% Digital Filter Specifications:
wp=0.2*pi;           %                digital Passband freq in rad
ws=0.3*pi;           %                digitap Stopband freq in rad
Rp=1;                %                Passband ripple in dB
As=15;               %                Stopband attenuation in dB
% Analog Prototype Specifications:
T=1;                   %                 Set T=1
OmegaP=(2/T)*tan(wp/2); %                prewarp Prototype Passband freq
OmegaS=(2/T)*tan(ws/2); %               Prewarp prototype Stopband freq
% Analog Prototype Order Calculation:
ep=sqrt(10^(Rp/10)-1); %                 Passband Ripple Factor
A=10^(As/20);          %                 Stopband Attenuation Factor
OmegaC=OmegaP;         %                 Analog Prototype Cutoff freq
OmegaR=OmegaS/OmegaP;  %                 Analog Prototype Transition Ratio
g=sqrt(A*A-1)/ep;      %                 Analog Prototype Intermediate cal.
N=ceil(log10(g+sqrt(g*g-1))/log10(OmegaR+sqrt(OmegaR*OmegaR-1)));
fprintf('\n***Chebyshev-1 Filter Order = %2.Of \n',N)
% ***Chebyshev-1 Filter Order=4
% Digital Chebyshev-I Filter Design:
wn=wp/pi;
[b,a]=cheby1(N,Rp,wn);
[b0,B,A]=dir2cas(b,a)