# Definition:Odd Function

## Definition

Let $X \subset \R$ be a symmetric set of real numbers:

$\forall x \in X: -x \in X$

A real function $f: X \to \R$ is an odd function if and only if:

$\forall x \in X: f \left({-x}\right) = -f \left({x}\right)$

## Also see

• Results about odd functions can be found here.