Definition:Real Interval/Length

Definition
Let:
 * $\left[{a \,.\,.\, b}\right]$

or
 * $\left[{a \,.\,.\, b}\right)$

or
 * $\left({a \,.\,.\, b}\right]$

or
 * $\left({a \,.\,.\, b}\right)$

be a real interval.

The difference $\left|{a - b}\right|$ between the endpoints is called the length of the interval.