function [trials, b1, b2, M]=xruin(p1, p2, p, frames, seed) 
% xruin(p1, p2, p, frames, seed)  simulates the "gamblers ruin" game. 
%    p1      your starting pile 
%    p2      bank's starting pile 
%    p       probability that you will win any given trial 
%    frames  max number of frames for the generated movie - a frame size of 
%               zero will cause no movie to be generated 
%    seed    seed for random number generator 
% 
%    output is of the form [trials, b1, b2, M] 
%    trials  number of trials run till completion 
%    b1      history of your pile - plot by bar(b1) 
%    b2      history of bank pile - plot by bar(b2) 
%    M       movie matrix - play by movie(M) 
if p>1 | p<0 
   error('invalid value for p') 
end 
if p1<0 
   error('invalid value for p1') 
end 
if p2<0 
   error('invalid value for p2') 
end 
if frames<0 
   error('invalid value for frames') 
end 
rand('seed', seed); 
if frames>0 
   M=moviein(frames); 
end 
currentsize=50; 
b1=zeros(1,50); 
b2=b1; 
trials=0; 
b1(1)=p1; 
b2(1)=p2; 
while p1>0 & p2>0 
   trials=trials+1; 
   if rand>p | p==0 
      p2=p2+1; 
      p1=p1-1; 
   else 
      p1=p1+1; 
      p2=p2-1; 
   end 
   if trials==currentsize 
      b1=[b1 zeros(1, 50)]; 
      b2=[b2 zeros(1, 50)]; 
      currentsize=currentsize+50; 
   end 
   b1(trials+1)=p1; 
   b2(trials+1)=p2; 
   if frames>0 
      bar(p1) 
      hold on 
      bar(p2, 'r') 
      if trials<=frames 
         M(:, trials)=getframe 
      end 
      hold off 
   end 
end 
index=length(b1); 
while b1(index)==0 
   index=index-1; 
end 
if p1==0 
   s='Bank'; 
   index=index+1; 
else 
   s='You'; 
end 
b1=b1(1:index); 
b2=b2(1:index); 
s=sprintf('%s won in %d trials', s, trials); 
disp(s) 
if trials>frames & frames>0 
   disp('Frames limit exceeded') 
end