
DGEBAK(l) ) DGEBAK(l)
NAME
DGEBAK  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 DGEBAL
SYNOPSIS
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, * )
PURPOSE
DGEBAK 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 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 ith argument had an illegal value.
LAPACK version 3.0 15 June 2000 DGEBAK(l) 
