% Chapter 4: Example 4.11:
%  zplane function:
%
b = [1,0]; a = [1, -0.9];
[H1,H2,H3] = zplane(b,a); 
set(H1,'markersize',10,'color',[0,1,0]); 
set(H2,'markersize',10,'color',[1,0,0]); 
title('Pole-Zero Plot');
text(0.85,-0.1,'0.9');text(0.01,-0.1,'0');