Trigamma function
= Trigamma function
{wiki}
The trigamma function is $\psi'(z)$. For real $z>0$,
$$
\psi'(z)=\frac1{z^2}+\sum_{k=1}^{\infty}\frac1{(z+k)^2}>0.
$$
= Trigamma function
{wiki}
The trigamma function is $\psi'(z)$. For real $z>0$,
$$
\psi'(z)=\frac1{z^2}+\sum_{k=1}^{\infty}\frac1{(z+k)^2}>0.
$$