.TH "SRC/dlaein.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
SRC/dlaein.f
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBdlaein\fP (rightv, noinit, n, h, ldh, wr, wi, vr, vi, b, ldb, work, eps3, smlnum, bignum, info)"
.br
.RI "\fBDLAEIN\fP computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration\&. "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine dlaein (logical rightv, logical noinit, integer n, double precision, dimension( ldh, * ) h, integer ldh, double precision wr, double precision wi, double precision, dimension( * ) vr, double precision, dimension( * ) vi, double precision, dimension( ldb, * ) b, integer ldb, double precision, dimension( * ) work, double precision eps3, double precision smlnum, double precision bignum, integer info)"

.PP
\fBDLAEIN\fP computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration\&.  
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\fBPurpose:\fP
.RS 4

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.nf
!>
!> DLAEIN uses inverse iteration to find a right or left eigenvector
!> corresponding to the eigenvalue (WR,WI) of a real upper Hessenberg
!> matrix H\&.
!> 
.fi
.PP
 
.RE
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\fBParameters\fP
.RS 4
\fIRIGHTV\fP 
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.nf
!>          RIGHTV is LOGICAL
!>          = \&.TRUE\&. : compute right eigenvector;
!>          = \&.FALSE\&.: compute left eigenvector\&.
!> 
.fi
.PP
.br
\fINOINIT\fP 
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.nf
!>          NOINIT is LOGICAL
!>          = \&.TRUE\&. : no initial vector supplied in (VR,VI)\&.
!>          = \&.FALSE\&.: initial vector supplied in (VR,VI)\&.
!> 
.fi
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.br
\fIN\fP 
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!>          N is INTEGER
!>          The order of the matrix H\&.  N >= 0\&.
!> 
.fi
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.br
\fIH\fP 
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!>          H is DOUBLE PRECISION array, dimension (LDH,N)
!>          The upper Hessenberg matrix H\&.
!> 
.fi
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.br
\fILDH\fP 
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!>          LDH is INTEGER
!>          The leading dimension of the array H\&.  LDH >= max(1,N)\&.
!> 
.fi
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\fIWR\fP 
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!>          WR is DOUBLE PRECISION
!> 
.fi
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.br
\fIWI\fP 
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!>          WI is DOUBLE PRECISION
!>          The real and imaginary parts of the eigenvalue of H whose
!>          corresponding right or left eigenvector is to be computed\&.
!> 
.fi
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\fIVR\fP 
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!>          VR is DOUBLE PRECISION array, dimension (N)
!> 
.fi
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.br
\fIVI\fP 
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!>          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\&.
!> 
.fi
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.br
\fIB\fP 
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!>          B is DOUBLE PRECISION array, dimension (LDB,N)
!> 
.fi
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.br
\fILDB\fP 
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!>          LDB is INTEGER
!>          The leading dimension of the array B\&.  LDB >= N+1\&.
!> 
.fi
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\fIWORK\fP 
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!>          WORK is DOUBLE PRECISION array, dimension (N)
!> 
.fi
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.br
\fIEPS3\fP 
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!>          EPS3 is DOUBLE PRECISION
!>          A small machine-dependent value which is used to perturb
!>          close eigenvalues, and to replace zero pivots\&.
!> 
.fi
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.br
\fISMLNUM\fP 
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!>          SMLNUM is DOUBLE PRECISION
!>          A machine-dependent value close to the underflow threshold\&.
!> 
.fi
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.br
\fIBIGNUM\fP 
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!>          BIGNUM is DOUBLE PRECISION
!>          A machine-dependent value close to the overflow threshold\&.
!> 
.fi
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.br
\fIINFO\fP 
.PP
.nf
!>          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\&.
!> 
.fi
.PP
 
.RE
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\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 

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Univ\&. of California Berkeley 

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Univ\&. of Colorado Denver 

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NAG Ltd\&. 
.RE
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Definition at line \fB170\fP of file \fBdlaein\&.f\fP\&.
.SH "Author"
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Generated automatically by Doxygen for LAPACK from the source code\&.