Abdelrahman Said
256 lines
7.3 KiB
C
256 lines
7.3 KiB
C
/* -- translated by f2c (version 20240504).
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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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#include "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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CHARACTER SIDE
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INTEGER INCV, LDC, M, N
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DOUBLE PRECISION TAU
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DOUBLE PRECISION C( LDC, * ), V( * ), WORK( * )
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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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> \date September 2012
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> \ingroup doubleOTHERauxiliary
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=====================================================================
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Subroutine */ int igraphdlarf_(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)
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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 igraphdger_(integer *, integer *, doublereal *,
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doublereal *, integer *, doublereal *, integer *, doublereal *,
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integer *);
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extern logical igraphlsame_(char *, char *);
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extern /* Subroutine */ int igraphdgemv_(char *, integer *, integer *,
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doublereal *, doublereal *, integer *, doublereal *, integer *,
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doublereal *, doublereal *, integer *);
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integer lastc, lastv;
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extern integer igraphiladlc_(integer *, integer *, doublereal *, integer *),
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igraphiladlr_(integer *, integer *, doublereal *, integer *);
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/* -- LAPACK auxiliary routine (version 3.4.2) --
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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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September 2012
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=====================================================================
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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 = igraphlsame_(side, "L");
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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 = igraphiladlc_(&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 = igraphiladlr_(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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igraphdgemv_("Transpose", &lastv, &lastc, &c_b4, &c__[c_offset], ldc, &
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v[1], incv, &c_b5, &work[1], &c__1);
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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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igraphdger_(&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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igraphdgemv_("No transpose", &lastc, &lastv, &c_b4, &c__[c_offset], ldc,
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&v[1], incv, &c_b5, &work[1], &c__1);
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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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igraphdger_(&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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} /* igraphdlarf_ */
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