% exa060301_levinson_aryule.m, for example 6.3.1 
% to estimate AR model parameters of x(n) by levinson and aryule 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
r=xcorr(xn,'biased');
r(1:length(xn)-1)=[];
La=levinson(r,4)
Ya=aryule(xn,4)