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sgebak.f(3) LAPACK sgebak.f(3)

NAME

sgebak.f

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

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Tue Nov 14 2017 Version 3.8.0