# expm1

(PHP 4 >= 4.0.7, PHP 5)

expm1 — Returns exp(number) - 1, computed in a way that is accurate even when the value of number is close to zero

### Description

float expm1 ( float `$arg` )
Warning

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(`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.

> Note: This function is not implemented on Windows platforms.

### Parameters

`arg`

  The argument to process

### Return Values

'e' to the power of `arg` minus one

### See Also

- log1p()
- exp()