Actual source code: galerkin.c
petsc-3.12.5 2020-03-29
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: KSPCheckSolve(jac->ksp,pc,jac->x);
29: if (jac->P) {
30: MatInterpolate(jac->P,jac->x,y);
31: } else {
32: MatInterpolate(jac->R,jac->x,y);
33: }
34: return(0);
35: }
37: static PetscErrorCode PCSetUp_Galerkin(PC pc)
38: {
40: PC_Galerkin *jac = (PC_Galerkin*)pc->data;
41: PetscBool a;
42: Vec *xx,*yy;
45: if (jac->computeasub) {
46: Mat Ap;
47: if (!pc->setupcalled) {
48: (*jac->computeasub)(pc,pc->pmat,NULL,&Ap,jac->computeasub_ctx);
49: KSPSetOperators(jac->ksp,Ap,Ap);
50: MatDestroy(&Ap);
51: } else {
52: KSPGetOperators(jac->ksp,NULL,&Ap);
53: (*jac->computeasub)(pc,pc->pmat,Ap,NULL,jac->computeasub_ctx);
54: }
55: }
57: if (!jac->x) {
58: KSPGetOperatorsSet(jac->ksp,&a,NULL);
59: if (!a) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Must set operator of PCGALERKIN KSP with PCGalerkinGetKSP()/KSPSetOperators()");
60: KSPCreateVecs(jac->ksp,1,&xx,1,&yy);
61: jac->x = *xx;
62: jac->b = *yy;
63: PetscFree(xx);
64: PetscFree(yy);
65: }
66: if (!jac->R && !jac->P) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Must set restriction or interpolation of PCGALERKIN with PCGalerkinSetRestriction()/Interpolation()");
67: /* should check here that sizes of R/P match size of a */
69: return(0);
70: }
72: static PetscErrorCode PCReset_Galerkin(PC pc)
73: {
74: PC_Galerkin *jac = (PC_Galerkin*)pc->data;
78: MatDestroy(&jac->R);
79: MatDestroy(&jac->P);
80: VecDestroy(&jac->x);
81: VecDestroy(&jac->b);
82: KSPReset(jac->ksp);
83: return(0);
84: }
86: static PetscErrorCode PCDestroy_Galerkin(PC pc)
87: {
88: PC_Galerkin *jac = (PC_Galerkin*)pc->data;
92: PCReset_Galerkin(pc);
93: KSPDestroy(&jac->ksp);
94: PetscFree(pc->data);
95: return(0);
96: }
98: static PetscErrorCode PCView_Galerkin(PC pc,PetscViewer viewer)
99: {
100: PC_Galerkin *jac = (PC_Galerkin*)pc->data;
102: PetscBool iascii;
105: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
106: if (iascii) {
107: PetscViewerASCIIPrintf(viewer," KSP on Galerkin follow\n");
108: PetscViewerASCIIPrintf(viewer," ---------------------------------\n");
109: }
110: KSPView(jac->ksp,viewer);
111: return(0);
112: }
114: static PetscErrorCode PCGalerkinGetKSP_Galerkin(PC pc,KSP *ksp)
115: {
116: PC_Galerkin *jac = (PC_Galerkin*)pc->data;
119: *ksp = jac->ksp;
120: return(0);
121: }
123: static PetscErrorCode PCGalerkinSetRestriction_Galerkin(PC pc,Mat R)
124: {
125: PC_Galerkin *jac = (PC_Galerkin*)pc->data;
129: PetscObjectReference((PetscObject)R);
130: MatDestroy(&jac->R);
131: jac->R = R;
132: return(0);
133: }
135: static PetscErrorCode PCGalerkinSetInterpolation_Galerkin(PC pc,Mat P)
136: {
137: PC_Galerkin *jac = (PC_Galerkin*)pc->data;
141: PetscObjectReference((PetscObject)P);
142: MatDestroy(&jac->P);
143: jac->P = P;
144: return(0);
145: }
147: static PetscErrorCode PCGalerkinSetComputeSubmatrix_Galerkin(PC pc,PetscErrorCode (*computeAsub)(PC,Mat,Mat,Mat*,void*),void *ctx)
148: {
149: PC_Galerkin *jac = (PC_Galerkin*)pc->data;
152: jac->computeasub = computeAsub;
153: jac->computeasub_ctx = ctx;
154: return(0);
155: }
157: /* -------------------------------------------------------------------------------- */
158: /*@
159: PCGalerkinSetRestriction - Sets the restriction operator for the "Galerkin-type" preconditioner
161: Logically Collective on PC
163: Input Parameter:
164: + pc - the preconditioner context
165: - R - the restriction operator
167: Notes:
168: Either this or PCGalerkinSetInterpolation() or both must be called
170: Level: Intermediate
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:
196: Either this or PCGalerkinSetRestriction() or both must be called
198: Level: Intermediate
200: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PCGALERKIN,
201: PCGalerkinSetRestriction(), PCGalerkinGetKSP()
203: @*/
204: PetscErrorCode PCGalerkinSetInterpolation(PC pc,Mat P)
205: {
210: PetscTryMethod(pc,"PCGalerkinSetInterpolation_C",(PC,Mat),(pc,P));
211: return(0);
212: }
214: /*@
215: PCGalerkinSetComputeSubmatrix - Provide a routine that will be called to compute the Galerkin submatrix
217: Logically Collective
219: Input Parameter:
220: + pc - the preconditioner context
221: . computeAsub - routine that computes the submatrix from the global matrix
222: - ctx - context used by the routine, or NULL
224: Calling sequence of computeAsub:
225: $ computeAsub(PC pc,Mat A, Mat Ap, Mat *cAP,void *ctx);
227: + PC - the Galerkin PC
228: . A - the matrix in the Galerkin PC
229: . Ap - the computed submatrix from any previous computation, if NULL it has not previously been computed
230: . cAp - the submatrix computed by this routine
231: - ctx - optional user-defined function context
233: Level: Intermediate
235: Notes:
236: 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:
243: If the user does not call this routine nor call PCGalerkinGetKSP() and KSPSetOperators() then PCGalerkin could
244: could automatically compute the submatrix via calls to MatGalerkin() or MatRARt()
246: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PCGALERKIN,
247: PCGalerkinSetRestriction(), PCGalerkinSetInterpolation(), PCGalerkinGetKSP()
249: @*/
250: PetscErrorCode PCGalerkinSetComputeSubmatrix(PC pc,PetscErrorCode (*computeAsub)(PC,Mat,Mat,Mat*,void*),void *ctx)
251: {
256: PetscTryMethod(pc,"PCGalerkinSetComputeSubmatrix_C",(PC,PetscErrorCode (*)(PC,Mat,Mat,Mat*,void*),void*),(pc,computeAsub,ctx));
257: return(0);
258: }
260: /*@
261: PCGalerkinGetKSP - Gets the KSP object in the Galerkin PC.
263: Not Collective
265: Input Parameter:
266: . pc - the preconditioner context
268: Output Parameters:
269: . ksp - the KSP object
271: Level: Intermediate
273: Notes:
274: 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: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PCGALERKIN,
278: PCGalerkinSetRestriction(), PCGalerkinSetInterpolation(), PCGalerkinSetComputeSubmatrix()
280: @*/
281: PetscErrorCode PCGalerkinGetKSP(PC pc,KSP *ksp)
282: {
288: PetscUseMethod(pc,"PCGalerkinGetKSP_C",(PC,KSP*),(pc,ksp));
289: return(0);
290: }
292: static PetscErrorCode PCSetFromOptions_Galerkin(PetscOptionItems *PetscOptionsObject,PC pc)
293: {
294: PC_Galerkin *jac = (PC_Galerkin*)pc->data;
296: const char *prefix;
297: PetscBool flg;
300: KSPGetOptionsPrefix(jac->ksp,&prefix);
301: PetscStrendswith(prefix,"galerkin_",&flg);
302: if (!flg) {
303: PCGetOptionsPrefix(pc,&prefix);
304: KSPSetOptionsPrefix(jac->ksp,prefix);
305: KSPAppendOptionsPrefix(jac->ksp,"galerkin_");
306: }
308: PetscOptionsHead(PetscOptionsObject,"Galerkin options");
309: if (jac->ksp) {
310: KSPSetFromOptions(jac->ksp);
311: }
312: PetscOptionsTail();
313: return(0);
314: }
316: /* -------------------------------------------------------------------------------------------*/
318: /*MC
319: PCGALERKIN - Build (part of) a preconditioner by P S R (where P is often R^T)
321: $ Use PCGalerkinSetRestriction(pc,R) and/or PCGalerkinSetInterpolation(pc,P) followed by
322: $ PCGalerkinGetKSP(pc,&ksp); KSPSetOperators(ksp,A,....)
324: Level: intermediate
326: Developer Note: If KSPSetOperators() has not been called on the inner KSP then PCGALERKIN could use MatRARt() or MatPtAP() to compute
327: the operators automatically.
328: Should there be a prefix for the inner KSP.
329: There is no KSPSetFromOptions_Galerkin() that calls KSPSetFromOptions() on the inner KSP
331: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PC,
332: PCSHELL, PCKSP, PCGalerkinSetRestriction(), PCGalerkinSetInterpolation(), PCGalerkinGetKSP()
334: M*/
336: PETSC_EXTERN PetscErrorCode PCCreate_Galerkin(PC pc)
337: {
339: PC_Galerkin *jac;
342: PetscNewLog(pc,&jac);
344: pc->ops->apply = PCApply_Galerkin;
345: pc->ops->setup = PCSetUp_Galerkin;
346: pc->ops->reset = PCReset_Galerkin;
347: pc->ops->destroy = PCDestroy_Galerkin;
348: pc->ops->view = PCView_Galerkin;
349: pc->ops->setfromoptions = PCSetFromOptions_Galerkin;
350: pc->ops->applyrichardson = NULL;
352: KSPCreate(PetscObjectComm((PetscObject)pc),&jac->ksp);
353: KSPSetErrorIfNotConverged(jac->ksp,pc->erroriffailure);
354: PetscObjectIncrementTabLevel((PetscObject)jac->ksp,(PetscObject)pc,1);
356: pc->data = (void*)jac;
358: PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinSetRestriction_C",PCGalerkinSetRestriction_Galerkin);
359: PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinSetInterpolation_C",PCGalerkinSetInterpolation_Galerkin);
360: PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinGetKSP_C",PCGalerkinGetKSP_Galerkin);
361: PetscObjectComposeFunction((PetscObject)pc,"PCGalerkinSetComputeSubmatrix_C",PCGalerkinSetComputeSubmatrix_Galerkin);
362: return(0);
363: }