Abstract
We study various real-variable techniques for determining whether a function is differentiable without actually calculating a derivative. These include:
approximation theory \item Fourier analysis
Sobolev spaces \item Poisson integral
finite differences
Campanato-Morrey theory
Landau's inequalities
Citation
Steven G. Krantz. "Verifying Differentiability Without Calculating the Derivative." Real Anal. Exchange 44 (2) 403 - 426, 2019. https://doi.org/10.14321/realanalexch.44.2.0403
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