claein.f(3)

Usage

Functions/Subroutines

subroutine claein (rightv, noinit, n, h, ldh, w, v, b, ldb, rwork, eps3, smlnum, info)
CLAEIN computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration.

Function/Subroutine Documentation

subroutine claein (logical rightv, logical noinit, integer n, complex, dimension( ldh, * ) h, integer ldh, complex w, complex, dimension( * ) v, complex, dimension( ldb, * ) b, integer ldb, real, dimension( * ) rwork, real eps3, real smlnum, integer info)

CLAEIN computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration.

Purpose:

!>
!> CLAEIN 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 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
!>          The eigenvalue of H whose corresponding right or left
!>          eigenvector is to be computed.
!>

V

!>          V is 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

!>          B is COMPLEX array, dimension (LDB,N)
!>

LDB

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

RWORK

!>          RWORK is REAL array, dimension (N)
!>

EPS3

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

SMLNUM

!>          SMLNUM is REAL
!>          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.

Definition at line 147 of file claein.f.

Releases

4 releases since Debian 7 (Wheezy); the text changed 3 times.

7
8
9
Arch