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slaein.f(3)				      LAPACK				      slaein.f(3)

NAME
       slaein.f -

SYNOPSIS
   Functions/Subroutines
       subroutine slaein (RIGHTV, NOINIT, N, H, LDH, WR, WI, VR, VI, B, LDB, WORK, EPS3, SMLNUM,
	   BIGNUM, INFO)
	   SLAEIN computes a specified right or left eigenvector of an upper Hessenberg matrix by
	   inverse iteration.

Function/Subroutine Documentation
   subroutine slaein (logicalRIGHTV, logicalNOINIT, integerN, real, dimension( ldh, * )H,
       integerLDH, realWR, realWI, real, dimension( * )VR, real, dimension( * )VI, real,
       dimension( ldb, * )B, integerLDB, real, dimension( * )WORK, realEPS3, realSMLNUM,
       realBIGNUM, integerINFO)
       SLAEIN computes a specified right or left eigenvector of an upper Hessenberg matrix by
       inverse iteration.

       Purpose:

	    SLAEIN 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 REAL 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 REAL

	   WI

		     WI is REAL
		     The real and imaginary parts of the eigenvalue of H whose
		     corresponding right or left eigenvector is to be computed.

	   VR

		     VR is REAL array, dimension (N)

	   VI

		     VI is REAL 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 REAL array, dimension (LDB,N)

	   LDB

		     LDB is INTEGER
		     The leading dimension of the array B.  LDB >= N+1.

	   WORK

		     WORK 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.

	   BIGNUM

		     BIGNUM is REAL
		     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 slaein.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2				 Tue Sep 25 2012			      slaein.f(3)
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