Julian set in matlab

fractal.m

[X,Y] = meshgrid(-1:.001:1);
Z = ones(size(X));

for x_ = 1: size(X,1)
    for y_ = 1: size(X,1)
        u = [X(x_,y_),Y(x_,y_)];
        for i = 1:100
            v = [u(1) * u(1) - u(2) * u(2)+ -0.550, u(2) * u(1) + u(2) * u(1)+ -0.550];
            if((v(1) * v(1) + v(2) * v(2)) > 4)
                break
            end
            u = v;
            Z(x_,y_) = i;
        end
    end
end
X = X(:);
Y = Y(:);

imagesc(X,Y,Z)