Definition:Signum Function/Natural Numbers

Definition
The signum function $\operatorname{sgn}: \N \to \left\{ {0, 1}\right\}$ is the restriction of the signum function to the natural numbers, defined as:
 * $\forall n \in \N: \operatorname{sgn} \left({n}\right) = \begin{cases}

0 & : n = 0 \\ 1 & : n > 0 \end{cases}$

Also see

 * Signum Function on Natural Numbers as Characteristic Function