# Mathematical model

A **mathematical model** uses mathematical language to describe a system. Mathematical models are used not only in the natural sciences and engineering disciplines (such as physics, biology, earth science, meteorology, and electrical engineering) but also in the social sciences (such as economics, psychology, sociology and political science); physicists, engineers, computer scientists, and economists use mathematical models most extensively.

Eykhoff (1974) defined a *mathematical model* as 'a representation of the essential aspects of an existing system (or a system to be constructed) which presents knowledge of that system in usable form'.

Mathematical models can take many forms, including but not limited to dynamical systems, statistical models, differential equations, or game theoretic models. These and other types of models can overlap, with a given model involving a variety of abstract structures.

## Examples of mathematical models

*Population Growth*. A simple (though approximate) model of population growth is the Malthusian growth model. The preferred population growth model is the logistic function.*Model of a particle in a potential-field*. In this model we consider a particle as being a point of mass*m*which describes a trajectory which is modeled by a function*x*:**R**→**R**³ given its coordinates in space as a function of time. The potential field is given by a function*V*:**R**³ →**R**and the trajectory is a solution of the differential equation

- Note this model assumes the particle is a point mass, which is certainly known to be false in many cases we use this model, for example, as a model of planetary motion.

*Model of rational behavior for a consumer*. In this model we assume a consumer faces a choice of*n*commodities labeled 1,2,...,*n*each with a market price. The problem of rational behavior in this model then becomes an optimization problem.

- This model has been used in general equilibrium theory, particularly to show existence and Pareto optimality of economic equilibria. However, the fact that this particular formulation assigns
*numerical values*to levels of satisfaction is the source of criticism (and even ridicule). However, it is not an essential ingredient of the theory and again this is an idealization.[1]