function sol = exer5
% exer5, exer5f, exer5h of tutorial.

% D.R. Wille' and C.T.H. Baker use Example 4 of DELSOL--
% a numerical code for the solution of systems of delay-
% differential equations, Appl. Numer. Math., 9 (992) 
% 223-234 to illustrate a discontinuous history. DDE23 
% treats any order discontinuity in the history as a 
% discontinuity in the solution itself, which is actually 
% the case for this example.

opts = ddeset('Jumps',[-1,-4/5,-3/5,-2/5,-1/5]);
sol = dde23(@exer5f,1,@exer5h,[0, 1],opts);
plot(sol.x,sol.y)
title('Example 4 of Wille'' and Baker.')
xlabel('time t');
ylabel('y(t)');

%================================================
function yp = exer5f(t,y,Z)
yp = Z;

%================================================
function y = exer5h(t)
y = (-1)^floor(-5*t);