Matlab extract coefficient from z transform function

Hi I have a z transform function 3/z + 5/z^2 + 6/z^3 + 1

How would I extract the coefficients from this equation? I have tried using coeffs and it says it is not a polynomial.

I would like the answer to come out as [3 5 6 1]

The symbolic z variable is declared as syms z

Answer 1

[Star Strider]

Use the sym2poly function, although here it’s necesary to do an intermediate step:

syms z 

fz = 3/z + 5/z^2 + 6/z^3 + 1

[fzn, fzd] = numden(fz)

fzc = sym2poly(fzn)

fzc = circshift(fzc, [0 -1])

produces:

fzc =

       3     5     6     1

[David]

Thank you so much for your input. It was exactly what I was looking for.

[Star Strider]

My pleasure!

The sym3poly function would work with a ‘normal’ polynomial, but the symbolic terms in the denominator require numden and then circshift.