transfer function 표현 - tf / tfdata

ex) 5*s^2 / (s^2 +2*s+1)

1) tf
    사용---------------------

    num=[5 0 0];
    den=[1 2 1];
    sys=tf(num,den)

    결과---------------------
                 5 s^2
           -------------
             s^2 + 2 s + 1


2) tfdata
                     5 s^2
    sys =    -------------     일때,
                 s^2 + 2 s + 1

    사용---------------------
    [num, den]=tfdata(sys,'v')

    결과---------------------
    num = [5 0 0]
    den  = [1 2 1]