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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.

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用户评论:

rks at rks dot org (13-Dec-2008 05:25)

I believe that "fact" computes the factorial of $x-1 not of $x. The for statement should be for ($i=2; $i <= $x; $i++) not for ($i=2; $i < $x; $i++) If you try to compute the factorial of 2 for example, the for loop will not be executed and the result will be 1.