A function
is Carathéodory differentiable at
if there exists a function
which is continuous
at
such that
Every function which is Carathéodory differentiable is also Fréchet differentiable.
A function
is Carathéodory differentiable at
if there exists a function
which is continuous
at
such that
Every function which is Carathéodory differentiable is also Fréchet differentiable.
Weisstein, Eric W. "Carathéodory Derivative." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/CaratheodoryDerivative.html