# Gauss's Integral Form of Digamma Function

## Theorem

Let $z$ be a complex number with a positive real part, then:

$\displaystyle \psi \left({z}\right) = \int_0^\infty \left({\frac{ e^{-t} } t - \frac {e^{-zt } } {1 - e^{-t} } }\right) \rd t$

where $\psi$ is the digamma function.

## Source of Name

This entry was named for Carl Friedrich Gauss.