247 lines
6.9 KiB
C
247 lines
6.9 KiB
C
/* -- translated by f2c (version 20240504).
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You must link the resulting object file with libf2c:
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on Microsoft Windows system, link with libf2c.lib;
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm
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or, if you install libf2c.a in a standard place, with -lf2c -lm
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-- in that order, at the end of the command line, as in
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cc *.o -lf2c -lm
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
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http://www.netlib.org/f2c/libf2c.zip
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*/
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#include "f2c.h"
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/* Table of constant values */
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static integer c__1 = 1;
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static doublereal c_b12 = 1.;
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static integer c_n1 = -1;
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/* > \brief \b DGETRS
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=========== DOCUMENTATION ===========
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Online html documentation available at
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http://www.netlib.org/lapack/explore-html/
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> \htmlonly
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> Download DGETRS + dependencies
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> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgetrs.
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f">
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> [TGZ]</a>
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> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgetrs.
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f">
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> [ZIP]</a>
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> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgetrs.
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f">
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> [TXT]</a>
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> \endhtmlonly
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Definition:
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===========
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SUBROUTINE DGETRS( TRANS, N, NRHS, A, LDA, IPIV, B, LDB, INFO )
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CHARACTER TRANS
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INTEGER INFO, LDA, LDB, N, NRHS
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INTEGER IPIV( * )
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DOUBLE PRECISION A( LDA, * ), B( LDB, * )
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> \par Purpose:
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=============
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>
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> \verbatim
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>
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> DGETRS solves a system of linear equations
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> A * X = B or A**T * X = B
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> with a general N-by-N matrix A using the LU factorization computed
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> by DGETRF.
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> \endverbatim
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Arguments:
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==========
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> \param[in] TRANS
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> \verbatim
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> TRANS is CHARACTER*1
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> Specifies the form of the system of equations:
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> = 'N': A * X = B (No transpose)
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> = 'T': A**T* X = B (Transpose)
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> = 'C': A**T* X = B (Conjugate transpose = Transpose)
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> \endverbatim
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>
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> \param[in] N
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> \verbatim
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> N is INTEGER
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> The order of the matrix A. N >= 0.
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> \endverbatim
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>
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> \param[in] NRHS
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> \verbatim
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> NRHS is 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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> \endverbatim
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>
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> \param[in] A
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> \verbatim
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> A is DOUBLE PRECISION array, dimension (LDA,N)
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> The factors L and U from the factorization A = P*L*U
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> as computed by DGETRF.
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> \endverbatim
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>
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> \param[in] LDA
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> \verbatim
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> LDA is INTEGER
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> The leading dimension of the array A. LDA >= max(1,N).
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> \endverbatim
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>
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> \param[in] IPIV
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> \verbatim
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> IPIV is INTEGER array, dimension (N)
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> The pivot indices from DGETRF; for 1<=i<=N, row i of the
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> matrix was interchanged with row IPIV(i).
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> \endverbatim
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>
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> \param[in,out] B
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> \verbatim
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> B is 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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> \endverbatim
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>
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> \param[in] LDB
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> \verbatim
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> LDB is INTEGER
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> The leading dimension of the array B. LDB >= max(1,N).
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> \endverbatim
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>
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> \param[out] INFO
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> \verbatim
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> INFO is 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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> \endverbatim
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Authors:
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========
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> \author Univ. of Tennessee
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> \author Univ. of California Berkeley
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> \author Univ. of Colorado Denver
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> \author NAG Ltd.
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> \date November 2011
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> \ingroup doubleGEcomputational
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=====================================================================
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Subroutine */ int igraphdgetrs_(char *trans, integer *n, integer *nrhs,
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doublereal *a, integer *lda, integer *ipiv, doublereal *b, integer *
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ldb, integer *info)
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{
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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 igraphlsame_(char *, char *);
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extern /* Subroutine */ int igraphdtrsm_(char *, char *, char *, char *,
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integer *, integer *, doublereal *, doublereal *, integer *,
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doublereal *, integer *), igraphxerbla_(
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char *, integer *, ftnlen), igraphdlaswp_(integer *, doublereal *,
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integer *, integer *, integer *, integer *, integer *);
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logical notran;
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/* -- LAPACK computational routine (version 3.4.0) --
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-- LAPACK is a software package provided by Univ. of Tennessee, --
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-- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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November 2011
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=====================================================================
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Test the input parameters.
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Parameter adjustments */
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a_dim1 = *lda;
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a_offset = 1 + a_dim1;
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a -= a_offset;
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--ipiv;
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b_dim1 = *ldb;
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b_offset = 1 + b_dim1;
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b -= b_offset;
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/* Function Body */
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*info = 0;
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notran = igraphlsame_(trans, "N");
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if (! notran && ! igraphlsame_(trans, "T") && ! igraphlsame_(
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trans, "C")) {
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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 = -8;
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}
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if (*info != 0) {
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i__1 = -(*info);
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igraphxerbla_("DGETRS", &i__1, (ftnlen)6);
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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 (notran) {
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/* Solve A * X = B.
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Apply row interchanges to the right hand sides. */
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igraphdlaswp_(nrhs, &b[b_offset], ldb, &c__1, n, &ipiv[1], &c__1);
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/* Solve L*X = B, overwriting B with X. */
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igraphdtrsm_("Left", "Lower", "No transpose", "Unit", n, nrhs, &c_b12, &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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igraphdtrsm_("Left", "Upper", "No transpose", "Non-unit", n, nrhs, &c_b12, &
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a[a_offset], lda, &b[b_offset], ldb);
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} else {
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/* Solve A**T * X = B.
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Solve U**T *X = B, overwriting B with X. */
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igraphdtrsm_("Left", "Upper", "Transpose", "Non-unit", n, nrhs, &c_b12, &a[
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a_offset], lda, &b[b_offset], ldb);
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/* Solve L**T *X = B, overwriting B with X. */
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igraphdtrsm_("Left", "Lower", "Transpose", "Unit", n, nrhs, &c_b12, &a[
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a_offset], lda, &b[b_offset], ldb);
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/* Apply row interchanges to the solution vectors. */
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igraphdlaswp_(nrhs, &b[b_offset], ldb, &c__1, n, &ipiv[1], &c_n1);
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}
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return 0;
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/* End of DGETRS */
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} /* igraphdgetrs_ */
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