276 lines
8.1 KiB
C++
276 lines
8.1 KiB
C++
/* fortran/dlarf.f -- translated by f2c (version 20200916).
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You must link the resulting object file with libf2c:
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on Microsoft Windows system, link with libf2c.lib;
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm
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or, if you install libf2c.a in a standard place, with -lf2c -lm
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-- in that order, at the end of the command line, as in
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cc *.o -lf2c -lm
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
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http://www.netlib.org/f2c/libf2c.zip
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "lmp_f2c.h"
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/* Table of constant values */
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static doublereal c_b4 = 1.;
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static doublereal c_b5 = 0.;
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static integer c__1 = 1;
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/* > \brief \b DLARF applies an elementary reflector to a general rectangular matrix. */
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/* =========== DOCUMENTATION =========== */
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/* Online html documentation available at */
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/* http://www.netlib.org/lapack/explore-html/ */
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/* > \htmlonly */
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/* > Download DLARF + dependencies */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlarf.f
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"> */
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/* > [TGZ]</a> */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlarf.f
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"> */
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/* > [ZIP]</a> */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlarf.f
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"> */
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/* > [TXT]</a> */
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/* > \endhtmlonly */
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/* Definition: */
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/* =========== */
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/* SUBROUTINE DLARF( SIDE, M, N, V, INCV, TAU, C, LDC, WORK ) */
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/* .. Scalar Arguments .. */
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/* CHARACTER SIDE */
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/* INTEGER INCV, LDC, M, N */
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/* DOUBLE PRECISION TAU */
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/* .. */
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/* .. Array Arguments .. */
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/* DOUBLE PRECISION C( LDC, * ), V( * ), WORK( * ) */
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/* .. */
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/* > \par Purpose: */
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/* ============= */
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/* > */
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/* > \verbatim */
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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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/* > */
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/* > H = I - tau * v * v**T */
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/* > */
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/* > where tau is a real scalar and v is a real vector. */
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/* > */
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/* > If tau = 0, then H is taken to be the unit matrix. */
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/* > \endverbatim */
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/* Arguments: */
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/* ========== */
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/* > \param[in] SIDE */
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/* > \verbatim */
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/* > SIDE is CHARACTER*1 */
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/* > = 'L': form H * C */
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/* > = 'R': form C * H */
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/* > \endverbatim */
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/* > */
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/* > \param[in] M */
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/* > \verbatim */
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/* > M is INTEGER */
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/* > The number of rows of the matrix C. */
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/* > \endverbatim */
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/* > */
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/* > \param[in] N */
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/* > \verbatim */
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/* > N is INTEGER */
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/* > The number of columns of the matrix C. */
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/* > \endverbatim */
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/* > */
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/* > \param[in] V */
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/* > \verbatim */
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/* > V is 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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/* > \endverbatim */
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/* > */
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/* > \param[in] INCV */
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/* > \verbatim */
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/* > INCV is INTEGER */
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/* > The increment between elements of v. INCV <> 0. */
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/* > \endverbatim */
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/* > */
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/* > \param[in] TAU */
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/* > \verbatim */
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/* > TAU is DOUBLE PRECISION */
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/* > The value tau in the representation of H. */
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/* > \endverbatim */
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/* > */
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/* > \param[in,out] C */
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/* > \verbatim */
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/* > C is 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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/* > \endverbatim */
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/* > */
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/* > \param[in] LDC */
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/* > \verbatim */
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/* > LDC is INTEGER */
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/* > The leading dimension of the array C. LDC >= max(1,M). */
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/* > \endverbatim */
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/* > */
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/* > \param[out] WORK */
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/* > \verbatim */
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/* > WORK is 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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/* > \endverbatim */
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/* Authors: */
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/* ======== */
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/* > \author Univ. of Tennessee */
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/* > \author Univ. of California Berkeley */
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/* > \author Univ. of Colorado Denver */
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/* > \author NAG Ltd. */
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/* > \ingroup doubleOTHERauxiliary */
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/* ===================================================================== */
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/* Subroutine */ int dlarf_(char *side, integer *m, integer *n, doublereal *v,
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integer *incv, doublereal *tau, doublereal *c__, integer *ldc,
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doublereal *work, ftnlen side_len)
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{
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/* System generated locals */
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integer c_dim1, c_offset;
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doublereal d__1;
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/* Local variables */
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integer i__;
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logical applyleft;
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extern /* Subroutine */ int dger_(integer *, integer *, doublereal *,
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doublereal *, integer *, doublereal *, integer *, doublereal *,
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integer *);
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extern logical lsame_(char *, char *, ftnlen, ftnlen);
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extern /* Subroutine */ int dgemv_(char *, integer *, integer *,
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doublereal *, doublereal *, integer *, doublereal *, integer *,
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doublereal *, doublereal *, integer *, ftnlen);
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integer lastc, lastv;
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extern integer iladlc_(integer *, integer *, doublereal *, integer *),
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iladlr_(integer *, integer *, doublereal *, integer *);
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/* -- LAPACK auxiliary routine -- */
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/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
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/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
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/* .. Scalar Arguments .. */
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/* .. */
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/* .. Array Arguments .. */
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/* .. */
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/* ===================================================================== */
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/* .. Parameters .. */
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/* .. */
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/* .. Local Scalars .. */
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/* .. */
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/* .. External Subroutines .. */
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/* .. */
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/* .. External Functions .. */
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/* .. */
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/* .. Executable Statements .. */
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/* Parameter adjustments */
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--v;
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c_dim1 = *ldc;
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c_offset = 1 + c_dim1;
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c__ -= c_offset;
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--work;
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/* Function Body */
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applyleft = lsame_(side, (char *)"L", (ftnlen)1, (ftnlen)1);
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lastv = 0;
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lastc = 0;
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if (*tau != 0.) {
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/* Set up variables for scanning V. LASTV begins pointing to the end */
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/* of V. */
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if (applyleft) {
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lastv = *m;
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} else {
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lastv = *n;
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}
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if (*incv > 0) {
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i__ = (lastv - 1) * *incv + 1;
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} else {
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i__ = 1;
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}
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/* Look for the last non-zero row in V. */
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while(lastv > 0 && v[i__] == 0.) {
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--lastv;
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i__ -= *incv;
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}
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if (applyleft) {
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/* Scan for the last non-zero column in C(1:lastv,:). */
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lastc = iladlc_(&lastv, n, &c__[c_offset], ldc);
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} else {
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/* Scan for the last non-zero row in C(:,1:lastv). */
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lastc = iladlr_(m, &lastv, &c__[c_offset], ldc);
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}
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}
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/* Note that lastc.eq.0 renders the BLAS operations null; no special */
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/* case is needed at this level. */
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if (applyleft) {
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/* Form H * C */
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if (lastv > 0) {
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/* w(1:lastc,1) := C(1:lastv,1:lastc)**T * v(1:lastv,1) */
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dgemv_((char *)"Transpose", &lastv, &lastc, &c_b4, &c__[c_offset], ldc, &
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v[1], incv, &c_b5, &work[1], &c__1, (ftnlen)9);
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/* C(1:lastv,1:lastc) := C(...) - v(1:lastv,1) * w(1:lastc,1)**T */
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d__1 = -(*tau);
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dger_(&lastv, &lastc, &d__1, &v[1], incv, &work[1], &c__1, &c__[
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c_offset], ldc);
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}
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} else {
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/* Form C * H */
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if (lastv > 0) {
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/* w(1:lastc,1) := C(1:lastc,1:lastv) * v(1:lastv,1) */
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dgemv_((char *)"No transpose", &lastc, &lastv, &c_b4, &c__[c_offset], ldc,
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&v[1], incv, &c_b5, &work[1], &c__1, (ftnlen)12);
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/* C(1:lastc,1:lastv) := C(...) - w(1:lastc,1) * v(1:lastv,1)**T */
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d__1 = -(*tau);
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dger_(&lastc, &lastv, &d__1, &work[1], &c__1, &v[1], incv, &c__[
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c_offset], 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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#ifdef __cplusplus
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}
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#endif
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