View source for Delay-differential equations

==Introduction==

Systems of delay differential equations now occupy a place of
central importance in all areas of science and particularly in the
biological sciences (''e.g.,'' population dynamics and epidemiology).
Baker, Paul, & Will&eacute; (1995) contains references for several application areas.

Interest in such systems often arises when traditional pointwise
modeling assumptions are replaced by more realistic distributed assumptions,
for example, when the birth rate of predators is affected by prior levels
of predators or prey rather than by only the current levels in a [[predator-prey model]].
The manner in which the properties of systems of delay differential equations differ from those of
systems of ordinary differential equations has been and remains an active area of research; see
Martin & Ruan (2001) and Raghothama & Narayanan (2002) for typical examples
of such studies.
See also Shampine, Gladwell, and Thompson (2003) for a description of several common models.