public static function PMF(int $k, float $p) : float { Support::checkLimits(self::LIMITS, ['k' => $k, 'p' => $p]); $⟮1 − p⟯ᵏ⁻¹ = pow(1 - $p, $k - 1); return $⟮1 − p⟯ᵏ⁻¹ * $p; }