# 'feedback' function in MATLAB

How do I use feedback function in MATLAB when I have sys1 and sys1 as impulse responses (and not transfer functions, as required)? The syntax for using feedback is as follows: sys = feedback(sys1, sys2);

Convert the impulse responses into z-domain transfer functions first. This can be done by using the tf function and entering a third argument (sampling time) along with the usual num and den. If unspecified, use -1. Then use the z-domain transfer functions in the usual way. Here is the code:
sys1_z = tf(sys1, 1, -1);