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