Actual source code: galerkin.c
petsc-3.8.4 2018-03-24
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: Either this or PCGalerkinSetInterpolation() or both must be called
168: Level: Intermediate
170: .keywords: PC, set, Galerkin preconditioner
172: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PCGALERKIN,
173: PCGalerkinSetInterpolation(), PCGalerkinGetKSP()
175: @*/
176: PetscErrorCode PCGalerkinSetRestriction(PC pc,Mat R)
177: {
182: PetscTryMethod(pc,"PCGalerkinSetRestriction_C",(PC,Mat),(pc,R));
183: return(0);
184: }
186: /*@
187: PCGalerkinSetInterpolation - Sets the interpolation operator for the "Galerkin-type" preconditioner
189: Logically Collective on PC
191: Input Parameter:
192: + pc - the preconditioner context
193: - R - the interpolation operator
195: Notes: Either this or PCGalerkinSetRestriction() or both must be called
197: Level: Intermediate
199: .keywords: PC, set, Galerkin preconditioner
201: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PCGALERKIN,
202: PCGalerkinSetRestriction(), PCGalerkinGetKSP()
204: @*/
205: PetscErrorCode PCGalerkinSetInterpolation(PC pc,Mat P)
206: {
211: PetscTryMethod(pc,"PCGalerkinSetInterpolation_C",(PC,Mat),(pc,P));
212: return(0);
213: }
215: /*@
216: PCGalerkinSetComputeSubmatrix - Provide a routine that will be called to compute the Galerkin submatrix
218: Logically Collective
220: Input Parameter:
221: + pc - the preconditioner context
222: . computeAsub - routine that computes the submatrix from the global matrix
223: - ctx - context used by the routine, or NULL
225: Calling sequence of computeAsub:
226: $ computeAsub(PC pc,Mat A, Mat Ap, Mat *cAP,void *ctx);
228: + PC - the Galerkin PC
229: . A - the matrix in the Galerkin PC
230: . Ap - the computed submatrix from any previous computation, if NULL it has not previously been computed
231: . cAp - the submatrix computed by this routine
232: - ctx - optional user-defined function context
234: Level: Intermediate
236: Notes: Instead of providing this routine you can call PCGalerkinGetKSP() and then KSPSetOperators() to provide the submatrix,
237: but that will not work for multiple KSPSolves with different matrices unless you call it for each solve.
239: 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
240: matrix and computes its values in cAp. On each subsequent call the routine should up the Ap matrix.
242: Developer Notes: If the user does not call this routine nor call PCGalerkinGetKSP() and KSPSetOperators() then PCGalerkin could
243: could automatically compute the submatrix via calls to MatGalerkin() or MatRARt()
245: .keywords: PC, get, Galerkin preconditioner, sub preconditioner
247: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PCGALERKIN,
248: PCGalerkinSetRestriction(), PCGalerkinSetInterpolation(), PCGalerkinGetKSP()
250: @*/
251: PetscErrorCode PCGalerkinSetComputeSubmatrix(PC pc,PetscErrorCode (*computeAsub)(PC,Mat,Mat,Mat*,void*),void *ctx)
252: {
257: PetscTryMethod(pc,"PCGalerkinSetComputeSubmatrix_C",(PC,PetscErrorCode (*)(PC,Mat,Mat,Mat*,void*),void*),(pc,computeAsub,ctx));
258: return(0);
259: }
261: /*@
262: PCGalerkinGetKSP - Gets the KSP object in the Galerkin PC.
264: Not Collective
266: Input Parameter:
267: . pc - the preconditioner context
269: Output Parameters:
270: . ksp - the KSP object
272: Level: Intermediate
274: Notes: Once you have called this routine you can call KSPSetOperators() on the resulting ksp to provide the operator for the Galerkin problem,
275: an alternative is to use PCGalerkinSetComputeSubmatrix() to provide a routine that computes the submatrix as needed.
277: .keywords: PC, get, Galerkin preconditioner, sub preconditioner
279: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PCGALERKIN,
280: PCGalerkinSetRestriction(), PCGalerkinSetInterpolation(), PCGalerkinSetComputeSubmatrix()
282: @*/
283: PetscErrorCode PCGalerkinGetKSP(PC pc,KSP *ksp)
284: {
290: PetscUseMethod(pc,"PCGalerkinGetKSP_C",(PC,KSP*),(pc,ksp));
291: return(0);
292: }
294: static PetscErrorCode PCSetFromOptions_Galerkin(PetscOptionItems *PetscOptionsObject,PC pc)
295: {
296: PC_Galerkin *jac = (PC_Galerkin*)pc->data;
298: const char *prefix;
299: PetscBool flg;
302: KSPGetOptionsPrefix(jac->ksp,&prefix);
303: PetscStrendswith(prefix,"galerkin_",&flg);
304: if (!flg) {
305: PCGetOptionsPrefix(pc,&prefix);
306: KSPSetOptionsPrefix(jac->ksp,prefix);
307: KSPAppendOptionsPrefix(jac->ksp,"galerkin_");
308: }
310: PetscOptionsHead(PetscOptionsObject,"Galerkin options");
311: if (jac->ksp) {
312: KSPSetFromOptions(jac->ksp);
313: }
314: PetscOptionsTail();
315: return(0);
316: }
318: /* -------------------------------------------------------------------------------------------*/
320: /*MC
321: PCGALERKIN - Build (part of) a preconditioner by P S R (where P is often R^T)
323: $ Use PCGalerkinSetRestriction(pc,R) and/or PCGalerkinSetInterpolation(pc,P) followed by
324: $ PCGalerkinGetKSP(pc,&ksp); KSPSetOperators(ksp,A,....)
326: Level: intermediate
328: Developer Note: If KSPSetOperators() has not been called on the inner KSP then PCGALERKIN could use MatRARt() or MatPtAP() to compute
329: the operators automatically.
330: Should there be a prefix for the inner KSP.
331: There is no KSPSetFromOptions_Galerkin() that calls KSPSetFromOptions() on the inner KSP
333: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PC,
334: PCSHELL, PCKSP, PCGalerkinSetRestriction(), PCGalerkinSetInterpolation(), PCGalerkinGetKSP()
336: M*/
338: PETSC_EXTERN PetscErrorCode PCCreate_Galerkin(PC pc)
339: {
341: PC_Galerkin *jac;
344: PetscNewLog(pc,&jac);
346: pc->ops->apply = PCApply_Galerkin;
347: pc->ops->setup = PCSetUp_Galerkin;
348: pc->ops->reset = PCReset_Galerkin;
349: pc->ops->destroy = PCDestroy_Galerkin;
350: pc->ops->view = PCView_Galerkin;
351: pc->ops->setfromoptions = PCSetFromOptions_Galerkin;
352: pc->ops->applyrichardson = NULL;
354: KSPCreate(PetscObjectComm((PetscObject)pc),&jac->ksp);
355: KSPSetErrorIfNotConverged(jac->ksp,pc->erroriffailure);
356: PetscObjectIncrementTabLevel((PetscObject)jac->ksp,(PetscObject)pc,1);
358: pc->data = (void*)jac;
360: PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinSetRestriction_C",PCGalerkinSetRestriction_Galerkin);
361: PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinSetInterpolation_C",PCGalerkinSetInterpolation_Galerkin);
362: PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinGetKSP_C",PCGalerkinGetKSP_Galerkin);
363: PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinSetComputeSubmatrix_C",PCGalerkinSetComputeSubmatrix_Galerkin);
364: return(0);
365: }