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 — Fija el parámetro de escala por defecto para todas las funciones matemáticas bc.
Descripción
bool bcscale
( int $escala
)
Esta función fija el parámetro de escala por defecto para las subsiguientes funciones matemáticas bc que no especifican dicho parámetro explícitamente. Devuelve TRUE si todo se llevó a cabo correctamente, FALSE en caso de fallo.
Example #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
?>
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
?>