302 lines
7.7 KiB
C
302 lines
7.7 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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/* > \brief \b DGEBAK
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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 DGEBAK + dependencies
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> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgebak.
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f">
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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/dgebak.
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f">
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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/dgebak.
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f">
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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 DGEBAK( JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV,
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INFO )
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CHARACTER JOB, SIDE
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INTEGER IHI, ILO, INFO, LDV, M, N
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DOUBLE PRECISION SCALE( * ), V( LDV, * )
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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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> DGEBAK forms the right or left eigenvectors of a real general matrix
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> by backward transformation on the computed eigenvectors of the
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> balanced matrix output by DGEBAL.
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> \endverbatim
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Arguments:
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==========
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> \param[in] JOB
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> \verbatim
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> JOB is CHARACTER*1
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> Specifies the type of backward transformation required:
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> = 'N', do nothing, return immediately;
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> = 'P', do backward transformation for permutation only;
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> = 'S', do backward transformation for scaling only;
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> = 'B', do backward transformations for both permutation and
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> scaling.
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> JOB must be the same as the argument JOB supplied to DGEBAL.
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> \endverbatim
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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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> = 'R': V contains right eigenvectors;
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> = 'L': V contains left eigenvectors.
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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 rows of the matrix V. N >= 0.
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> \endverbatim
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>
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> \param[in] ILO
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> \verbatim
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> ILO is INTEGER
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> \endverbatim
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>
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> \param[in] IHI
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> \verbatim
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> IHI is INTEGER
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> The integers ILO and IHI determined by DGEBAL.
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> 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
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> \endverbatim
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>
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> \param[in] SCALE
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> \verbatim
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> SCALE is DOUBLE PRECISION array, dimension (N)
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> Details of the permutation and scaling factors, as returned
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> by DGEBAL.
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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 columns of the matrix V. M >= 0.
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> \endverbatim
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>
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> \param[in,out] V
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> \verbatim
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> V is DOUBLE PRECISION array, dimension (LDV,M)
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> On entry, the matrix of right or left eigenvectors to be
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> transformed, as returned by DHSEIN or DTREVC.
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> On exit, V is overwritten by the transformed eigenvectors.
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> \endverbatim
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>
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> \param[in] LDV
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> \verbatim
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> LDV is INTEGER
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> The leading dimension of the array V. LDV >= max(1,N).
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> \endverbatim
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>
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> \param[out] INFO
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> \verbatim
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> INFO is INTEGER
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> = 0: successful exit
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> < 0: if INFO = -i, the i-th argument had an illegal value.
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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 November 2011
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> \ingroup doubleGEcomputational
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=====================================================================
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Subroutine */ int igraphdgebak_(char *job, char *side, integer *n, integer *ilo,
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integer *ihi, doublereal *scale, integer *m, doublereal *v, integer *
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ldv, integer *info)
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{
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/* System generated locals */
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integer v_dim1, v_offset, i__1;
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/* Local variables */
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integer i__, k;
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doublereal s;
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integer ii;
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extern /* Subroutine */ int igraphdscal_(integer *, doublereal *, doublereal *,
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integer *);
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extern logical igraphlsame_(char *, char *);
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extern /* Subroutine */ int igraphdswap_(integer *, doublereal *, integer *,
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doublereal *, integer *);
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logical leftv;
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extern /* Subroutine */ int igraphxerbla_(char *, integer *, ftnlen);
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logical rightv;
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/* -- LAPACK computational routine (version 3.4.0) --
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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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November 2011
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=====================================================================
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Decode and Test the input parameters
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Parameter adjustments */
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--scale;
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v_dim1 = *ldv;
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v_offset = 1 + v_dim1;
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v -= v_offset;
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/* Function Body */
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rightv = igraphlsame_(side, "R");
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leftv = igraphlsame_(side, "L");
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*info = 0;
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if (! igraphlsame_(job, "N") && ! igraphlsame_(job, "P") && ! igraphlsame_(job, "S")
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&& ! igraphlsame_(job, "B")) {
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*info = -1;
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} else if (! rightv && ! leftv) {
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*info = -2;
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} else if (*n < 0) {
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*info = -3;
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} else if (*ilo < 1 || *ilo > max(1,*n)) {
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*info = -4;
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} else if (*ihi < min(*ilo,*n) || *ihi > *n) {
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*info = -5;
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} else if (*m < 0) {
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*info = -7;
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} else if (*ldv < max(1,*n)) {
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*info = -9;
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}
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if (*info != 0) {
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i__1 = -(*info);
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igraphxerbla_("DGEBAK", &i__1, (ftnlen)6);
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return 0;
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}
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/* Quick return if possible */
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if (*n == 0) {
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return 0;
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}
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if (*m == 0) {
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return 0;
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}
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if (igraphlsame_(job, "N")) {
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return 0;
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}
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if (*ilo == *ihi) {
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goto L30;
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}
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/* Backward balance */
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if (igraphlsame_(job, "S") || igraphlsame_(job, "B")) {
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if (rightv) {
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i__1 = *ihi;
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for (i__ = *ilo; i__ <= i__1; ++i__) {
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s = scale[i__];
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igraphdscal_(m, &s, &v[i__ + v_dim1], ldv);
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/* L10: */
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}
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}
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if (leftv) {
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i__1 = *ihi;
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for (i__ = *ilo; i__ <= i__1; ++i__) {
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s = 1. / scale[i__];
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igraphdscal_(m, &s, &v[i__ + v_dim1], ldv);
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/* L20: */
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}
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}
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}
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/* Backward permutation
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For I = ILO-1 step -1 until 1,
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IHI+1 step 1 until N do -- */
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L30:
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if (igraphlsame_(job, "P") || igraphlsame_(job, "B")) {
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if (rightv) {
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i__1 = *n;
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for (ii = 1; ii <= i__1; ++ii) {
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i__ = ii;
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if (i__ >= *ilo && i__ <= *ihi) {
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goto L40;
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}
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if (i__ < *ilo) {
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i__ = *ilo - ii;
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}
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k = (integer) scale[i__];
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if (k == i__) {
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goto L40;
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}
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igraphdswap_(m, &v[i__ + v_dim1], ldv, &v[k + v_dim1], ldv);
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L40:
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;
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}
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}
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if (leftv) {
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i__1 = *n;
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for (ii = 1; ii <= i__1; ++ii) {
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i__ = ii;
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if (i__ >= *ilo && i__ <= *ihi) {
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goto L50;
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}
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if (i__ < *ilo) {
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i__ = *ilo - ii;
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}
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k = (integer) scale[i__];
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if (k == i__) {
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goto L50;
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}
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igraphdswap_(m, &v[i__ + v_dim1], ldv, &v[k + v_dim1], ldv);
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L50:
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;
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}
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}
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}
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return 0;
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/* End of DGEBAK */
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} /* igraphdgebak_ */
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