ex04ch4.m

these codes are for solving OED with matlab

function sol = ex04ch4
sol = dde23(@ddes,[1, 0.5],@history,[0, 1]);
plot(sol.x,sol.y);
%===========================================
function dydt = ddes(t,y,Z)
ylag1 = Z(:,1);
ylag2 = Z(:,2);
dydt = zeros(5,1);
dydt(1) = ylag1(5) + ylag1(3);
dydt(2) = ylag1(1) + ylag2(2);
dydt(3) = ylag1(3) + ylag2(1);
dydt(4) = ylag1(5)*ylag1(4);
dydt(5) = ylag1(1);

function v = history(t)
v = zeros(5,1);
v(1) = exp(t+1);
v(2) = exp(t+0.5);
v(3) = sin(t+1);
v(4) = v(1);
v(5) = v(1);