Actual source code: svdlapack.c
1: /*
2: This file implements a wrapper to the LAPACK SVD subroutines.
4: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
5: SLEPc - Scalable Library for Eigenvalue Problem Computations
6: Copyright (c) 2002-2013, Universitat Politecnica de Valencia, Spain
8: This file is part of SLEPc.
10: SLEPc is free software: you can redistribute it and/or modify it under the
11: terms of version 3 of the GNU Lesser General Public License as published by
12: the Free Software Foundation.
14: SLEPc is distributed in the hope that it will be useful, but WITHOUT ANY
15: WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
16: FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
17: more details.
19: You should have received a copy of the GNU Lesser General Public License
20: along with SLEPc. If not, see <http://www.gnu.org/licenses/>.
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22: */
24: #include <slepc-private/svdimpl.h> /*I "slepcsvd.h" I*/
25: #include <slepcblaslapack.h>
29: PetscErrorCode SVDSetUp_LAPACK(SVD svd)
30: {
32: PetscInt M,N;
35: SVDMatGetSize(svd,&M,&N);
36: svd->ncv = N;
37: if (svd->mpd) { PetscInfo(svd,"Warning: parameter mpd ignored\n"); }
38: svd->max_it = 1;
39: if (svd->ncv!=svd->n) {
40: VecDuplicateVecs(svd->tl,svd->ncv,&svd->U);
41: PetscLogObjectParents(svd,svd->ncv,svd->U);
42: }
43: DSSetType(svd->ds,DSSVD);
44: DSAllocate(svd->ds,PetscMax(M,N));
45: return(0);
46: }
50: PetscErrorCode SVDSolve_LAPACK(SVD svd)
51: {
53: PetscInt M,N,n,i,j,k,ld;
54: Mat mat;
55: PetscScalar *pU,*pVT,*pmat,*pu,*pv,*A,*w;
58: DSGetLeadingDimension(svd->ds,&ld);
59: MatConvert(svd->OP,MATSEQDENSE,MAT_INITIAL_MATRIX,&mat);
60: MatGetSize(mat,&M,&N);
61: DSSetDimensions(svd->ds,M,N,0,0);
62: MatDenseGetArray(mat,&pmat);
63: DSGetArray(svd->ds,DS_MAT_A,&A);
64: for (i=0;i<M;i++)
65: for (j=0;j<N;j++)
66: A[i+j*ld] = pmat[i+j*M];
67: DSRestoreArray(svd->ds,DS_MAT_A,&A);
68: MatDenseRestoreArray(mat,&pmat);
69: DSSetState(svd->ds,DS_STATE_RAW);
71: n = PetscMin(M,N);
72: PetscMalloc(sizeof(PetscScalar)*n,&w);
73: DSSolve(svd->ds,w,NULL);
74: DSSort(svd->ds,w,NULL,NULL,NULL,NULL);
76: /* copy singular vectors */
77: DSGetArray(svd->ds,DS_MAT_U,&pU);
78: DSGetArray(svd->ds,DS_MAT_VT,&pVT);
79: for (i=0;i<n;i++) {
80: if (svd->which == SVD_SMALLEST) k = n - i - 1;
81: else k = i;
82: svd->sigma[k] = PetscRealPart(w[i]);
83: VecGetArray(svd->U[k],&pu);
84: VecGetArray(svd->V[k],&pv);
85: if (M>=N) {
86: for (j=0;j<M;j++) pu[j] = pU[i*ld+j];
87: for (j=0;j<N;j++) pv[j] = PetscConj(pVT[j*ld+i]);
88: } else {
89: for (j=0;j<N;j++) pu[j] = PetscConj(pVT[j*ld+i]);
90: for (j=0;j<M;j++) pv[j] = pU[i*ld+j];
91: }
92: VecRestoreArray(svd->U[k],&pu);
93: VecRestoreArray(svd->V[k],&pv);
94: }
95: DSRestoreArray(svd->ds,DS_MAT_U,&pU);
96: DSRestoreArray(svd->ds,DS_MAT_VT,&pVT);
98: svd->nconv = n;
99: svd->reason = SVD_CONVERGED_TOL;
101: MatDestroy(&mat);
102: PetscFree(w);
103: return(0);
104: }
108: PetscErrorCode SVDReset_LAPACK(SVD svd)
109: {
113: VecDestroyVecs(svd->n,&svd->U);
114: return(0);
115: }
119: PetscErrorCode SVDDestroy_LAPACK(SVD svd)
120: {
124: PetscFree(svd->data);
125: return(0);
126: }
130: PETSC_EXTERN PetscErrorCode SVDCreate_LAPACK(SVD svd)
131: {
133: svd->ops->setup = SVDSetUp_LAPACK;
134: svd->ops->solve = SVDSolve_LAPACK;
135: svd->ops->destroy = SVDDestroy_LAPACK;
136: svd->ops->reset = SVDReset_LAPACK;
137: if (svd->transmode == PETSC_DECIDE)
138: svd->transmode = SVD_TRANSPOSE_IMPLICIT; /* don't build the transpose */
139: return(0);
140: }