Definition:Differentiable Mapping/Vector-Valued Function

From ProofWiki
Jump to navigation Jump to search

Definition

Let $m, n \ge 1$ be natural numbers.

At a Point

$f$ is differentiable at $x \in \R^n$ if and only if there exists a linear transformation $T: \R^n \to \R^m$ and a mapping $r : U \to \R^m$ such that:

$(1): \quad \map f {x + h} = \map f x + \map T h + \map r h \cdot \norm h$
$(2): \quad \ds \lim_{h \mathop \to 0} \map r h = 0$


In an Open Set

Let $S \subseteq \mathbb X$.


Then $f$ is differentiable in the open set $S$ if and only if $f$ is differentiable at each $x$ in $S$.


This can be denoted $f \in \map {\CC^1} {S, \R^m}$.


Sources