ms12_4.m

《数字信号处理实验(MATLAB版)》这

N=100;
xn=[0,1,2,3,4,5,6,7,zeros(1,N-8)];
n=0:N-1;k=0:N-1;
Xk=xn*exp(-j*2*pi/N).^(n'*k);   %离散傅里叶变换
x=(Xk*exp(j*2*pi/N).^(n'*k))/N; %离散傅里叶逆变换
subplot(2,2,1),stem(n,xn,'k');
title('x(n)');axis([0,N,1.1*min(xn),1.1*max(xn)]);
subplot(2,2,2),stem(n,abs(x),'k');   %显示逆变换结果
title('IDFT|X(k)|');
axis([0,N,1.1*min(x),1.1*max(x)]);
subplot(2,2,3),stem(k,abs(Xk),'k');  %显示序列的幅度谱
title('|X(k)|');
axis([0,N,1.1*min(abs(Xk)),1.1*max(abs(Xk))]);
subplot(2,2,4),stem(k,angle(Xk),'k');%显示序列的相位谱
title('arg[X(k)]');
axis([0,N,1.1*min(angle(Xk)),1.1*max(angle(Xk))]);