Is there any solution to this kind of equation? Or any clue to explore it? - MathOverflow [closed] most recent 30 from http://mathoverflow.net 2013-05-21T06:32:58Z http://mathoverflow.net/feeds/question/99415 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/99415/is-there-any-solution-to-this-kind-of-equation-or-any-clue-to-explore-it Is there any solution to this kind of equation? Or any clue to explore it? Zou Fangyu 2012-06-13T08:59:09Z 2012-06-13T09:29:24Z <blockquote> <p><strong>Possible Duplicate:</strong><br> <a href="http://mathoverflow.net/questions/17605/how-to-solve-ffx-cosx" rel="nofollow">How to solve f(f(x)) = cos(x) ?</a> </p> </blockquote> <p>$f(f(x))=sin x$</p> http://mathoverflow.net/questions/99415/is-there-any-solution-to-this-kind-of-equation-or-any-clue-to-explore-it/99417#99417 Answer by 4v4l0n42 for Is there any solution to this kind of equation? Or any clue to explore it? 4v4l0n42 2012-06-13T09:21:21Z 2012-06-13T09:21:21Z <p>I don't know if this helps you, but you may write it also as:</p> <p>$f(f(x)) = \frac{1}{2} ie^{-i x}-\frac{1}{2} i e^{ix}$</p> http://mathoverflow.net/questions/99415/is-there-any-solution-to-this-kind-of-equation-or-any-clue-to-explore-it/99419#99419 Answer by Moustafa for Is there any solution to this kind of equation? Or any clue to explore it? Moustafa 2012-06-13T09:29:24Z 2012-06-13T09:29:24Z <p>Answered here <a href="http://mathoverflow.net/questions/17605/how-to-solve-ffx-cosx" rel="nofollow">http://mathoverflow.net/questions/17605/how-to-solve-ffx-cosx</a> Or even more general here <a href="http://mathoverflow.net/questions/17614/solving-ffxgx" rel="nofollow">http://mathoverflow.net/questions/17614/solving-ffxgx</a></p>