# Natural logarithm

From ACT Wiki

1. *Options analysis*.

The natural logarithm *ln(x)* is the logarithm to the base ‘e’, and mathematically the inverse function of the exponential function *e ^{x}*.

So for example ln(100) = 4.60517...

And e^{4.60517...} = 100

Also known for short as the 'natural log'.

Also sometimes known - loosely - as the 'Napierian logarithm'.

(Not to be confused with Lognormal, which is different.)

2. *Maths*.

The natural log - as used in options analysis above - is exactly the same as the concept used more broadly in maths and financial maths applications.