Creating and Manipulating Models

Explicit Conversion

Model conversions are performed by tf, ss, zpk, and frd. Given any TF, SS, or ZPK model sys, the syntax for conversion to another model type is

sys = tf(sys)	% Conversion to TF
sys = zpk(sys)	% Conversion to ZPK
sys = ss(sys)	% Conversion to SS
sys = frd(sys,frequency)	% Conversion to FRD

Notice that FRD models can't be converted to the other model types. In addition, you must also include a vector of frequencies (frequency) as an input argument when converting to an FRD model.

For example, you can convert the state-space model

• sys = ss(-2,1,1,3)
  

to a zero-pole-gain model by typing

• zpk(sys)
  

to which MATLAB responds

• Zero/pole/gain:
  3 (s+2.333)
  -----------
     (s+2)
  

Note that the transfer function of a state-space model with data is

for continuous-time models, and

for discrete-time models.

Model Conversion

Automatic Conversion