Abdelrahman Said
202 lines
6.2 KiB
C
202 lines
6.2 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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/* > \brief <b> DGESV computes the solution to system of linear equations A * X = B for GE matrices</b>
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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 DGESV + dependencies
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> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgesv.f
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">
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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/dgesv.f
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">
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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/dgesv.f
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">
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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 DGESV( N, NRHS, A, LDA, IPIV, B, LDB, INFO )
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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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> DGESV computes the solution to a real system of linear equations
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> A * X = B,
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> where A is an N-by-N matrix and X and B are N-by-NRHS matrices.
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>
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> The LU decomposition with partial pivoting and row interchanges is
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> used to factor A as
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> A = P * L * U,
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> where P is a permutation matrix, L is unit lower triangular, and U is
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> upper triangular. The factored form of A is then used to solve the
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> system of equations A * X = B.
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> \endverbatim
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Arguments:
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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 number of linear equations, i.e., the order of the
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> 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,out] A
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> \verbatim
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> A is DOUBLE PRECISION array, dimension (LDA,N)
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> On entry, the N-by-N coefficient matrix A.
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> On exit, the factors L and U from the factorization
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> A = P*L*U; the unit diagonal elements of L are not stored.
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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[out] IPIV
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> \verbatim
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> IPIV is INTEGER array, dimension (N)
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> The pivot indices that define the permutation matrix P;
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> row i of the 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 N-by-NRHS matrix of right hand side matrix B.
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> On exit, if INFO = 0, the N-by-NRHS 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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> > 0: if INFO = i, U(i,i) is exactly zero. The factorization
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> has been completed, but the factor U is exactly
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> singular, so the solution could not be computed.
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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 doubleGEsolve
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=====================================================================
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Subroutine */ int igraphdgesv_(integer *n, integer *nrhs, doublereal *a, integer
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*lda, integer *ipiv, doublereal *b, integer *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 /* Subroutine */ int igraphdgetrf_(integer *, integer *, doublereal *,
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integer *, integer *, integer *), igraphxerbla_(char *, integer *,
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ftnlen), igraphdgetrs_(char *, integer *, integer *, doublereal *,
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integer *, integer *, doublereal *, integer *, integer *);
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/* -- LAPACK driver 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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if (*n < 0) {
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*info = -1;
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} else if (*nrhs < 0) {
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*info = -2;
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} else if (*lda < max(1,*n)) {
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*info = -4;
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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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igraphxerbla_("DGESV ", &i__1, (ftnlen)6);
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return 0;
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}
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/* Compute the LU factorization of A. */
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igraphdgetrf_(n, n, &a[a_offset], lda, &ipiv[1], info);
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if (*info == 0) {
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/* Solve the system A*X = B, overwriting B with X. */
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igraphdgetrs_("No transpose", n, nrhs, &a[a_offset], lda, &ipiv[1], &b[
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b_offset], ldb, info);
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}
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return 0;
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/* End of DGESV */
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} /* igraphdgesv_ */
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