Definition:Signum Function/Natural Numbers

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

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

Also see

 * Signum Function on Natural Numbers as Characteristic Function