Discrete-event simulation: Difference between revisions

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A '''discrete-event simulation''' ('''DES''') models the operation of a [[system]] as a ([[discrete time|discrete]]) [[sequence of events]] in time. Each event occurs at a particular instant in time and marks a change of [[State (computer science)|state]] in the system.<ref>{{cite book|title=''Simulation – The practice of model development and use''|author=Stewart Robinson|publisher=Wiley|year=2004}}</ref> Between consecutive events, no change in the system is assumed to occur; thus the simulation time can directly jump to the occurrence time of the next event, which is called '''next-event time progression'''.

In addition to next-event time progression, there is also an alternative approach, called '''fixed-incrementincremental time progression''', where time is broken up into small time slices and the system state is updated according to the set of events/activities happening in the time slice.<ref name="matloff">{{cite web|last=Matloff|first=Norm|title=Introduction to Discrete-Event Simulation and the SimPy Language|url=http://heather.cs.ucdavis.edu/~matloff/156/PLN/DESimIntro.pdf|access-date=24 January 2013}}</ref> Because not every time slice has to be simulated, a next-event time simulation can typically run much faster than a corresponding fixed-incrementincremental time simulation.

Both forms of DES contrast with [[continuous simulation]] in which the system state is changed continuously over time on the basis of a set of [[Differential equation|differential equations]] defining the rates of change of state variables.