Discrete-event simulation: Difference between revisions

Revision as of 08:27, 16 January 2021

Revision as of 19:29, 11 February 2021

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===Events list===

The simulation maintains at least one list of simulation events. This is sometimes called the ''pending event set'' because it lists events that are pending as a result of previously simulated event but have yet to be simulated themselves. An event is described by the time at which it occurs and a type, indicating the code that will be used to simulate that event. It is common for the event code to be parametrized, in which case, the event description also contains parameters to the event code.

because it lists events that are pending as a result of previously simulated event but have yet to be simulated themselves.

An event is described by the time at which it occurs and a type, indicating the

code that will be used to simulate that event. It is common for the event code to be parametrized, in which case, the event description also contains parameters to the event code.

When events are instantaneous, activities that extend over time are modeled as sequences of events. Some simulation frameworks allow the time of an event to be specified as an interval, giving the start time and the end time of each event.

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Because events are bootstrapped, theoretically a discrete-event simulation could run forever. So the simulation designer must decide when the simulation will end. Typical choices are "at time t" or "after processing n number of events" or, more generally, "when statistical measure X reaches the value x".

===Three-Phased Approach===

Pidd (1998) has proposed the three-phased approach to discrete event simulation. In this approach, the first phase is to jump to the next chronological event. The second phase is to execute all events that unconditionally occur at that time (these are called B-events). The third phase is to execute all events that conditionally occur at that time (these are called C-events). The three phase approach is a refinement of the event-based approach in which simultaneous events are ordered so as to make the most efficient use of computer resources. The three-phase approach is used by a number of commercial simulation software packages, but from the user's point of view, the specifics of the underlying simulation method are generally hidden.

== Common uses ==

===Diagnosing process issues===

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{{#section:Network_simulation|transclusionLabelG20170307T1400GMT1}}

== See also ==

System modeling approaches:

* [[Finite-state machines]] and [[Markov chains]]

* [[Stochastic process]] and a special case, [[Markov process]]

* [[Queueing theory]] and in particular [[birth-deathbirth–death process]]

* [[Discrete Event System Specification]]

* [[Transaction-level modeling]] (TLM)

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* [[Monte Carlo method]]

* [[Variance reduction]]

* [[PseudoPseudorandom number generator|Pseudo-random number generator]]

Software:

* [[List of computer simulation software]]