bround.inc.php

<?php
/*
	Banker's Rounding v1.01, 2006-08-15
	Copyright 2006 Michael Boone
	[email protected] (remove the X)
	http://boonedocks.net/

	Provided under the GNU General Public License
	Contact me for use outside the bounds of that license

	---------------------------------------------------------------	
	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.
	
	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	The GNU General Public License can be found at:
	http://www.gnu.org/copyleft/gpl.html
	---------------------------------------------------------------	

	Release History:
	2006-01-05: v1.00: Initial Release
	2006-08-15: v1.01: Updated with faster even/odd test
	
*/

function bround($dVal,$iDec) {
	// banker's style rounding or round-half-even
	// (round down when even number is left of 5, otherwise round up)
	// $dVal is value to round
	// $iDec specifies number of decimal places to retain
	static $dFuzz=0.00001; // to deal with floating-point precision loss
	$iRoundup=0; // amount to round up by
	
	$iSign=($dVal!=0.0) ? intval($dVal/abs($dVal)) : 1;
	$dVal=abs($dVal);

	// get decimal digit in question and amount to right of it as a fraction
	$dWorking=$dVal*pow(10.0,$iDec+1)-floor($dVal*pow(10.0,$iDec))*10.0;
	$iEvenOddDigit=floor($dVal*pow(10.0,$iDec))-floor($dVal*pow(10.0,$iDec-1))*10.0;

	if (abs($dWorking-5.0)<$dFuzz) $iRoundup=($iEvenOddDigit & 1) ? 1 : 0;
	else $iRoundup=($dWorking>5.0) ? 1 : 0;

	return $iSign*((floor($dVal*pow(10.0,$iDec))+$iRoundup)/pow(10.0,$iDec));
}

?>