
SGEBAK(l) ) SGEBAK(l)
NAME
SGEBAK  form the right or left eigenvectors of a real general matrix by backward trans
formation 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 JOB, SIDE
INTEGER IHI, ILO, INFO, LDV, M, N
REAL V( LDV, * ), SCALE( * )
PURPOSE
SGEBAK forms the right or left eigenvectors of a real general matrix by backward transfor
mation on the computed eigenvectors of the balanced matrix output by SGEBAL.
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 SGEBAL.
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 SGEBAL. 1 <= ILO
<= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
SCALE (input) REAL array, dimension (N)
Details of the permutation and scaling factors, as returned by SGEBAL.
M (input) INTEGER
The number of columns of the matrix V. M >= 0.
V (input/output) REAL array, dimension (LDV,M)
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) INTEGER
The leading dimension of the array V. LDV >= max(1,N).
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value.
LAPACK version 3.0 15 June 2000 SGEBAK(l) 
