gmp_fact
Here's my solution for getting the GCD of several numbers.
<?php
/*
* function gcd()
*
* returns greatest common divisor
* between two numbers
* tested against gmp_gcd()
*/
function gcd($a, $b)
{
if ($a == 0 || $b == 0)
return abs( max(abs($a), abs($b)) );
$r = $a % $b;
return ($r != 0) ?
gcd($b, $r) :
abs($b);
}
/*
* function gcd_array()
*
* gets greatest common divisor among
* an array of numbers
*/
function gcd_array($array, $a = 0)
{
$b = array_pop($array);
return ($b === null) ?
(int)$a :
gcd_array($array, gcd($a, $b));
}
?>
gmp_gcd
(PHP 4 >= 4.0.4, PHP 5)
gmp_gcd — Calcula o MDC
Descrição
resource gmp_gcd
( resource $a
, resource $b
)
Calcula o máximo divisor comum de a e b . O resultado é sempre positivo, mesmo que um, ou ambos os argumentos sejam negativos.
Parâmetros
- a
-
Ele pode ser qualquer número GMP resource, ou uma string numérica que é possível convertê-la para um número.
- b
-
Ele pode ser qualquer número GMP resource, ou uma string numérica que é possível convertê-la para um número.
Valor Retornado
Um número positivo GMP que divide a e b .
Exemplos
Exemplo #1 Exemplo da gmp_gcd()
<?php
$gcd = gmp_gcd("12", "21");
echo gmp_strval($gcd) . "\n";
?>
O exemplo acima irá imprimir:
3
add a note
User Contributed Notesgmp_gcd
sean__remove__ at eternalrise_r_emove__ dot com
11-Nov-2008 03:50
11-Nov-2008 03:50
jim dot mayes at gmail dot com
03-Apr-2008 09:53
03-Apr-2008 09:53
Try...
function gcd($a, $b){
$b = ( $a == 0 )? 0 : $b;
return ( $a % $b )? gcd($b, abs($a - $b)) : $b;
}
always returns positive number even if one or both numbers are negative (as per the gmp_gcd function)
order agnostic, larger number can be $b or $a doesn't matter
also, other examples here were failing when one of the numbers was 0
limas at kultur-online dot at
01-Dec-2007 06:44
01-Dec-2007 06:44
The previous function returns just 1 under php 5.2.4 but the following seems to work (m>0,n>0):
function gcd($m,$n)
{
$_m=$m;$r=1;
if($m<$n){$t=$m;$m=$n;$n=$t;}
while($r)
{
$r=(floor($m/$n)*$n)-$m;
$_n=$n;$n=$r;$m=$_m;
}
return abs($_n);
}
bigkm1 at gmail dot com
26-Aug-2006 04:33
26-Aug-2006 04:33
here is an elegant recursive solution
<?php
function gcd($a,$b) {
return ($a % $b) ? gcd($b,$a % $b) : $b;
}
?>
scr02001 at student dot mdh dot se
16-Aug-2003 01:58
16-Aug-2003 01:58
If you do not consier a or b as possible negative numbers, a GCD funktion may return a negative GCD, wich is NOT a greatest common divisor, therefore a funktion like this may be better. This considers the simplyfying of (-3)-(-6) where gcd on -3 and -6 would result in 3, not -3 as with the other function. (-3)-(-6) is (-1)-(-2) NOT (1)-(2)
function eGCD($a,$b){
if($a < 0) $a=0-$a;
if($b < 0 ) $b=0-$b;
if($a == 0 || $b == 0) return 1;
if($a == $b) return a;
do{
$rest=(int) $a % $b; $a=$b; $b=$rest;
}while($rest >0);
return $a;
}
Ludwig Heymbeeck
12-Jan-2003 06:33
12-Jan-2003 06:33
The following function is more accurate:
function GCD($num1, $num2) {
/* finds the greatest common factor between two numbers */
while ($num2 != 0){
$t = $num1 % $num2;
$num1 = $num2;
$num2 = $t;
}
return $num1;
}
x-empt-php dot net at ispep dot cx
07-Jul-2002 06:16
07-Jul-2002 06:16
No need to compile gmp functions in just for the GCD function... use this one instead:
function GCD($num1, $num2) {
/* finds the greatest common factor between two numbers */
if ($num1 < $num2) {
$t = $num1;
$num1 = $num2;
$num2 = $t;
}
while ($t = ($num1 % $num2) != 0) {
$num1 = $num2;
$num2 = $t;
}
return $num2;
}