User`s guide

Representing Frequency-Response Data Using idfrd Objects
For example, the following command references frequency-response data from
input channel
3 to output channel 2:
fr_data(2,3)
You can also access the data in specific channels using channel names. To list
multiple channel names, use a cell array. For example, to retrieve the power
output, and the voltage and speed inputs, use the following syntax:
fr_data('power',{'voltage','speed'})
To retrieve only the responses corresponding to frequency values between 20 0
and 300, use the following command:
fr_data_sub = fselect(fr_data,[20 0:300])
You can also use logical expressions to subreference data. For example, to
retrieve all frequency-response values between frequencies
1.27 and 9.3 in
the
idfrd object fr_data,usethefollowingsyntax:
fr_data_sub = fselect(fr_data,fr_ data.f>1.27&fr_data.f<9 .3)
Note You do not need to type the entire property nam e. In this example, f in
fr_data.f uniquely identifies the Fr eque ncy property of the idfrd object.
Concatenating idfrd Objects
• “About Concate natin g idfrd Mod els” on page 1-71
• “Horizontal Concatenation of idfrd O bjects” on page 1 -72
• “Vertical Concatenation of idfrd Objects” on page 1-72
• “Concatenating Noise Spectral Data of idfrd Objects” on page 1-73
About Concatenating idfrd Models
The horizontal and vertical concatenation of idfrd objects combine
information in the
ResponseData properties of these objects. Respon seDa ta is
an
ny-by-nu-by-nf array that stores the response of the system, where ny is
1-71