function dx = ODE_ProchiralPing(t,x,k,EobySo)
% Now just calculate the derivatives for the evolution of the state variables
% - this is for prochiral Ping model
% 	x_dot = F*theta
% 	s_dot = J*s + F  - now removed

% Check input and output arguments are correctly supplied
if nargin~=4
    error('Four input arguments are required');
end


% Index to k's
%1	    2	3       4	5       6	7	8	    9	    10	    11      12
%k1n	k2	k3Rn	k4R	k3Sn	k4S	km1	km2n	km3R	km4Rn	km3S	km4Sn

%Index to x's
%1	2	3	4       5       6	7	8	9	10
%En	EDn	Esn	ESRn	ESSn	Dn	Qn	Sn	PRn	PSn

F = [-x(1)*x(6), 0, 0, x(4), 0, x(5), x(2), 0, 0, -x(1)*x(9), 0, -x(1)*x(10);
x(1)*x(6), -x(2), 0, 0, 0, 0, -x(2), x(3)*x(7), 0, 0, 0, 0;
0, x(2), -x(3)*x(8), 0, -x(3)*x(8), 0, 0, -x(3)*x(7), x(4), 0, x(5), 0;
0, 0, x(3)*x(8), -x(4), 0, 0, 0, 0, -x(4), x(1)*x(9), 0, 0;
0, 0, 0, 0, x(3)*x(8), -x(5), 0, 0, 0, 0, -x(5), x(1)*x(10);
-EobySo*x(1)*x(6), 0, 0, 0, 0, 0, EobySo*x(2), 0, 0, 0, 0, 0;
0, EobySo*x(2), 0, 0, 0, 0, 0, -EobySo*x(3)*x(7), 0, 0, 0, 0;
0, 0, -EobySo*x(3)*x(8), 0, -EobySo*x(3)*x(8), 0, 0, 0, EobySo*x(4), 0, EobySo*x(5), 0;
0, 0, 0, EobySo*x(4), 0, 0, 0, 0, 0, -EobySo*x(1)*x(9), 0, 0;
0, 0, 0, 0, 0, EobySo*x(5), 0, 0, 0, 0, 0, -EobySo*x(1)*x(10)];

    
dx = F*k;