function?[?output_args?]?=?Untitled（?input_args?）
%UNtitleD?Summary?of?this?function?goes?here
%???Detailed?explanation?goes?here
wp=0.35*pi;ws=0.4*pi;
Rp=1;Rs=60;?????????????????????????%%?通帶\阻帶波動（dB）
Fs=1;Ts=1/Fs;
wp1=2/Ts*tan（wp/2）;?????????????????%將模擬指標(biāo)轉(zhuǎn)換成數(shù)字指標(biāo)
ws1=2/Ts*tan（ws/2）;?
[NWn]=buttord（wp1ws1RpRs‘s‘）;??%選擇濾波器的最小階數(shù)
[ZPK]=buttap（N）;??????????????????%求N階的butterworth模擬濾波器的零、極點(diǎn)和增益因子
[BapAap]=zp2tf（ZPK）;?????????????%根據(jù)系統(tǒng)的零、極點(diǎn)、增益還原出H（z）的分子分母系數(shù)
[ba]=lp2lp（