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/* Ergo, version 3.8, a program for linear scaling electronic structure
* calculations.
* Copyright (C) 2019 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_LADIV_HEADER
#define TEMPLATE_LAPACK_LADIV_HEADER
template<class Treal>
int template_lapack_ladiv(const Treal *a, const Treal *b, const Treal *c__,
const Treal *d__, Treal *p, Treal *q)
{
/* -- 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
=======
DLADIV performs complex division in real arithmetic
a + i*b
p + i*q = ---------
c + i*d
The algorithm is due to Robert L. Smith and can be found
in D. Knuth, The art of Computer Programming, Vol.2, p.195
Arguments
=========
A (input) DOUBLE PRECISION
B (input) DOUBLE PRECISION
C (input) DOUBLE PRECISION
D (input) DOUBLE PRECISION
The scalars a, b, c, and d in the above expression.
P (output) DOUBLE PRECISION
Q (output) DOUBLE PRECISION
The scalars p and q in the above expression.
===================================================================== */
Treal e, f;
if (absMACRO(*d__) < absMACRO(*c__)) {
e = *d__ / *c__;
f = *c__ + *d__ * e;
*p = (*a + *b * e) / f;
*q = (*b - *a * e) / f;
} else {
e = *c__ / *d__;
f = *d__ + *c__ * e;
*p = (*b + *a * e) / f;
*q = (-(*a) + *b * e) / f;
}
return 0;
/* End of DLADIV */
} /* dladiv_ */
#endif
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