onion.m

一些常被用于教学或者参考的概率论的实例的源代码

%onion.m/created by PJNahin for "Duelling Idiots"(1/5/99)
%This m-file uniformly slices the unit interval, from left to right,
%ten times, and forms the sum of the widths of the slices. It does
%this 5000 times and then plots the distribution function of the sum.
%
%
rand('state',100*sum(clock));       %new seed for generator;
rsum=zeros(1,5000);
for cutting=1:5000
   total_thickness=0;
   L=1;
   for dice=1:10
      slice=L*rand;
      total_thickness=total_thickness+slice;
      L=slice;
   end
   index=round(100*total_thickness+.5);      %adding the '.5' prevents
   rsum(index)=rsum(index)+1;                %getting a zero index;
end
x=.01:.01:5;
dist(1)=rsum(1);
for index=2:500
   dist(index)=dist(index-1)+rsum(index);
end
plot(x,dist/5000)
grid
xlabel('thickness')
ylabel('probability')
title('Fig.5.2-Distribution of Total Thickness from 5,000 Cuttings')
figure(1)