利用perl计算person相关系数

#!/usr/bin/perl

use warnings;
use strict;

my @c1=(1,2,3,4);
my @c2=(2,3,5,6);
my $c3=cor(\@c1,\@c2);
print "$c3\n";

sub cor {
    my @x = @{$_[0]};
    my @y = @{$_[1]};
    my $x_mean = mean(@x);
    my $y_mean = mean(@y);
    my $cov_x_y = 0;
    my $cov_x = 0;
    my $cov_y = 0;
    foreach  (0..$#x) {
        $cov_x_y += (($x[$_]-$x_mean)*($y[$_]-$y_mean));
        $cov_x += (($x[$_]-$x_mean)*($x[$_]-$x_mean));
        $cov_y += (($y[$_]-$y_mean)*($y[$_]-$y_mean));
    }
    return $cov_x_y/(sqrt($cov_x)*sqrt($cov_y));
}

sub mean {
    my @a = @_;
    my $sum = 0;
    foreach  (@a) {
        $sum += $_;
    }
    return $sum/($#a+1);
}