\begin{definition}[Definition:Complex Number as Vector]
Let $z = x + i y$ be a complex number.
Then $z$ can be considered as a vector $OP$ in the complex plane such that:
: its initial point is the origin
: its terminal point $P$ is the point $\tuple {x, y}$.
Two vectors which have the same magnitude and direction, but different initial points, are considered '''equal'''.
\end{definition}