function Z = ecg_model(X,Phasemn)
%
% Synthetic ECG
%
% Open Source ECG Toolbox, version 1.0, November 2006
% Released under the GNU General Public License
% Copyright (C) 2006  Reza Sameni
% Sharif University of Technology, Tehran, Iran -- LIS-INPG, Grenoble, France
% reza.sameni@gmail.com
%
% Modified: Joachim Behar - 02-09-2013
%
% Reference: 
%   McSharry P.E., Clifford G.D., Tarassenko L., Smith L.: A dynamical model 
%   for generating synthetic electrocardiogram signals, 
%   IEEE Transactions On Biomedical Engineering, 50(3), 289-294, March 2003.
%
% This program is free software; you can redistribute it and/or modify it
% under the terms of the GNU General Public License as published by the
% Free Software Foundation; either version 2 of the License, or (at your
% option) any later version.
% This program is distributed in the hope that it will be useful, but
% WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
% Public License for more details.

L = (length(X)/3);

alphai = X(1:L);
bi = X(L+1:2*L);
tetai = X(2*L+1:3*L);

Z = zeros(size(Phasemn));
for j = 1:length(alphai),
    dtetai = rem(Phasemn - tetai(j) + pi,2*pi)-pi;
    Z = Z + alphai(j) .* exp(-dtetai .^2 ./ (2*bi(j) .^ 2));
end