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_inv_vb_ecd_gui.m
    path of file: ./repos/spm
    
    the code of the file until where you have to start completion: function D = spm_eeg_inv_vb_ecd_gui(D,val)
% GUI function for variational Bayesian ECD inversion

    
function D = spm_eeg_inv_vb_ecd_gui(D,val)
% GUI function for variational Bayesian ECD inversion
%
% Fills in the following fields of the inverse structure:
% inverse = struct( ...
%     'F',            % free energies as dipoles are removed
%     'pst',          % all time points in data epoch
%     'tb',           % time window/bin used
%     'ltb',          % list of time points used
%     'ltr',          % list of trial types used
%     'n_dip',        % number of dipoles used
%     'Lecd',         % dipole lead fields
%     'loc',          % loc of dipoles (n_dip x 3)
%     'exitflag',     % Converged (1) or not (0)
%     'P'             % forward model
%
% In brief, this routine:
% - load the necessary data, if not provided,
% - fill in all the necessary bits for the VB-ECD inversion routine,
% - launch variational Bayesian model inversion,
% - eliminates redundant dipoles using Bayesian model reduction,
% - displays the results.
%
% This routine provides a Bayes optimal solution to the ECD problem. It
% finesses the nonlinear inversion problem by starting with a large number
% of dipoles (on the cortical surface). It then fits the principal spatial
% modes of the data over a specified peristimulus time window using fixed
% dipole orientations. Finally, it uses Bayesian model reduction to
% eliminate the least likely dipoles, until the specified number of dipoles
% is obtained.
%
% The purpose of this routine is to find the location of a small number of
% dipoles that accurately explain fluctuations in activity over
% peristimulus time. It is anticipated that the moments of the dipoles will
% be estimated as needed using a standard pseudo-inverse (ordinary least
% squares) estimator - should it be required. examples of this are provided
% during the presentation of the results below.
%__________________________________________________________________________

% Karl Friston
% Copyright (C) 2016-2022 Wellcome Centre for Human Neuroimaging


% Load data, if necessary
%==========================================================================
if nargin < 1
    D = spm_eeg_load;
end