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_gx_mfm.m
    path of file: ./repos/bspm/thirdparty/spm8/toolbox/Neural_Models
    
    the code of the file until where you have to start completion: function [m] = spm_gx_mfm(x,u,P,M)
% observer for a mean-field model (spiking)
% FORMAT [m] = spm_gx_mfm(x,u,P,M)
% x      - state vector
% m      - spiking activity (ns x np)
%__________________________________________________________________________
%
% David O, Friston KJ (2003) A neural mass model for MEG/EEG: coupling and
% neuronal dynamics. NeuroImage 20: 1743-1755
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging
 

    
function [m] = spm_gx_mfm(x,u,P,M)
% observer for a mean-field model (spiking)
% FORMAT [m] = spm_gx_mfm(x,u,P,M)
% x      - state vector
% m      - spiking activity (ns x np)
%__________________________________________________________________________
%
% David O, Friston KJ (2003) A neural mass model for MEG/EEG: coupling and
% neuronal dynamics. NeuroImage 20: 1743-1755
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging
 
% Karl Friston
% $Id: spm_gx_mfm.m 2941 2009-03-24 17:45:56Z maria $
 
% get dimensions and configure state variables
%--------------------------------------------------------------------------
if iscell(x)
    mfm = 1;                                    % mean-field model
else
    mfm = 0;
    x = {x};                                    % neural-mass model
end