\begin{definition}[Definition:Series/Complex]
Let $\sequence {a_n}$ be a sequence in $\C$.
A '''complex series''' $S_n$ is the limit to infinity of the sequence of partial sums of a complex sequence $\sequence {a_n}$:
{{begin-eqn}}
{{eqn | l = S_n
      | r = \lim_{N \mathop \to \infty} \sum_{n \mathop = 1}^N a_n
      | c = 
}}
{{eqn | r = \sum_{n \mathop = 1}^\infty a_n
      | c = 
}}
{{eqn | r = a_1 + a_2 + a_3 + \cdots
      | c = 
}}
{{end-eqn}}
\end{definition}