bcscale

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

bcscaleConfigura ou obtêm o parâmetro escala para todas as funções bc

Descrição

bcscale(int $scale): int

Configura o parâmetro de escala padrão para todas as chamadas subsequentes às funções bcmath que não tenham o parâmatro escala informado explicitamente.

bcscale(null $scale = null): int

Retorna o valor de escala atual.

Parâmetros

scale

O fator de escala.

Valor Retornado

Retorna o valor de escala antigo quando configurando um novo, senão retorna o valor atual.

Changelog

Versão Descrição
8.0.0 scale agora pode ser null.
7.3.0 bcscale() pode ser utilizado para obter o falor de escala atual, quando utilizado para configurar. Anteriormente, scale era obrigatório, e bcscale() sempre retornava true.

Exemplos

Exemplo #1 Exemplo da bcscale()

<?php

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

// Obtém o mesmo resultado sem bcscale()
echo bcdiv('105', '6.55957', 3); // 16.007

?>

add a note

User Contributed Notes 8 notes

up
20
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);
}
?>
up
13
sicerwork at aliyun dot com
6 years ago
Executing bcsacle() will change the scale value of fpm.conf, not only the current process.
up
4
ravenswd at gmail dot com
11 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>
up
4
herslyadam at gmail dot com
9 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);
}
?>
up
-1
nemesarial at gmail dot com
8 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

?>
up
-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
?>
up
-1
yan dot uniko dot 102 at gmail dot com
3 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 ??
up
-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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