function y = interpolate(X, Y, x)
	n = size(X, 2);
	m = size(Y, 2);
%	Y(1), X(n+1-m)
	if m == 1
		y = Y(1);
		return;
	end
%	Y1 = Y(1:m-1) - Y(2:m);
	y = Y(1) + (x - X(n+1-m)) .* interpolate(X, (Y(1:m-1) - Y(2:m)) ./ (X(1:m-1) - X(2+n-m:n)), x);