You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: spm_eeg_ft_multitaper_powermap.m
    path of file: ./repos/malini/Codes/deconvolution - model/spm8/toolbox/MEEGtools
    
    the code of the file until where you have to start completion: function Dtf = spm_eeg_ft_multitaper_powermap(S)
% Function for computing spectra of stationary data using multitaper
%
% FORMAT D = spm_eeg_ft_multitaper_powermap(S)
%
% S           - input structure (optional)
% (optional) fields of S:
%   S.D       - filename, or M/EEG object

    
function Dtf = spm_eeg_ft_multitaper_powermap(S)
% Function for computing spectra of stationary data using multitaper
%
% FORMAT D = spm_eeg_ft_multitaper_powermap(S)
%
% S           - input structure (optional)
% (optional) fields of S:
%   S.D       - filename, or M/EEG object
%   S.freqwin  - frequency window (Hz)
%   S.freqres  - frequency resolution (Hz)
%   S.log      - compute log of power (1 - yes, 0- no)
%
% Output
%   Dtf - dataset with the spectra where the frequency dimension has been
%         converted to time dimension as a hack to allow export to images
% Disclaimer: this code is provided as an example and is not guaranteed to work
% with data on which it was not tested. If it does not work for you, feel
% free to improve it and contribute your improvements to the MEEGtools toolbox
% in SPM (http://www.fil.ion.ucl.ac.uk/spm)
%
% _______________________________________________________________________
% Copyright (C) 2009 Institute of Neurology, UCL

% Vladimir Litvak
% $Id: spm_eeg_ft_multitaper_powermap.m 3729 2010-02-17 12:47:21Z vladimir $
 
%%
SVNrev = '$Rev: 3729 $';

%-Startup
%--------------------------------------------------------------------------
spm('FnBanner', mfilename, SVNrev);
spm('FigName','Fieldtrip multitaper power map'); 

%%
%-Test for the presence of required Matlab toolbox
%--------------------------------------------------------------------------
if ~license('test','signal_toolbox')
    error('This function requires the Signal Processing Toolbox.');
end