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log
(PHP 4, PHP 5)
log — Natural logarithm
Описание
float log ( float $arg [, float $base ] )
If the optional base parameter is specified, log() returns logbase arg , otherwise log() returns the natural logarithm of arg .
Список параметров
- arg
-
The value to calculate the logarithm for
- base
-
The optional logarithmic base to use (defaults to 'e' and so to the natural logarithm).
Возвращаемые значения
The logarithm of arg to base , if given, or the natural logarithm.
Список изменений
| Версия | Описание |
|---|---|
| Since 4.3.0 | The optinal 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. |
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