gusucode.com > ​数字信号处理，包括：各种现有信号及随机信号的输入，从文件读取数据的输入 > Digital Signal Matlab ex1/Butterworth.m

    axes(handles.axes3);
Xaxis=str2num(get(handles.EditX,'String'));
Yaxis=str2num(get(handles.EditY,'String'));
x=1:512;
global SignalFFT
y=SignalFFT;
%N=5;%阶数
Wp=1;Ws=2;Rp=3;Rs=30;
[N,Wn]=buttord(Wp,Ws,Rp,Rs,'s');
[z,p,k]=buttap(N);
[b,a]=zp2tf(z,p,k);
d=filter(b,a,y);
global SignalTran;
SignalTran=d;
%subplot(2,2,3);
stem(d,x,'.k');
length=length(d);
axis([-Xaxis,Xaxis,-length/2,length/2]);
title('滤波器')