log

(PHP 4, PHP 5, PHP 7)

log — Natural logarithm

float log ( float $arg [, float $base = M_E ] )

If the optional base parameter is specified, log() returns log_base arg, otherwise log() returns the natural logarithm of arg.

arg: The value to calculate the logarithm for
base: The optional logarithmic base to use (defaults to 'e' and so to the natural logarithm).

The logarithm of arg to base, if given, or the natural logarithm.