% julia sets (SLOW)

c = input('Enter complex parameter -> ');

if abs(c)>=2
	disp('Warning: Using a parameter with absolute value')
	disp('greater than 2 is not recommended.');
end;

z0 = input('Please enter lower left corner -> ');
z1 = input('Please enter upper right corner -> ');

x0 = real(z0);
y0 = imag(z0);

x1 = real(z1);
y1 = imag(z1);

maxsteps = input('Please enter escape time -> ');

hres = input('Please enter horizontal resolution -> ');

vres = ceil( abs( hres * (y1-y0)/(x1-x0)) );

dx = (x1-x0)/hres;
dy = (y1-y0)/vres;

pict = zeros(hres+1,vres+1);

for a = 1:hres+1, for b=1:vres+1
	z = x0 + a*dx + (y0 + b*dy)*i;
	count = 1;
	while(abs(z) <= 2)
		if count >= maxsteps
			count = 0;
			break;
		end;
		z = z^2 + c;
		count = count + 1;
	end;
	pict(a,b) = count;
end;end;


image(pict')
axis('image')
axis('xy')
axis('off')

% uncomment exactly one of the following lines:
colormap(gray(maxsteps))	% for gray-scale monitors
%colormap(hsv(maxsteps))		% for color monitors