ergo
template_lapack_larnv.h
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1/* Ergo, version 3.8, a program for linear scaling electronic structure
2 * calculations.
3 * Copyright (C) 2019 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_LARNV_HEADER
38#define TEMPLATE_LAPACK_LARNV_HEADER
39
40
41template<class Treal>
42int template_lapack_larnv(const integer *idist, integer *iseed, const integer *n,
43 Treal *x)
44{
45/* -- LAPACK auxiliary routine (version 3.0) --
46 Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
47 Courant Institute, Argonne National Lab, and Rice University
48 September 30, 1994
49
50
51 Purpose
52 =======
53
54 DLARNV returns a vector of n random real numbers from a uniform or
55 normal distribution.
56
57 Arguments
58 =========
59
60 IDIST (input) INTEGER
61 Specifies the distribution of the random numbers:
62 = 1: uniform (0,1)
63 = 2: uniform (-1,1)
64 = 3: normal (0,1)
65
66 ISEED (input/output) INTEGER array, dimension (4)
67 On entry, the seed of the random number generator; the array
68 elements must be between 0 and 4095, and ISEED(4) must be
69 odd.
70 On exit, the seed is updated.
71
72 N (input) INTEGER
73 The number of random numbers to be generated.
74
75 X (output) DOUBLE PRECISION array, dimension (N)
76 The generated random numbers.
77
78 Further Details
79 ===============
80
81 This routine calls the auxiliary routine DLARUV to generate random
82 real numbers from a uniform (0,1) distribution, in batches of up to
83 128 using vectorisable code. The Box-Muller method is used to
84 transform numbers from a uniform to a normal distribution.
85
86 =====================================================================
87
88
89 Parameter adjustments */
90 /* System generated locals */
91 integer i__1, i__2, i__3;
92 /* Local variables */
93 integer i__;
94 Treal u[128];
95 integer il, iv;
96 integer il2;
97
98 --x;
99 --iseed;
100
101 /* Function Body */
102 i__1 = *n;
103 for (iv = 1; iv <= i__1; iv += 64) {
104/* Computing MIN */
105 i__2 = 64, i__3 = *n - iv + 1;
106 il = minMACRO(i__2,i__3);
107 if (*idist == 3) {
108 il2 = il << 1;
109 } else {
110 il2 = il;
111 }
112
113/* Call DLARUV to generate IL2 numbers from a uniform (0,1)
114 distribution (IL2 <= LV) */
115
116 dlaruv_(&iseed[1], &il2, u);
117
118 if (*idist == 1) {
119
120/* Copy generated numbers */
121
122 i__2 = il;
123 for (i__ = 1; i__ <= i__2; ++i__) {
124 x[iv + i__ - 1] = u[i__ - 1];
125/* L10: */
126 }
127 } else if (*idist == 2) {
128
129/* Convert generated numbers to uniform (-1,1) distribution */
130
131 i__2 = il;
132 for (i__ = 1; i__ <= i__2; ++i__) {
133 x[iv + i__ - 1] = u[i__ - 1] * 2. - 1.;
134/* L20: */
135 }
136 } else if (*idist == 3) {
137
138/* Convert generated numbers to normal (0,1) distribution */
139
140 i__2 = il;
141 for (i__ = 1; i__ <= i__2; ++i__) {
142 x[iv + i__ - 1] = template_blas_sqrt(template_blas_log(u[(i__ << 1) - 2]) * -2.) * template_blas_cos(u[(
143 i__ << 1) - 1] * 6.2831853071795864769252867663);
144/* L30: */
145 }
146 }
147/* L40: */
148 }
149 return 0;
150
151/* End of DLARNV */
152
153} /* dlarnv_ */
154
155#endif
Treal template_blas_sqrt(Treal x)
Treal template_blas_log(Treal x)
Treal template_blas_cos(Treal x)
int integer
Definition: template_blas_common.h:40
#define minMACRO(a, b)
Definition: template_blas_common.h:46
int template_lapack_larnv(const integer *idist, integer *iseed, const integer *n, Treal *x)
Definition: template_lapack_larnv.h:42
int dlaruv_(integer *iseed, const integer *n, Treal *x)
Definition: template_lapack_laruv.h:42