User`s guide

Representing Frequency-Response Data Using idfrd Objects
Representing Frequency-Response Data Using idfrd
Objects
In this section...
“idfrd C onstructor” on page 1-67
“idfrd Properties” on page 1-68
“Subreferencing idfrd Objects” on page 1-70
“Concatenating idfrd O bjects” on page 1-71
“See Also” on page 1-74
idfrd Constructor
The idfrd represents complex frequency-response data. Before you can
create an
idfrd object, you must import your data as described in “Importing
Frequency-Response Data into MATLAB” on page 1-10.
Note The idfrd object can only encapsulate one f requency-response data
set. It does not support the
iddata equivalent of multiexperiment data.
Use the following syntax to create the data object fr_data:
fr_data = idfrd(response,f,Ts)
Suppose that ny is the number of output channels, nu is the number of
input channels, and
nf is a vector of frequency v alues. response is an
ny-by-nu-by-nf 3-D array. f is the frequency vector that contains the
frequencies of the response.
Ts is the sampling time, which is used when
measuring or computing the frequency response. If you are working with a
continuous-time system, set
Ts to 0.
response(ky,ku,kf),whereky, ku,andkf reference the kth output, input,
and frequency value, respectively, is interpreted as the complex-valued
frequency response from input
ku to output ky at frequency f( kf).
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