Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help ft_preproc_hilbert”.

  FT_PREPROC_HILBERT computes the Hilbert transpose of the data and optionally
  performs post-processing on the complex representation, e.g. the absolute
  value of the Hilbert transform of a band-pass filtered signal corresponds
  with the amplitude envelope.
  Use as
    [dat] = ft_preproc_hilbert(dat, option)
    dat        data matrix (Nchans X Ntime)
    option     string that determines whether and how the Hilbert transform
               should be post-processed, can be
  The default is to return the absolute value of the Hilbert transform.
  See also PREPROC