% Hessian of the state transition function in UNGM-model.% Copyright (C) 2007 Jouni Hartikainen%% This software is distributed under the GNU General Public % Licence (version 2 or later); please refer to the file % Licence.txt, included with the software, for details.function d = ungm_d2f_dx2(x,param)    d = 25*(-6*x+2*x.^5-4*x.^3)/((1+x.^2).^4);