function []=mandel(r)
%  MANDEL
%   The command mandel(res) produces a plot of the Mandelbrot set for
%  Z0=0 in full color with resolution in both real and imaginary directions
%  of res points.  If no resolution is supplied, the default is 100.
%
%   When the plot is complete, the mouse can be used to zoom in on a 
%  specific area.  Clicking on a single point will cause that spot to be
%  blown up by a factor of 100.  Clicking in the title bar will exit the 
%  routine.

%                                                   RJM  1/11/97

if nargin==0, r=100;, end

flag=0;

xmin=-2;, xmax=1;
ymin=-1.5;, ymax=1.5;



figure(1);

while flag==0,

m=zeros(r);
x=0;,y=0;
i=sqrt(-1);
z0=0;

xx=linspace(xmax,xmin,r);
yy=linspace(ymin,ymax,r);

for a=xx,x=x+1;   % up and down
 for b=yy,y=y+1;  % horizontal
  c=a+i*b;
  k=0;
  z=z0;
  while (z<10000)&(k<128),
   z=z.^2+c;
   k=k+1;
  end
  m(x,y)=k;
 end
 y=0;
 end
figure(1),surf(xx,yy,log(log(m'))),view(0,90),shading('interp')
title('Click on figure to zoom -or- Click here (  ) to end')
[xnew,ynew]=ginput(1);
if ynew > ymax, flag=1;, end

xd=xmax-xmin;
xmax=xnew+xd/20;
xmin=xnew-xd/20;
yd=ymax-ymin;
ymax=ynew+yd/20;
ymin=ynew-yd/20;

end