High Quality Content by WIKIPEDIA articles! In mathematics, a function is a relation between a given set of elements called the domain and a set of elements called the codomain. The function associates each element in the domain with exactly one element in the codomain. The elements so related can be any kind of thing but are typically mathematical quantities, such as real numbers. There are many ways to represent or visualize functions: a function may be described by a formula, by a plot or graph, by an algorithm that computes it, by arrows between objects, or by a description of its properties. Sometimes, a function is described through its relationship to other functions for example, inverse functions. In applied disciplines, functions are frequently specified by tables of values or by formulae.