% exa060303_armcov.m, for example 6.3.3 
% to estimate AR model parameters of x(n) by armcov function;

clear;
randn('seed',0)
a=[1 0.12 0.33 0.65 0.94];
xn=impz(1,a,20)+randn(20,1)/20;

% 計算AR模型的參數
Ca=armcov(xn,4)