( float number )
This function is
EXPERIMENTAL. The behaviour of this function, the
name of this function, and anything else documented about this
function may change without notice in a future release of PHP.
Use this function at your own risk.
log1p() returns log(1 +
number) computed in a way that is accurante even
when the value of number is close to zero.
Note: This function is not
implemented on Windows platforms.
See also expm1() and