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

exp
floor
Math Functions
PHP Manual

# expm1

(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

### Description

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.

### Parameters

`arg`

  The argument to process

### Return Values

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

### Changelog

Version | Description
--- | ---
5.3.0 | This function is now available on all platforms

### See Also

- log1p() - Returns log(1 + number), computed in a way that is accurate even when the value of number is close to zero
- exp() - Calculates the exponent of e

exp
floor
Math Functions
PHP Manual