%script file to plot filled julia sets of cubics

%create real and imaginary value arrays
[X,Y]=meshgrid([-2:0.01:2]);
[m,n]=size(X);
maxiters=30;
T=maxiters*ones(m,n);
%set the parameters
a=-1.5+0*i;
b=0+0*i;
%compute the cubic escape criteria
escrit=[abs(b),sqrt(abs(a)+2)]
escriter=max(escrit);
for j=1:m
    fprintf ('on iterate %d\n',j);
    for k=1:n
        z=X(j,k)+i*Y(j,k);
        for t=1:maxiters
            y=z^3+a*z+b;
            z=y;
            if abs(z)>2
                T(j,k)=t;
                break;
            end
        end
    end
end
imagesc(T);
colorbar;