Definition:Digamma Function

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The digamma function, $\psi$, is defined, for $z \in \C \setminus \Z_{\le 0}$, by the logarithmic derivative of the gamma function:

$\map \psi z = \dfrac {\map {\Gamma'} z} {\map \Gamma z}$

where $\Gamma$ is the gamma function, and $\Gamma'$ denotes its derivative.

Also known as

The digamma function is also known as the psi function.

Also see

  • Results about the digamma function can be found here.