# sgebak.f - Man Page

## Synopsis

### Functions/Subroutines

subroutine **sgebak** (JOB, SIDE, **N**, ILO, IHI, SCALE, M, V, LDV, INFO)**SGEBAK**

## Function/Subroutine Documentation

### subroutine sgebak (character JOB, character SIDE, integer N, integer ILO, integer IHI, real, dimension( * ) SCALE, integer M, real, dimension( ldv, * ) V, integer LDV, integer INFO)

**SGEBAK**

**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.

**Parameters:***JOB*JOB is 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*SIDE is CHARACTER*1 = 'R': V contains right eigenvectors; = 'L': V contains left eigenvectors.

*N*N is INTEGER The number of rows of the matrix V. N >= 0.

*ILO*ILO is INTEGER

*IHI*IHI is 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*SCALE is REAL array, dimension (N) Details of the permutation and scaling factors, as returned by SGEBAL.

*M*M is INTEGER The number of columns of the matrix V. M >= 0.

*V*V is 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*LDV is INTEGER The leading dimension of the array V. LDV >= max(1,N).

*INFO*INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value.

**Author:**Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**December 2016

Definition at line 132 of file sgebak.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page sgebak(3) is an alias of sgebak.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK