Definition:Weight Function

Definition
A weight function on a set $S$ is a mapping from $S$ to the real numbers:
 * $w: S \to \R$

It is common for the requirements of a specific application under discussion for the codomain of $w$ to be restricted to the positive reals:
 * $w: S \to \R_{\ge 0}$

The thing that determines whether a given mapping is a weight function depends more on how it is used.

Also see

 * Definition:Normalized Weight Function


 * Definition:Weighted Mean


 * Definition:Weighted Graph, the application of a weight function to the edges of a graph.