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_dem_occlusion_movie.m
    path of file: ./repos/bspm/thirdparty/spm12/toolbox/DEM
    
    the code of the file until where you have to start completion: function spm_dem_occlusion_movie(DEM)
% creates a movie of visual pursuit with occlusion
% FORMAT spm_dem_occlusion_movie(DEM)
%
% DEM - DEM structure from simulations
%
% hidden causes and states
%==========================================================================
% x    - hidden states:
%   x.o(1) - oculomotor angle
%   x.o(2) - oculomotor velocity
%   x.x(1) - target location - extrinsic coordinates
%
% v    - causal states: force on target
%
% g    - sensations:
%   g(1) - oculomotor angle (proprioception)
%   g(2) - oculomotor velocity
%   g(:) - visual input - intrinsic coordinates
%--------------------------------------------------------------------------

    
function spm_dem_occlusion_movie(DEM)
% creates a movie of visual pursuit with occlusion
% FORMAT spm_dem_occlusion_movie(DEM)
%
% DEM - DEM structure from simulations
%
% hidden causes and states
%==========================================================================
% x    - hidden states:
%   x.o(1) - oculomotor angle
%   x.o(2) - oculomotor velocity
%   x.x(1) - target location - extrinsic coordinates
%
% v    - causal states: force on target
%
% g    - sensations:
%   g(1) - oculomotor angle (proprioception)
%   g(2) - oculomotor velocity
%   g(:) - visual input - intrinsic coordinates
%--------------------------------------------------------------------------
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging
 
% Karl Friston
% $Id: spm_dem_occlusion_movie.m 4663 2012-02-27 11:56:23Z karl $
 
 
 
% movie
%--------------------------------------------------------------------------
for i = 1:length(DEM.pU.v{2})
    
    
    % stimulus and tracking in extrinsic coordinates
    %======================================================================
    subplot(2,2,1), cla, axis image ij, hold on
    px  = spm_unvec(DEM.pU.x{1}(:,i),DEM.M(1).x);   % extrinsic target
    qx  = spm_unvec(DEM.qU.x{1}(:,i),DEM.M(1).x);   % conditional estimate
    
    
    % target location
    %----------------------------------------------------------------------
    plot(0,0,'+','MarkerSize',32,'Color',[1 1 1]*(1 - 1/8))
    c   = max(DEM.pU.v{1}(3:end