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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_LABAD_HEADER
#define TEMPLATE_LAPACK_LABAD_HEADER
template<class Treal>
int template_lapack_labad(Treal *small, Treal *large)
{
/* -- LAPACK auxiliary routine (version 3.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
October 31, 1992
Purpose
=======
DLABAD takes as input the values computed by DLAMCH for underflow and
overflow, and returns the square root of each of these values if the
log of LARGE is sufficiently large. This subroutine is intended to
identify machines with a large exponent range, such as the Crays, and
redefine the underflow and overflow limits to be the square roots of
the values computed by DLAMCH. This subroutine is needed because
DLAMCH does not compensate for poor arithmetic in the upper half of
the exponent range, as is found on a Cray.
Arguments
=========
SMALL (input/output) DOUBLE PRECISION
On entry, the underflow threshold as computed by DLAMCH.
On exit, if LOG10(LARGE) is sufficiently large, the square
root of SMALL, otherwise unchanged.
LARGE (input/output) DOUBLE PRECISION
On entry, the overflow threshold as computed by DLAMCH.
On exit, if LOG10(LARGE) is sufficiently large, the square
root of LARGE, otherwise unchanged.
=====================================================================
If it looks like we're on a Cray, take the square root of
SMALL and LARGE to avoid overflow and underflow problems. */
if (template_blas_lg10(large) > 2e3) {
*small = template_blas_sqrt(*small);
*large = template_blas_sqrt(*large);
}
return 0;
/* End of DLABAD */
} /* dlabad_ */
#endif
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