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lib/BioUtil/Util.pm  view on Meta::CPAN

=head2 mean_and_stdev

return mean and stdev of a list

Example:
    my @list = qq/1 2 3/;
    mean_and_stdev(\@list);

=cut
sub mean_and_stdev($) {
    my ($list) = @_;
    return ( 0, 0 ) if @$list == 0;
    my $sum = 0;
    $sum += $_ for @$list;
    my $sum_square = 0;
    $sum_square += $_ * $_ for @$list;
    my $mean     = $sum / @$list;
    my $variance = $sum_square / @$list - $mean * $mean;
    my $std      = sqrt $variance;
    return ( $mean, $std );