gmp_fact

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

gmp_factFactorial

설명

GMP gmp_fact ( mixed $a )

Calculates factorial (a!) of a.

인수

a

The factorial number.

PHP 5.5 이전에서 GMP 수 resource나, PHP 5.6 이후에서 GMP 객체, 또는 수로 변환할 수 있는 문자열일 수 있습니다.

반환값

PHP 5.5 이전에서는 GMP 수 resource, PHP 5.6 이후에서는 GMP 객체.

예제

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";
?>

위 예제의 출력:

120
30414093201713378043612608166064768844377641568960512000000000000

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User Contributed Notes 2 notes

up
2
raholl
3 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()
up
-13
raholl
3 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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