Man page - laed5(3)

Packages contains this manual

Manual

laed5

NAME
SYNOPSIS
Functions
Detailed Description
Function Documentation
subroutine dlaed5 (integer i, double precision, dimension( 2 ) d, doubleprecision, dimension( 2 ) z, double precision, dimension( 2 ) delta,double precision rho, double precision dlam)
subroutine slaed5 (integer i, real, dimension( 2 ) d, real, dimension( 2 )z, real, dimension( 2 ) delta, real rho, real dlam)
Author

NAME

laed5 - laed5: D&C step: secular equation, 2x2

SYNOPSIS

Functions

subroutine dlaed5 (i, d, z, delta, rho, dlam)
DLAED5 used by DSTEDC. Solves the 2-by-2 secular equation.
subroutine slaed5 (i, d, z, delta, rho, dlam)
SLAED5 used by SSTEDC. Solves the 2-by-2 secular equation.

Detailed Description

Function Documentation

subroutine dlaed5 (integer i, double precision, dimension( 2 ) d, doubleprecision, dimension( 2 ) z, double precision, dimension( 2 ) delta,double precision rho, double precision dlam)

DLAED5 used by DSTEDC. 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 DOUBLE PRECISION array, dimension (2)
The original eigenvalues. We assume D(1) < D(2).

Z

Z is DOUBLE PRECISION array, dimension (2)
The components of the updating vector.

DELTA

DELTA is DOUBLE PRECISION array, dimension (2)
The vector DELTA contains the information necessary
to construct the eigenvectors.

RHO

RHO is DOUBLE PRECISION
The scalar in the symmetric updating formula.

DLAM

DLAM is DOUBLE PRECISION
The computed lambda_I, the I-th updated eigenvalue.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Contributors:

Ren-Cang Li, Computer Science Division, University of California at Berkeley, USA

subroutine slaed5 (integer i, real, dimension( 2 ) d, real, dimension( 2 )z, real, dimension( 2 ) delta, real rho, real dlam)

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.

Contributors:

Ren-Cang Li, Computer Science Division, University of California at Berkeley, USA

Author

Generated automatically by Doxygen for LAPACK from the source code.