The space of continuously differentiable functions is denoted 
, and corresponds to the 
case of a C-k function.
Continuously Differentiable Function
See also
C-k Function, Continuous FunctionExplore with Wolfram|Alpha
References
Krantz, S. G. "Continuously Differential and
Functions" and "Differentiable and 
Curves." §1.3.1 and 2.1.3 in Handbook
of Complex Variables. Boston, MA: Birkhäuser, pp. 12-13 and 21,
1999.Referenced on Wolfram|Alpha
Continuously Differentiable FunctionCite this as:
Weisstein, Eric W. "Continuously Differentiable Function." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ContinuouslyDifferentiableFunction.html