Actual source code: pcksp.c
petsc-3.5.4 2015-05-23
2: #include <petsc-private/pcimpl.h>
3: #include <petscksp.h> /*I "petscksp.h" I*/
5: typedef struct {
6: KSP ksp;
7: PetscInt its; /* total number of iterations KSP uses */
8: } PC_KSP;
13: static PetscErrorCode PCKSPCreateKSP_KSP(PC pc)
14: {
16: const char *prefix;
17: PC_KSP *jac = (PC_KSP*)pc->data;
20: KSPCreate(PetscObjectComm((PetscObject)pc),&jac->ksp);
21: PetscObjectIncrementTabLevel((PetscObject)jac->ksp,(PetscObject)pc,1);
22: PCGetOptionsPrefix(pc,&prefix);
23: KSPSetOptionsPrefix(jac->ksp,prefix);
24: KSPAppendOptionsPrefix(jac->ksp,"ksp_");
25: return(0);
26: }
30: static PetscErrorCode PCApply_KSP(PC pc,Vec x,Vec y)
31: {
33: PetscInt its;
34: PC_KSP *jac = (PC_KSP*)pc->data;
37: KSPSetInitialGuessNonzero(jac->ksp,pc->nonzero_guess);
38: KSPSolve(jac->ksp,x,y);
39: KSPGetIterationNumber(jac->ksp,&its);
40: jac->its += its;
41: return(0);
42: }
46: static PetscErrorCode PCApplyTranspose_KSP(PC pc,Vec x,Vec y)
47: {
49: PetscInt its;
50: PC_KSP *jac = (PC_KSP*)pc->data;
53: KSPSolveTranspose(jac->ksp,x,y);
54: KSPGetIterationNumber(jac->ksp,&its);
55: jac->its += its;
56: return(0);
57: }
61: static PetscErrorCode PCSetUp_KSP(PC pc)
62: {
64: PC_KSP *jac = (PC_KSP*)pc->data;
65: Mat mat;
68: if (!jac->ksp) {PCKSPCreateKSP_KSP(pc);}
69: KSPSetFromOptions(jac->ksp);
70: if (pc->useAmat) mat = pc->mat;
71: else mat = pc->pmat;
73: KSPSetOperators(jac->ksp,mat,pc->pmat);
74: KSPSetUp(jac->ksp);
75: return(0);
76: }
78: /* Default destroy, if it has never been setup */
81: static PetscErrorCode PCReset_KSP(PC pc)
82: {
83: PC_KSP *jac = (PC_KSP*)pc->data;
87: if (jac->ksp) {KSPReset(jac->ksp);}
88: return(0);
89: }
93: static PetscErrorCode PCDestroy_KSP(PC pc)
94: {
95: PC_KSP *jac = (PC_KSP*)pc->data;
99: PCReset_KSP(pc);
100: KSPDestroy(&jac->ksp);
101: PetscFree(pc->data);
102: return(0);
103: }
107: static PetscErrorCode PCView_KSP(PC pc,PetscViewer viewer)
108: {
109: PC_KSP *jac = (PC_KSP*)pc->data;
111: PetscBool iascii;
114: if (!jac->ksp) {PCKSPCreateKSP_KSP(pc);}
115: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
116: if (iascii) {
117: if (pc->useAmat) {
118: PetscViewerASCIIPrintf(viewer,"Using Amat (not Pmat) as operator on inner solve\n");
119: }
120: PetscViewerASCIIPrintf(viewer,"KSP and PC on KSP preconditioner follow\n");
121: PetscViewerASCIIPrintf(viewer,"---------------------------------\n");
122: }
123: PetscViewerASCIIPushTab(viewer);
124: KSPView(jac->ksp,viewer);
125: PetscViewerASCIIPopTab(viewer);
126: if (iascii) {
127: PetscViewerASCIIPrintf(viewer,"---------------------------------\n");
128: }
129: return(0);
130: }
134: static PetscErrorCode PCKSPGetKSP_KSP(PC pc,KSP *ksp)
135: {
136: PC_KSP *jac = (PC_KSP*)pc->data;
140: if (!jac->ksp) {PCKSPCreateKSP_KSP(pc);}
141: *ksp = jac->ksp;
142: return(0);
143: }
147: /*@
148: PCKSPGetKSP - Gets the KSP context for a KSP PC.
150: Not Collective but KSP returned is parallel if PC was parallel
152: Input Parameter:
153: . pc - the preconditioner context
155: Output Parameters:
156: . ksp - the PC solver
158: Notes:
159: You must call KSPSetUp() before calling PCKSPGetKSP().
161: Level: advanced
163: .keywords: PC, KSP, get, context
164: @*/
165: PetscErrorCode PCKSPGetKSP(PC pc,KSP *ksp)
166: {
172: *ksp = NULL;
173: PetscTryMethod(pc,"PCKSPGetKSP_C",(PC,KSP*),(pc,ksp));
174: return(0);
175: }
177: /* ----------------------------------------------------------------------------------*/
179: /*MC
180: PCKSP - Defines a preconditioner that can consist of any KSP solver.
181: This allows, for example, embedding a Krylov method inside a preconditioner.
183: Options Database Key:
184: . -pc_use_amat - use the matrix that defines the linear system, Amat as the matrix for the
185: inner solver, otherwise by default it uses the matrix used to construct
186: the preconditioner, Pmat (see PCSetOperators())
188: Level: intermediate
190: Concepts: inner iteration
192: Notes: Using a Krylov method inside another Krylov method can be dangerous (you get divergence or
193: the incorrect answer) unless you use KSPFGMRES as the other Krylov method
195: Developer Notes: PCApply_KSP() uses the flag set by PCSetInitialGuessNonzero(), I think this is totally wrong, because it is then not
196: using this inner KSP as a preconditioner (that is a linear operator applied to some vector), it is actually just using
197: the inner KSP just like the outer KSP.
199: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PC,
200: PCSHELL, PCCOMPOSITE, PCSetUseAmat(), PCKSPGetKSP()
202: M*/
206: PETSC_EXTERN PetscErrorCode PCCreate_KSP(PC pc)
207: {
209: PC_KSP *jac;
212: PetscNewLog(pc,&jac);
214: pc->ops->apply = PCApply_KSP;
215: pc->ops->applytranspose = PCApplyTranspose_KSP;
216: pc->ops->setup = PCSetUp_KSP;
217: pc->ops->reset = PCReset_KSP;
218: pc->ops->destroy = PCDestroy_KSP;
219: pc->ops->setfromoptions = 0;
220: pc->ops->view = PCView_KSP;
221: pc->ops->applyrichardson = 0;
223: pc->data = (void*)jac;
226: jac->its = 0;
227: PetscObjectComposeFunction((PetscObject)pc,"PCKSPGetKSP_C",PCKSPGetKSP_KSP);
228: return(0);
229: }