how can i stay 7t longer in my code

[t,y]=ode45(@seirl,[0,300],[1,0,0.0014,0,0])
plot(t,y) 
legend('S','E','I','R','l')


a=0.015;
b=0.6;
c=0.7;
e=0.2;

dydt=zeros(4,1);
dydt(1)=-a*y(1)*y(2);
dydt(2)=a*y(1)*y(2)-b*y(2)
dydt(3)=b*y(2)-c*y(3)
dydt(4)=c*y(3)
end

ive wrote those code to make SEIR model. But at the code I wrote, there are no incubation time,,, I want to make delay for 7t when moving dydt(2) to dydt(3) (when code goes dydt(2) to dydt(3), stay 7t to move on.) please help me :(

Answer 1

[Steven Lord]

If your equations depend not just on the value of the solution at the current time but also the value of the solution at a previous time, you don't have a system of ordinary differential equations. Instead use a delay differential equation solver like dde23 or ddesd.