ABSTRACT
A simulation is a series of calculations (almost always on the computer) that predict what the state variables of a system will be at each time step from the beginning until the end. This is called the dynamic response of the system, which is governed by certain principles (Newton’s Second Law, for example). In general, the principles are expressed mathematically by a set of differential equations, which are converted to difference equations for computational purposes. Initial conditions (like the aim of a cannon) are applied at time zero, and perhaps various forcing functions (like wind gusts) are applied during the run. If the conditions at the end of the run are not satisfactory (if the projectile misses its target), the initial conditions must be adjusted and the calculations performed again. Many cannon firings may be required before the target is hit. Such exercises are called initial-value problems.
