User`s guide

LTI Properties
2-35
This sets the Ts property to the v alue 0.5, as is confirmed by
h.Ts
ans =
0.5000
Forcontinuous-timemodels,thesampletimepropertyTs is 0 by convention.
For example, type
h = tf(1,[1 0]);
get(h,'Ts')
ans =
0
To leave the sample time of a discrete-time LTI model unspecified, set Ts to .
For example,
h = tf(1,[1 –1],–1)
produces
Transfer function:
1
-----
z – 1
Sampling time: unspecified
The same result is obtained by using the Variable property.
h = tf(1,[1 –1],'var','z')
In operatio ns that combine several discrete- time models, all specified sample
times must be identical, and the resulting discrete-time model inherits this
common sample time. The sample time of the resultant model is unspecified if
all operands have unspecified sample times. With this inheritance rule for
Ts,
the following two models are equivalent.
tf(0.1,[1 –1],0.1) + tf(1,[1 0.5],–1)
and
tf(0.1,[1 –1],0.1) + tf(1,[1 0.5],0.1)
1
–