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

Popis

float expm1 ( float $arg )

Warning

Táto funkcia je EXPERIMENTÁLNA. Správanie tejto funkcie, názov tejto funkcie a hocičo iné zdokumentované o tejto funkcii sa môže zmeniť bez povšimnutia v budúcom vydaní PHP. Používajte túto funkcii na svoje vlastné riziko.

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: Táto funkcia nie je implementovaná na platformách Windows.

Parametre

arg: The argument to process

Vrátené hodnoty

'e' to the power of arg minus one

Tiež pozri

add a note User Contributed Notes
expm1

hagen at von-eitzen dot de
24-Feb-2003 03:57


Compare this to log1p (which is its inverse).



Also, You may have to use a similar workaraound in case the underlying C library

does not support expm1:



function expm1($x) {

     return ($x>-1.0e-6 && $x<1.0e-6) ? ($x + $x*$x/2) : (exp($x)-1);

}

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floor

exp

Last updated: Sun, 25 Nov 2007