bcscale

(PHP 4, PHP 5, PHP 7, PHP 8)

bcscale — Establece los parametros de scale por defecto para todas las funciones matemáticas de bc

Descripción

bcscale(int $scale): bool

Establece los parametros de scale para todas las subsiguientes llamadas a funciones matemáticas bc, donde no se especifica el parametro de scale.

Parámetros

scale: El factor scale.

Valores devueltos

Devuelve true en caso de éxito o false en caso de error.

Ejemplos

Ejemplo #1 Ejemplo bcscale()


<?php

// default scale : 3
bcscale(3);
echo bcdiv('105', '6.55957'); // 16.007

// this is the same without bcscale()
echo bcdiv('105', '6.55957', 3); // 16.007

?>

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User Contributed Notes 8 notes

down

mwgamera at gmail dot com ¶

15 years ago


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);
        }
?>

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sicerwork at aliyun dot com ¶

6 years ago


Executing bcsacle() will change the scale value of fpm.conf, not only the current process.

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ravenswd at gmail dot com ¶

10 years ago


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>

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herslyadam at gmail dot com ¶

8 years ago


edited bcround function with negative number support:
<?php
function bcround($number, $scale=0) {
    if($scale < 0) $scale = 0;
    $sign = '';
    if(bccomp('0', $number, 64) == 1) $sign = '-';
    $increment = $sign . '0.' . str_repeat('0', $scale) . '5';
    $number = bcadd($number, $increment, $scale+1);
    return bcadd($number, '0', $scale);
}
?>

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-1

nemesarial at gmail dot com ¶

7 years ago


To remove trailing zeros when using large bcscale number can be done by casting to float when ready to display the number.

<?php
bcscale(15);
$a=123.456;
$b=0.123;

$_ab=bcadd($a,$b);
echo $_ab;
// 123.579000000000000

$ab = (float)$_ab;
echo $ab;
// 123.579

?>

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-2

invincible at limitedintelligence dot com ¶

17 years ago


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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-1

yan dot uniko dot 102 at gmail dot com ¶

2 years ago


Does not work with big scale values, but accept INT as type, but can not process the max INT value, by example for calculate the cube root:

<?php

echo pow(1331, 1/3); // 11 (11^3=1331)
echo bcpow(1331, bcdiv(1, 3, PHP_INT_MAX)); // 1 ??
echo bcdiv(1, 3, PHP_INT_MAX); // 0 ??

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-6

rastislav dot bostik at bwd21 dot cz ¶

11 years ago


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
?>

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