Bilateral Z-transform in MATLAB

Divergent13

I was curious as to how I can go about doing a bilateral Z transform in MATLAB.

MATLAB only provides uni-lateral Z-transform and Inverse Transform
through its "ztrans" and "iztrans" commands.

How can I go about doing this?

In addition, if I wanted to find the z transform of a function that is multiplied by a unit step, such like a^n * (u[u]-u[n-7]), how can I represent the unit step in MATLAB in order for it to return a valid answer?

Thank you for answering both of these questions!