perl_mean_sd.pl

# subroutines for mean and sd
# copy paste into perl script
# source:1://edwards.sdsu.edu/research/calculating-the-average-and-standard-deviation/ 
sub average{
        my($data) = @_;
        if (not @$data) {
                die("Empty arrayn");
        }
        my $total = 0;
        foreach (@$data) {
                $total += $_;
        }
        my $average = $total / @$data;
        return $average;
}
sub stdev{
        my($data) = @_;
        if(@$data == 1){
                return 0;
        }
        my $average = &average($data);
        my $sqtotal = 0;
        foreach(@$data) {
                $sqtotal += ($average-$_) ** 2;
        }
        my $std = ($sqtotal / (@$data-1)) ** 0.5;
        return $std;
}