function [c4n,n4e,Nb,Db] = triang_disk(L)
c4n = 1/sqrt(2) * [-1 -1;1 -1;1 1;-1 1;0 0];
n4e = [1 2 5;2 3 5;3 4 5;4 1 5];
Nb = [1 2;2 3;3 4;4 1]; Db = [];
for j = 1:L
    [c4n,n4e,Db,Nb] = red_refine(c4n,n4e,Db,Nb);
    c4n(Nb,:) = c4n(Nb,:)./(sqrt(c4n(Nb,1).^2+c4n(Nb,2).^2)*[1,1]);
end
