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/* Ergo, version 3.8.2, a program for linear scaling electronic structure
* calculations.
* Copyright (C) 2023 Elias Rudberg, Emanuel H. Rubensson, Pawel Salek,
* and Anastasia Kruchinina.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Primary academic reference:
* Ergo: An open-source program for linear-scaling electronic structure
* calculations,
* Elias Rudberg, Emanuel H. Rubensson, Pawel Salek, and Anastasia
* Kruchinina,
* SoftwareX 7, 107 (2018),
* <http://dx.doi.org/10.1016/j.softx.2018.03.005>
*
* For further information about Ergo, see <http://www.ergoscf.org>.
*/
/* This file belongs to the template_lapack part of the Ergo source
* code. The source files in the template_lapack directory are modified
* versions of files originally distributed as CLAPACK, see the
* Copyright/license notice in the file template_lapack/COPYING.
*/
#ifndef TEMPLATE_LAPACK_GETRS_HEADER
#define TEMPLATE_LAPACK_GETRS_HEADER
template<class Treal>
int template_lapack_getrs(const char *trans, const integer *n, const integer *nrhs,
const Treal *a, const integer *lda, const integer *ipiv, Treal *b, const integer *
ldb, integer *info)
{
/* -- LAPACK routine (version 3.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
March 31, 1993
Purpose
=======
DGETRS solves a system of linear equations
A * X = B or A' * X = B
with a general N-by-N matrix A using the LU factorization computed
by DGETRF.
Arguments
=========
TRANS (input) CHARACTER*1
Specifies the form of the system of equations:
= 'N': A * X = B (No transpose)
= 'T': A'* X = B (Transpose)
= 'C': A'* X = B (Conjugate transpose = Transpose)
N (input) INTEGER
The order of the matrix A. N >= 0.
NRHS (input) INTEGER
The number of right hand sides, i.e., the number of columns
of the matrix B. NRHS >= 0.
A (input) DOUBLE PRECISION array, dimension (LDA,N)
The factors L and U from the factorization A = P*L*U
as computed by DGETRF.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,N).
IPIV (input) INTEGER array, dimension (N)
The pivot indices from DGETRF; for 1<=i<=N, row i of the
matrix was interchanged with row IPIV(i).
B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
On entry, the right hand side matrix B.
On exit, the solution matrix X.
LDB (input) INTEGER
The leading dimension of the array B. LDB >= max(1,N).
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
=====================================================================
Test the input parameters.
Parameter adjustments */
/* Table of constant values */
integer c__1 = 1;
Treal c_b12 = 1.;
integer c_n1 = -1;
/* System generated locals */
integer a_dim1, a_offset, b_dim1, b_offset, i__1;
/* Local variables */
logical notran;
a_dim1 = *lda;
a_offset = 1 + a_dim1 * 1;
a -= a_offset;
--ipiv;
b_dim1 = *ldb;
b_offset = 1 + b_dim1 * 1;
b -= b_offset;
/* Function Body */
*info = 0;
notran = template_blas_lsame(trans, "N");
if (! notran && ! template_blas_lsame(trans, "T") && ! template_blas_lsame(
trans, "C")) {
*info = -1;
} else if (*n < 0) {
*info = -2;
} else if (*nrhs < 0) {
*info = -3;
} else if (*lda < maxMACRO(1,*n)) {
*info = -5;
} else if (*ldb < maxMACRO(1,*n)) {
*info = -8;
}
if (*info != 0) {
i__1 = -(*info);
template_blas_erbla("GETRS ", &i__1);
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. */
template_lapack_laswp(nrhs, &b[b_offset], ldb, &c__1, n, &ipiv[1], &c__1);
/* Solve L*X = B, overwriting B with X. */
template_blas_trsm("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. */
template_blas_trsm("Left", "Upper", "No transpose", "Non-unit", n, nrhs, &c_b12, &
a[a_offset], lda, &b[b_offset], ldb);
} else {
/* Solve A' * X = B.
Solve U'*X = B, overwriting B with X. */
template_blas_trsm("Left", "Upper", "Transpose", "Non-unit", n, nrhs, &c_b12, &a[
a_offset], lda, &b[b_offset], ldb);
/* Solve L'*X = B, overwriting B with X. */
template_blas_trsm("Left", "Lower", "Transpose", "Unit", n, nrhs, &c_b12, &a[
a_offset], lda, &b[b_offset], ldb);
/* Apply row interchanges to the solution vectors. */
template_lapack_laswp(nrhs, &b[b_offset], ldb, &c__1, n, &ipiv[1], &c_n1);
}
return 0;
/* End of DGETRS */
} /* dgetrs_ */
#endif
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