| Simulation provides a third alternative, which is | | | | the program on a massively parallel computer. |
| cheap and fast, and thus fills the gap between | | | | This is called parallel and distributed simulation. For |
| exact analysis and physical intuition. Occasionally, | | | | many large-scale models, this is the only feasible |
| Simulation is also used even when an exact | | | | way of getting answers back in a reasonable |
| analytic solution is possible, but it is too expensive | | | | amount of time. |
| in terms of computation time. | | | | Simulation of a system can be done at many |
| Computer simulation is the discipline of designing a | | | | different levels of fidelity so that whereas one |
| model of an actual or theoretical physical system, | | | | reader will think of physics-based models and |
| executing the model on a digital computer, and | | | | output, another may think of more abstract |
| analyzing the execution output. Simulation | | | | models, which yield higher-level, less detailed |
| embodies the principle of ``learning by doing'' --- to | | | | output as in a queuing network. Models are |
| learn about the system we must first build a | | | | designed to provide answers at a given |
| model of some sort and then operate the model. | | | | abstraction level --- the more detailed the model, |
| The use of simulation is an activity that is as | | | | the more detailed the output. The kind of output |
| natural as a child who role plays. Children | | | | you need will suggest the type of model you will |
| understand the world around them by simulating | | | | employ. |
| (with toys and figurines) most of their interactions | | | | |
| with other people, animals and objects. As | | | | Simulation in science and engineering |
| adultswe lose some of this childlike behavior but | | | | research: Earlier most experiments were |
| recapture it later on through computer simulation. | | | | carried out physically in the laboratories, but today |
| To understand reality and all of its complexity, we | | | | a majority of experiments are simulated on |
| must build artificial objects and dynamically act out | | | | computers. ‘Computer Experiments’ |
| roles with them. | | | | besides being much faster, cheaper, and easier, |
| Computer simulation is the electronic equivalent of | | | | frequently better insight into the system than |
| this type of role-playing and it serves to drive | | | | laboratory experiments do. |
| synthetic environments and virtual worlds. Within | | | | |
| the overall task of simulation, there are three | | | | Simulation in soft sciences: Simulation can be |
| primary sub-fields: model design, model execution | | | | expected to play even a more vital role in biology, |
| and model analysis . | | | | sociology, economics, medicine, psychology etc. |
| To simulate something physical, you will first | | | | where experiments could be very expensive, |
| need to create a mathematical model, which | | | | dangerous, or even impossible. Thus Simulation |
| represents that physical object. Models can take | | | | has become an indispensable tool for a modern |
| many forms including declarative, functional, | | | | researcher in most social, biological and life |
| constraint, spatial or multimodel. | | | | sciences. |
| Multimodel is a model containing multiple integrated | | | | |
| models each of which represents a level of | | | | Simulation for business executives: There are |
| granularity for the physical system. The next | | | | many problems faced by management that |
| task, once a model has been developed, is to | | | | cannot be solved by standard operations research |
| execute the model on a computer --- that is, you | | | | tools like linear and dynamic programming, |
| need to create a computer program which steps | | | | inventory and queuing theory. Therefore, instead |
| through time while updating the state and event | | | | of taking decisions solely on intuition and |
| variables in your mathematical model. There are | | | | experience, now a business executive can use |
| many ways to ``step through time.'' You can, for | | | | computer simulation to make better and more |
| instance, leap through time using event scheduling | | | | powerful decisions. Simulation has been used |
| or you can employ small time increments using | | | | widely for inventory control, facility planning, |
| time slicing. You can also execute (i.e., simulate) | | | | production scheduling and the like. |