sgebak(3P) Sun Performance Library sgebak(3P)NAMEsgebak - form the right or left eigenvectors of a real general matrix
by backward transformation on the computed eigenvectors of the balanced
matrix output by SGEBAL
SYNOPSIS
SUBROUTINE SGEBAK(JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV, INFO)
CHARACTER * 1 JOB, SIDE
INTEGER N, ILO, IHI, M, LDV, INFO
REAL SCALE(*), V(LDV,*)
SUBROUTINE SGEBAK_64(JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV, INFO)
CHARACTER * 1 JOB, SIDE
INTEGER*8 N, ILO, IHI, M, LDV, INFO
REAL 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, DIMENSION(:) :: SCALE
REAL, 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, DIMENSION(:) :: SCALE
REAL, DIMENSION(:,:) :: V
C INTERFACE
#include <sunperf.h>
void sgebak(char job, char side, int n, int ilo, int ihi, float *scale,
int m, float *v, int ldv, int *info);
void sgebak_64(char job, char side, long n, long ilo, long ihi, float
*scale, long m, float *v, long ldv, long *info);
PURPOSEsgebak forms the right or left eigenvectors of a real general matrix by
backward transformation on the computed eigenvectors of the balanced
matrix output by SGEBAL.
ARGUMENTS
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 scaling only; = 'B', do backward transfor‐
mations 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 illegal value.
6 Mar 2009 sgebak(3P)