Actual source code: shift.c
slepc-3.11.2 2019-07-30
1: /*
2: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3: SLEPc - Scalable Library for Eigenvalue Problem Computations
4: Copyright (c) 2002-2019, 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: Shift spectral transformation, applies (A + sigma I) as operator, or
12: inv(B)(A + sigma B) for generalized problems
13: */
15: #include <slepc/private/stimpl.h>
17: PetscErrorCode STApply_Shift(ST st,Vec x,Vec y)
18: {
22: if (st->nmat>1) {
23: /* generalized eigenproblem: y = B^-1 (A - sB) x */
24: MatMult(st->T[0],x,st->work[0]);
25: STMatSolve(st,st->work[0],y);
26: } else {
27: /* standard eigenproblem: y = (A - sI) x */
28: MatMult(st->T[0],x,y);
29: }
30: return(0);
31: }
33: PetscErrorCode STApplyTranspose_Shift(ST st,Vec x,Vec y)
34: {
38: if (st->nmat>1) {
39: /* generalized eigenproblem: y = (A - sB)^T B^-T x */
40: STMatSolveTranspose(st,x,st->work[0]);
41: MatMultTranspose(st->T[0],st->work[0],y);
42: } else {
43: /* standard eigenproblem: y = (A^T - sI) x */
44: MatMultTranspose(st->T[0],x,y);
45: }
46: return(0);
47: }
49: PetscErrorCode STBackTransform_Shift(ST st,PetscInt n,PetscScalar *eigr,PetscScalar *eigi)
50: {
51: PetscInt j;
54: for (j=0;j<n;j++) {
55: eigr[j] += st->sigma;
56: }
57: return(0);
58: }
60: PetscErrorCode STPostSolve_Shift(ST st)
61: {
65: if (st->shift_matrix == ST_MATMODE_INPLACE) {
66: if (st->nmat>1) {
67: MatAXPY(st->A[0],st->sigma,st->A[1],st->str);
68: } else {
69: MatShift(st->A[0],st->sigma);
70: }
71: st->Astate[0] = ((PetscObject)st->A[0])->state;
72: st->state = ST_STATE_INITIAL;
73: }
74: return(0);
75: }
77: PetscErrorCode STSetUp_Shift(ST st)
78: {
80: PetscInt k,nc,nmat=PetscMax(st->nmat,2);
81: PetscScalar *coeffs=NULL;
84: if (st->nmat>1) {
85: STSetWorkVecs(st,1);
86: }
87: if (nmat<3 || st->transform) {
88: if (nmat>2) {
89: nc = (nmat*(nmat+1))/2;
90: PetscMalloc1(nc,&coeffs);
91: /* Compute coeffs */
92: STCoeffs_Monomial(st,coeffs);
93: }
94: /* T[n] = A_n */
95: k = nmat-1;
96: PetscObjectReference((PetscObject)st->A[k]);
97: MatDestroy(&st->T[k]);
98: st->T[k] = st->A[k];
99: for (k=0;k<nmat-1;k++) {
100: STMatMAXPY_Private(st,nmat>2?st->sigma:-st->sigma,0.0,k,coeffs?coeffs+((nmat-k)*(nmat-k-1))/2:NULL,PetscNot(st->state==ST_STATE_UPDATED),&st->T[k]);
101: }
102: if (nmat>2) { PetscFree(coeffs); }
103: } else {
104: for (k=0;k<nmat;k++) {
105: PetscObjectReference((PetscObject)st->A[k]);
106: MatDestroy(&st->T[k]);
107: st->T[k] = st->A[k];
108: }
109: }
110: if (nmat>=2 && st->transform) {
111: PetscObjectReference((PetscObject)st->T[nmat-1]);
112: MatDestroy(&st->P);
113: st->P = st->T[nmat-1];
114: }
115: if (st->P) {
116: if (!st->ksp) { STGetKSP(st,&st->ksp); }
117: STCheckFactorPackage(st);
118: KSPSetOperators(st->ksp,st->P,st->P);
119: KSPSetUp(st->ksp);
120: }
121: return(0);
122: }
124: PetscErrorCode STSetShift_Shift(ST st,PetscScalar newshift)
125: {
127: PetscInt k,nc,nmat=PetscMax(st->nmat,2);
128: PetscScalar *coeffs=NULL;
131: if (st->transform) {
132: if (st->shift_matrix == ST_MATMODE_COPY && nmat>2) {
133: nc = (nmat*(nmat+1))/2;
134: PetscMalloc1(nc,&coeffs);
135: /* Compute coeffs */
136: STCoeffs_Monomial(st,coeffs);
137: }
138: for (k=0;k<nmat-1;k++) {
139: STMatMAXPY_Private(st,nmat>2?newshift:-newshift,nmat>2?st->sigma:-st->sigma,k,coeffs?coeffs+((nmat-k)*(nmat-k-1))/2:NULL,PETSC_FALSE,&st->T[k]);
140: }
141: if (st->shift_matrix == ST_MATMODE_COPY && nmat>2) {
142: PetscFree(coeffs);
143: }
144: }
145: return(0);
146: }
148: SLEPC_EXTERN PetscErrorCode STCreate_Shift(ST st)
149: {
151: st->ops->apply = STApply_Shift;
152: st->ops->getbilinearform = STGetBilinearForm_Default;
153: st->ops->applytrans = STApplyTranspose_Shift;
154: st->ops->postsolve = STPostSolve_Shift;
155: st->ops->backtransform = STBackTransform_Shift;
156: st->ops->setup = STSetUp_Shift;
157: st->ops->setshift = STSetShift_Shift;
158: st->ops->setdefaultksp = STSetDefaultKSP_Default;
159: return(0);
160: }