Specifications

Creating LTI Models
2-13
1 Defining the variable s as a ZPK model
s = zpk('s')
2 Entering the transfer function as a rational expression in s.
For example, once
s is defined with zpk,
H = –2s/((s – 2)*(s^2 + 2*s + 2));
returns the same ZPK model as
h = zpk([0], [2 –1–i –1+i ], –2);
Note You need only define the ZPK variable s once. All subsequent rational
expressions of
s will be ZPK models, unless you convert the variable s to TF.
See “Model Conversion” on page 2-40 for more information on conversion to
other model types.
MIMO Zero-Pole-Gain Models
Just as with TF models, you can also specify a MIMO ZPK model by
concatenation of its SISO entries (see “Model Interconnection Functions” on
page 3-16).
You can also use the command
zpk to specify MIMO ZPK models. The syntax
to create a p-by-m MIMO zero-pole-gain model using
zpk is
H = zpk(Z,P,K)
where
•
Z is the p-by-m cell array of zeros (Z{i,j} = zeros of )
•
P is the p-by-m cell array of poles (P{i,j} = poles of )
•
K is the p-by-m matrix of gains (K(i,j) = gain of )
For example, typing
Z = {[],–5;[1–i 1+i] []};
P = {0,[–1 –1];[1 2 3],[]};
H
ij
s
()
H
ij
s
()
H
ij
s
()