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template_lapack_lapy2.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_LAPY2_HEADER
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#define TEMPLATE_LAPACK_LAPY2_HEADER
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template
<
class
Treal>
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Treal
template_lapack_lapy2
(Treal *x, Treal *y)
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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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DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary
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overflow.
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Arguments
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=========
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X (input) DOUBLE PRECISION
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Y (input) DOUBLE PRECISION
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X and Y specify the values x and y.
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===================================================================== */
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/* System generated locals */
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Treal ret_val, d__1;
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/* Local variables */
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Treal xabs, yabs, w, z__;
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xabs =
absMACRO
(*x);
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yabs =
absMACRO
(*y);
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w =
maxMACRO
(xabs,yabs);
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z__ =
minMACRO
(xabs,yabs);
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if
(z__ == 0.) {
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ret_val = w;
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}
else
{
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/* Computing 2nd power */
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d__1 = z__ / w;
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ret_val = w *
template_blas_sqrt
(d__1 * d__1 + 1.);
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}
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return
ret_val;
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/* End of DLAPY2 */
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}
/* dlapy2_ */
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#endif
source
matrix
template_lapack
lapack
template_lapack_lapy2.h
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