The expm1() function returns exp(x) - 1.
float expm1 ( float $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.
| Parameter | Description |
|---|---|
| arg | The argument to process. |
'e' to the power of arg minus one