dp = 0.1;
ds = 0.01;
fp = 0.22;
fs = 0.25;
Rp = 20*log10((1+dp)/(1-dp));
Rs = -20*log10(ds);
Wp = 2*pi*Rp;
Ws = 2*pi*Rs;

[n,w]=cheb1ord(Wp,Ws,Rp,Rs,'s');

[b,a]=cheby1(n,Rp,Wp,'s');
figure, freqz(b,a);

figure, grpdelay(b,a)
%%filtru digital filt, filtru analogic tf
H=filt(b,a)

%stabilitate
if isstable(b,a)==1
    disp('Filtru digital este stabil')
else
    disp('Filtru digital este instabil')
end