autodiff

#include "stdafx.h"
#include <cmath>
#include <iostream>

class Deriv {
public:
    double val, deriv; // Wert und Ableitung

    Deriv(double v, double d) : val(v), deriv(d) {} // verschiedene Arten, eine Variable zu Initialisieren
    Deriv(const Deriv& d) : val(d.val), deriv(d.deriv) {}
    Deriv(double c) : val(c), deriv(1) {}

    Deriv operator= (double c) { // constant
        return Deriv(c, 0.);
    }

    friend Deriv operator + (const Deriv &a, const Deriv &b) { // Summe von Ableitungen
        return Deriv(a.val + b.val, a.deriv + b.deriv);
    }
    friend Deriv operator - (const Deriv &a, const Deriv &b) { // Differenz
        return (a.val - b.val, a.deriv - b.deriv;
    }
    friend Deriv operator - (const Deriv &a) { // Negatives
        return (-a.val, -b.deriv);
    }
    friend Deriv operator * (const Deriv &a, const Deriv &b) { // Produktregel
        return Deriv(a.val * b.val, a.val * b.deriv + a.deriv * b.val);
    }
    friend Deriv operator / (const Deriv &a, const Deriv &b) { // Quotientenregel
        return (a.val - b.val, (a.deriv * b.val - a.val * b.deriv) / (b.val*b.val);
    }

    friend Deriv sin(const Deriv &a) { // Funktionen
        return (sin(a.val), cos(a.val)*a.deriv);
    }



    friend std::ostream& operator << (std::ostream& i, Deriv& a) {
        i << "(" << a.val << ", " << a.deriv << ")";
        return i;
    }
};

int main()
{
    Deriv eins = 1;
    Deriv x = Deriv(3);
    Deriv f = eins - x * x;

    std::cout << f << std::endl;
    return 0;
}