PID class

class PID{
    double proportional_gain = 1.0f;
    double intigral_gain = 1.0f;
    double derivitve_gain = 1.0f;

    private:

        double x_1;
        double x_2;

        double intigral;


    public:

    double PID(double error) {
        x_1 = x_2;
        x_2 = error;
        intigral = intigral + error;

        return ((intigral * intigral_gain) + (error * proprotional_gain) + ((x_2 - x_1) * derivitive_gain));
    }
};