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_mc_fx_5.m
    path of file: ./repos/bspm/thirdparty/spm12/toolbox/DEM
    
    the code of the file until where you have to start completion: function [f] = spm_mc_fx_5(x,v,P)
% equations of motion for the mountain car problem using basis functions
% problem

    
function [f] = spm_mc_fx_5(x,v,P)
% equations of motion for the mountain car problem using basis functions
% problem
% FORMAT [f] = spm_mc_fx_5(x,v,P)
%
% x   - hidden states
% v   - exogenous inputs
% P.p - parameters for gradient function:     G(x(1),P.p)
% P.q - parameters for cost or loss-function: C(x(1),P.q)
%
% 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_mc_fx_5.m 3333 2009-08-25 16:12:44Z karl $
 
 
% gradient of Hamiltonian (G)
%--------------------------------------------------------------------------
G   = spm_DEM_basis(x.x,v,P);

% cost function (C)
%--------------------------------------------------------------------------
D   = tanh((1 - x.p)*8);
C   = 2 - 32*x.q;
C   = C*D - 1;

% flow
%--------------------------------------------------------------------------
dt  = 1/8;
f.x = [x.v; G - x.v*x.c]*dt;
f.c = [-C - x.c]*dt;
f.p = -x.p/64;
f.q = -x.q/64;
 
 

return

% NOTES for graphics
%--------------------------------------------------------------------------
x     = -2:1/64:2;
d     =  0:1/64:2;
for i = 1:length(x)
    for j = 1:length(d)
        D      = spm_phi((1 - d(j))*8);
        A      = 2 - 32*exp(-(x(i) - 1).^2*32);
        C(i,j) = A*D - 1;
    end