.TH "slaein.f" 3 "Sun May 26 2013" "Version 3.4.1" "LAPACK" \" -*- nroff -*- .ad l .nh .SH NAME slaein.f \- .SH SYNOPSIS .br .PP .SS "Functions/Subroutines" .in +1c .ti -1c .RI "subroutine \fBslaein\fP (RIGHTV, NOINIT, N, H, LDH, WR, WI, VR, VI, B, LDB, WORK, EPS3, SMLNUM, BIGNUM, INFO)" .br .RI "\fI\fBSLAEIN\fP \fP" .in -1c .SH "Function/Subroutine Documentation" .PP .SS "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)" .PP \fBSLAEIN\fP .PP \fBPurpose: \fP .RS 4 .PP .nf SLAEIN 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 .PP \fBParameters:\fP .RS 4 \fIRIGHTV\fP .PP .nf RIGHTV is LOGICAL = .TRUE. : compute right eigenvector; = .FALSE.: compute left eigenvector. .fi .PP .br \fINOINIT\fP .PP .nf NOINIT is LOGICAL = .TRUE. : no initial vector supplied in (VR,VI). = .FALSE.: initial vector supplied in (VR,VI). .fi .PP .br \fIN\fP .PP .nf N is INTEGER The order of the matrix H. N >= 0. .fi .PP .br \fIH\fP .PP .nf H is REAL array, dimension (LDH,N) The upper Hessenberg matrix H. .fi .PP .br \fILDH\fP .PP .nf LDH is INTEGER The leading dimension of the array H. LDH >= max(1,N). .fi .PP .br \fIWR\fP .PP .nf WR is REAL .fi .PP .br \fIWI\fP .PP .nf WI is REAL The real and imaginary parts of the eigenvalue of H whose corresponding right or left eigenvector is to be computed. .fi .PP .br \fIVR\fP .PP .nf VR is REAL array, dimension (N) .fi .PP .br \fIVI\fP .PP .nf 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. .fi .PP .br \fIB\fP .PP .nf B is REAL array, dimension (LDB,N) .fi .PP .br \fILDB\fP .PP .nf LDB is INTEGER The leading dimension of the array B. LDB >= N+1. .fi .PP .br \fIWORK\fP .PP .nf WORK is REAL array, dimension (N) .fi .PP .br \fIEPS3\fP .PP .nf EPS3 is REAL A small machine-dependent value which is used to perturb close eigenvalues, and to replace zero pivots. .fi .PP .br \fISMLNUM\fP .PP .nf SMLNUM is REAL A machine-dependent value close to the underflow threshold. .fi .PP .br \fIBIGNUM\fP .PP .nf BIGNUM is REAL A machine-dependent value close to the overflow threshold. .fi .PP .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 .PP \fBAuthor:\fP .RS 4 Univ\&. of Tennessee .PP Univ\&. of California Berkeley .PP Univ\&. of Colorado Denver .PP NAG Ltd\&. .RE .PP \fBDate:\fP .RS 4 November 2011 .RE .PP .PP Definition at line 172 of file slaein\&.f\&. .SH "Author" .PP Generated automatically by Doxygen for LAPACK from the source code\&.