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2 votes
1 answer
164 views

Another weird limit involving gamma and digamma function via continued fraction

Context : I want to find a closed form to : $$\lim_{x\to 0}\left(\frac{f(x)}{f(0)}\right)^{\frac{1}{x}}=L,f(x)=\left(\frac{1}{1+x}\right)!×\left(\frac{1}{1+\frac{1}{1+x}}\right)!\cdots$$ Some ...
Ranger-of-trente-deux-glands's user avatar
5 votes
3 answers
650 views

Alternative approaches to showing that $\Gamma'(1/2)=-\sqrt\pi\left(\gamma+\log(4)\right)$

Starting from the definition of the Gamma function as expressed by $$\Gamma(z)=\int_0^\infty x^{z-1}e^{-x}\,dx\tag1$$ we can show that the derivative of $\Gamma(z)$ evaluated at $z=1/2$ is given by $$\...
Mark Viola's user avatar
  • 181k
4 votes
2 answers
394 views

On a log-gamma definite integral

A very famous log-gamma integral due to Raabe is $$\int_0^1 \log \Gamma (x) \, dx = \frac{1}{2} \log (2\pi).$$ Several proofs of this result can be found here. I would like to know about the ...
omegadot's user avatar
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