log
(PHP 3, PHP 4 )
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.
Note: 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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