ms14r22.m

《数字信号处理实验(MATLAB版)》这

Fs=20;Ts=1/Fs;
C=[8,32,64];                 %输入不同的N值 
for r=0:2;
    N=C(r+1);
    xn=[1,0.5,0,0.5,1,1,0.5,0];   %建立x(n)
    N1=length(xn);
    xn=[xn,N-N1];                 %加长序列
D=2*pi/(N*Ts);
k=floor(-(N-1)/2:(N-1)/2);
X=fftshift(fft(xn,N));
subplot(3,2,2*r+1);plot(k*D,abs(X),'k');
axis([-100,100,min(abs(X)),max(abs(X))]);
subplot(3,2,2*r+2);stairs(k*D,angle(X),'k');
axis([-100,100,1.1*min(angle(X)),1.1*max(angle(X))]);
end