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: spectopo.m
    path of file: ./repos/eeglab/functions/sigprocfunc
    
    the code of the file until where you have to start completion: % SPECTOPO - Plot the power spectral density (PSD) of winsize length segments of data 
%              epochs at all channels as a bundle of traces. At specified frequencies,
%              plot the relative topographic distribution of PSD. If available, uses
%      
    
function from Octave\n');
         end
    end
        
    if isempty(g.nfft) && strcmp(g.wintype,'hamming')
        %fftlength = 2^(nextpow2(winlength))*g.freqfac;
        fftlength = winlength*g.freqfac;
    elseif ~isempty(g.nfft) && strcmp(g.wintype,'hamming')
        fftlength = g.nfft;
    elseif strcmp(g.wintype,'blackmanharris')
        fftlength = 2^(nextpow2(length(winlength)))*g.freqfac;
    end
    
    if ~usepwelch
        myfprintf(g.verbose, '\nSignal processing toolbox (SPT) absent: spectrum computed using the pwelch()\n');
        myfprintf(g.verbose, 'function from Octave which is supposedly 100%% compatible with the Matlab pwelch function\n');
    end
    myfprintf(g.verbose,' (window length %d; fft length: %d; overlap %d):\n', winlength, fftlength, g.overlap);	
        
	for c=1:nchans % scan channels or components
		if exist('newweights') == 1
			if strcmp(g.icamode, 'normal')
				tmpdata = newweights(c,:)*data; % component activity
			else % data - component contribution
                tmpdata = data(g.plotchan,:) - (g.icawinv(g.plotchan,c)*newweights(c,:))*data;
			end