Hi, today i will try to plot poles and zeros of an parametric equation. 
A parametric equation type is given below b(n) and a(n) are the coefficients 
of the equation 

Assume we know the  coefficients. Let's try to plot at z- plane.

b1=[1 -0.4944 0.64];
b2=[1 0.4944 0.64];

root_a1=roots(a1); 
root_b1=roots(b1);

figure;zplane(root_b1,root_a1);
title('Pole-Zero Diagram of a1-b1 System');
%http://ozturkgokhan.com

As u see we managed the process.
Best wishes;
Gökhan ÖZTÜRK