Definition:Exponential Function

Definition
The exponential function is denoted $\exp$ and can be defined in several ways, as described below.

Notation
The exponential of $x$, $\exp x$, is frequently written as $e^x$. The consistency of this power notation is demonstrated in $\exp x$ equals $e^x$.

Also see

 * Equivalence of Definitions of Complex Exponential Function
 * Properties of Exponential Function
 * Properties of Complex Exponential Function