/* -- translated by f2c (version 20100827).
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*/
#include "f2c.h"
/* > \brief \b DGEBAK
=========== DOCUMENTATION ===========
Online html documentation available at
http://www.netlib.org/lapack/explore-html/
> \htmlonly
> Download DGEBAK + dependencies
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f">
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> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgebak.
f">
> [TXT]</a>
> \endhtmlonly
Definition:
===========
SUBROUTINE DGEBAK( JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV,
INFO )
CHARACTER JOB, SIDE
INTEGER IHI, ILO, INFO, LDV, M, N
DOUBLE PRECISION SCALE( * ), V( LDV, * )
> \par Purpose:
=============
>
> \verbatim
>
> DGEBAK forms the right or left eigenvectors of a real general matrix
> by backward transformation on the computed eigenvectors of the
> balanced matrix output by DGEBAL.
> \endverbatim
Arguments:
==========
> \param[in] JOB
> \verbatim
> JOB is CHARACTER*1
> Specifies the type of backward transformation required:
> = 'N', do nothing, return immediately;
> = 'P', do backward transformation for permutation only;
> = 'S', do backward transformation for scaling only;
> = 'B', do backward transformations for both permutation and
> scaling.
> JOB must be the same as the argument JOB supplied to DGEBAL.
> \endverbatim
>
> \param[in] SIDE
> \verbatim
> SIDE is CHARACTER*1
> = 'R': V contains right eigenvectors;
> = 'L': V contains left eigenvectors.
> \endverbatim
>
> \param[in] N
> \verbatim
> N is INTEGER
> The number of rows of the matrix V. N >= 0.
> \endverbatim
>
> \param[in] ILO
> \verbatim
> ILO is INTEGER
> \endverbatim
>
> \param[in] IHI
> \verbatim
> IHI is INTEGER
> The integers ILO and IHI determined by DGEBAL.
> 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
> \endverbatim
>
> \param[in] SCALE
> \verbatim
> SCALE is DOUBLE PRECISION array, dimension (N)
> Details of the permutation and scaling factors, as returned
> by DGEBAL.
> \endverbatim
>
> \param[in] M
> \verbatim
> M is INTEGER
> The number of columns of the matrix V. M >= 0.
> \endverbatim
>
> \param[in,out] V
> \verbatim
> V is DOUBLE PRECISION array, dimension (LDV,M)
> On entry, the matrix of right or left eigenvectors to be
> transformed, as returned by DHSEIN or DTREVC.
> On exit, V is overwritten by the transformed eigenvectors.
> \endverbatim
>
> \param[in] LDV
> \verbatim
> LDV is INTEGER
> The leading dimension of the array V. LDV >= max(1,N).
> \endverbatim
>
> \param[out] INFO
> \verbatim
> INFO is INTEGER
> = 0: successful exit
> < 0: if INFO = -i, the i-th argument had an illegal value.
> \endverbatim
Authors:
========
> \author Univ. of Tennessee
> \author Univ. of California Berkeley
> \author Univ. of Colorado Denver
> \author NAG Ltd.
> \date November 2011
> \ingroup doubleGEcomputational
=====================================================================
Subroutine */ int igraphdgebak_(char *job, char *side, integer *n, integer *ilo,
integer *ihi, doublereal *scale, integer *m, doublereal *v, integer *
ldv, integer *info)
{
/* System generated locals */
integer v_dim1, v_offset, i__1;
/* Local variables */
integer i__, k;
doublereal s;
integer ii;
extern /* Subroutine */ int igraphdscal_(integer *, doublereal *, doublereal *,
integer *);
extern logical igraphlsame_(char *, char *);
extern /* Subroutine */ int igraphdswap_(integer *, doublereal *, integer *,
doublereal *, integer *);
logical leftv;
extern /* Subroutine */ int igraphxerbla_(char *, integer *, ftnlen);
logical rightv;
/* -- LAPACK computational routine (version 3.4.0) --
-- LAPACK is a software package provided by Univ. of Tennessee, --
-- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
November 2011
=====================================================================
Decode and Test the input parameters
Parameter adjustments */
--scale;
v_dim1 = *ldv;
v_offset = 1 + v_dim1;
v -= v_offset;
/* Function Body */
rightv = igraphlsame_(side, "R");
leftv = igraphlsame_(side, "L");
*info = 0;
if (! igraphlsame_(job, "N") && ! igraphlsame_(job, "P") && ! igraphlsame_(job, "S")
&& ! igraphlsame_(job, "B")) {
*info = -1;
} else if (! rightv && ! leftv) {
*info = -2;
} else if (*n < 0) {
*info = -3;
} else if (*ilo < 1 || *ilo > max(1,*n)) {
*info = -4;
} else if (*ihi < min(*ilo,*n) || *ihi > *n) {
*info = -5;
} else if (*m < 0) {
*info = -7;
} else if (*ldv < max(1,*n)) {
*info = -9;
}
if (*info != 0) {
i__1 = -(*info);
igraphxerbla_("DGEBAK", &i__1, (ftnlen)6);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
if (*m == 0) {
return 0;
}
if (igraphlsame_(job, "N")) {
return 0;
}
if (*ilo == *ihi) {
goto L30;
}
/* Backward balance */
if (igraphlsame_(job, "S") || igraphlsame_(job, "B")) {
if (rightv) {
i__1 = *ihi;
for (i__ = *ilo; i__ <= i__1; ++i__) {
s = scale[i__];
igraphdscal_(m, &s, &v[i__ + v_dim1], ldv);
/* L10: */
}
}
if (leftv) {
i__1 = *ihi;
for (i__ = *ilo; i__ <= i__1; ++i__) {
s = 1. / scale[i__];
igraphdscal_(m, &s, &v[i__ + v_dim1], ldv);
/* L20: */
}
}
}
/* Backward permutation
For I = ILO-1 step -1 until 1,
IHI+1 step 1 until N do -- */
L30:
if (igraphlsame_(job, "P") || igraphlsame_(job, "B")) {
if (rightv) {
i__1 = *n;
for (ii = 1; ii <= i__1; ++ii) {
i__ = ii;
if (i__ >= *ilo && i__ <= *ihi) {
goto L40;
}
if (i__ < *ilo) {
i__ = *ilo - ii;
}
k = (integer) scale[i__];
if (k == i__) {
goto L40;
}
igraphdswap_(m, &v[i__ + v_dim1], ldv, &v[k + v_dim1], ldv);
L40:
;
}
}
if (leftv) {
i__1 = *n;
for (ii = 1; ii <= i__1; ++ii) {
i__ = ii;
if (i__ >= *ilo && i__ <= *ihi) {
goto L50;
}
if (i__ < *ilo) {
i__ = *ilo - ii;
}
k = (integer) scale[i__];
if (k == i__) {
goto L50;
}
igraphdswap_(m, &v[i__ + v_dim1], ldv, &v[k + v_dim1], ldv);
L50:
;
}
}
}
return 0;
/* End of DGEBAK */
} /* igraphdgebak_ */