"PCGalerkinSetRestriction_C",(PC,Mat),(pc,R));
184:   return(0);
185: }

187: /*@
188:    PCGalerkinSetInterpolation - Sets the interpolation operator for the "Galerkin-type" preconditioner

190:    Logically Collective on PC

192:    Input Parameter:
193: +  pc - the preconditioner context
194: -  R - the interpolation operator

196:    Notes:
197:     Either this or PCGalerkinSetRestriction() or both must be called

199:    Level: Intermediate

201: .keywords: PC, set, Galerkin preconditioner

203: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PCGALERKIN,
204:            PCGalerkinSetRestriction(), PCGalerkinGetKSP()

206: @*/
207: PetscErrorCode  PCGalerkinSetInterpolation(PC pc,Mat P)
208: {

213:   PetscTryMethod(pc,"PCGalerkinSetInterpolation_C",(PC,Mat),(pc,P));
214:   return(0);
215: }

217: /*@
218:    PCGalerkinSetComputeSubmatrix - Provide a routine that will be called to compute the Galerkin submatrix

220:    Logically Collective

222:    Input Parameter:
223: +  pc - the preconditioner context
224: .  computeAsub - routine that computes the submatrix from the global matrix
225: -  ctx - context used by the routine, or NULL

227:    Calling sequence of computeAsub:
228: $    computeAsub(PC pc,Mat A, Mat Ap, Mat *cAP,void *ctx);

230: +  PC - the Galerkin PC
231: .  A - the matrix in the Galerkin PC
232: .  Ap - the computed submatrix from any previous computation, if NULL it has not previously been computed
233: .  cAp - the submatrix computed by this routine
234: -  ctx - optional user-defined function context

236:    Level: Intermediate

238:    Notes:
239:     Instead of providing this routine you can call PCGalerkinGetKSP() and then KSPSetOperators() to provide the submatrix,
240:           but that will not work for multiple KSPSolves with different matrices unless you call it for each solve.

242:           This routine is called each time the outter matrix is changed. In the first call the Ap argument is NULL and the routine should create the
243:           matrix and computes its values in cAp. On each subsequent call the routine should up the Ap matrix.

245:    Developer Notes:
246:     If the user does not call this routine nor call PCGalerkinGetKSP() and KSPSetOperators() then PCGalerkin could
247:                     could automatically compute the submatrix via calls to MatGalerkin() or MatRARt()

249: .keywords: PC, get, Galerkin preconditioner, sub preconditioner

251: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PCGALERKIN,
252:            PCGalerkinSetRestriction(), PCGalerkinSetInterpolation(), PCGalerkinGetKSP()

254: @*/
255: PetscErrorCode  PCGalerkinSetComputeSubmatrix(PC pc,PetscErrorCode (*computeAsub)(PC,Mat,Mat,Mat*,void*),void *ctx)
256: {

261:   PetscTryMethod(pc,"PCGalerkinSetComputeSubmatrix_C",(PC,PetscErrorCode (*)(PC,Mat,Mat,Mat*,void*),void*),(pc,computeAsub,ctx));
262:   return(0);
263: }

265: /*@
266:    PCGalerkinGetKSP - Gets the KSP object in the Galerkin PC.

268:    Not Collective

270:    Input Parameter:
271: .  pc - the preconditioner context

273:    Output Parameters:
274: .  ksp - the KSP object

276:    Level: Intermediate

278:    Notes:
279:     Once you have called this routine you can call KSPSetOperators() on the resulting ksp to provide the operator for the Galerkin problem,
280:           an alternative is to use PCGalerkinSetComputeSubmatrix() to provide a routine that computes the submatrix as needed.

282: .keywords: PC, get, Galerkin preconditioner, sub preconditioner

284: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PCGALERKIN,
285:            PCGalerkinSetRestriction(), PCGalerkinSetInterpolation(), PCGalerkinSetComputeSubmatrix()

287: @*/
288: PetscErrorCode  PCGalerkinGetKSP(PC pc,KSP *ksp)
289: {

295:   PetscUseMethod(pc,"PCGalerkinGetKSP_C",(PC,KSP*),(pc,ksp));
296:   return(0);
297: }

299: static PetscErrorCode PCSetFromOptions_Galerkin(PetscOptionItems *PetscOptionsObject,PC pc)
300: {
301:   PC_Galerkin    *jac = (PC_Galerkin*)pc->data;
303:   const char     *prefix;
304:   PetscBool      flg;

307:   KSPGetOptionsPrefix(jac->ksp,&prefix);
308:   PetscStrendswith(prefix,"galerkin_",&flg);
309:   if (!flg) {
310:     PCGetOptionsPrefix(pc,&prefix);
311:     KSPSetOptionsPrefix(jac->ksp,prefix);
312:     KSPAppendOptionsPrefix(jac->ksp,"galerkin_");
313:   }

315:   PetscOptionsHead(PetscOptionsObject,"Galerkin options");
316:   if (jac->ksp) {
317:     KSPSetFromOptions(jac->ksp);
318:   }
319:   PetscOptionsTail();
320:   return(0);
321: }

323: /* -------------------------------------------------------------------------------------------*/

325: /*MC
326:      PCGALERKIN - Build (part of) a preconditioner by P S R (where P is often R^T)

328: $   Use PCGalerkinSetRestriction(pc,R) and/or PCGalerkinSetInterpolation(pc,P) followed by
329: $   PCGalerkinGetKSP(pc,&ksp); KSPSetOperators(ksp,A,....)

331:    Level: intermediate

333:    Developer Note: If KSPSetOperators() has not been called on the inner KSP then PCGALERKIN could use MatRARt() or MatPtAP() to compute
334:                    the operators automatically.
335:                    Should there be a prefix for the inner KSP.
336:                    There is no KSPSetFromOptions_Galerkin() that calls KSPSetFromOptions() on the inner KSP

338: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC,
339:            PCSHELL, PCKSP, PCGalerkinSetRestriction(), PCGalerkinSetInterpolation(), PCGalerkinGetKSP()

341: M*/

343: PETSC_EXTERN PetscErrorCode PCCreate_Galerkin(PC pc)
344: {
346:   PC_Galerkin    *jac;

349:   PetscNewLog(pc,&jac);

351:   pc->ops->apply           = PCApply_Galerkin;
352:   pc->ops->setup           = PCSetUp_Galerkin;
353:   pc->ops->reset           = PCReset_Galerkin;
354:   pc->ops->destroy         = PCDestroy_Galerkin;
355:   pc->ops->view            = PCView_Galerkin;
356:   pc->ops->setfromoptions  = PCSetFromOptions_Galerkin;
357:   pc->ops->applyrichardson = NULL;

359:   KSPCreate(PetscObjectComm((PetscObject)pc),&jac->ksp);
360:   KSPSetErrorIfNotConverged(jac->ksp,pc->erroriffailure);
361:   PetscObjectIncrementTabLevel((PetscObject)jac->ksp,(PetscObject)pc,1);

363:   pc->data = (void*)jac;

365:   PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinSetRestriction_C",PCGalerkinSetRestriction_Galerkin);
366:   PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinSetInterpolation_C",PCGalerkinSetInterpolation_Galerkin);
367:   PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinGetKSP_C",PCGalerkinGetKSP_Galerkin);
368:   PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinSetComputeSubmatrix_C",PCGalerkinSetComputeSubmatrix_Galerkin);
369:   return(0);
370: }