NAME

slaed5 - subroutine computes the I-th eigenvalue of a symmetric rank-one modification of a 2-by-2 diagonal matrix   diag( D ) + RHO  The diagonal elements in the array D are assumed to satisfy   D(i) < D(j) for i < j

SYNOPSIS

SUBROUTINE SLAED5(
I, D, Z, DELTA, RHO, DLAM )

void slaed5(long int i, float ∗d, float ∗sz, float ∗delta,
float srho, float ∗dlam)

INTEGER I

REAL DLAM, RHO

REAL D( 2 ), DELTA( 2 ), Z( 2 )

PURPOSE

This subroutine computes the I-th eigenvalue of a symmetric rank-one modification of a 2-by-2 diagonal matrix
 
We also assume RHO > 0 and that the Euclidean norm of the vector Z is one.
 

ARGUMENTS

I      (input) INTEGER
The index of the eigenvalue to be computed.  I = 1 or I = 2.

D      (input) REAL array, dimension (2)
The original eigenvalues.  We assume D(1) < D(2).

Z      (input) REAL array, dimension (2)
The components of the updating vector.

DELTA  (output) REAL array, dimension (2)
The vector DELTA contains the information necessary to construct the eigenvectors.

RHO    (input) REAL
The scalar in the symmetric updating formula.

DLAM   (output) REAL
The computed lambda_I, the I-th updated eigenvalue.

Sun, Inc.  —  Last change: 20 Sep 1996