ergo
template_lapack_org2r.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_LAPACK_ORG2R_HEADER
38#define TEMPLATE_LAPACK_ORG2R_HEADER
39
40
41template<class Treal>
42int template_lapack_org2r(const integer *m, const integer *n, const integer *k, Treal *
43 a, const integer *lda, const Treal *tau, Treal *work, integer *info)
44{
45/* -- LAPACK routine (version 3.0) --
46 Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
47 Courant Institute, Argonne National Lab, and Rice University
48 February 29, 1992
49
50
51 Purpose
52 =======
53
54 DORG2R generates an m by n real matrix Q with orthonormal columns,
55 which is defined as the first n columns of a product of k elementary
56 reflectors of order m
57
58 Q = H(1) H(2) . . . H(k)
59
60 as returned by DGEQRF.
61
62 Arguments
63 =========
64
65 M (input) INTEGER
66 The number of rows of the matrix Q. M >= 0.
67
68 N (input) INTEGER
69 The number of columns of the matrix Q. M >= N >= 0.
70
71 K (input) INTEGER
72 The number of elementary reflectors whose product defines the
73 matrix Q. N >= K >= 0.
74
75 A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
76 On entry, the i-th column must contain the vector which
77 defines the elementary reflector H(i), for i = 1,2,...,k, as
78 returned by DGEQRF in the first k columns of its array
79 argument A.
80 On exit, the m-by-n matrix Q.
81
82 LDA (input) INTEGER
83 The first dimension of the array A. LDA >= max(1,M).
84
85 TAU (input) DOUBLE PRECISION array, dimension (K)
86 TAU(i) must contain the scalar factor of the elementary
87 reflector H(i), as returned by DGEQRF.
88
89 WORK (workspace) DOUBLE PRECISION array, dimension (N)
90
91 INFO (output) INTEGER
92 = 0: successful exit
93 < 0: if INFO = -i, the i-th argument has an illegal value
94
95 =====================================================================
96
97
98 Test the input arguments
99
100 Parameter adjustments */
101 /* Table of constant values */
102 integer c__1 = 1;
103
104 /* System generated locals */
105 integer a_dim1, a_offset, i__1, i__2;
106 Treal d__1;
107 /* Local variables */
108 integer i__, j, l;
109#define a_ref(a_1,a_2) a[(a_2)*a_dim1 + a_1]
110
111
112 a_dim1 = *lda;
113 a_offset = 1 + a_dim1 * 1;
114 a -= a_offset;
115 --tau;
116 --work;
117
118 /* Function Body */
119 *info = 0;
120 if (*m < 0) {
121 *info = -1;
122 } else if (*n < 0 || *n > *m) {
123 *info = -2;
124 } else if (*k < 0 || *k > *n) {
125 *info = -3;
126 } else if (*lda < maxMACRO(1,*m)) {
127 *info = -5;
128 }
129 if (*info != 0) {
130 i__1 = -(*info);
131 template_blas_erbla("ORG2R ", &i__1);
132 return 0;
133 }
134
135/* Quick return if possible */
136
137 if (*n <= 0) {
138 return 0;
139 }
140
141/* Initialise columns k+1:n to columns of the unit matrix */
142
143 i__1 = *n;
144 for (j = *k + 1; j <= i__1; ++j) {
145 i__2 = *m;
146 for (l = 1; l <= i__2; ++l) {
147 a_ref(l, j) = 0.;
148/* L10: */
149 }
150 a_ref(j, j) = 1.;
151/* L20: */
152 }
153
154 for (i__ = *k; i__ >= 1; --i__) {
155
156/* Apply H(i) to A(i:m,i:n) from the left */
157
158 if (i__ < *n) {
159 a_ref(i__, i__) = 1.;
160 i__1 = *m - i__ + 1;
161 i__2 = *n - i__;
162 template_lapack_larf("Left", &i__1, &i__2, &a_ref(i__, i__), &c__1, &tau[i__], &
163 a_ref(i__, i__ + 1), lda, &work[1]);
164 }
165 if (i__ < *m) {
166 i__1 = *m - i__;
167 d__1 = -tau[i__];
168 template_blas_scal(&i__1, &d__1, &a_ref(i__ + 1, i__), &c__1);
169 }
170 a_ref(i__, i__) = 1. - tau[i__];
171
172/* Set A(1:i-1,i) to zero */
173
174 i__1 = i__ - 1;
175 for (l = 1; l <= i__1; ++l) {
176 a_ref(l, i__) = 0.;
177/* L30: */
178 }
179/* L40: */
180 }
181 return 0;
182
183/* End of DORG2R */
184
185} /* dorg2r_ */
186
187#undef a_ref
188
189
190#endif
int template_blas_erbla(const char *srname, integer *info)
Definition: template_blas_common.cc:146
int integer
Definition: template_blas_common.h:40
#define maxMACRO(a, b)
Definition: template_blas_common.h:45
int template_blas_scal(const integer *n, const Treal *da, Treal *dx, const integer *incx)
Definition: template_blas_scal.h:43
int template_lapack_larf(const char *side, const integer *m, const integer *n, const Treal *v, const integer *incv, const Treal *tau, Treal *c__, const integer *ldc, Treal *work)
Definition: template_lapack_larf.h:42
#define a_ref(a_1, a_2)
int template_lapack_org2r(const integer *m, const integer *n, const integer *k, Treal *a, const integer *lda, const Treal *tau, Treal *work, integer *info)
Definition: template_lapack_org2r.h:42