function w = sign(w)
   %SIGN Signum function for waveforms.
   % WAVEFORM = SIGN(WAVEFORM)
   % see sign
   
   % AUTHOR: Celso Reyes, Geophysical Institute, Univ. of Alaska Fairbanks
   % $Date$
   % $Revision$
   
   for n=1:numel(w)
      % w(n) = set(w(n),'data',sign(double(get(w(n),'data'))));
      w(n).data = sign(w(n).data);
   end
end
