\begin{definition}[Definition:Schwarz Function]
Let $f: \R \to \C$ be a function.
$f$ is a '''Schwarz function''' {{iff}}:
:$\forall c \in \R, n \in \N_0: \size {\map {f^{\paren n} } x} = \map o {\size x^c}$
where:
:$f^{\paren n}$ denotes the $n$th derivative
:$o$ is the little-o notation.
\end{definition}