范例

Example #1 Factorial function using GMP

  <?php
 function  fact ( $x ) 
{
     $return  =  1 ;
    for ( $i = 2 ;  $i  <=  $x ;  $i ++) {
         $return  =  gmp_mul ( $return ,  $i );
    }
    return  $return ;
}

echo  gmp_strval ( fact ( 1000 )) .  "\n" ;
 ?>

This will calculate factorial of 1000 (pretty big number) very fast.

用户评论:

[#1] Ganzert [2015-10-16 04:58:19]

in the example above, this following line:
for ($i=2; $i < $x; $i++) {

should be replaced by:

for ($i=2; $i <=$x; $i++) {

Cheers

Ganzert

[#2] Juliano Barreto [2015-09-15 17:59:42]

I forgot to mention. You need (obviously) to remove the gmp function for a usual one. Like this:

function fact($num)
{
$res = 1;
for ($n = $num; $n >= 1; $n--)
$res = $res*$n;
return $res;
}

[#3] Juliano Barreto [2015-09-15 17:38:25]

This function isn't pointless if you don't have the GMP library installed.

[#4] Jonathon [2014-02-06 03:21:54]

Of course, this example is pointless because there is gmp_fact().