Actual source code: sinvert.c
slepc-3.21.1 2024-04-26
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;
82: PetscScalar *coeffs=NULL;
84: PetscFunctionBegin;
85: if (nmat>1) PetscCall(STSetWorkVecs(st,1));
86: /* if the user did not set the shift, use the target value */
87: if (!st->sigma_set) st->sigma = st->defsigma;
88: if (nmat>2) { /* set-up matrices for polynomial eigenproblems */
89: if (st->transform) {
90: nc = (nmat*(nmat+1))/2;
91: PetscCall(PetscMalloc1(nc,&coeffs));
92: /* Compute coeffs */
93: PetscCall(STCoeffs_Monomial(st,coeffs));
94: /* T[0] = A_n */
95: k = nmat-1;
96: PetscCall(PetscObjectReference((PetscObject)st->A[k]));
97: PetscCall(MatDestroy(&st->T[0]));
98: st->T[0] = st->A[k];
99: 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]));
100: PetscCall(PetscFree(coeffs));
101: PetscCall(PetscObjectReference((PetscObject)st->T[nmat-1]));
102: PetscCall(MatDestroy(&st->P));
103: st->P = st->T[nmat-1];
104: if (st->Psplit) { /* build custom preconditioner from the split matrices */
105: PetscCall(STMatMAXPY_Private(st,st->sigma,0.0,0,coeffs?coeffs+((nmat-1)*nmat)/2:NULL,PETSC_TRUE,PETSC_TRUE,&st->Pmat));
106: }
107: PetscCall(ST_KSPSetOperators(st,st->P,st->Pmat?st->Pmat:st->P));
108: } else {
109: for (k=0;k<nmat;k++) {
110: PetscCall(PetscObjectReference((PetscObject)st->A[k]));
111: PetscCall(MatDestroy(&st->T[k]));
112: st->T[k] = st->A[k];
113: }
114: }
115: }
116: if (st->P) PetscCall(KSPSetUp(st->ksp));
117: PetscFunctionReturn(PETSC_SUCCESS);
118: }
120: static PetscErrorCode STSetShift_Sinvert(ST st,PetscScalar newshift)
121: {
122: PetscInt nmat=PetscMax(st->nmat,2),k,nc;
123: PetscScalar *coeffs=NULL;
125: PetscFunctionBegin;
126: if (st->transform) {
127: if (st->matmode == ST_MATMODE_COPY && nmat>2) {
128: nc = (nmat*(nmat+1))/2;
129: PetscCall(PetscMalloc1(nc,&coeffs));
130: /* Compute coeffs */
131: PetscCall(STCoeffs_Monomial(st,coeffs));
132: }
133: 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]));
134: if (st->matmode == ST_MATMODE_COPY && nmat>2) PetscCall(PetscFree(coeffs));
135: if (st->P!=st->T[nmat-1]) {
136: PetscCall(PetscObjectReference((PetscObject)st->T[nmat-1]));
137: PetscCall(MatDestroy(&st->P));
138: st->P = st->T[nmat-1];
139: }
140: if (st->Psplit) { /* build custom preconditioner from the split matrices */
141: 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));
142: }
143: }
144: if (st->P) {
145: PetscCall(ST_KSPSetOperators(st,st->P,st->Pmat?st->Pmat:st->P));
146: PetscCall(KSPSetUp(st->ksp));
147: }
148: PetscFunctionReturn(PETSC_SUCCESS);
149: }
151: SLEPC_EXTERN PetscErrorCode STCreate_Sinvert(ST st)
152: {
153: PetscFunctionBegin;
154: st->usesksp = PETSC_TRUE;
156: st->ops->apply = STApply_Generic;
157: st->ops->applytrans = STApplyTranspose_Generic;
158: st->ops->applyhermtrans = STApplyHermitianTranspose_Generic;
159: st->ops->backtransform = STBackTransform_Sinvert;
160: st->ops->setshift = STSetShift_Sinvert;
161: st->ops->getbilinearform = STGetBilinearForm_Default;
162: st->ops->setup = STSetUp_Sinvert;
163: st->ops->computeoperator = STComputeOperator_Sinvert;
164: st->ops->postsolve = STPostSolve_Sinvert;
165: st->ops->checknullspace = STCheckNullSpace_Default;
166: st->ops->setdefaultksp = STSetDefaultKSP_Default;
167: PetscFunctionReturn(PETSC_SUCCESS);
168: }