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bcdiv

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

bcdivDivide due numeri a precisione arbitraria

Descrizione

bcdiv(string $primo operando, string $secondo operando, int $precisione = ?): string

Divide il primo operando per il secondo operando e restituisce il risultato. Il parametro opzionale precisione imposta il numero di cifre dopo il punto decimale nel risultato.

Esempi

Example #1 esempio di bcdiv()

<?php

echo bcdiv(105, 6.55957, 3); // 16.007

?>

Vedere anche:

bcmul().

add a note

User Contributed Notes 4 notes

up
-1
MM
16 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;
up
-8
Anonymous
13 years ago
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'

?>
up
-10
cristianDOTzuddas]NOSPAM[gmailDOTcom
18 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
up
-13
Gautam
16 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
?>
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