ergo
template_blas_idamax.h
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1/* Ergo, version 3.8.2, a program for linear scaling electronic structure
2 * calculations.
3 * Copyright (C) 2023 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_BLAS_IDAMAX_HEADER
38#define TEMPLATE_BLAS_IDAMAX_HEADER
39
40
41template<class Treal>
42integer template_blas_idamax(const integer *n, const Treal *dx, const integer *incx)
43{
44 /* System generated locals */
45 integer ret_val, i__1;
46 Treal d__1;
47 /* Local variables */
48 Treal dmax__;
49 integer i__, ix;
50/* finds the index of element having max. absolute value.
51 jack dongarra, linpack, 3/11/78.
52 modified 3/93 to return if incx .le. 0.
53 modified 12/3/93, array(1) declarations changed to array(*)
54 Parameter adjustments */
55 --dx;
56 /* Function Body */
57 ret_val = 0;
58 if (*n < 1 || *incx <= 0) {
59 return ret_val;
60 }
61 ret_val = 1;
62 if (*n == 1) {
63 return ret_val;
64 }
65 if (*incx == 1) {
66 goto L20;
67 }
68/* code for increment not equal to 1 */
69 ix = 1;
70 dmax__ = absMACRO(dx[1]);
71 ix += *incx;
72 i__1 = *n;
73 for (i__ = 2; i__ <= i__1; ++i__) {
74 if ((d__1 = dx[ix], absMACRO(d__1)) <= dmax__) {
75 goto L5;
76 }
77 ret_val = i__;
78 dmax__ = (d__1 = dx[ix], absMACRO(d__1));
79L5:
80 ix += *incx;
81/* L10: */
82 }
83 return ret_val;
84/* code for increment equal to 1 */
85L20:
86 dmax__ = absMACRO(dx[1]);
87 i__1 = *n;
88 for (i__ = 2; i__ <= i__1; ++i__) {
89 if ((d__1 = dx[i__], absMACRO(d__1)) <= dmax__) {
90 goto L30;
91 }
92 ret_val = i__;
93 dmax__ = (d__1 = dx[i__], absMACRO(d__1));
94L30:
95 ;
96 }
97 return ret_val;
98} /* idamax_ */
99
100#endif
int integer
Definition template_blas_common.h:40
#define absMACRO(x)
Definition template_blas_common.h:47
integer template_blas_idamax(const integer *n, const Treal *dx, const integer *incx)
Definition template_blas_idamax.h:42