up/down concordance rate

gistfile1.6pl

sub udcr {
	my ($X, $Y) = @_;

	if (scalar(@{$X}) < 2 || scalar(@{$X}) != scalar(@{$Y})) {
		return;
	}

	my $j = 0;
	for (my $i = 1; $i < scalar(@{$X}); $i++) {
		my $_x = $X->[$i] - $X->[$i - 1];
		my $_y = $Y->[$i] - $Y->[$i - 1];

		if ($_x == $_y || $_x * $_y > 0) {
			$j++;
		}
	}

	return $j / (scalar(@{$X}) - 1);
}