public static function CDF($x, $k, $λ) { Support::checkLimits(self::LIMITS, ['k' => $k, 'λ' => $λ]); if ($x < 0) { return 0; } $ℯ⁻⁽x/λ⁾ᵏ = exp(-pow($x / $λ, $k)); return 1 - $ℯ⁻⁽x/λ⁾ᵏ; }