IDO.m

function dydt=IDO(t,y)

km1=0.009; km2=0.1; e0=0.01; %i0=1; %s0=1; k2=0.01; k4=0.001;

%Made by Chris 7/13/09 %y1 is S %y2 is I %y3 is P %y4 is J

dydt=zeros(4,1); dydt(1,:)=-k2*e0*y(1)./(y(1)+km1/km2*y(2)+km1); dydt(2,:)=-k4*e0*y(2)./(y(2)+km2/km1*y(1)+km2); dydt(3,:)=k2*e0*y(1)./(y(1)+km1/km2*y(2)+km1); dydt(4,:)=k4*e0*y(2)./(y(2)+km2/km1*y(1)+km2); return