Definition:Polygamma Function

Definition

The $n$th polygamma function $\psi_n$ is defined as the $n$th derivative of the digamma function:

$\map {\psi_n} z = \dfrac {\d^n} {\d z^n} \map \psi z$

for $z \in \C \setminus \Z_{\le 0}$.

Also see

• Results about the polygamma function can be found here.

Sources

• Weisstein, Eric W. "Polygamma Function." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/PolygammaFunction.html