MathPHP\Probability\Distribution\Continuous\Pareto::PDF PHP Метод

    public static function PDF($x, $a, $b)
    {
        Support::checkLimits(self::LIMITS, ['x' => $x, 'a' => $a, 'b' => $b]);
        if ($x < $b) {
            return 0;
        }
        $abᵃ = $a * $b ** $a;
        $xᵃ⁺¹ = pow($x, $a + 1);
        return $abᵃ / $xᵃ⁺¹;
    }