i'm study meromorphic function at the complex plane extended, but i have a trouble. I know if $ f \colon D \subseteq \mathbb{C} \to \mathbb{C} $ $f$ is meromorphic on D if the singularities of $f$ are poles in $D$ But whats mean $f$ is meromorphic at a point $a \in \mathbb {C}$?
Other quickly question, anyone knows why $\infty$ is branched point of $log(z) $?
Thanks