gmp_fact

    (PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

    gmp_fact — Factorial

    Description

    gmp_fact(GMP|int|string $num): GMP

    Calculates factorial (num!) of num.

    Parameters

    num

    The factorial number.

    A GMP object, an int or a numeric string.

    Return Values

    A GMP object.

    Examples

    Example #1 gmp_fact() example

    <?php
    $fact1     = gmp_fact(5); // 5 * 4 * 3 * 2 * 1
    echo gmp_strval($fact1) . "\n";

    $fact2 = gmp_fact(50); // 50 * 49 * 48, ... etc
    echo gmp_strval($fact2) . "\n";
    ?>

    The above example will output:

    120
30414093201713378043612608166064768844377641568960512000000000000

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    User Contributed Notes 1 note

    up
    -2
    raholl
    6 years ago
    I was expecting gmp_fact() is more effective than doing a while loop, but measurements show opposite:

    <?php
    $cislo     = 112;
    $fact = $cislo;
    $ffact = 1;
    $mt = microtime();
    while(    $fact >= 1)
    {
    $ffact = $fact * $ffact;
    $fact--;
    }
    $md=number_format(microtime()-$mt, 6);
    echo     "<h1>LOOP ($md):</h1>";
    echo     $ffact;

    $mt = microtime();
    $vec = gmp_fact($cislo);
    $md=number_format(microtime()-$mt, 6);
    echo     "<h1>GMP FACT ($md):</h1>";
    echo     $vec;
    exit();
    ?>

    WILL OUTPUT:

    LOOP (0.000022s):
    1.9745068572211E+182

    GMP FACT (0.000132s):
    1.9745068572211E+182

    Result is 0.000022s loop, and 0.000132s gmp_fact()
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