%---------------------------------------------------%
% binfill4.m                                        %
%                                                   %
% (P335-S11) Baierlein problem 2.1                  %
%                                                   %
% Uses random number generator to fill NBIN bins    % 
% with NUM particles. The "simulation" is run for   %
% 4 different NUM values and a 2x2 layout of bar    %
% graphs is produced.                               %
%                                                   %
% Press F5-key to run program.                      %
%                                       1/10/05     %
%---------------------------------------------------%
clear;                         %clear all variables
rand('state',sum(100*clock));  %initialize random number generator


NUM=[100 100 100 100];  %numbers of particles ... feel free to change these
NBIN=10;                    %number of bins


figure(1);   %create figure window

for i=1:4              % do calulation for each of the 4 NUM values
    x=zeros(1,NBIN);   % initialize x-array with NBIN entries all = 0.0
    for j=1:NUM(i)
        val =rand;          % random number in range 0.0<val<1.0
	    bin=ceil(NBIN*val); % convert to integer in range 1<bin<NBIN
        x(bin)=x(bin)+1;    % add 1 to the selected bin
    end

    %create plot for current NUM value
    subplot(2,2,i); %ith subplot in 2x2 plot layout
    bar(x,'w');  %draw bar graph of x-array, fill color = white
    title([num2str(NUM(i)),' particles in ',num2str(NBIN), ' bins']);
    if (i==3 | i==4)
        xlabel('bin number');
    end
    if (i==1 | i==3)
        ylabel('# in bin');
    end
end