bcscale

(PHP 4, PHP 5)

bcscale — すべての BC 演算関数におけるデフォルトのスケールを設定する

説明

bool bcscale ( int $scale )

デフォルトのスケールを設定します。これ以降、 BC 演算関数で明示的にスケールを指定しなかった場合にこの値を使用します。

パラメータ

scale: スケール。

返り値

成功した場合に TRUE を、失敗した場合に FALSE を返します。

例

例1 bcscale() の例


<?php

// デフォルトのスケールを 3 とします
bcscale(3);
echo bcdiv('105', '6.55957'); // 16.007

// これは、bcscale() を使用せずにおなじ結果を得ます
echo bcdiv('105', '6.55957', 3); // 16.007

?>

bcsqrt

bcpowmod

[edit] Last updated: Fri, 25 May 2012

add a note User Contributed Notes bcscale

ravenswd at gmail dot com 30-Apr-2012 12:43


Simple, easy way to remove excess trailing zeros using rtrim:

<php>

  // $total is the result of a bcmath calculation

  if ( strpos($total, '.') !== false ):

    $total = rtrim($total, '0');

    $total = rtrim($total, '.');

  endif;

</php>

rastislav dot bostik at bwd21 dot cz 25-Jan-2012 07:20


Previously stated one liner trailing 0 removing using rtrim() works fine except following class of subcases:



<?php 

echo rtrim('100.0000', '0.'); // 1 instead 100

echo rtrim('1230.00000000', '0.'); // 123 instead 1230

?>



What seems to be working to me is using regular expression replacement. Althought it`s probably not that fast as rtrim(), I hope it should be more reliable:



<?php 

function removeFloatNumStringZeroTrailer($input) {

    $patterns = array('/[\.][0]+$/','/([\.][0-9]*[1-9])([0]*)$/');

    $replaces = array('','$1');

    return preg_replace($patterns,$replaces,$input);

}



echo removeFloatNumStringZeroTrailer('100.0000'); // says 100

echo removeFloatNumStringZeroTrailer('1230.00000000'); // says 1230

?>

dcz at phpbb-seo dot com 25-Mar-2011 01:05


The general approach for a one liner trailing 0 removing would be :


<?php


echo rtrim('1.2500000000', '0.'); // 1.25


echo rtrim('1.00000000', '0.'); // 1


?>





Which seems totally appropriate since we are working with strings, and also is likely to be the fastest way.

Nitrogen 25-Jan-2009 02:00


Good day,

I made a little function to remove the excess zeroes after calculations.. it makes them cleaner and more presentable.



<?php



function DecimalClean($Input) {

  $Input=explode('.',$Input,2);

  if(!isset($Input[1])) $Input[1]=0;

  for($i=(strlen($Input[1])-1);$i>0;$i--) {

    if($Input[1]{$i}=='0')

      $Input[1]=substr($Input[1],0,-1);

    else break;

  }

  return(sprintf('%s%s',$Input[0],($Input[1]!='0')?".{$Input[1]}":''));

}



BCScale(10); // allow 10 decimals

$Sum = BCDiv(10,8); // make a calculation



printf("Result #1: %s\n", $Sum);

// 1.2500000000



printf("Result #2: %s\n", DecimalClean($Sum));

// 1.25



?>



Hope this helps,

Nitrogen.

mwgamera at gmail dot com 05-Dec-2007 11:45


These functions DO NOT round off your values. No arbitrary precision libraries do it this way. It stops calculating after reaching scale of decimal places, which mean that your value is cut off after scale number of digits, not rounded. To do the rounding use something like this:

<?php

        function bcround($number, $scale=0) {

                $fix = "5";

                for ($i=0;$i<$scale;$i++) $fix="0$fix";

                $number = bcadd($number, "0.$fix", $scale+1);

                return    bcdiv($number, "1.0",    $scale);

        }

?>

invincible at limitedintelligence dot com 07-Feb-2006 08:50


If you don't set the default scale, be careful when you're chaining together several BC math functions - since by default, these functions will round off your values, losing accuracy very quickly:



<?php

$a = 1.234

$b = 2.345

$c = 7.890



$ab = bcmul($a,$b);           // 2

$abc = bcmul($ab,$c);



echo $abc;                 // 15

?>



... compare with the answer you get when you use more decimal places:



<?php

$a = 1.234

$b = 2.345

$c = 7.890



bcscale(15);

$ab = bcmul($a,$b);           // 2.893730

$abc = bcmul($ab,$c);



echo $abc;                 // 22.83152970

?>

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