Actual source code: sinvert.c
slepc-3.22.2 2024-12-02
1: /*
2: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3: SLEPc - Scalable Library for Eigenvalue Problem Computations
4: Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain
6: This file is part of SLEPc.
7: SLEPc is distributed under a 2-clause BSD license (see LICENSE).
8: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
9: */
10: /*
11: Implements the shift-and-invert technique for eigenvalue problems
12: */
14: #include <slepc/private/stimpl.h>
16: static PetscErrorCode STBackTransform_Sinvert(ST st,PetscInt n,PetscScalar *eigr,PetscScalar *eigi)
17: {
18: PetscInt j;
19: #if !defined(PETSC_USE_COMPLEX)
20: PetscScalar t;
21: #endif
23: PetscFunctionBegin;
24: #if !defined(PETSC_USE_COMPLEX)
25: for (j=0;j<n;j++) {
26: if (eigi[j] == 0) eigr[j] = 1.0 / eigr[j] + st->sigma;
27: else {
28: t = eigr[j] * eigr[j] + eigi[j] * eigi[j];
29: eigr[j] = eigr[j] / t + st->sigma;
30: eigi[j] = - eigi[j] / t;
31: }
32: }
33: #else
34: for (j=0;j<n;j++) {
35: eigr[j] = 1.0 / eigr[j] + st->sigma;
36: }
37: #endif
38: PetscFunctionReturn(PETSC_SUCCESS);
39: }
41: static PetscErrorCode STPostSolve_Sinvert(ST st)
42: {
43: PetscFunctionBegin;
44: if (st->matmode == ST_MATMODE_INPLACE) {
45: if (st->nmat>1) PetscCall(MatAXPY(st->A[0],st->sigma,st->A[1],st->str));
46: else PetscCall(MatShift(st->A[0],st->sigma));
47: st->Astate[0] = ((PetscObject)st->A[0])->state;
48: st->state = ST_STATE_INITIAL;
49: st->opready = PETSC_FALSE;
50: }
51: PetscFunctionReturn(PETSC_SUCCESS);
52: }
54: /*
55: Operator (sinvert):
56: Op P M
57: if nmat=1: (A-sI)^-1 A-sI NULL
58: if nmat=2: (A-sB)^-1 B A-sB B
59: */
60: static PetscErrorCode STComputeOperator_Sinvert(ST st)
61: {
62: PetscFunctionBegin;
63: /* if the user did not set the shift, use the target value */
64: if (!st->sigma_set) st->sigma = st->defsigma;
65: PetscCall(PetscObjectReference((PetscObject)st->A[1]));
66: PetscCall(MatDestroy(&st->T[0]));
67: st->T[0] = st->A[1];
68: PetscCall(STMatMAXPY_Private(st,-st->sigma,0.0,0,NULL,PetscNot(st->state==ST_STATE_UPDATED),PETSC_FALSE,&st->T[1]));
69: PetscCall(PetscObjectReference((PetscObject)st->T[1]));
70: PetscCall(MatDestroy(&st->P));
71: st->P = st->T[1];
72: st->M = (st->nmat>1)? st->T[0]: NULL;
73: if (st->Psplit) { /* build custom preconditioner from the split matrices */
74: PetscCall(STMatMAXPY_Private(st,-st->sigma,0.0,0,NULL,PETSC_TRUE,PETSC_TRUE,&st->Pmat));
75: }
76: PetscFunctionReturn(PETSC_SUCCESS);
77: }
79: static PetscErrorCode STSetUp_Sinvert(ST st)
80: {
81: PetscInt k,nc,nmat=st->nmat,nsub;
82: PetscScalar *coeffs=NULL;
83: PetscBool islu;
84: KSP *subksp;
85: PC pc,pcsub;
86: Mat A00;
87: MatType type;
88: PetscBool flg;
89: char str[64];
91: PetscFunctionBegin;
92: if (nmat>1) PetscCall(STSetWorkVecs(st,1));
93: /* if the user did not set the shift, use the target value */
94: if (!st->sigma_set) st->sigma = st->defsigma;
95: if (nmat>2) { /* set-up matrices for polynomial eigenproblems */
96: if (st->transform) {
97: nc = (nmat*(nmat+1))/2;
98: PetscCall(PetscMalloc1(nc,&coeffs));
99: /* Compute coeffs */
100: PetscCall(STCoeffs_Monomial(st,coeffs));
101: /* T[0] = A_n */
102: k = nmat-1;
103: PetscCall(PetscObjectReference((PetscObject)st->A[k]));
104: PetscCall(MatDestroy(&st->T[0]));
105: st->T[0] = st->A[k];
106: for (k=1;k<nmat;k++) PetscCall(STMatMAXPY_Private(st,nmat>2?st->sigma:-st->sigma,0.0,nmat-k-1,coeffs?coeffs+(k*(k+1))/2:NULL,PetscNot(st->state==ST_STATE_UPDATED),PETSC_FALSE,&st->T[k]));
107: PetscCall(PetscFree(coeffs));
108: PetscCall(PetscObjectReference((PetscObject)st->T[nmat-1]));
109: PetscCall(MatDestroy(&st->P));
110: st->P = st->T[nmat-1];
111: if (st->Psplit) { /* build custom preconditioner from the split matrices */
112: PetscCall(STMatMAXPY_Private(st,st->sigma,0.0,0,coeffs?coeffs+((nmat-1)*nmat)/2:NULL,PETSC_TRUE,PETSC_TRUE,&st->Pmat));
113: }
114: PetscCall(ST_KSPSetOperators(st,st->P,st->Pmat?st->Pmat:st->P));
115: } else {
116: for (k=0;k<nmat;k++) {
117: PetscCall(PetscObjectReference((PetscObject)st->A[k]));
118: PetscCall(MatDestroy(&st->T[k]));
119: st->T[k] = st->A[k];
120: }
121: }
122: }
123: if (st->structured) {
124: /* ./ex55 -st_type sinvert -eps_target 0 -eps_target_magnitude
125: -st_ksp_type preonly -st_pc_type fieldsplit
126: -st_fieldsplit_0_ksp_type preonly -st_fieldsplit_0_pc_type lu
127: -st_fieldsplit_1_ksp_type preonly -st_fieldsplit_1_pc_type lu
128: -st_pc_fieldsplit_type schur -st_pc_fieldsplit_schur_fact_type full
129: -st_pc_fieldsplit_schur_precondition full */
130: PetscCall(KSPGetPC(st->ksp,&pc));
131: PetscCall(PetscObjectTypeCompare((PetscObject)pc,PCLU,&islu));
132: if (islu) { /* assume PCLU means the user has not set any options */
133: PetscCall(KSPSetType(st->ksp,KSPPREONLY));
134: PetscCall(PCSetType(pc,PCFIELDSPLIT));
135: PetscCall(PCFieldSplitSetType(pc,PC_COMPOSITE_SCHUR));
136: PetscCall(PCFieldSplitSetSchurFactType(pc,PC_FIELDSPLIT_SCHUR_FACT_FULL));
137: PetscCall(PCFieldSplitSetSchurPre(pc,PC_FIELDSPLIT_SCHUR_PRE_FULL,NULL));
138: /* hack to set Mat type of Schur complement equal to A00, assumes default prefixes */
139: PetscCall(PetscOptionsHasName(((PetscObject)st)->options,((PetscObject)st)->prefix,"-st_fieldsplit_1_explicit_operator_mat_type",&flg));
140: if (!flg) {
141: PetscCall(MatNestGetSubMat(st->A[0],0,0,&A00));
142: PetscCall(MatGetType(A00,&type));
143: PetscCall(PetscSNPrintf(str,sizeof(str),"-%sst_fieldsplit_1_explicit_operator_mat_type %s",((PetscObject)st)->prefix?((PetscObject)st)->prefix:"",type));
144: PetscCall(PetscOptionsInsertString(((PetscObject)st)->options,str));
145: }
146: /* set preonly+lu on block solvers */
147: PetscCall(KSPSetUp(st->ksp));
148: PetscCall(PCFieldSplitGetSubKSP(pc,&nsub,&subksp));
149: PetscCall(KSPSetType(subksp[0],KSPPREONLY));
150: PetscCall(KSPGetPC(subksp[0],&pcsub));
151: PetscCall(PCSetType(pcsub,PCLU));
152: PetscCall(KSPSetType(subksp[1],KSPPREONLY));
153: PetscCall(KSPGetPC(subksp[1],&pcsub));
154: PetscCall(PCSetType(pcsub,PCLU));
155: PetscCall(PetscFree(subksp));
156: }
157: } else {
158: if (st->P) PetscCall(KSPSetUp(st->ksp));
159: }
160: PetscFunctionReturn(PETSC_SUCCESS);
161: }
163: static PetscErrorCode STSetShift_Sinvert(ST st,PetscScalar newshift)
164: {
165: PetscInt nmat=PetscMax(st->nmat,2),k,nc;
166: PetscScalar *coeffs=NULL;
168: PetscFunctionBegin;
169: if (st->transform) {
170: if (st->matmode == ST_MATMODE_COPY && nmat>2) {
171: nc = (nmat*(nmat+1))/2;
172: PetscCall(PetscMalloc1(nc,&coeffs));
173: /* Compute coeffs */
174: PetscCall(STCoeffs_Monomial(st,coeffs));
175: }
176: for (k=1;k<nmat;k++) PetscCall(STMatMAXPY_Private(st,nmat>2?newshift:-newshift,nmat>2?st->sigma:-st->sigma,nmat-k-1,coeffs?coeffs+(k*(k+1))/2:NULL,PETSC_FALSE,PETSC_FALSE,&st->T[k]));
177: if (st->matmode == ST_MATMODE_COPY && nmat>2) PetscCall(PetscFree(coeffs));
178: if (st->P!=st->T[nmat-1]) {
179: PetscCall(PetscObjectReference((PetscObject)st->T[nmat-1]));
180: PetscCall(MatDestroy(&st->P));
181: st->P = st->T[nmat-1];
182: }
183: if (st->Psplit) { /* build custom preconditioner from the split matrices */
184: PetscCall(STMatMAXPY_Private(st,nmat>2?newshift:-newshift,nmat>2?st->sigma:-st->sigma,0,coeffs?coeffs+((nmat-1)*nmat)/2:NULL,PETSC_FALSE,PETSC_TRUE,&st->Pmat));
185: }
186: }
187: if (st->P) {
188: PetscCall(ST_KSPSetOperators(st,st->P,st->Pmat?st->Pmat:st->P));
189: PetscCall(KSPSetUp(st->ksp));
190: }
191: PetscFunctionReturn(PETSC_SUCCESS);
192: }
194: SLEPC_EXTERN PetscErrorCode STCreate_Sinvert(ST st)
195: {
196: PetscFunctionBegin;
197: st->usesksp = PETSC_TRUE;
199: st->ops->apply = STApply_Generic;
200: st->ops->applytrans = STApplyTranspose_Generic;
201: st->ops->applyhermtrans = STApplyHermitianTranspose_Generic;
202: st->ops->backtransform = STBackTransform_Sinvert;
203: st->ops->setshift = STSetShift_Sinvert;
204: st->ops->getbilinearform = STGetBilinearForm_Default;
205: st->ops->setup = STSetUp_Sinvert;
206: st->ops->computeoperator = STComputeOperator_Sinvert;
207: st->ops->postsolve = STPostSolve_Sinvert;
208: st->ops->checknullspace = STCheckNullSpace_Default;
209: st->ops->setdefaultksp = STSetDefaultKSP_Default;
210: PetscFunctionReturn(PETSC_SUCCESS);
211: }