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

# expm1

(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)

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

### Description

expm1(float `$num`): float

expm1() returns the equivalent to `exp($`num`) - 1` computed in a way that is accurate even if the value of `num` is near zero, a case where `exp($`num`) - 1` would be inaccurate due to subtraction of two numbers that are nearly equal.

### Parameters

`num`

  The argument to process

### Return Values

`e` to the power of `num`, minus one.

### 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

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