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CentOS 7.0 - man page for dlaein (centos section 3)

dlaein.f(3)						LAPACK						  dlaein.f(3)

NAME
dlaein.f -
SYNOPSIS
Functions/Subroutines subroutine dlaein (RIGHTV, NOINIT, N, H, LDH, WR, WI, VR, VI, B, LDB, WORK, EPS3, SMLNUM, BIGNUM, INFO) DLAEIN computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration. Function/Subroutine Documentation subroutine dlaein (logicalRIGHTV, logicalNOINIT, integerN, double precision, dimension( ldh, * )H, integerLDH, double precisionWR, double precisionWI, double precision, dimension( * )VR, double precision, dimension( * )VI, double precision, dimension( ldb, * )B, integerLDB, double precision, dimension( * )WORK, double precisionEPS3, double precisionSMLNUM, double precisionBIGNUM, integerINFO) DLAEIN computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration. Purpose: DLAEIN uses inverse iteration to find a right or left eigenvector corresponding to the eigenvalue (WR,WI) of a real 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 (VR,VI). = .FALSE.: initial vector supplied in (VR,VI). N N is INTEGER The order of the matrix H. N >= 0. H H is DOUBLE PRECISION array, dimension (LDH,N) The upper Hessenberg matrix H. LDH LDH is INTEGER The leading dimension of the array H. LDH >= max(1,N). WR WR is DOUBLE PRECISION WI WI is DOUBLE PRECISION The real and imaginary parts of the eigenvalue of H whose corresponding right or left eigenvector is to be computed. VR VR is DOUBLE PRECISION array, dimension (N) VI VI is DOUBLE PRECISION array, dimension (N) On entry, if NOINIT = .FALSE. and WI = 0.0, VR must contain a real starting vector for inverse iteration using the real eigenvalue WR; if NOINIT = .FALSE. and WI.ne.0.0, VR and VI must contain the real and imaginary parts of a complex starting vector for inverse iteration using the complex eigenvalue (WR,WI); otherwise VR and VI need not be set. On exit, if WI = 0.0 (real eigenvalue), VR contains the computed real eigenvector; if WI.ne.0.0 (complex eigenvalue), VR and VI contain the real and imaginary parts of the computed complex eigenvector. The eigenvector is 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|. VI is not referenced if WI = 0.0. B B is DOUBLE PRECISION array, dimension (LDB,N) LDB LDB is INTEGER The leading dimension of the array B. LDB >= N+1. WORK WORK 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. BIGNUM BIGNUM is DOUBLE PRECISION A machine-dependent value close to the overflow threshold. INFO INFO is INTEGER = 0: successful exit = 1: inverse iteration did not converge; VR is set to the last iterate, and so is VI if WI.ne.0.0. Author: Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Date: September 2012 Definition at line 172 of file dlaein.f. Author Generated automatically by Doxygen for LAPACK from the source code. Version 3.4.2 Tue Sep 25 2012 dlaein.f(3)


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