eval {
	drr (
		@$zb-1-$p[2][1], @$zb-1-$p[3][1],
		$p[2][0], $p[2][0],
		-($p[3][0]-$p[2][0])/($p[3][1]-$p[2][1]),
		-($p[1][0]-$p[2][0])/($p[1][1]-$p[2][1]),
		$p[2][2],
		-($p[3][2]-$p[2][2])/($p[3][1]-$p[2][1]),
		($p[1][2]-$p[3][2])/($p[1][0]-$p[3][0]),
		$col, $zb
		);
	}; $@ and do {
	$@=~m/division by zero/ or die $@;
	};