Definition:Inverse Cotangent/Real

Definition
Let $x \in \R$ be a real number such that $-1 \le x \le 1$.

The inverse cotangent of $x$ is the multifunction defined as:
 * $\cot^{-1} \left({x}\right) := \left\{{y \in \R: \cot \left({y}\right) = x}\right\}$

where $\cot\left({y}\right)$ is the cotangent of $y$.