Domain and range of a relation | Functions and their graphs | Algebra II | Khan Academy
Mathematics | Composition of relations | part 1 | Relations and functions
Algebra 13 - Domain and Range of Binary Relations
Relation and Function
Class 12: Binary Operations
In mathematics, a function was originally the idealization of how a varying quantity depends on another quantity. For example, the position of a planet is a function of time. Historically, the concept was elaborated with the infinitesimal calculus at the end of the 17th century, and, until the 19th century, the functions that were considered were differentiable. The concept of function was formalized at the end of the 19th century in terms of set theory, and this greatly enlarged the domains of application of the concept.