User`s guide

frd
11-79
11frd
Purpose Create a frequency response data (FRD) object or convert another model type
to an FRD model
Syntax sys = frd(response,frequency)
sys = frd(response,frequency,Ts)
sys = frd
sys = frd(response,frequency,ltisys)
sysfrd = frd(sys,frequency)
sysfrd = frd(sys,frequency,'Units',units)
Description sys = frd(response,frequency) creates an FRD model sys from the
frequency response data stored in the mul tidimensional array
response.The
vector
frequency represents the underlying frequencies for the frequency
response data. See Table 11-14, “Data Format for the Argument response in
FRD Models,” on page 80.
sys = frd(response,frequency,Ts) creates a discrete-time FRD model sys
with scalar sample time Ts.SetTs = –1 to create a discrete-time FRD model
without specifying the samp le time.
sys = frd create s an empty FRD model.
The input argument list for any of these syntaxes can be followed by property
name/property v alue pairs of the form
'PropertyName',PropertyValue
Youcan use theseextra argumentsto set the various propertiesof FRD models
(see the
set command, or “LTI Properties” on page 2-26 and “Model-Specific
Properties” on page 2-28). These properties include
'Units'. The default units
for FRD models are in
'rad/s'.
To force an FRD model
sys to inherit a ll of its generic LTI properties from any
existing LTI model
refsys,usethesyntaxsys =
frd(response,frequency,ltisys)
.
sysfrd = frd(sys,frequency) converts a TF, SS, or ZPK model to an FRD
model. T he frequency response is computed at the frequencies provided by the
vector
frequency.