#!/usr/bin/perl -w
use Math::GSL::Matrix;
use strict;
my $matrix = Math::GSL::Matrix->new(2,2)
                              ->set_row(0, [0,-1] )
                              ->set_row(1, [1, 0] );
print <<STUFF;
Finding eigenvalue/eigenvectors for
[ 0  -1 ]
[ 1   0 ]
STUFF
# this actually calculates the eigenvalues and eigenvectors and returns
# an array reference of eigenvalues (scalars which may be Math::Complex objects)
# and an array reference of Math::GSL::VectorComplex objects
my ($eigenvalues, $eigenvectors) = $matrix->eigenpair;
my ($eig1,$eig2) = @$eigenvalues;
my ($u,$v)       = @$eigenvectors;
my ($u1,$u2)     = $u->as_list;
my ($v1,$v2)     = $v->as_list;
print <<ANSWER;
Eigenvectors:
u = ($u1,$u2)
v = ($v1,$v2)
Eigenvalues:
lambda_0 = $eig1
lambda_1 = $eig2
ANSWER