MATLAB Mathematics - SERC - Index of

Initial Value Problems for DDEs
The demo ddex2 plots only the third component, the heart rate, which shows a
sharp change at t = 600.
Solve by Restarting. The example could have solved this problem by breaking it
into two pieces
sol = dde23(@ddex2de,tau,history,[0, 600]);
sol = dde23(@ddex2de,tau,sol,[600, 1000]);
The solution structure sol on the interval [0,600] serves as history for
restarting the integration at t = 600. In the second call, dde23 extends sol so
that on return the solution is available on the whole interval [0,1000]. That
is, after this second return,
Sint = deval(sol,[300,900]);
evaluates the solution obtained in the first integration at t = 300, and the
solution obtained in the second integration at t = 900.
When discontinuities occur in low order derivatives at points known in
advance, it is better to use the Jumps property. When you use event functions
to locate such discontinuities, you must restart the integration at
discontinuities.
1.7
Heart Rate for Baroflex−Feedback Mechanism.
1.6
1.5
H(t)
1.4
1.3
1.2
1.1
1
0 200 400 600 800 1000
time t
5-59