Wp=0.2*pi;Ws=0.3*pi;Rp=7;As=16;
Ripple=10^(-Rp/20);Attn=10^(-As/20);
% Analog filter design;
[b,a]=afd_butt(Wp,Ws,Rp,As)
%***Butterworth Filter Order=3
%Calculation of second-order sections:
[C,B,A]=sdir2cas(b,a)
%Calculation of Frequency Response:
[db,mag,pha,w]=freqs_m(b,a,0.5*pi);
%Calculation of Impulse response:
[ha,x,t]=impulse(b,a);