# Definition:Positive Real Function

## Definition

Let $I$ be a real interval.

Let $f$ be a real function.

Then $f$ is positive (on $I$) if and only if:

$\forall x \in I: f \left({x}\right) \ge 0$

## Also known as

A positive real function is also described as non-negative in order to avoid confusing with a strictly positive real function.