Function (Mathematics)

A function is a mathematical relationship that assigns to each element of one set, called the domain, exactly one element of another set, called the codomain. When a function f sends an element x to a corresponding value y, this is written y equals f of x. The idea grew out of efforts in the late seventeenth century to describe how one changing quantity depends on another, such as a planet's position over time, and for a long time focused on functions smooth enough to differentiate. Only in the late nineteenth century did mathematicians give functions a fully general definition through set theory, extending the concept far beyond its calculus origins into nearly every branch of mathematics. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/