use Statistics::LineFit;

my $x = [ 1..100 ];
my $y = [ map $_*2, 11..110 ];

my $lfit = Statistics::LineFit->new();
$lfit->setData($x, $y);

printf "a=%.4f, b=%.4f,  R2=%.4f\n", $lfit->coefficients(), $lfit->rSquared();


# which outputs:  a=20.0000, b=2.0000,  R2=1.0000