function [D] = disclap(n)
	D = zeros(n, n);
	for i = 1:n
		D(i, i) = -2;
	end
	for i = 1:n-1
		D(i, i+1) = 1;
	end
	for i = 2:n
		D(i, i-1) = 1;
	end
end
