%  ex_06_04_1.m :  習題 6.4
clear;

fp=[44 56];
fs=[47 53];
rp=3;
rs=50;
Fs=1000;
wp=2*fp/Fs;ws=2*fs/Fs;
[n,wn]=cheb1ord(wp,ws,rp,rs);
[b,a]=cheby1(n,rp,wn,'stop')
[h,w]=freqz(b,a,256,Fs);
h=20*log10(abs(h));
plot(w,h);grid;