# exponential

Who has not be amazed to learn that the function y = e^{x}, like a phoenix rising
again from its own ashes, is its own derivative? |

– Francois le Lionnais |

An exponential is anything that grows at a rate proportional to its size. The simplest form of the exponential function is just

*y*=

*e*

^{x}, where

*e*is about 2.712... The exponential function to base

*a*can be written as

*f*(

*x*) =

*a*

^{x}. See also exponent.