Definition:Laurent Series

Let $$f: \C \to \C \ $$ be a function and $$z_0 \in U \subset \C \ $$ such that $$f \ $$ is analytic in $$U - \left\{{z_0}\right\} \ $$.

A Laurent series is a sum:
 * $$\sum_{j=-\infty}^\infty a_j (z-z_0)^j \ $$

such that the sum converges to $$f \ $$ in $$U - \left\{{z_0}\right\} \ $$.