slaed5.f(3) LAPACK slaed5.f(3)NAMEslaed5.f-
SYNOPSIS
Functions/Subroutines
subroutine slaed5 (I, D, Z, DELTA, RHO, DLAM)
SLAED5 used by sstedc. Solves the 2-by-2 secular equation.
Function/Subroutine Documentation
subroutine slaed5 (integerI, real, dimension( 2 )D, real, dimension( 2 )Z,
real, dimension( 2 )DELTA, realRHO, realDLAM)
SLAED5 used by sstedc. Solves the 2-by-2 secular equation.
Purpose:
This subroutine computes the I-th eigenvalue of a symmetric rank-one
modification of a 2-by-2 diagonal matrix
diag( D ) + RHO * Z * transpose(Z) .
The diagonal elements in the array D are assumed to satisfy
D(i) < D(j) for i < j .
We also assume RHO > 0 and that the Euclidean norm of the vector
Z is one.
Parameters:
I
I is INTEGER
The index of the eigenvalue to be computed. I = 1 or I = 2.
D
D is REAL array, dimension (2)
The original eigenvalues. We assume D(1) < D(2).
Z
Z is REAL array, dimension (2)
The components of the updating vector.
DELTA
DELTA is REAL array, dimension (2)
The vector DELTA contains the information necessary
to construct the eigenvectors.
RHO
RHO is REAL
The scalar in the symmetric updating formula.
DLAM
DLAM is REAL
The computed lambda_I, the I-th updated eigenvalue.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Contributors:
Ren-Cang Li, Computer Science Division, University of California at
Berkeley, USA
Definition at line 109 of file slaed5.f.
Author
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Version 3.4.2 Sat Nov 16 2013 slaed5.f(3)
