function seiar = seiar(t,x)
N = 1000;
alpha = 2.0;
beta = 0.25;
gamma = 0.1;
delta = 0.1;
epsilon = 0.2;
zeta = 0.6;
seiar = zeros(4,1);
seiar(1) = - beta * (x(1) / N) * (x(3) + alpha * x(4)); %dS/dt
seiar(2) = beta * (x(1) / N) * (x(3) + alpha * x(4)) - epsilon * x(2); %dE/dt
seiar(3) = epsilon * zeta * x(2) - gamma * x(3); %dI/dt
seiar(4) = epsilon * (1.0 - zeta) * x(2) - gamma * x(4); %dA/dt

