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log

PHP function Edit on GitHub ✎

(PHP 4, PHP 5, PHP 7, PHP 8)

Natural logarithm

Description

log(float $num, float $base = M_E): float

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

num: 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 num to base, if given, or the natural logarithm.

Throws a ValueError if base is less than or equal to 0.

Version	Description
8.0.0	Now throws a `ValueError` if `base` is less than or equal to `0`. Previously, an `E_WARNING` was raised and false was returned.