dgebak (l)  Linux Manuals
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
Command to display dgebak
manual in Linux: $ man l dgebak
NAME
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
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 transformation on the computed eigenvectors of the
balanced matrix output by DGEBAL.
ARGUMENTS
 JOB (input) CHARACTER*1

Specifies the type of backward transformation required:
= aqNaq, do nothing, return immediately;
= aqPaq, do backward transformation for permutation only;
= aqSaq, do backward transformation for scaling only;
= aqBaq, do backward transformations for both permutation and
scaling.
JOB must be the same as the argument JOB supplied to DGEBAL.
 SIDE (input) CHARACTER*1

= aqRaq: V contains right eigenvectors;
= aqLaq: 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.
Pages related to dgebak
 dgebak (3)
 dgebal (l)  balances a general real matrix A
 dgebd2 (l)  reduces a real general m by n matrix A to upper or lower bidiagonal form B by an orthogonal transformation
 dgebrd (l)  reduces a general real MbyN matrix A to upper or lower bidiagonal form B by an orthogonal transformation
 dgecon (l)  estimates the reciprocal of the condition number of a general real matrix A, in either the 1norm or the infinitynorm, using the LU factorization computed by DGETRF
 dgeequ (l)  computes row and column scalings intended to equilibrate an MbyN matrix A and reduce its condition number
 dgeequb (l)  computes row and column scalings intended to equilibrate an MbyN matrix A and reduce its condition number
 dgees (l)  computes for an NbyN real nonsymmetric matrix A, the eigenvalues, the real Schur form T, and, optionally, the matrix of Schur vectors Z