(PHP 4, PHP 5)
log — Natural logarithm
$arg
[, float $base
= M_E ] ) If the optional base
parameter is specified, log() returns logbase 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.
Version | Description |
---|---|
4.3.0 | The optional parameter base became available. For older versions you can calculate the logarithm in base b of a number n, but using the mathematical identity: logb(n) = log(n)/log(b), where log is the neperian (or natural) logarithm. |