dgebak-f(3)

dgebak.f –

Synopsis

Functions/Subroutines

subroutine dgebak (JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV, INFO)
DGEBAK

Function/Subroutine Documentation

subroutine dgebak (characterJOB, characterSIDE, integerN, integerILO, integerIHI, double precision, dimension( * )SCALE, integerM, double precision, dimension( ldv, * )V, integerLDV, integerINFO)

DGEBAK

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.

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 DGEBAL.

SIDE

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

 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 DGEBAL.
 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.

SCALE

 SCALE is DOUBLE PRECISION array, dimension (N)
 Details of the permutation and scaling factors, as returned
 by DGEBAL.

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

 V is 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

 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:

November 2011

Definition at line 130 of file dgebak.f.

Author

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