table of contents
other versions
- jessie 3.5.0-4
- jessie-backports 3.7.0-1~bpo8+1
- stretch 3.7.0-2
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)
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.
RIGHTV
Author:
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 PRECISIONWI
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.
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.Wed Oct 15 2014 | Version 3.4.2 |