The Mackey-Glass equation is a nonlinear delay differential equation with a constant delay and a nonmonotonic feedback term (Mackey and Glass
1977, Glass and Mackey 2010). For nonnegative
, one form is
where
is the derivative with respect to time
,
, and
. The constant solution
always exists. There is also a positive constant solution
when
. Numerical studies show both periodic
solutions and chaos as the parameters vary (Glass and Mackey
2010).