Method factorial

MathParser/src/com/aghajari/math/Functions.java:272–279

(double x)

    }

    public static double factorial(double x) {
        int number = (int) x;
        long result = 1;
        for (int factor = 2; factor <= number; factor++) {
            result *= factor;
        }
        return result;
    }

    // ignore Math.log as base e
    public static double log(double a) {