f02bbf

f02bbf © Numerical Algorithms Group, 2002.

Purpose

F02BBF Selected eigenvalues and eigenvectors of real symmetric matrix (Black Box)

Synopsis

[mm,r,v,icount,ifail] = f02bbf(a,alb,ub<,m,ifail>)

Description

 
 The real symmetric matrix A is reduced to a symmetric tridiagonal
 matrix T by Householder's method. The eigenvalues which lie 
 within a given interval [l,u], are calculated by the method of 
 bisection. The corresponding eigenvectors of T are calculated by 
 inverse iteration. A back-transformation is then performed to 
 obtain the eigenvectors of the original matrix A.

Parameters

f02bbf

Required Input Arguments:

a (:,:)                               real
alb                                   real
ub                                    real

Optional Input Arguments:                       <Default>

m                                     integer  size(a,2)
ifail                                 integer  -1

Output Arguments:

mm                                    integer
r (m)                                 real
v (:,m)                               real
icount (m)                            integer
ifail                                 integer