function xdot=netfun(t,x,flag,PE)
%% Two Population System, Equations 6.22 and 6.23
%% Simulations like for Figures 6.12 and 6.13
%% Carol Lucas

E=x(1,1);
I=x(2,1);

a=16;b=12;c=16;d=5;PI=-4;tauE=1;tauI=1;
fE=1/(1+exp(-(a*E-b*I+PE)));
fI=1/(1+exp(-(c*E-d*I+PI)));

xdot(1,1)=(-E+fE)/tauE;
xdot(2,1)=(-I+fI)/tauI;