% Number of times to run the simulation
Mall = [100 1000 10000 100000];
% Matrix holding the 21 probabilities for each value of M
p = zeros(21,length(Mall));

% Loop over M values
for midx = 1:length(Mall)
  M = Mall(midx)
  % y postion at the end of each 10 step simulation
  last_stop = zeros(M,1);
  for idx = 1:M
    mash_walk = mash(10);
    last_stop(idx) = mash_walk(end,2);
  end

  % Collect the statistics on the y position at the end of each stop
  % The vector p will hold the probabilities
  for idx = -10:10
    tmp = sum(last_stop==idx)/M;
    p(idx+11,midx) = tmp;
  end
end

% Display the results
figure(1);clf
subplot(221)
stem(-10:10,p(:,1));xlabel('y position');title('N = 100')
subplot(222)
stem(-10:10,p(:,2));xlabel('y position');title('N = 1000')
subplot(223)
stem(-10:10,p(:,3));xlabel('y position');title('N = 10000')
subplot(224)
stem(-10:10,p(:,4));xlabel('y position');title('N = 100000')

print -djpeg ps02p1.jpg