内容介绍：>> N=256; >> t=-N+1:N-1; >> y=cos(2*pi*t*20.4/N)+0.001*cos(2*pi*t*28.2/N+pi/2); >> y1=y(N:2*N-1); >> win=hanning(N)\'; >> win1=win/sum(win); >> y11=y1.*win1; >> y11_fft=fft(y11,N); >> a1=abs(y11_