public static function CDF($x, $μ, $b) : float { Support::checkLimits(self::LIMITS, ['x' => $x, 'μ' => $μ, 'b' => $b]); if ($x < $μ) { return 1 / 2 * exp(($x - $μ) / $b); } return 1 - 1 / 2 * exp(-($x - $μ) / $b); }