User`s guide

1 Data Processing
Command
Description
complex(data)
For time-domain data, this command makes the iddata
object complex—even when the imaginary parts are
zero. For frequency-domain data that only stores
the values for nonnegative frequencies, such that
realdata(data)=1, it adds signal values for negative
frequencies using com plex conjugation.
imag(data)
Selects the imaginary parts of each signal in idda ta
object.
isreal(data)
1
when data (time-domain or fre quency -dom ain)
contains only real input and output signals, and returns
0 when d ata (time-domain or frequency-domain)
contains complex signals.
real(data)
Real part of complex s i gn a ls in iddata object.
realdata(data)
Returns a value of 1 when data is a real-valued,
time-domain signal, and returns
0 otherwise.
For example, suppose that you create a frequency-domain iddata object Datf
by applying fft to a real-va lu ed time-domain signal to tak e t he Fourier
transform of the signal. The following is true for
Datf:
isreal(Datf) = 0
realdata(Datf) = 1
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