How to convert a transfer fuction (tf class) to a symbolic equation (sym)?

I have a transfer function that I need in symbolic form but I haven't been able to find a way of doing this. This is what I have:

 EQN =
       6
  -----------
  s^3 + 2 s^2

Continuous-time transfer function.

This is what I need:

eqn = 6/(s^3 + 2*s^2)

Any ideas?

Answer 1

[lasttccasey]

Never mind I figured it out, but to those who want to know:

sys = tf([1 0],[1 2 3])
[Num,Den] = tfdata(sys);
sys_syms = poly2sym(cell2mat(Num),s)/poly2sym(cell2mat(Den),s)

Credit goes to:

• Cleve Moler
• [e-mail]

[lorenzo sguaitamatti]

Reading your solution I found this way:

[Num,Den] = tfdata(sys,'v')

syms s

sys_syms=poly2sym(Num,s)/poly2sym(Den,s)

Answer 2

[Fabian Acuña]

s = tf('s')
G = s^3/(s^2 + 3*s + s^4 + 1)
syms s
Numerator = poly2sym(G.Numerator{1,1},s)
Denominator = poly2sym(G.Denominator{1,1},s)
Gsym = Numerator/Denominator