bccomp
If you don't have bcmath installed and you need to use bcdiv() with a defined precision / scale you may need this function:
if( !function_exists( "bcdiv" ) )
{
function bcdiv( $first, $second, $scale = 0 )
{
$res = $first / $second;
return round( $res, $scale );
}
}
bcdiv
(PHP 4, PHP 5)
bcdiv — Divide two arbitrary precision numbers
Описание
string bcdiv
( string $left_operand
, string $right_operand
[, int $scale
] )
Divides the left_operand by the right_operand .
Список параметров
- left_operand
-
The left operand, as a string.
- right_operand
-
The right operand, as a string.
- scale
-
This optional parameter is used to set the number of digits after the decimal place in the result. You can also set the global default scale for all functions by using bcscale().
Возвращаемые значения
Returns the result of the division as a string, or NULL if right_operand is 0.
Примеры
Пример #1 bcdiv() example
<?php
echo bcdiv('105', '6.55957', 3); // 16.007
?>
add a note
User Contributed Notesbcdiv
no at answer dot com
05-Jul-2008 01:06
05-Jul-2008 01:06
MM
18-Jan-2008 03:29
18-Jan-2008 03:29
Perhaps some one can find useful this function to compute the modular inverse of a integer (extended euclidean algorithm):
function invmod($a,$b) {
$n=$b;
$x=0; $lx=1; $y=1; $ly=0;
while ($b) {
$t=$b;
$q=bcdiv($a,$b,0);
$b=bcmod($a,$b);
$a=$t;
$t=$x; $x=bcsub($lx,bcmod(bcmul($q,$x),$n)); $lx=$t;
$t=$y; $y=bcsub($ly,bcmod(bcmul($q,$y),$n)); $ly=$t;
}
if (bccomp($lx,0) == -1)
$lx=bcadd($lx,$n);
return $lx;
}
// verify
$n="2447995268898324993537772139997802321";
$t="64941057316178801556773346239351236811";
$m="123456789";
$i=invmod($t,$n);
// (t*m)*inv(t) is m
echo bcmod(bcmul(bcmod(bcmul($t,$m),$n),$i),$n) == $m;
Gautam
29-Aug-2007 07:56
29-Aug-2007 07:56
<?php
//converting in to required precision of decimal points
$result= bcdiv(89.99999999997,2.57865741235478,2);
echo "$result"; // 34.90 result with 2 decimal points
?>
cristianDOTzuddas]NOSPAM[gmailDOTcom
24-Jul-2005 05:10
24-Jul-2005 05:10
Decimal to binary conversion, using BC Math.
Note: this function is VERY slow if the decimal number is too big!
<?
function bc_decbin($dec_str) {
if (strlen($dec_str)>0) {
$bin_str = '';
do {
if (((int)$dec_str[strlen($dec_str)-1] % 2) === 0)
$bin_str .= '0';
else
$bin_str .= '1';
$dec_str = bcdiv($dec_str, '2');
} while ($dec_str!='0');
return strrev($bin_str);
}
else
return null;
}
?>
-----
Cristian
www.CodeFlower.com