#!/usr/bin/perl -w
use strict;

use Math::GSL::Fit "gsl_fit_linear";
use Math::GSL::Statistics "gsl_stats_tss";

my $x = [1,2,3,4,5];
my $y = [5,7,8,12,13];
my $n = @$y;

my ($status, $c0, $c1, $cov00, $cov01, $cov11, $ss_resid)
    = gsl_fit_linear($x, 1, $y, 1, $n);

my $ss_total = gsl_stats_tss($y, 1, $n);

print "SS residual = $ss_resid\n";
print "SS total    = $ss_total\n";

my $R2 = 1 - $ss_resid / $ss_total;

print "R^2 = $R2\n";