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/* dgebak.f -- translated by f2c (version 20061008).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#include "f2c.h"
#include "blaswrap.h"
/* Subroutine */ int dgebak_(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 dscal_(integer *, doublereal *, doublereal *,
integer *);
extern logical lsame_(char *, char *);
extern /* Subroutine */ int dswap_(integer *, doublereal *, integer *,
doublereal *, integer *);
logical leftv;
extern /* Subroutine */ int xerbla_(char *, integer *);
logical rightv;
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* 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. */
/* Arguments */
/* ========= */
/* JOB (input) 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. */
/* SIDE (input) CHARACTER*1 */
/* = 'R': V contains right eigenvectors; */
/* = 'L': V contains left eigenvectors. */
/* N (input) INTEGER */
/* The number of rows of the matrix V. N >= 0. */
/* ILO (input) INTEGER */
/* IHI (input) INTEGER */
/* The integers ILO and IHI determined by DGEBAL. */
/* 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. */
/* SCALE (input) DOUBLE PRECISION array, dimension (N) */
/* Details of the permutation and scaling factors, as returned */
/* by DGEBAL. */
/* M (input) INTEGER */
/* The number of columns of the matrix V. M >= 0. */
/* V (input/output) 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. */
/* LDV (input) INTEGER */
/* The leading dimension of the array V. LDV >= max(1,N). */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument had an illegal value. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Decode and Test the input parameters */
/* Parameter adjustments */
--scale;
v_dim1 = *ldv;
v_offset = 1 + v_dim1;
v -= v_offset;
/* Function Body */
rightv = lsame_(side, "R");
leftv = lsame_(side, "L");
*info = 0;
if (! lsame_(job, "N") && ! lsame_(job, "P") && ! lsame_(job, "S")
&& ! lsame_(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);
xerbla_("DGEBAK", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
if (*m == 0) {
return 0;
}
if (lsame_(job, "N")) {
return 0;
}
if (*ilo == *ihi) {
goto L30;
}
/* Backward balance */
if (lsame_(job, "S") || lsame_(job, "B")) {
if (rightv) {
i__1 = *ihi;
for (i__ = *ilo; i__ <= i__1; ++i__) {
s = scale[i__];
dscal_(m, &s, &v[i__ + v_dim1], ldv);
/* L10: */
}
}
if (leftv) {
i__1 = *ihi;
for (i__ = *ilo; i__ <= i__1; ++i__) {
s = 1. / scale[i__];
dscal_(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 (lsame_(job, "P") || lsame_(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;
}
dswap_(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;
}
dswap_(m, &v[i__ + v_dim1], ldv, &v[k + v_dim1], ldv);
L50:
;
}
}
}
return 0;
/* End of DGEBAK */
} /* dgebak_ */
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