(PHP 4 >= 4.1.0, PHP 5)
expm1 — Returns exp(number) - 1, computed in a way that is accurate even when the value of number is close to zero
$arg
   )
   expm1() returns the equivalent to
   'exp(arg) -  1' computed in a way that is
   accurate even if the value of arg is near zero,
   a case where 'exp (arg) - 1' would be
   inaccurate due to subtraction of two numbers that are nearly equal.
  
argThe argument to process
   'e' to the power of arg minus one
  
| Version | Description | 
|---|---|
| 5.3.0 | This function is now available on all platforms |