What is simulation

What is Simulation?
Simulation is a concept that involves building a model, which mimics reality. The term simulation was derived from the Latin simulare , which means to pretend . Simulation can be defined as an experiment performed on a model .
Shannon [1975] defines simulation as an "experimental and applied methodology which seeks to:
1. describe the behavior of systems;
2. construct theories or hypotheses that account for the observed behavior;
3. Use these theories to predict future behavior, that is, the effects that will be produced by changes in the system or in its method of operation.
Besides that, Simulation can be defined as a tool that evaluates the performance of a system, existing or proposed, under different configurations of interest and over long periods of real time.
The term Computer Simulation means designs a model of an actual or theoretical physical system, execute the model on a digital computer, and analyze the execution output.
Systems, Models, and Simulation


Classification of simulation models
– Static vs. dynamic
– Deterministic vs. stochastic
– Continuous vs. discrete
Deterministic models are models which do not contain the element of probability. Examples are: linear programming, non-linear programming and dynamic programming.
Stochastic models are models which contain the element of probability. Examples are: queuing theory, stochastic processes, and simulation techniques
Continuous simulation is a model in which systems change continuously over time, a continuous simulation model is characterized by its state variables, which typically can be described as functions of time
Discrete simulation models are only concerned with what happens to the individual elements in the system and will jump to that next step.
The History of Simulation
1- The early years:
In the late 1950s and 1960s, simulation was a very expensive and specialized tool that was generally used only by large corporations. Typical simulation users were found in steel corporations. These organizations would form groups of people, mostly PH.D.s, who would develop large, complex simulation models using available languages, such as FORTRAN. These models would then be run