Is there a real function that is differentiable at any point but nowhere monotone?
Differentiable+Not monotone
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real-analysis
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0And see [here](http://math.stackexchange.com/a/802647/462) for details of the Katznelson-Stromberg construction. – 2014-05-21
1 Answers
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Yes. See for example "Everywhere Differentiable, Nowhere Monotone, Functions" by Y. Katznelson and Karl Stromberg.
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0The link above seems broken as well. Anyway, details have been posted [here](http://math.stackexchange.com/a/802647/462). – 2014-05-21