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template_lapack_labad.h
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/* Ergo, version 3.2, a program for linear scaling electronic structure
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* calculations.
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* Copyright (C) 2012 Elias Rudberg, Emanuel H. Rubensson, and Pawel Salek.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* Primary academic reference:
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* KohnâSham Density Functional Theory Electronic Structure Calculations
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* with Linearly Scaling Computational Time and Memory Usage,
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* Elias Rudberg, Emanuel H. Rubensson, and Pawel Salek,
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* J. Chem. Theory Comput. 7, 340 (2011),
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* <http://dx.doi.org/10.1021/ct100611z>
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*
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* For further information about Ergo, see <http://www.ergoscf.org>.
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*/
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/* This file belongs to the template_lapack part of the Ergo source
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* code. The source files in the template_lapack directory are modified
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* versions of files originally distributed as CLAPACK, see the
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* Copyright/license notice in the file template_lapack/COPYING.
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*/
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#ifndef TEMPLATE_LAPACK_LABAD_HEADER
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#define TEMPLATE_LAPACK_LABAD_HEADER
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template
<
class
Treal>
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int
template_lapack_labad
(Treal *small, Treal *large)
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{
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/* -- LAPACK auxiliary routine (version 3.0) --
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Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
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Courant Institute, Argonne National Lab, and Rice University
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October 31, 1992
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Purpose
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=======
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DLABAD takes as input the values computed by DLAMCH for underflow and
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overflow, and returns the square root of each of these values if the
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log of LARGE is sufficiently large. This subroutine is intended to
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identify machines with a large exponent range, such as the Crays, and
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redefine the underflow and overflow limits to be the square roots of
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the values computed by DLAMCH. This subroutine is needed because
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DLAMCH does not compensate for poor arithmetic in the upper half of
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the exponent range, as is found on a Cray.
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Arguments
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=========
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SMALL (input/output) DOUBLE PRECISION
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On entry, the underflow threshold as computed by DLAMCH.
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On exit, if LOG10(LARGE) is sufficiently large, the square
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root of SMALL, otherwise unchanged.
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LARGE (input/output) DOUBLE PRECISION
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On entry, the overflow threshold as computed by DLAMCH.
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On exit, if LOG10(LARGE) is sufficiently large, the square
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root of LARGE, otherwise unchanged.
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=====================================================================
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If it looks like we're on a Cray, take the square root of
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SMALL and LARGE to avoid overflow and underflow problems. */
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if
(
template_blas_lg10
(large) > 2e3) {
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*small =
template_blas_sqrt
(*small);
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*large =
template_blas_sqrt
(*large);
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}
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return
0;
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/* End of DLABAD */
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}
/* dlabad_ */
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#endif
source
matrix
template_lapack
lapack
template_lapack_labad.h
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