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template_lapack_larf.h
Go to the documentation of this file.
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/* Ergo, version 3.2, a program for linear scaling electronic structure
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* calculations.
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* Copyright (C) 2012 Elias Rudberg, Emanuel H. Rubensson, and Pawel Salek.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* Primary academic reference:
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* KohnâSham Density Functional Theory Electronic Structure Calculations
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* with Linearly Scaling Computational Time and Memory Usage,
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* Elias Rudberg, Emanuel H. Rubensson, and Pawel Salek,
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* J. Chem. Theory Comput. 7, 340 (2011),
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* <http://dx.doi.org/10.1021/ct100611z>
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*
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* For further information about Ergo, see <http://www.ergoscf.org>.
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*/
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/* This file belongs to the template_lapack part of the Ergo source
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* code. The source files in the template_lapack directory are modified
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* versions of files originally distributed as CLAPACK, see the
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* Copyright/license notice in the file template_lapack/COPYING.
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*/
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#ifndef TEMPLATE_LAPACK_LARF_HEADER
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#define TEMPLATE_LAPACK_LARF_HEADER
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template
<
class
Treal>
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int
template_lapack_larf
(
const
char
*
side
,
const
integer
*m,
const
integer
*n,
const
Treal *v,
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const
integer
*incv,
const
Treal *tau, Treal *c__,
const
integer
*ldc,
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Treal *work)
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{
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/* -- LAPACK auxiliary routine (version 3.0) --
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Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
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Courant Institute, Argonne National Lab, and Rice University
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February 29, 1992
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Purpose
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=======
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DLARF applies a real elementary reflector H to a real m by n matrix
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C, from either the left or the right. H is represented in the form
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H = I - tau * v * v'
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where tau is a real scalar and v is a real vector.
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If tau = 0, then H is taken to be the unit matrix.
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Arguments
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=========
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SIDE (input) CHARACTER*1
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= 'L': form H * C
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= 'R': form C * H
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M (input) INTEGER
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The number of rows of the matrix C.
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N (input) INTEGER
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The number of columns of the matrix C.
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V (input) DOUBLE PRECISION array, dimension
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(1 + (M-1)*abs(INCV)) if SIDE = 'L'
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or (1 + (N-1)*abs(INCV)) if SIDE = 'R'
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The vector v in the representation of H. V is not used if
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TAU = 0.
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INCV (input) INTEGER
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The increment between elements of v. INCV <> 0.
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TAU (input) DOUBLE PRECISION
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The value tau in the representation of H.
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C (input/output) DOUBLE PRECISION array, dimension (LDC,N)
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On entry, the m by n matrix C.
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On exit, C is overwritten by the matrix H * C if SIDE = 'L',
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or C * H if SIDE = 'R'.
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LDC (input) INTEGER
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The leading dimension of the array C. LDC >= max(1,M).
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WORK (workspace) DOUBLE PRECISION array, dimension
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(N) if SIDE = 'L'
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or (M) if SIDE = 'R'
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=====================================================================
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Parameter adjustments */
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/* Table of constant values */
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Treal c_b4 = 1.;
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Treal c_b5 = 0.;
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integer
c__1 = 1;
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/* System generated locals */
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integer
c_dim1, c_offset;
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Treal d__1;
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--v;
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c_dim1 = *ldc;
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c_offset = 1 + c_dim1 * 1;
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c__ -= c_offset;
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--work;
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/* Function Body */
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if
(
template_blas_lsame
(side,
"L"
)) {
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/* Form H * C */
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if
(*tau != 0.) {
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/* w := C' * v */
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template_blas_gemv
(
"Transpose"
, m, n, &c_b4, &c__[c_offset], ldc, &v[1], incv,
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&c_b5, &work[1], &c__1);
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/* C := C - v * w' */
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d__1 = -(*tau);
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template_blas_ger
(m, n, &d__1, &v[1], incv, &work[1], &c__1, &c__[c_offset],
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ldc);
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}
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}
else
{
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/* Form C * H */
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if
(*tau != 0.) {
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/* w := C * v */
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template_blas_gemv
(
"No transpose"
, m, n, &c_b4, &c__[c_offset], ldc, &v[1],
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incv, &c_b5, &work[1], &c__1);
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/* C := C - w * v' */
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d__1 = -(*tau);
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template_blas_ger
(m, n, &d__1, &work[1], &c__1, &v[1], incv, &c__[c_offset],
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ldc);
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}
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}
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return
0;
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/* End of DLARF */
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}
/* dlarf_ */
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#endif
source
matrix
template_lapack
lapack
template_lapack_larf.h
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