Transformig digital transferfct in analog transferfct

Dear MatLab Community,

is there any function to transform the coefficients of z-transfer functions into the coefficients of a s-transfer function?

I know, that there is one the other way around : the bilinear() fct, but I havent found a similar one for my problem..

Kind regards.

Answer 1

[Bora Eryilmaz]

Take a look at the d2c function: D2C.

% Discrete transfer function
H = tf([1 -1],[1 1 0.3],0.1)

H =
 
      z - 1
  -------------
  z^2 + z + 0.3
 
Sample time: 0.1 seconds
Discrete-time transfer function.

% Convert to continuous transfer function
Hc = d2c(H)

Hc =
 
   121.7 s + 3.668e-12
  ---------------------
  s^2 + 12.04 s + 776.7
 
Continuous-time transfer function.

% And back for confirmation
c2d(Hc,0.1)

ans =
 
      z - 1
  -------------
  z^2 + z + 0.3
 
Sample time: 0.1 seconds
Discrete-time transfer function.