How to take a function_handle's coefficients

I don't think it's too complex but I can't see a solution anywhere.

I have a function_handle f =@(y) (y^3 -5) which clearly has coefficients [1 0 0 -5] but I do not know what I need to write to be able to extract it from function_handle.

i.e. q = [(coefficients extracted)]

I want to be able to take this because then i can work out the roots of the polynomial straight from roots(q) where q is the row vector of coefficients of the function handle.

Is anyone able to help, I would really appreciate it.

[Jan]

This might not be trivial. What do you expect for:

f = @(y) sin(y)

? Is the function guaranteed to be a polynomial? Then why not defining it as [1,0,0,-5] directly?

Answer 1

[M]

syms y
q=sym2poly(f(y))
q =

     1     0     0    -5