clear; close all
%
%  Problem 30 p. 216
%
%  Sierpinski triangles
%
x = 0;
y = 0;
n = 30000;
r = randi(3,n,1);
f = sqrt(3)/4;
for i=1:n-1
    switch r(i)
        case 1
            x(i+1) = 0.5*x(i);
            y(i+1) = 0.5*y(i);
        case 2
            x(i+1) = 0.5*x(i) + 0.25;
            y(i+1) = 0.5*y(i) + f;
        case 3
            x(i+1) = 0.5*x(i)+ 0.5;
            y(i+1) = 0.5*y(i);
    end
end
plot(x,y,'^')
axis off