ENCYCLOPEDIA 4U .com

# Encyclopedia Home Page

 Web Encyclopedia4u.com

# Function domain

In mathematics, a function domain is a description of the possible input values to a function.

Given a function fA → B, the set A is called the domain, or domain of definition of f.

The set of all values in the codomain that f maps to is called the range of f, or f(A).

A well-defined function must map every element of the domain to an element of its codomain. So, for example, the function:

f: x → 1/x

has no valid value for f(0). It is thus not a function on the set R of real numbers; R can't be its domain. It is usually either defined as a function on R \\ {0}, or the "gap" is plugged by specifically defining f(0); for example:

f: x → 1/x , x ≠ 0
f: 0 → 0

The domain of given function can be restricted to a subset. Suppose that gA → B, and S ⊆ A. Then the restriction of g to S is written:

g|S: SB

Content on this web site is provided for informational purposes only. We accept no responsibility for any loss, injury or inconvenience sustained by any person resulting from information published on this site. We encourage you to verify any critical information with the relevant authorities.

Copyright © 2005 Par Web Solutions All Rights reserved.
| Privacy

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Function domain".