MATLAB: Hilbert Transform

frequencyMATLAB

Does anyone else find it odd that the hilbert function does not compute the Hilbert Transform? According to the help:
X = HILBERT(Xr) computes the so-called discrete-time analytic signal X = Xr + i*Xi such that Xi is the Hilbert transform of real vector Xr.
In other words, if you want to take the Hilbert transform of Xr you need imag(hilbert(Xr)). This seems so backwards to me.

Best Answer

It is backwards if you just want the Hilbert transform, but hilbert is part of the Signal Processing Toolbox, and maybe the users of this toolbox always use a Hilbert transform this way. To quote the documentation, "The Hilbert transform is useful in calculating instantaneous attributes of a time series, especially the amplitude and frequency. The instantaneous amplitude is the amplitude of the complex Hilbert transform; the instantaneous frequency is the time rate of change of the instantaneous phase angle."
But you have a point - they could have named the function analyticsignal.
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