Nice post.<p>I never really thought about evaluating a z-transform at a particular value, so I tied together some of the various solutions with derivations and greater generality here:<p><a href="http:&#x2F;&#x2F;bit.ly&#x2F;1WQ0Zkn" rel="nofollow">http:&#x2F;&#x2F;bit.ly&#x2F;1WQ0Zkn</a>