t1=cputime
U=rand(1,200000);  % crude Monte Carlo
F=(exp(U)-1)/(exp(1)-1); % value of 200000 discounted values of the call option
m=mean(F) % average discounted value of call = .474
   S1=var(F)/length(F) %\ the sample standard deviation 
   t1=[t1 cputime];
 %%%%%%%%%%%%  *****************************************
U=rand(1,100000);  %  use of antithetic random number
F=.5*(exp(U)-1)/(exp(1)-1)+.5*(exp(1-U)-1)/(exp(1)-1);
mean(F)	
S2=var(F)/length(F)   
t1=[t1 cputime];
display(['times ' mat2str(diff(t1))])
display(['efficiency= ' num2str(S1/S2)])


	
