$log
From Scriptwiki
Returns the natural (base e (approximately 2.71828183)) logarithm of a given number.
$log(N)
- N is any number great than 0 (as imaginary numbers are not considered in mIRC)
Example
$calc(2.71828183^ $log(10)) = 9.9999999 (10)
$calc(($log(100) / $log(10))) = 2 (Essentially log base 10 of 100)