Руководство по PHP
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# log

(PHP 3, PHP 4, PHP 5)

log -- Natural logarithm

## Description

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`.

> Замечание: The `base` parameter became available with PHP 4.3.0.

> As always 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.

See also exp().

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log1p | Уровень выше | max