% Mandelbrot set drawing, using MATLAB tricks
% so it should be faster than mandel.m

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;


[X,Y] = meshdom(x0:dx:x1, y0:dy:y1);

c = X + Y*i;
z = c;
pict = 0*z;
clear X Y

for k=1:maxsteps
	bigs = find(abs(z)>=2);
	pict(bigs) = k*ones(size(bigs));
	z(bigs) = zeros(size(bigs));
	c(bigs) = zeros(size(bigs));
	z = z.^2 + c;
end;

image(flipud(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