function lastx = walk(n)        % random walk

  y = 2*unidrnd(2,1,n)-3; 
  s = zeros(1,n);
  s(1) = y(1);
  lastx = 0;
  
  for i=2:n 
    s(i) = s(i-1) + y(i);
    if s(i)==0 lastx = i; endif
  endfor
  
  plot(s,'b-',[0,n], [0,0], 'r-', [lastx], [0], 'g*');
  tstring = [ int2str(n) " steps, " "last crossing at " int2str(lastx)];
  title( tstring, "fontsize", 18 );

endfunction