ex14ch4.m

these codes are for solving OED with matlab

function sol = ex14ch4
% The parameter state = +1 if ylag >= -0.427, -1 otherwise.
% With this definition of history, state is initially +1.
state = +1;
opts = ddeset('Events',@events);
sol = dde23(@ddes,12,0.6,[0, 120],opts,state);
while sol.x(end) < 120
   fprintf('Restart at %5.1f.\n',sol.x(end));
   state = - state;
   sol = dde23(@ddes,12,sol,[sol.x(end), 120],opts,state);
end
plot(sol.x,sol.y);
title('Marriott-DeLisle Controller Problem')
xlabel('Restart each time y(t - 12) = -0.427.');
%==========================================================
function v = ddes(t,y,Z,state)
xb = -0.427;
a = 0.16;
epsilon = 0.02;
u = 0.5;
tau = 1;
Delta = Z - xb;
v = (-y + pi * (a + epsilon*state - u*sin(Delta)^2)) / tau;

function [value,isterminal,direction] = events(t,y,Z,state)
xb = -0.427;
value = Z - xb;
isterminal = 1;
direction = 0;