实用文档
y=filter(B,A,st); fyt=fft(y,N);
subplot(2,1,1),plot(t,y),grid,xlabel('t/s'),ylabel('y(t)'), axis([0,Tp/4,min(y),max(y)]),title('(a) y(t)的波形') subplot(2,1,2);
stem(f,abs(fyt)/max(abs(fyt)),'.');grid;title('(b) y(t)的频谱') axis([0,Fs/5,0,1.2]);
xlabel('f/Hz');ylabel('幅度')