Log

Log[z] gives the natural logarithm of z (logarithm to base e).

Log[b, z] gives the logarithm to base b.

Examples

Natural logarithm:

Log[E]
(* 1 *)

Log[E^2]
(* 2 *)

Logarithm with a base:

Log[10, 1000]
(* 3 *)

Please visit the official Wolfram Language Reference for more details.