ergo
template_lapack_lapy2.h
Go to the documentation of this file.
1 /* Ergo, version 3.7, a program for linear scaling electronic structure
2  * calculations.
3  * Copyright (C) 2018 Elias Rudberg, Emanuel H. Rubensson, Pawel Salek,
4  * and Anastasia Kruchinina.
5  *
6  * This program is free software: you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation, either version 3 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program. If not, see <http://www.gnu.org/licenses/>.
18  *
19  * Primary academic reference:
20  * Ergo: An open-source program for linear-scaling electronic structure
21  * calculations,
22  * Elias Rudberg, Emanuel H. Rubensson, Pawel Salek, and Anastasia
23  * Kruchinina,
24  * SoftwareX 7, 107 (2018),
25  * <http://dx.doi.org/10.1016/j.softx.2018.03.005>
26  *
27  * For further information about Ergo, see <http://www.ergoscf.org>.
28  */
29 
30  /* This file belongs to the template_lapack part of the Ergo source
31  * code. The source files in the template_lapack directory are modified
32  * versions of files originally distributed as CLAPACK, see the
33  * Copyright/license notice in the file template_lapack/COPYING.
34  */
35 
36 
37 #ifndef TEMPLATE_LAPACK_LAPY2_HEADER
38 #define TEMPLATE_LAPACK_LAPY2_HEADER
39 
40 
41 template<class Treal>
42 Treal template_lapack_lapy2(Treal *x, Treal *y)
43 {
44 /* -- LAPACK auxiliary routine (version 3.0) --
45  Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
46  Courant Institute, Argonne National Lab, and Rice University
47  October 31, 1992
48 
49 
50  Purpose
51  =======
52 
53  DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary
54  overflow.
55 
56  Arguments
57  =========
58 
59  X (input) DOUBLE PRECISION
60  Y (input) DOUBLE PRECISION
61  X and Y specify the values x and y.
62 
63  ===================================================================== */
64  /* System generated locals */
65  Treal ret_val, d__1;
66  /* Local variables */
67  Treal xabs, yabs, w, z__;
68 
69 
70 
71  xabs = absMACRO(*x);
72  yabs = absMACRO(*y);
73  w = maxMACRO(xabs,yabs);
74  z__ = minMACRO(xabs,yabs);
75  if (z__ == 0.) {
76  ret_val = w;
77  } else {
78 /* Computing 2nd power */
79  d__1 = z__ / w;
80  ret_val = w * template_blas_sqrt(d__1 * d__1 + 1.);
81  }
82  return ret_val;
83 
84 /* End of DLAPY2 */
85 
86 } /* dlapy2_ */
87 
88 #endif
#define absMACRO(x)
Definition: template_blas_common.h:47
Treal template_lapack_lapy2(Treal *x, Treal *y)
Definition: template_lapack_lapy2.h:42
#define maxMACRO(a, b)
Definition: template_blas_common.h:45
#define minMACRO(a, b)
Definition: template_blas_common.h:46
Treal template_blas_sqrt(Treal x)