sgebak (l)  Linux Manuals
sgebak: 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
Command to display sgebak
manual in Linux: $ man l sgebak
NAME
SGEBAK  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
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 transformation on the computed eigenvectors of the
balanced matrix output by SGEBAL.
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 SGEBAL.
 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 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.
Pages related to sgebak
 sgebak (3)
 sgebal (l)  balances a general real matrix A
 sgebd2 (l)  reduces a real general m by n matrix A to upper or lower bidiagonal form B by an orthogonal transformation
 sgebrd (l)  reduces a general real MbyN matrix A to upper or lower bidiagonal form B by an orthogonal transformation
 sgecon (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 SGETRF
 sgeequ (l)  computes row and column scalings intended to equilibrate an MbyN matrix A and reduce its condition number
 sgeequb (l)  computes row and column scalings intended to equilibrate an MbyN matrix A and reduce its condition number
 sgees (l)  computes for an NbyN real nonsymmetric matrix A, the eigenvalues, the real Schur form T, and, optionally, the matrix of Schur vectors Z