bcscale

(PHP 4, PHP 5)

bcscale Imposta il valore di precisione di default per tutte le funzioni matematich BCMath

Descrizione

bool bcscale ( int $precisione )

Questa funzione imposta il valore di default del parametro precisione per tutte le funzioni BCMath susseguenti, che non specifichino esplicitamente un parametro di precisione numerica. Restituisce TRUE in caso di successo, FALSE in caso di fallimento.

Esempi

Example #1 esempio di bcscale()

<?php

// precisione di default : 3
bcscale(3);
echo 
bcdiv(1056.55957); // 16.007

// la stessa cosa, senza utilizzare bcscale()
echo bcdiv(1056.559573); // 16.007

?>
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User Contributed Notes 5 notes

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7
mwgamera at gmail dot com
6 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",    $scale);
        }
?>
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0
herslyadam at gmail dot com
16 days ago
edited bcround function with negative number support:
<?php
function bcround($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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0
ravenswd at gmail dot com
1 year 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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0
rastislav dot bostik at bwd21 dot cz
2 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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0
invincible at limitedintelligence dot com
8 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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