Definition:Trigamma Function

Definition

The trigamma function, $\psi_1$, is defined, for $z \in \C \setminus \Z_{\le 0}$, to be the $1$st derivative of the digamma function:

$\map {\psi_1} z = \dfrac {\d} {\d z} \map \psi z$

where $\psi$ is the digamma function.

Also see

• Results about the trigamma function can be found here.

Sources

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