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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_RSCL_HEADER
#define TEMPLATE_LAPACK_RSCL_HEADER
template<class Treal>
int template_lapack_rscl(const integer *n, const Treal *sa, Treal *sx,
const integer *incx)
{
/* -- LAPACK auxiliary routine (version 3.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
September 30, 1994
Purpose
=======
DRSCL multiplies an n-element real vector x by the real scalar 1/a.
This is done without overflow or underflow as long as
the final result x/a does not overflow or underflow.
Arguments
=========
N (input) INTEGER
The number of components of the vector x.
SA (input) DOUBLE PRECISION
The scalar a which is used to divide each component of x.
SA must be >= 0, or the subroutine will divide by zero.
SX (input/output) DOUBLE PRECISION array, dimension
(1+(N-1)*abs(INCX))
The n-element vector x.
INCX (input) INTEGER
The increment between successive values of the vector SX.
> 0: SX(1) = X(1) and SX(1+(i-1)*INCX) = x(i), 1< i<= n
=====================================================================
Quick return if possible
Parameter adjustments */
Treal cden;
logical done;
Treal cnum, cden1, cnum1;
Treal bignum, smlnum, mul;
--sx;
/* Function Body */
if (*n <= 0) {
return 0;
}
/* Get machine parameters */
smlnum = template_lapack_lamch("S", (Treal)0);
bignum = 1. / smlnum;
template_lapack_labad(&smlnum, &bignum);
/* Initialize the denominator to SA and the numerator to 1. */
cden = *sa;
cnum = 1.;
L10:
cden1 = cden * smlnum;
cnum1 = cnum / bignum;
if (absMACRO(cden1) > absMACRO(cnum) && cnum != 0.) {
/* Pre-multiply X by SMLNUM if CDEN is large compared to CNUM. */
mul = smlnum;
done = FALSE_;
cden = cden1;
} else if (absMACRO(cnum1) > absMACRO(cden)) {
/* Pre-multiply X by BIGNUM if CDEN is small compared to CNUM. */
mul = bignum;
done = FALSE_;
cnum = cnum1;
} else {
/* Multiply X by CNUM / CDEN and return. */
mul = cnum / cden;
done = TRUE_;
}
/* Scale the vector X by MUL */
dscal_(n, &mul, &sx[1], incx);
if (! done) {
goto L10;
}
return 0;
/* End of DRSCL */
} /* drscl_ */
#endif
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