ex13ch4.m

these codes are for solving OED with matlab

function sol = ex13ch4
global ds T
% The three delays:
Delays = [0.2 1.0 2.4];
opts = ddeset('RelTol',1e-5,'AbsTol',1e-8);
for ds = 1:4
   for i = 1:3
      T = Delays(i); 
      sol(i) = dde23(@ddes,T,3.5,[0, 25],opts);
   end
   figure
   plot(sol(1).x,sol(1).y,sol(2).x,sol(2).y,sol(3).x,sol(3).y)
   legend('T = 0.2','T = 1.0','T = 2.4',0)
   xlabel('time t')
   title(['Maturation Delay and Nonlinear' ...
          ' Birth Problem-Data Set ',num2str(ds)])
end
%=============================================================
function v = ddes(t,y,Z)
global ds T
% The four data sets:
a  = [1 1 1 1];
d  = [1 1 1 1];
d1 = [1 1 0 0];
b  = [20 80 20 80];
v = b(ds) * exp(-a(ds)*Z)*Z*exp(-d1(ds)*T) - d(ds)*y;