% 第八章: 例 8.2
%        給定|Ha(jW)|求巴特沃斯濾波器的 Ha(s)
%
N = 3; OmegaC = 0.5;
[b,a] = u_buttap(N,OmegaC);
[C,B,A] = sdir2cas(b,a)
%%C = 0.1250
%%B = 0     0     1
%%A = 1.0000    0.5000    0.2500
%%         0    1.0000    0.5000