Definition:Square/Function/Definition 2

Definition
Let $\F$ denote one of the standard classes of numbers: $\N$, $\Z$, $\Q$, $\R$, $\C$.

The square (function) on $\F$ is the mapping $f: \F \to \F$ defined as:
 * $\forall x \in \F: \map f x = x^2$

where $x^2$ denotes the $2$nd power of $x$.

Also see

 * Equivalence of Definitions of Square Function