Symbols:C

Roman Numeral

 * $\mathrm C$ or $\mathrm c$

The Roman numeral for $100$.

Set of Complex Numbers

 * $\C$

The set of complex numbers.

Set of Non-Zero Complex Numbers

 * $\C_{\ne 0}$

The set of non-zero complex numbers:
 * $\C_{\ne 0} = \C \setminus \left\{{0}\right\}$

Deprecated

 * $\C^*$

The set of non-zero complex numbers:
 * $\C^* = \C \setminus \left\{{0}\right\}$

Relative Complement

 * $\relcomp S T$ or $\map {\mathcal C_S} T$

Set Complement

 * $\map \complement S$ or $\map {\mathcal C} S$