Here is a small matlab reference for feedback calculations or simulations:

- roots: Find polynomial roots
- poly: Convert roots to polynomial
- conv: Convolution and polynomial multiplication
- polyval: Evaluate polynomial
- tf: Creation of transfer functions or conversion to transfer function
- pzmap: Pole-zero map of LTI models
- pole: Compute the poles of LTI models
- zero: Computes the transmission zeros of LTI models
- series: Series interconnection of the two LTI models
- parallel: Parallel interconnection of two LTI models
- feedback: Feedback connection of two LTI models
- minreal: Minimal realization and pole-zero cancellation
- step: Step response of LTI models