User`s guide

frdata
11-82
11frdata
Purpose Quick access to data for a frequency response data object
Syntax [response,freq] = frdata(sys)
[response,freq,Ts] = frdata(sys)
[response,freq] = frdata(sys,'v')
Description [response,freq] = frdata(sys) returns the response da ta and frequency
samples of the FRD model
sys. For an FRD model with Ny outputs and Nu
inputs at Nf frequencies:
•
response is an Ny-by-Nu-by-Nf m ultidimensi ona l array whe re the (i,j)
entry specifies the response from input j to output i.
•
freq is a column vector of length Nf that contains the frequency samples of
the FRD mo del.
See Table 11 -14, “Da ta Forma t for the Argument resp onse in FRD Mod els, ” on
page 80 for more information on the data format for FRD response data.
For SISO F RD models, the syntax
[response,freq] = frdata(sys,'v')
forces frdata to return the response data and frequencies directly as column
vectors rather than as cell arrays (see example below).
[response,freq,Ts] = frdata(sys) also returns the sample time Ts.
Other properties of
sys can be accessed with get or by direct structure-like
referencing (e.g.,
sys.Units).
Arguments The input argument sys to frdata must be an FRD model.
Example Typing the commands
freq = logspace(1,2,2);
resp = .05*(freq).*exp(i*2*freq);
sys = frd(resp,freq);
[resp,freq] = frdata(sys,'v')