| public static multinomial ( array $groups ) : integer | ||
| $groups | array | Sizes of each subgroup |
| Результат | integer | Number of divisions of n items into r distinct nonoverlapping subgroups |
public static function multinomial(array $groups)
{
$n = array_sum($groups);
$n！ = self::factorial($n);
$k₁！k₂！⋯km！ = array_product(array_map('self::factorial', $groups));
return $n！ / $k₁！k₂！⋯km！;
}