So do it. What is the problem? If z is known, then just type it in, pretty much as written.
Do you know how to raise a number to a power? Actually, z^-1 is just 1/z, a far simpler way to write the power. For example:
A = [1-1.8629/z + 0.8669/z^2, 0; ...
0, 1 - 1.8695/z + 0.8737/z^2]
A =
0.1434 0
0 0.1420
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
If all of this seems foreign to you, then you STRONGLY need to start with the basics of MATLAB. Do the MATLAB Onramp. And there are other basic MATLAB tutorials to be found.