%PROGRAM p204
%Elliptic analog lowpass prototype
n=0:0.01:2;
N=8;
Rp=1;
Rs=10;
[z,p,k]=ellipap(N,Rp,Rs);
[b,a]=zp2tf(z,p,k);%Zero-pole to transfer function conversion.
[H,w]=freqs(b,a,n);%returns the complex frequency response vector H of the filter b/a:
magH=(abs(H)).^2;   
plot(w,magH);
axis([0 2 0 1]);%AXIS([XMIN XMAX YMIN YMAX]) sets scaling for the x- and y-axes on the current plot    
xlabel('w/wc');
ylabel('|H(jw)|^2');
title('N=8');
grid