%rand('state',100*sum(clock))
clear all

wns=0
wws=0;
s1=1/3;
s2=2/3;
for i=1:10000;
   d=rand;				%put the prize behind a door
   if d<=s1;
      door_prize=1;
      
   elseif d<=s2;
      door_prize=2;
      
   else
      door_prize=3;
   end
   choice=rand;		%select a door
   if choice<=s1;
      door_sel=1;
      
   elseif choice<=s2;
      door_sel=2;
      
   else
      door_sel=3;
   end
   
   if door_prize==door_sel;  %if you select the right door
      wns=wns+1;				%you win if you do not switch WNS
   else
      wws=wws+1; %if you did not select the right door you win
   end				% if you switch WWS
end
wws
wns