PHP: bcpow - Manual

bcpow

Robert Lozyniak
03-May-2006 09:13


I hate every living thing that ever lived, except for Ms. A.Sh.O. and maybe also Ms. C.D.F. I hate the person who posted the silly joke below my post, and I hate myself immeasurably more.



That having been said:



This function takes arbitrary integers as exponents:



<?php



function bcpowislame($base,$exp,$scale) {

// I take arbitrary integers as exponents

// Remember, I take ONLY integers as exponents!

// bcpow is lame; I am a substitute

$wexp=bcadd($exp,'0',0);

if (bccomp($exp,$wexp)) return false;

$wbase=$base; $wscale=$scale+strlen($wexp)+3; // the 3 is arbitrary

if ($wexp{0}=='-')

  {$wbase=bcdiv('1',$wbase,$wscale); $wexp=bcsub('0',$wexp,0);}

if ($wexp=='0') return bcadd('1','0',$scale);

$scr='1'; $scrm=$wbase; $loop=true;

while ($loop) {

if (bcmod($wexp,'2')=='1') $scr=bcmul($scr,$scrm,$wscale);

if (bccomp($wexp,'1')==0) $loop=false;

else {$scrm=bcmul($scrm,$scrm,$wscale); $wexp=bcdiv($wexp,'2',0);}}

return bcadd('0',$scr,$scale); }



?>



I also hate my interpreter for not letting this work on negative exponents.

This seems to work great on positive exponents though.

11-Feb-2005 01:58


Well, if bcpow has limits, then this should work:

<?php

function bcpow_($num, $power) {

    $awnser = "1";

    while ($power) {

        $awnser = bcmul($awnser, $num, 100);

        $power = bcsub($power, "1");

    }

    return rtrim($awnser, '0.');

}

?>

Just that $power cannot have decimal digits in it.

Michael Bailey (jinxidoru at byu dot net)
09-Aug-2004 05:42


bcpow() only supports exponents less than or equal to 2^31-1.  Also, bcpow() does not support decimal numbers.  If you have scale set to 0, then the exponent is converted to an interger; otherwise an error is generated.



--

Michael Bailey

http://www.jinxidoru.com

bcpow

Description

Примеры

Смотрите также