( 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.
expm1() returns the equivalent to
'exp(number) - 1' computed in a way that is
accurate even if the value of number is near zero,
a case where 'exp (number) - 1' would be
inaccurate due to subtraction of two numbers that are nearly equal.
Note: This function is not
implemented on Windows platforms.
See also log1p() and