Sei

${\displaystyle G\colon \mathbb {R} ^{n}\longrightarrow \mathbb {R} ^{n}}$

ein Gradientenfeld und sei

${\displaystyle \varphi \colon J\longrightarrow \mathbb {R} ^{n}}$

(${\displaystyle {}J\subseteq \mathbb {R} }$ ein offenes Intervall)

${\displaystyle {}v'=G(v)}$

${\displaystyle {}\varphi '(t)\neq 0}$

${\displaystyle {}t\in J}$

${\displaystyle {}\varphi }$