function test
close all;
clear all;
%configuration
p_ini_r=0.5; %%initial probabilitity
p_ini_l=0.7;
m_ini_r=100; %%initial money
m_ini_l=100;
max_iter=100; %%bet 100 times at most
sum_r=zeros(1,max_iter);
sum_l=zeros(1,max_iter);
%rand('twister',sum(100*clock));%set to different state every time
for i=1:100
[a_r,a_l]=one_trace(p_ini_r,p_ini_l,m_ini_r,m_ini_l,max_iter);
sum_r=sum_r+a_r;
sum_l=sum_l+a_l;
end
figure;
plot(sum_r/100,'.r');
hold on;
plot(sum_l/100,'.b');
plot((sum_r+sum_l)/100,'.k');
legend('money at right','money at left','total');
function [a_r,a_l]=one_trace(p_ini_r,p_ini_l,m_ini_r,m_ini_l,max_iter)
a_r=zeros(1,max_iter); %result array, money
a_l=zeros(1,max_iter);
d_r=zeros(1,max_iter); %times of zeros in r's decision
d_l=zeros(1,max_iter);
%first bet
tmp_r=generate(p_ini_r);
tmp_l=generate(p_ini_l);
[tmp_vr,tmp_vl]=bet_decision(tmp_r,tmp_l);
a_r(1)=m_ini_r+tmp_vr;
a_l(1)=m_ini_l+tmp_vl;
if tmp_r==0
d_r(1)=1;
else
d_r(1)=0;
end
if tmp_l==0
d_l(1)=1;
else
d_l(1)=0;
end
for i=2:max_iter
tmp_r=generate(d_l(i-1)/(i-1));
tmp_l=generate(d_r(i-1)/(i-1));
[tmp_vr,tmp_vl]=bet_decision(tmp_r,tmp_l);
a_r(i)=a_r(i-1)+tmp_vr;
a_l(i)=a_l(i-1)+tmp_vl;
if tmp_r==0
d_r(i)=d_r(i-1)+1;
else
d_r(i)=d_r(i-1);
end
if tmp_l==0
d_l(i)=d_l(i-1)+1;
else
d_l(i)=d_l(i-1);
end
end
function a=generate(prob)
% generate a 0 with prob
tmp=rand();
if tmp>prob
a=1;
else
a=0;
end
function [vr,vl]=bet_decision(r,l)
%%
%% qiutubeilun method,0 for red,1 for black
%%
if r==0
if l==0
vr=1;
vl=1;
else
vr=-2;
vl=2;
end
else
if l==0
vr=2;
vl=-2;
else
vr=-1;
vl=-1;
end
end
