Provided by: liblapack-doc_3.3.1-1_all NAME

LAPACK-3 - uses inverse iteration to find a right or left eigenvector corresponding to the
eigenvalue W of a complex upper Hessenberg matrix H

SYNOPSIS

SUBROUTINE CLAEIN( RIGHTV, NOINIT, N, H, LDH, W, V, B, LDB, RWORK, EPS3, SMLNUM, INFO )

LOGICAL        NOINIT, RIGHTV

INTEGER        INFO, LDB, LDH, N

REAL           EPS3, SMLNUM

COMPLEX        W

REAL           RWORK( * )

COMPLEX        B( LDB, * ), H( LDH, * ), V( * )

PURPOSE

CLAEIN uses inverse iteration to find a right or left  eigenvector  corresponding  to  the
eigenvalue W of a complex upper Hessenberg matrix H.

ARGUMENTS

RIGHTV   (input) LOGICAL
= .TRUE. : compute right eigenvector;
= .FALSE.: compute left eigenvector.

NOINIT   (input) LOGICAL
= .TRUE. : no initial vector supplied in V
= .FALSE.: initial vector supplied in V.

N       (input) INTEGER
The order of the matrix H.  N >= 0.

H       (input) COMPLEX array, dimension (LDH,N)
The upper Hessenberg matrix H.

LDH     (input) INTEGER
The leading dimension of the array H.  LDH >= max(1,N).

W       (input) COMPLEX
The eigenvalue of H whose corresponding right or left
eigenvector is to be computed.

V       (input/output) COMPLEX array, dimension (N)
On entry, if NOINIT = .FALSE., V must contain a starting
vector for inverse iteration; otherwise V need not be set.
On exit, V contains the computed eigenvector, normalized so
that the component of largest magnitude has magnitude 1; here
the magnitude of a complex number (x,y) is taken to be
|x| + |y|.

B       (workspace) COMPLEX array, dimension (LDB,N)

LDB     (input) INTEGER
The leading dimension of the array B.  LDB >= max(1,N).

RWORK   (workspace) REAL array, dimension (N)

EPS3    (input) REAL
A small machine-dependent value which is used to perturb
close eigenvalues, and to replace zero pivots.

SMLNUM  (input) REAL
A machine-dependent value close to the underflow threshold.

INFO    (output) INTEGER
= 0:  successful exit
= 1:  inverse iteration did not converge; V is set to the
last iterate.

LAPACK auxiliary routine (version 3.3.1)   April 2011                            CLAEIN(3lapack)