Determine conditions for $a,b>0$ such that $f(x)=\sum b^n\sin(a^nx)$ be continuous but nowhere differentiable in $\mathbb{R}$

was answered with a paper, but if you see the unanswered questions list is still there. Since answer is a comment.


You can either comment to Gerry Myerson, asking him to post the information in his comment as an answer, or post an answer with that information yourself (it is common, when doing the latter, to make the answer CW, since it is not your answer per se).

  • $\begingroup$ ty, now I replied him $\endgroup$ – Gaston Burrull Apr 2 '13 at 21:04
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    $\begingroup$ And I complied. $\endgroup$ – Gerry Myerson Apr 3 '13 at 12:48
  • $\begingroup$ The option to make the answer CW does not offend anyone, true? Or is it always better to ask first the person that answered (in the comments) to post the answer? $\endgroup$ – Alejandro Tolcachier Jan 15 '20 at 14:02

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