Weight function

A weight function is a mathematical device used when performing a sum, integral, or average to give some elements more "weight" or influence on the result than other elements in the same set. The result of this application of a weight function is a weighted sum or weighted average. Weight functions occur frequently in statistics and analysis, and are closely related to the concept of a measure. Weight functions can be employed in both discrete and continuous settings. They can be used to construct systems of calculus called "weighted calculus" and "meta-calculus".

Discrete weights

General definition

In the discrete setting, a weight function is a positive function defined on a discrete set , which is typically finite or countable. The weight function corresponds to the unweighted situation in which all elements have equal weight. One can then apply this weight to various concepts.

If the function is a real-valued function, then the unweighted sum of on is defined as