% POISSAPP file poissapp.m  Comparison of Poisson and gaussian
% Version of 5/24/96
% Plots distribution functions for specified parameter mu
mu = input('Enter the parameter mu  ');
n = floor(1.5*mu);
k = floor(mu-2*sqrt(mu)):floor(mu+2*sqrt(mu));              
FP = cumsum(ipoisson(mu,0:n));
FG = gaussian(mu,mu,k); 
FC = gaussian(mu,mu,k-0.5);      
stairs(k,FP(k))                 
hold on
plot(k,FG,'-.',k,FC,'o') 
hold off
grid
xlabel('t values')
ylabel('Distribution function')
title('Gaussian Approximation to Poisson Distribution')
legend('Poisson','Gaussian','Adjusted Gaussian')
disp('See Figure for results')