166 lines
5.0 KiB
C
166 lines
5.0 KiB
C
/*BHEADER**********************************************************************
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* Copyright (c) 2006 The Regents of the University of California.
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* Produced at the Lawrence Livermore National Laboratory.
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* Written by the HYPRE team <hypre-users@llnl.gov>, UCRL-CODE-222953.
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* All rights reserved.
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*
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* This file is part of HYPRE (see http://www.llnl.gov/CASC/hypre/).
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* Please see the COPYRIGHT_and_LICENSE file for the copyright notice,
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* disclaimer and the GNU Lesser General Public License.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License (as published by the Free
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* Software Foundation) version 2.1 dated February 1999.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the IMPLIED WARRANTY OF MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the terms and conditions of the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* $Revision$
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***********************************************************************EHEADER*/
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#include "hypre_lapack.h"
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#include "f2c.h"
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/* Subroutine */ int dpotrs_(char *uplo, integer *n, integer *nrhs,
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doublereal *a, integer *lda, doublereal *b, integer *ldb, integer *
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info)
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{
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/* -- LAPACK routine (version 3.0) --
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Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
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Courant Institute, Argonne National Lab, and Rice University
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March 31, 1993
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Purpose
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=======
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DPOTRS solves a system of linear equations A*X = B with a symmetric
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positive definite matrix A using the Cholesky factorization
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A = U**T*U or A = L*L**T computed by DPOTRF.
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Arguments
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=========
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UPLO (input) CHARACTER*1
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= 'U': Upper triangle of A is stored;
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= 'L': Lower triangle of A is stored.
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N (input) INTEGER
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The order of the matrix A. N >= 0.
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NRHS (input) INTEGER
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The number of right hand sides, i.e., the number of columns
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of the matrix B. NRHS >= 0.
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A (input) DOUBLE PRECISION array, dimension (LDA,N)
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The triangular factor U or L from the Cholesky factorization
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A = U**T*U or A = L*L**T, as computed by DPOTRF.
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LDA (input) INTEGER
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The leading dimension of the array A. LDA >= max(1,N).
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B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
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On entry, the right hand side matrix B.
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On exit, the solution matrix X.
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LDB (input) INTEGER
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The leading dimension of the array B. LDB >= max(1,N).
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INFO (output) INTEGER
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= 0: successful exit
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< 0: if INFO = -i, the i-th argument had an illegal value
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=====================================================================
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Test the input parameters.
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Parameter adjustments */
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/* Table of constant values */
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static doublereal c_b9 = 1.;
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/* System generated locals */
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integer a_dim1, a_offset, b_dim1, b_offset, i__1;
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/* Local variables */
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extern logical lsame_(char *, char *);
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extern /* Subroutine */ int dtrsm_(char *, char *, char *, char *,
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integer *, integer *, doublereal *, doublereal *, integer *,
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doublereal *, integer *);
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static logical upper;
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extern /* Subroutine */ int xerbla_(char *, integer *);
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a_dim1 = *lda;
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a_offset = 1 + a_dim1 * 1;
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a -= a_offset;
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b_dim1 = *ldb;
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b_offset = 1 + b_dim1 * 1;
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b -= b_offset;
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/* Function Body */
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*info = 0;
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upper = lsame_(uplo, "U");
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if (! upper && ! lsame_(uplo, "L")) {
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*info = -1;
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} else if (*n < 0) {
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*info = -2;
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} else if (*nrhs < 0) {
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*info = -3;
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} else if (*lda < max(1,*n)) {
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*info = -5;
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} else if (*ldb < max(1,*n)) {
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*info = -7;
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}
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if (*info != 0) {
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i__1 = -(*info);
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xerbla_("DPOTRS", &i__1);
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return 0;
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}
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/* Quick return if possible */
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if (*n == 0 || *nrhs == 0) {
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return 0;
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}
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if (upper) {
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/* Solve A*X = B where A = U'*U.
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Solve U'*X = B, overwriting B with X. */
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dtrsm_("Left", "Upper", "Transpose", "Non-unit", n, nrhs, &c_b9, &a[
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a_offset], lda, &b[b_offset], ldb);
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/* Solve U*X = B, overwriting B with X. */
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dtrsm_("Left", "Upper", "No transpose", "Non-unit", n, nrhs, &c_b9, &
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a[a_offset], lda, &b[b_offset], ldb);
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} else {
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/* Solve A*X = B where A = L*L'.
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Solve L*X = B, overwriting B with X. */
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dtrsm_("Left", "Lower", "No transpose", "Non-unit", n, nrhs, &c_b9, &
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a[a_offset], lda, &b[b_offset], ldb);
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/* Solve L'*X = B, overwriting B with X. */
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dtrsm_("Left", "Lower", "Transpose", "Non-unit", n, nrhs, &c_b9, &a[
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a_offset], lda, &b[b_offset], ldb);
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}
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return 0;
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/* End of DPOTRS */
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} /* dpotrs_ */
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