User`s guide

LTI Models
1-3
LTI Models
You can specify linear time-invariant (LTI) systems a s transfer function (TF)
models, zero/pole/gain (ZPK) models, state-space (SS) models, o r frequency
response data (FRD) model. You can construct the corresponding models using
the constructor functions.
sys = tf(num,den) % transfer function
sys = zpk(z,p,k) % zero/pole/gain
sys = ss(a,b,c,d) % state space
sys = frd(response,frequencies) % frequency response data
To find out information about LTI models, type
ltimodels
See also “Creating LTI M odels” on page 2-8.
The output
sys is a model-specific data structure called a TF, ZPK, SS, or FRD
object, respectively. These objects store the model data and enable you t o
manipulate the LTI model as a single entity; see “LTI Objects” on page 2-3 for
more information. For example, type
h = tf(1,[1 1]) % creates transfer function 1/(s+1)
and MATLAB responds with
Transfer function:
1
-----
s + 1
Type
1+h
MATLAB responds with
Transfer function:
s + 2
-----
s + 1