global a b d d1 e gamma T

a  = 1;
b  = 80;
d  = 1;
d1 = 1;
e  = 10;
gamma = 0.5;
T = 0.2;

lambda = 12;
sol = dde23('prob5f',T,[2; 3.5],[0, 25],[],lambda);

plot(sol.x,sol.y)
legend('I(t)','N(t)',0)
title(['Problem 5. Cooke et al. Epidemic Model with ' ...
       ' \lambda = ',num2str(lambda),'.'])
xlabel('time t')