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zlaein.f(3) LAPACK zlaein.f(3)

zlaein.f -


subroutine zlaein (RIGHTV, NOINIT, N, H, LDH, W, V, B, LDB, RWORK, EPS3, SMLNUM, INFO)
 
ZLAEIN computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration.

ZLAEIN computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration.
Purpose:
 ZLAEIN uses inverse iteration to find a right or left eigenvector
 corresponding to the eigenvalue W of a complex upper Hessenberg
 matrix H.
Parameters:
RIGHTV
          RIGHTV is LOGICAL
          = .TRUE. : compute right eigenvector;
          = .FALSE.: compute left eigenvector.
NOINIT
          NOINIT is LOGICAL
          = .TRUE. : no initial vector supplied in V
          = .FALSE.: initial vector supplied in V.
N
          N is INTEGER
          The order of the matrix H.  N >= 0.
H
          H is COMPLEX*16 array, dimension (LDH,N)
          The upper Hessenberg matrix H.
LDH
          LDH is INTEGER
          The leading dimension of the array H.  LDH >= max(1,N).
W
          W is COMPLEX*16
          The eigenvalue of H whose corresponding right or left
          eigenvector is to be computed.
V
          V is COMPLEX*16 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
          B is COMPLEX*16 array, dimension (LDB,N)
LDB
          LDB is INTEGER
          The leading dimension of the array B.  LDB >= max(1,N).
RWORK
          RWORK is DOUBLE PRECISION array, dimension (N)
EPS3
          EPS3 is DOUBLE PRECISION
          A small machine-dependent value which is used to perturb
          close eigenvalues, and to replace zero pivots.
SMLNUM
          SMLNUM is DOUBLE PRECISION
          A machine-dependent value close to the underflow threshold.
INFO
          INFO is INTEGER
          = 0:  successful exit
          = 1:  inverse iteration did not converge; V is set to the
                last iterate.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 149 of file zlaein.f.

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Sat Nov 16 2013 Version 3.4.2

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