bcpowmod
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);
}
?>
bcscale
(PHP 4, PHP 5)
bcscale — Configura o parâmentro escala para todas as funções bc
Descrição
bool bcscale
( int $escala
)
Configura o parâmetro escala padrão para todas as chamadas subsequentes às funções bcmath que não tenham o parâmatro escala informado explicitamente.
Parâmetros
- scale
-
A escala do fator.
Valor Retornado
Retorna TRUE em caso de sucesso ou FALSE em falhas.
Exemplos
Exemplo #1 Exemplo da bcscale()
<?php
// escala default: 3
bcscale(3);
echo bcdiv('105', '6.55957'); // 16.007
// this is the same without bcscale()
echo bcdiv('105', '6.55957', 3); // 16.007
?>
add a note
User Contributed Notesbcscale
mwgamera at gmail dot com
06-Dec-2007 03:45
06-Dec-2007 03:45
invincible at limitedintelligence dot com
08-Feb-2006 12:50
08-Feb-2006 12:50
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
?>