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_dcm_fmri_csd_data.m
    path of file: ./repos/bspm/thirdparty/spm12
    
    the code of the file until where you have to start completion: function DCM = spm_dcm_fmri_csd_data(DCM)
% Get cross-spectral density data-features using a VAR model
% FORMAT DCM = spm_dcm_fmri_csd_data(DCM)
% DCM    -  DCM structure or fMRI
%
% sets
%
%    DCM.Y.pst     - Peristimulus Time [ms] sampled
%    DCM.Y.dt      - sampling in seconds [s] (down-sampled)
%    DCM.Y.csd     - cross spectral density over sources
%    DCM.Y.Hz      - Frequency bins
%
%    DCM.U.csd     - cross spectral density of inputs
%__________________________________________________________________________
% Copyright (C) 2013 Wellcome Trust Centre for Neuroimaging
 

    
function DCM = spm_dcm_fmri_csd_data(DCM)
% Get cross-spectral density data-features using a VAR model
% FORMAT DCM = spm_dcm_fmri_csd_data(DCM)
% DCM    -  DCM structure or fMRI
%
% sets
%
%    DCM.Y.pst     - Peristimulus Time [ms] sampled
%    DCM.Y.dt      - sampling in seconds [s] (down-sampled)
%    DCM.Y.csd     - cross spectral density over sources
%    DCM.Y.Hz      - Frequency bins
%
%    DCM.U.csd     - cross spectral density of inputs
%__________________________________________________________________________
% Copyright (C) 2013 Wellcome Trust Centre for Neuroimaging
 
% Karl Friston
% $Id: spm_dcm_fmri_csd_data.m 6759 2016-03-27 19:45:17Z karl $

% add spectral toolbox
%--------------------------------------------------------------------------
if ~isdeployed
    addpath(fullfile(spm('Dir'),'toolbox', 'spectral'));
end