ergo
template_lapack_lapy3.h
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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_LAPY3_HEADER
38 #define TEMPLATE_LAPACK_LAPY3_HEADER
39 
40 
41 template<class Treal>
42 Treal template_lapack_lapy3(Treal *x, Treal *y, Treal *z__)
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  DLAPY3 returns sqrt(x**2+y**2+z**2), taking care not to cause
54  unnecessary overflow.
55 
56  Arguments
57  =========
58 
59  X (input) DOUBLE PRECISION
60  Y (input) DOUBLE PRECISION
61  Z (input) DOUBLE PRECISION
62  X, Y and Z specify the values x, y and z.
63 
64  ===================================================================== */
65  /* System generated locals */
66  Treal ret_val, d__1, d__2, d__3;
67  /* Local variables */
68  Treal xabs, yabs, zabs, w;
69 
70 
71 
72  xabs = absMACRO(*x);
73  yabs = absMACRO(*y);
74  zabs = absMACRO(*z__);
75 /* Computing MAX */
76  d__1 = maxMACRO(xabs,yabs);
77  w = maxMACRO(d__1,zabs);
78  if (w == 0.) {
79  ret_val = 0.;
80  } else {
81 /* Computing 2nd power */
82  d__1 = xabs / w;
83 /* Computing 2nd power */
84  d__2 = yabs / w;
85 /* Computing 2nd power */
86  d__3 = zabs / w;
87  ret_val = w * template_blas_sqrt(d__1 * d__1 + d__2 * d__2 + d__3 * d__3);
88  }
89  return ret_val;
90 
91 /* End of DLAPY3 */
92 
93 } /* dlapy3_ */
94 
95 #endif
#define absMACRO(x)
Definition: template_blas_common.h:47
Treal template_lapack_lapy3(Treal *x, Treal *y, Treal *z__)
Definition: template_lapack_lapy3.h:42
#define maxMACRO(a, b)
Definition: template_blas_common.h:45
Treal template_blas_sqrt(Treal x)