/* -- translated by f2c (version 20100827).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
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*/
#include "f2c.h"
/* Table of constant values */
static integer c__1 = 1;
static doublereal c_b12 = 1.;
static integer c_n1 = -1;
/* > \brief \b DGETRS
=========== DOCUMENTATION ===========
Online html documentation available at
http://www.netlib.org/lapack/explore-html/
> \htmlonly
> Download DGETRS + dependencies
> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgetrs.
f">
> [TGZ]</a>
> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgetrs.
f">
> [ZIP]</a>
> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgetrs.
f">
> [TXT]</a>
> \endhtmlonly
Definition:
===========
SUBROUTINE DGETRS( TRANS, N, NRHS, A, LDA, IPIV, B, LDB, INFO )
CHARACTER TRANS
INTEGER INFO, LDA, LDB, N, NRHS
INTEGER IPIV( * )
DOUBLE PRECISION A( LDA, * ), B( LDB, * )
> \par Purpose:
=============
>
> \verbatim
>
> DGETRS solves a system of linear equations
> A * X = B or A**T * X = B
> with a general N-by-N matrix A using the LU factorization computed
> by DGETRF.
> \endverbatim
Arguments:
==========
> \param[in] TRANS
> \verbatim
> TRANS is CHARACTER*1
> Specifies the form of the system of equations:
> = 'N': A * X = B (No transpose)
> = 'T': A**T* X = B (Transpose)
> = 'C': A**T* X = B (Conjugate transpose = Transpose)
> \endverbatim
>
> \param[in] N
> \verbatim
> N is INTEGER
> The order of the matrix A. N >= 0.
> \endverbatim
>
> \param[in] NRHS
> \verbatim
> NRHS is INTEGER
> The number of right hand sides, i.e., the number of columns
> of the matrix B. NRHS >= 0.
> \endverbatim
>
> \param[in] A
> \verbatim
> A is DOUBLE PRECISION array, dimension (LDA,N)
> The factors L and U from the factorization A = P*L*U
> as computed by DGETRF.
> \endverbatim
>
> \param[in] LDA
> \verbatim
> LDA is INTEGER
> The leading dimension of the array A. LDA >= max(1,N).
> \endverbatim
>
> \param[in] IPIV
> \verbatim
> IPIV is INTEGER array, dimension (N)
> The pivot indices from DGETRF; for 1<=i<=N, row i of the
> matrix was interchanged with row IPIV(i).
> \endverbatim
>
> \param[in,out] B
> \verbatim
> B is DOUBLE PRECISION array, dimension (LDB,NRHS)
> On entry, the right hand side matrix B.
> On exit, the solution matrix X.
> \endverbatim
>
> \param[in] LDB
> \verbatim
> LDB is INTEGER
> The leading dimension of the array B. LDB >= max(1,N).
> \endverbatim
>
> \param[out] INFO
> \verbatim
> INFO is INTEGER
> = 0: successful exit
> < 0: if INFO = -i, the i-th argument had an illegal value
> \endverbatim
Authors:
========
> \author Univ. of Tennessee
> \author Univ. of California Berkeley
> \author Univ. of Colorado Denver
> \author NAG Ltd.
> \date November 2011
> \ingroup doubleGEcomputational
=====================================================================
Subroutine */ int igraphdgetrs_(char *trans, integer *n, integer *nrhs,
doublereal *a, integer *lda, integer *ipiv, doublereal *b, integer *
ldb, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, b_dim1, b_offset, i__1;
/* Local variables */
extern logical igraphlsame_(char *, char *);
extern /* Subroutine */ int igraphdtrsm_(char *, char *, char *, char *,
integer *, integer *, doublereal *, doublereal *, integer *,
doublereal *, integer *), igraphxerbla_(
char *, integer *, ftnlen), igraphdlaswp_(integer *, doublereal *,
integer *, integer *, integer *, integer *, integer *);
logical notran;
/* -- LAPACK computational routine (version 3.4.0) --
-- LAPACK is a software package provided by Univ. of Tennessee, --
-- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
November 2011
=====================================================================
Test the input parameters.
Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
--ipiv;
b_dim1 = *ldb;
b_offset = 1 + b_dim1;
b -= b_offset;
/* Function Body */
*info = 0;
notran = igraphlsame_(trans, "N");
if (! notran && ! igraphlsame_(trans, "T") && ! igraphlsame_(
trans, "C")) {
*info = -1;
} else if (*n < 0) {
*info = -2;
} else if (*nrhs < 0) {
*info = -3;
} else if (*lda < max(1,*n)) {
*info = -5;
} else if (*ldb < max(1,*n)) {
*info = -8;
}
if (*info != 0) {
i__1 = -(*info);
igraphxerbla_("DGETRS", &i__1, (ftnlen)6);
return 0;
}
/* Quick return if possible */
if (*n == 0 || *nrhs == 0) {
return 0;
}
if (notran) {
/* Solve A * X = B.
Apply row interchanges to the right hand sides. */
igraphdlaswp_(nrhs, &b[b_offset], ldb, &c__1, n, &ipiv[1], &c__1);
/* Solve L*X = B, overwriting B with X. */
igraphdtrsm_("Left", "Lower", "No transpose", "Unit", n, nrhs, &c_b12, &a[
a_offset], lda, &b[b_offset], ldb);
/* Solve U*X = B, overwriting B with X. */
igraphdtrsm_("Left", "Upper", "No transpose", "Non-unit", n, nrhs, &c_b12, &
a[a_offset], lda, &b[b_offset], ldb);
} else {
/* Solve A**T * X = B.
Solve U**T *X = B, overwriting B with X. */
igraphdtrsm_("Left", "Upper", "Transpose", "Non-unit", n, nrhs, &c_b12, &a[
a_offset], lda, &b[b_offset], ldb);
/* Solve L**T *X = B, overwriting B with X. */
igraphdtrsm_("Left", "Lower", "Transpose", "Unit", n, nrhs, &c_b12, &a[
a_offset], lda, &b[b_offset], ldb);
/* Apply row interchanges to the solution vectors. */
igraphdlaswp_(nrhs, &b[b_offset], ldb, &c__1, n, &ipiv[1], &c_n1);
}
return 0;
/* End of DGETRS */
} /* igraphdgetrs_ */