Contents
dgebak - form the right or left eigenvectors of a real gen-
eral matrix by backward transformation on the computed
eigenvectors of the balanced matrix output by SGEBAL
SUBROUTINE DGEBAK(JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV, INFO)
CHARACTER * 1 JOB, SIDE
INTEGER N, ILO, IHI, M, LDV, INFO
DOUBLE PRECISION SCALE(*), V(LDV,*)
SUBROUTINE DGEBAK_64(JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV, INFO)
CHARACTER * 1 JOB, SIDE
INTEGER*8 N, ILO, IHI, M, LDV, INFO
DOUBLE PRECISION SCALE(*), V(LDV,*)
F95 INTERFACE
SUBROUTINE GEBAK(JOB, SIDE, [N], ILO, IHI, SCALE, [M], V, [LDV],
[INFO])
CHARACTER(LEN=1) :: JOB, SIDE
INTEGER :: N, ILO, IHI, M, LDV, INFO
REAL(8), DIMENSION(:) :: SCALE
REAL(8), DIMENSION(:,:) :: V
SUBROUTINE GEBAK_64(JOB, SIDE, [N], ILO, IHI, SCALE, [M], V, [LDV],
[INFO])
CHARACTER(LEN=1) :: JOB, SIDE
INTEGER(8) :: N, ILO, IHI, M, LDV, INFO
REAL(8), DIMENSION(:) :: SCALE
REAL(8), DIMENSION(:,:) :: V
C INTERFACE
#include <sunperf.h>
void dgebak(char job, char side, int n, int ilo, int ihi,
double *scale, int m, double *v, int ldv, int
*info);
void dgebak_64(char job, char side, long n, long ilo, long
ihi, double *scale, long m, double *v, long ldv,
long *info);
dgebak forms the right or left eigenvectors of a real gen-
eral matrix by backward transformation on the computed
eigenvectors of the balanced matrix output by SGEBAL.
JOB (input)
Specifies the type of backward transformation
required: = 'N', do nothing, return immediately;
= 'P', do backward transformation for permutation
only; = 'S', do backward transformation for scal-
ing only; = 'B', do backward transformations for
both permutation and scaling. JOB must be the
same as the argument JOB supplied to SGEBAL.
SIDE (input)
= 'R': V contains right eigenvectors;
= 'L': V contains left eigenvectors.
N (input) The number of rows of the matrix V. N >= 0.
ILO (input)
The integers ILO and IHI determined by SGEBAL. 1
<= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if
N=0.
IHI (input)
See the description for ILO.
SCALE (input)
Details of the permutation and scaling factors, as
returned by SGEBAL.
M (input) The number of columns of the matrix V. M >= 0.
V (input/output)
On entry, the matrix of right or left eigenvectors
to be transformed, as returned by SHSEIN or
STREVC. On exit, V is overwritten by the
transformed eigenvectors.
LDV (input)
The leading dimension of the array V. LDV >=
max(1,N).
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an ille-
gal value.