(PHP 4, PHP 5)
log — Natural logarithm
If the optional base parameter is specified, log() returns logbase arg , otherwise log() returns the natural logarithm of arg .
The value to calculate the logarithm for
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 |
|---|---|
| Since 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. |