%產生信號序列
n=linspace(-pi,pi,1024);
xn=2*sin(n*40)+cos(n*100);
figure,plot(xn);
title('Input Signal');
%計算序列的DFT及PSD
M=64;
L=length(n)/M;
Pbw=zeros(1,M);
for i=1:L
    for j=1:M
        x(j)=xn(M*(i-1)+j);
    end
    y1=fft(x);
    y2=conj(y1);
    Plw=y1.*y2/M;
    Pbw=Plw+Pbw;
end
%繪圖
figure,plot(Pbw/L);
grid on
title('Bartlett Method');