subroutine zlaein (RIGHTV, NOINIT, N, H, LDH, W, V, B, LDB, RWORK, EPS3, SMLNUM, INFO)
subroutine zlaein (logicalRIGHTV, logicalNOINIT, integerN, complex*16, dimension( ldh, * )H, integerLDH, complex*16W, complex*16, dimension( * )V, complex*16, dimension( ldb, * )B, integerLDB, double precision, dimension( * )RWORK, double precisionEPS3, double precisionSMLNUM, integerINFO)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.
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.
Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd.Date:
September 2012Definition at line 149 of file zlaein.f.