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

Returns exp(number) - 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)

expm1Returns 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

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