The custom bcdiv function listed at the top of this page produces very different results from bcdiv, as it rounds instead of truncating the result. Consider the following:
<?php
function bcdiv_cust( $first, $second, $scale = 0 )
{
$res = $first / $second;
return round( $res, $scale );
}
echo bcdiv('1','2','0') . " vs. " bcdiv_cust('1','2','0'); // prints '0 vs. 1'
?>
bcdiv
(PHP 4, PHP 5, PHP 7)
bcdiv — Divide two arbitrary precision numbers
Description
bcdiv
( string
$dividend
, string $divisor
[, int $scale = 0
] ) : string
Divides the dividend by the
divisor.
Parameters
-
dividend -
The dividend, as a string.
-
divisor -
The divisor, as a string.
-
scale -
This optional parameter is used to set the number of digits after the decimal place in the result. If omitted, it will default to the scale set globally with the bcscale() function, or fallback to 0 if this has not been set.
Return Values
Returns the result of the division as a string, or NULL if
divisor is 0.
Examples
Example #1 bcdiv() example
<?php
echo bcdiv('105', '6.55957', 3); // 16.007
?>
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User Contributed Notes 4 notes
Anonymous ¶
9 years ago
MM ¶
11 years ago
Perhaps some one can find useful this function to compute the modular inverse of a integer (extended euclidean algorithm):
function invmod($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 ¶
12 years ago
<?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 ¶
14 years ago
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
