Definition:Root of Unity/Complex/Primitive

Definition
Let $n \in \Z_{>0}$ be a (strictly) positive integer.

Let $U_n$ denote the complex $n$th roots of unity:
 * $U_n = \left\{ {z \in \C: z^n = 1}\right\}$

A primitive (complex) $n$th root of unity is an element $\omega \in U_n$ such that:


 * $U_n = \left\{ {1, \omega, \ldots, \omega^{n - 1} }\right\}$

Equivalently, an $n$th root of unity is primitive iff its order is $n$.