public static function PDF($x, $α, $β)
{
Support::checkLimits(self::LIMITS, ['x' => $x, 'α' => $α, 'β' => $β]);
$⟮β／α⟯⟮x／α⟯ᵝ⁻¹ = $β / $α * pow($x / $α, $β - 1);
$⟮1 ＋ ⟮x／α⟯ᵝ⟯² = pow(1 + ($x / $α) ** $β, 2);
return $⟮β／α⟯⟮x／α⟯ᵝ⁻¹ / $⟮1 ＋ ⟮x／α⟯ᵝ⟯²;
}