ex03cch4.m

these codes are for solving OED with matlab

function sol = ex03cch4 
options = ddeset('RelTol',1e-5);
sol = dde23(@ddes,0.05,[2; 10],[0,10],options);
plot(sol.y(1,:),sol.y(2,:),5,68/5,'r*');
title('Plot in phase plane for \tau = 0.05.')
xlabel('Equilibrium point at (5,68/5).')
%============================================================
function dydt = ddes(t,y,Z)
xoft = y(1);
yoft = y(2);
xlag = Z(1);
ylag = Z(2);
dydt = [  xoft*(20 - xoft - yoft) - 7
         -15*yoft + 3*xlag*ylag       ];