Question

I want to calc root and pole from a TF object. But I didn’t find a function for that in the manuals.

For example:

I have a given TF object. And I want to know where are the roots and the poles.

The purpose is that I have two objects, multiply them and from the result I want to know the roots and poles.

Answer 1

The easiest way is to get the Zero Pole Gain (ZPK) data from the tf object. You can do this as follows:

G = tf([1], [1 0.1 1]);
[z,p,k] = zpkdata(G);

z % are the zeros (roots as you call them)
p % are the poles
k % is a static gain

You can also get a graphical representation using pzmap(G).