m = 40;                                   % number of steps per animation
N = 500;                                  % number of points on each half

a  = [];
aa = [];
c  = [];

a  = [0.5*rand(N,1) rand(N,1)];           % black points
aa = [0.5 + 0.5*rand(N,1) rand(N,1)];     % green points

a = [a; aa];                              % concatenate them

c = [];


for i = 1:N,
  c(i)   = 'k';                           % color the points
  c(i+N) = 'g';
end

c = 'kg';

figure(1)
clf
title('Baker''s transformation');

for r = 1:100,
  b = [2*a(:,1) 0.5*a(:,2)];              % locations after squash
  animatepoints(a,b,c,60);
  clf 
  title('Baker''s transformation');
  bb = [mod(b(:,1),1) b(:,2)+0.5*(a(:,1) > 0.5)];
  animatepoints(b,bb,c,20);
  clf
  title('Baker''s transformation');
  a = bb;
end