Monday, 17 October 2016

Example of real analytic function



We were taught real analytic functions in class today. I am playing around trying to construct examples. I see exponential, sine, cosine and logarithmic functions (for $x > 0$). One function I am having trouble with is $f(x) = \frac{1}{1 + e^x}$. In spirit, this function is like $e^{-x}$, so I want to say it is real analytic, but not totally sure. Any help, please?


Answer



To recall that the reciprocal of an analytic function with no zeros is analytic is one way. For an argument see Is the reciprocal of an analytic function analytic?


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