Definition:Positive/Real Number

Definition
The positive real numbers are the set:
 * $\R_{\ge 0} = \set {x \in \R: x \ge 0}$

That is, all the real numbers that are greater than or equal to zero.

Thus, in Wirth interval notation:
 * $\R_{\ge 0} = \hointr 0 \to$

Also known as
In order to remove all confusion as to whether positive real number is intended to mean strictly positive real number, the use of the term non-negative real number is often recommended instead.

The -specific notation $\R_{\ge 0}$ is actually non-standard. The conventional symbols to denote this concept are $\R_+$ and $\R^+$, but these can be confused with the set $\set {x \in \R: x > 0}$.