fs=51.2;N=1024;n=0:N-1;t=n/fs;x=0.5-0.5*sign(t-1);Y=fft(x,N);mag=abs(Y);Y1=fftshift(Y);mag1=abs(Y1);fn2=(-N/10.24:N/10.24)*fs/N;subplot(2,1,1)plot(fn2,mag1(N/2-N/10.24+1):(N/2+N/10.24+1);set(gca,XTick,(-5:0.5:5);set(gca,YTick,(0:10:60);xlabel(频率/Hz);ylabel(振幅);title(图1：矩形函数的FFT结果，N=512，fs=51.2Hz);grid on;f=linspace(-5,5,1000);y=sqrt(2-2*cos(2*pi*f)./abs(2*pi*f);subplot(2,1,2)plot(f,y);set(gca,XTick,(-5:0.5:5);set(gca,YTick,(0:0.2
