Definition:Periodic Real Function/Frequency

Definition
Let $f: \R \to \R$ be a periodic real function.

The frequency $\nu$ of $f$ is the reciprocal of the period $L$ of $f$:
 * $\nu = \dfrac 1 L$

where:
 * $\forall x \in X: \map f x = \map f {x + L}$

where $\size L$ is the modulus of $L$.

Also defined as
In some contexts, the frequency of a periodic real function is given by the letter $f$, but as this letter is also used for the general function, this can be seen often to be inadequate.