Actual source code: lcd.c
1: #include <../src/ksp/ksp/impls/lcd/lcdimpl.h>
3: static PetscErrorCode KSPSetUp_LCD(KSP ksp)
4: {
5: KSP_LCD *lcd = (KSP_LCD *)ksp->data;
6: PetscInt restart = lcd->restart;
8: PetscFunctionBegin;
9: /* get work vectors needed by LCD */
10: PetscCall(KSPSetWorkVecs(ksp, 2));
12: PetscCall(VecDuplicateVecs(ksp->work[0], restart + 1, &lcd->P));
13: PetscCall(VecDuplicateVecs(ksp->work[0], restart + 1, &lcd->Q));
14: PetscFunctionReturn(PETSC_SUCCESS);
15: }
17: /* KSPSolve_LCD - This routine actually applies the left conjugate
18: direction method
20: Input Parameter:
21: . ksp - the Krylov space object that was set to use LCD, by, for
22: example, KSPCreate(MPI_Comm,KSP *ksp); KSPSetType(ksp,KSPLCD);
24: Output Parameter:
25: . its - number of iterations used
27: */
28: static PetscErrorCode KSPSolve_LCD(KSP ksp)
29: {
30: PetscInt it, j, max_k;
31: PetscScalar alfa, beta, num, den, mone;
32: PetscReal rnorm = 0.0;
33: Vec X, B, R, Z;
34: KSP_LCD *lcd;
35: Mat Amat, Pmat;
37: PetscFunctionBegin;
38: lcd = (KSP_LCD *)ksp->data;
39: X = ksp->vec_sol;
40: B = ksp->vec_rhs;
41: R = ksp->work[0];
42: Z = ksp->work[1];
43: max_k = lcd->restart;
44: mone = -1;
46: PetscCall(PCGetOperators(ksp->pc, &Amat, &Pmat));
48: ksp->its = 0;
49: if (!ksp->guess_zero) {
50: PetscCall(KSP_MatMult(ksp, Amat, X, Z)); /* z <- b - Ax */
51: PetscCall(VecAYPX(Z, mone, B));
52: } else {
53: PetscCall(VecCopy(B, Z)); /* z <- b (x is 0) */
54: }
56: PetscCall(KSP_PCApply(ksp, Z, R)); /* r <- M^-1z */
57: if (ksp->normtype != KSP_NORM_NONE) {
58: PetscCall(VecNorm(R, NORM_2, &rnorm));
59: KSPCheckNorm(ksp, rnorm);
60: }
61: PetscCall(KSPLogResidualHistory(ksp, rnorm));
62: PetscCall(KSPMonitor(ksp, 0, rnorm));
63: ksp->rnorm = rnorm;
65: /* test for convergence */
66: PetscCall((*ksp->converged)(ksp, 0, rnorm, &ksp->reason, ksp->cnvP));
67: if (ksp->reason) PetscFunctionReturn(PETSC_SUCCESS);
69: PetscCall(VecCopy(R, lcd->P[0]));
71: while (!ksp->reason && ksp->its < ksp->max_it) {
72: it = 0;
73: PetscCall(KSP_MatMult(ksp, Amat, lcd->P[it], Z));
74: PetscCall(KSP_PCApply(ksp, Z, lcd->Q[it]));
76: while (!ksp->reason && it < max_k && ksp->its < ksp->max_it) {
77: ksp->its++;
78: PetscCall(VecDot(lcd->P[it], R, &num));
79: PetscCall(VecDot(lcd->P[it], lcd->Q[it], &den));
80: KSPCheckDot(ksp, den);
81: alfa = num / den;
82: PetscCall(VecAXPY(X, alfa, lcd->P[it]));
83: PetscCall(VecAXPY(R, -alfa, lcd->Q[it]));
84: if (ksp->normtype != KSP_NORM_NONE) {
85: PetscCall(VecNorm(R, NORM_2, &rnorm));
86: KSPCheckNorm(ksp, rnorm);
87: }
89: ksp->rnorm = rnorm;
90: PetscCall(KSPLogResidualHistory(ksp, rnorm));
91: PetscCall(KSPMonitor(ksp, ksp->its, rnorm));
92: PetscCall((*ksp->converged)(ksp, ksp->its, rnorm, &ksp->reason, ksp->cnvP));
94: if (ksp->reason) break;
96: PetscCall(VecCopy(R, lcd->P[it + 1]));
97: PetscCall(KSP_MatMult(ksp, Amat, lcd->P[it + 1], Z));
98: PetscCall(KSP_PCApply(ksp, Z, lcd->Q[it + 1]));
100: for (j = 0; j <= it; j++) {
101: PetscCall(VecDot(lcd->P[j], lcd->Q[it + 1], &num));
102: KSPCheckDot(ksp, num);
103: PetscCall(VecDot(lcd->P[j], lcd->Q[j], &den));
104: beta = -num / den;
105: PetscCall(VecAXPY(lcd->P[it + 1], beta, lcd->P[j]));
106: PetscCall(VecAXPY(lcd->Q[it + 1], beta, lcd->Q[j]));
107: }
108: it++;
109: }
110: PetscCall(VecCopy(lcd->P[it], lcd->P[0]));
111: }
112: if (ksp->its >= ksp->max_it && !ksp->reason) ksp->reason = KSP_DIVERGED_ITS;
113: PetscCall(VecCopy(X, ksp->vec_sol));
114: PetscFunctionReturn(PETSC_SUCCESS);
115: }
116: /*
117: KSPDestroy_LCD - Frees all memory space used by the Krylov method
119: */
120: static PetscErrorCode KSPReset_LCD(KSP ksp)
121: {
122: KSP_LCD *lcd = (KSP_LCD *)ksp->data;
124: PetscFunctionBegin;
125: if (lcd->P) PetscCall(VecDestroyVecs(lcd->restart + 1, &lcd->P));
126: if (lcd->Q) PetscCall(VecDestroyVecs(lcd->restart + 1, &lcd->Q));
127: PetscFunctionReturn(PETSC_SUCCESS);
128: }
130: static PetscErrorCode KSPDestroy_LCD(KSP ksp)
131: {
132: PetscFunctionBegin;
133: PetscCall(KSPReset_LCD(ksp));
134: PetscCall(PetscFree(ksp->data));
135: PetscFunctionReturn(PETSC_SUCCESS);
136: }
138: /*
139: KSPView_LCD - Prints information about the current Krylov method being used
141: Currently this only prints information to a file (or stdout) about the
142: symmetry of the problem. If your Krylov method has special options or
143: flags that information should be printed here.
145: */
146: static PetscErrorCode KSPView_LCD(KSP ksp, PetscViewer viewer)
147: {
148: KSP_LCD *lcd = (KSP_LCD *)ksp->data;
149: PetscBool isascii;
151: PetscFunctionBegin;
152: PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
153: if (isascii) {
154: PetscCall(PetscViewerASCIIPrintf(viewer, " restart=%" PetscInt_FMT "\n", lcd->restart));
155: PetscCall(PetscViewerASCIIPrintf(viewer, " happy breakdown tolerance=%g\n", (double)lcd->haptol));
156: }
157: PetscFunctionReturn(PETSC_SUCCESS);
158: }
160: /*
161: KSPSetFromOptions_LCD - Checks the options database for options related to the
162: LCD method.
163: */
164: static PetscErrorCode KSPSetFromOptions_LCD(KSP ksp, PetscOptionItems PetscOptionsObject)
165: {
166: PetscBool flg;
167: KSP_LCD *lcd = (KSP_LCD *)ksp->data;
169: PetscFunctionBegin;
170: PetscOptionsHeadBegin(PetscOptionsObject, "KSP LCD options");
171: PetscCall(PetscOptionsBoundedInt("-ksp_lcd_restart", "Number of vectors conjugate", "KSPLCDSetRestart", lcd->restart, &lcd->restart, &flg, 1));
172: PetscCall(PetscOptionsBoundedReal("-ksp_lcd_haptol", "Tolerance for exact convergence (happy breakdown)", "KSPLCDSetHapTol", lcd->haptol, &lcd->haptol, &flg, 0.0));
173: PetscFunctionReturn(PETSC_SUCCESS);
174: }
176: /*MC
177: KSPLCD - Implements the LCD (left conjugate direction) method
179: Options Database Keys:
180: + -ksp_lcd_restart - number of vectors conjugate
181: - -ksp_lcd_haptol - tolerance for exact convergence (happy breakdown)
183: Level: beginner
185: Notes:
186: Support only for left preconditioning
188: See {cite}`yuan2004semi`, {cite}`dai2004study`, {cite}`catabriga2004evaluating`, and {cite}`catabriga2006performance`
190: Contributed by:
191: Lucia Catabriga <luciac@ices.utexas.edu>
193: .seealso: [](ch_ksp), `KSPCreate()`, `KSPSetType()`, `KSPType`, `KSP`, `KSPCG`,
194: `KSPCGSetType()`, `KSPLCDSetRestart()`, `KSPLCDSetHapTol()`
195: M*/
197: PETSC_EXTERN PetscErrorCode KSPCreate_LCD(KSP ksp)
198: {
199: KSP_LCD *lcd;
201: PetscFunctionBegin;
202: PetscCall(PetscNew(&lcd));
203: ksp->data = (void *)lcd;
204: PetscCall(KSPSetSupportedNorm(ksp, KSP_NORM_NONE, PC_LEFT, 1));
205: PetscCall(KSPSetSupportedNorm(ksp, KSP_NORM_PRECONDITIONED, PC_LEFT, 3));
206: lcd->restart = 30;
207: lcd->haptol = 1.0e-30;
209: /*
210: Sets the functions that are associated with this data structure
211: (in C++ this is the same as defining virtual functions)
212: */
213: ksp->ops->setup = KSPSetUp_LCD;
214: ksp->ops->solve = KSPSolve_LCD;
215: ksp->ops->reset = KSPReset_LCD;
216: ksp->ops->destroy = KSPDestroy_LCD;
217: ksp->ops->view = KSPView_LCD;
218: ksp->ops->setfromoptions = KSPSetFromOptions_LCD;
219: ksp->ops->buildsolution = KSPBuildSolutionDefault;
220: ksp->ops->buildresidual = KSPBuildResidualDefault;
221: PetscFunctionReturn(PETSC_SUCCESS);
222: }