How do I get a vector with the coefficients from a transfer function?

I tried to use the coeffs function, but it's not compatible with tfs

I've this tf:

s = tf('s');
f = s^2 + 2.673 s + 49.92;

It seems simple, but which function can I use to get a vector with the coefficients [1 2.673 49.92]?

Answer 1

[Massimo Zanetti]

Hi Lara,

the tf you generate is a structure and it stores the information you need in the NUM cell. To get your coefficient vector access the NUM cell like this:

s = tf('s');
f = s^2 + 2.673*s + 49.92;
A = tf(f).num{:};

Now, vector A is what you need. :)

[Lara Silva]

thanks, it worked :D