public static function CDF($x, int $k)
{
Support::checkLimits(self::LIMITS, ['x' => $x, 'k' => $k]);
// Numerator
$γ⟮k/2、x/2⟯ = Special::γ($k / 2, $x / 2);
// Demoninator
$Γ⟮k/2⟯ = Special::Γ($k / 2);
return $γ⟮k/2、x/2⟯ / $Γ⟮k/2⟯;
}