%% ODE for 2 equation closed-cell Keizer Levine model (Figure 5.7)
%% Carol Lucas

function xdot=klclosefun(t,x,flag,CT)

fi=0.01;kserca=0.2;vserca=100;vRyR=5;vleak=.2;sig=.02;
ka=0.4;kb=0.6;kc=.1;kcm=.1;

C=x(1,1);
w=x(2,1);

winf=(1+(ka/C)^4+(C/kb)^3)/(1+(1/kc)+(ka/C)^4+(C/kb)^3);
CER=(CT-C)/sig;
tau=winf/kcm;
Po=w*(1+(C/kb)^3)/(1+(ka/C)^4 + (C/kb)^3);

jRyR=vRyR*Po*(CER-C);
jserca=vserca*C^2/(kserca^2+C^2);
jleak=vleak*(CER-C);

xdot(1,1)=fi*(jRyR+jleak-jserca);
xdot(2,1)=-(w-winf)/tau;