[FieldTrip] logic behind normalizing tapers

[David Groppe]

Hi again Fieldtrippers,
   I noticed that when estimating power spectra ft_specest_mtmfft.m
scales tapers such that their sum squared value is 1 before applying
them to the data.  For example:

%lines 106-108 of ft_specest_mtmfft.m
  case 'hanning'
    tap = hanning(ndatsample)';
    tap = tap./norm(tap, 'fro');

I realize this simply scales the power spectrum, but what's the
rationale for this?  Other EEG analysis software and tutorials I've
read don't do this.
        much thanks,
             -David

-- 
David Groppe, Ph.D.
dgroppe at cogsci.ucsd.edu
http://www.cogsci.ucsd.edu/~dgroppe/