Function (mathematics)

In mathematics, a function is a rule that assigns each element from one set (the domain) to exactly one element of another set (the codomain). Functions are often represented by letters such as f, g, and h, with the value of a function at an element x denoted by f(x). The concept of functions, which originated from the idea of how one quantity depends on another, has been formalized in terms of set theory and is central to most fields of mathematics, science, and engineering.