convert linalg library from Fortran to C++
This commit is contained in:
Axel Kohlmeyer
217
lib/linalg/dgesv.cpp
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217
lib/linalg/dgesv.cpp
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/* fortran/dgesv.f -- translated by f2c (version 20200916).
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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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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "lmp_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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/* .. Scalar Arguments .. */
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/* INTEGER INFO, LDA, LDB, N, NRHS */
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/* .. */
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/* .. Array Arguments .. */
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/* INTEGER IPIV( * ) */
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/* DOUBLE PRECISION A( LDA, * ), B( LDB, * ) */
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/* .. */
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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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/* > \ingroup doubleGEsolve */
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/* ===================================================================== */
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/* Subroutine */ int dgesv_(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 dgetrf_(integer *, integer *, doublereal *,
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integer *, integer *, integer *), xerbla_(char *, integer *,
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ftnlen), dgetrs_(char *, integer *, integer *, doublereal *,
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integer *, integer *, doublereal *, integer *, integer *, ftnlen);
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/* -- LAPACK driver routine -- */
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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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/* .. Scalar Arguments .. */
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/* .. */
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/* .. Array Arguments .. */
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/* .. */
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/* ===================================================================== */
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/* .. External Subroutines .. */
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/* .. */
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/* .. Intrinsic Functions .. */
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/* .. */
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/* .. Executable Statements .. */
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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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xerbla_((char *)"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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dgetrf_(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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dgetrs_((char *)"No transpose", n, nrhs, &a[a_offset], lda, &ipiv[1], &b[
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b_offset], ldb, info, (ftnlen)12);
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}
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return 0;
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/* End of DGESV */
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} /* dgesv_ */
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#ifdef __cplusplus
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}
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#endif
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