% Test
%

close all; clear;

b = [24 24]; a = [1 6 2 1 3];
y = freqz(b, a);
figure; zplane(b, a);

a = [1 4 6 100];
figure; zplane(b, a); title('19 (a)'); 

a = [1 6 10 17 6];
figure; zplane(b, a); title('19 (b)');

a = [1 6 3];
figure; zplane(b, a); title('19 (c)');