transfer functio S to z

how can i change this function transfer f(s) to function f(z)

f(s)= 2^-s / (1+s)^2

Answer 1

[Mathieu NOE]

help c2dm

help c2dm

 C2DM   Conversion of continuous LTI systems to discrete-time.
 
    [Ad,Bd,Cd,Dd] = C2DM(A,B,C,D,Ts,'method') converts the continuous-
    time state-space system (A,B,C,D) to discrete time using 'method':
      'zoh'         Convert to discrete time assuming a zero order
            hold on the inputs.
      'foh'         Convert to discrete time assuming a first order 
            hold on the inputs.
      'tustin'      Convert to discrete time using the bilinear 
            (Tustin) approximation to the derivative.
      'prewarp'     Convert to discrete time using the bilinear 
            (Tustin) approximation with frequency prewarping.
            Specify the critical frequency with an additional
            argument, i.e. C2DM(A,B,C,D,Ts,'prewarp',Wc)
      'matched'     Convert the SISO system to discrete time using the
            matched pole-zero method.
 
    [NUMd,DENd] = C2DM(NUM,DEN,Ts,'method') converts the continuous-
    time polynomial transfer function G(s) = NUM(s)/DEN(s) to discrete
    time, G(z) = NUMd(z)/DENd(z), using 'method'.
 
    See also: C2D, and D2CM.