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_cost_fx.m
    path of file: ./repos/malini/Codes/deconvolution - model/spm8/toolbox/DEM
    
    the code of the file until where you have to start completion: function [f] = spm_cost_fx(x,v,P)
% equations of motion for foragaing problem
% problem
% FORMAT [f] = spm_cost_fx(x,v,P)
%
% x   - hidden states
% v   - exogenous inputs
% P.p - parameters for gradient function:     G(x(1),P.p)
%
% returns f = dx/dt = f  = [x(2);
%                           G - x(2)*C]*dt;
%
% where C determines divergence of flow x(2) at any position x(1).
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging
 
% Karl Friston
% $Id: spm_cost_fx.m 3757 2010-03-08 11:41:53Z guillaume $
 

% dominant physiological state
%--------------------------------------------------------------------------
f     = x;
[p i] = min([x.p; 1]);

    
function [f] = spm_cost_fx(x,v,P)
% equations of motion for foragaing problem
% problem
% FORMAT [f] = spm_cost_fx(x,v,P)
%
% x   - hidden states
% v   - exogenous inputs
% P.p - parameters for gradient function:     G(x(1),P.p)
%
% returns f = dx/dt = f  = [x(2);
%                           G - x(2)*C]*dt;
%
% where C determines divergence of flow x(2) at any position x(1).
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging
 
% Karl Friston
% $Id: spm_cost_fx.m 3757 2010-03-08 11:41:53Z guillaume $
 

% dominant physiological state
%--------------------------------------------------------------------------
f     = x;
[p i] = min([x.p; 1]);

if i > length(x.p)
    
    A = [0;0];
    C = -1;
    
else
    
    A = P.p(:,i);
    q = x.q(i);
    
    % cost function
    %----------------------------------------------------------------------
    u = 1/16;
    C = (q < u)*1/8 - (q > u)*8;
    
end