Jensen's Formula

$\begin{displaymath} \int_0^{2\pi} \ln\vert z+e^{i\theta}\vert\,d\theta=2\pi\ln^+\vert z\vert, \end{displaymath}$

where

$\begin{displaymath} \ln^+\equiv \max(0, \ln x) \end{displaymath}$

and $\ln x$ is the Natural Logarithm.