%%  Open Cell Gonadotroph Model.  Jin = 1200 for first 40 seconds
%%  Carol Lucas
%%  Figure 5.14 and 5.15 simulations

function xdot=lropenfun(t,x)

fi=0.01;
% Vi = pL
Vi=4;
% L,P = pL/s
L=0.37;P=26640;
% I, C, Ce, Ct,I, Ki, Ka, Ke, Kd, Kp = uM 
I=0.9;Ki=1.0;Ka=0.4;
% Ve, Vp = aMol/s [sic]
Ve=400;Ke=0.2;A=0.5;Kd=0.4;
% sigma,eps, fi = unitless
sigma=0.185;eps=0.01;Vp=2000;Kp=0.3;

Jin=1200*(t<=40);

C=x(1,1);
h=x(2,1);
Ct=x(3,1);

Ce = (Ct - C)/sigma;

xdot(1,1)= fi/Vi*( (L + P*( (I*C*h)/( (I+Ki)*(C+Ka) ) )^3 )*(Ce - C) - Ve*C*C/(Ke*Ke+C*C) + eps*(Jin - Vp*C*C/(Kp*Kp + C*C)) );
xdot(2,1) = A*( Kd - (C + Kd)*h );
xdot(3,1) = fi/Vi*eps*(Jin - Vp*C*C/(Kp*Kp + C*C));