double xdata[7] = {1.0,2.0,3.0,4.0,5.0,6.0,7.0};
double ydata[7] = {1.1,4.1,8.9,15.7,24.8,36.2,49.2};

class parabolaResidFunc:public residFunc {
 public:
  parabolaResidFunc(unsigned int nIn): n(nIn), p(3) {};
  void resid(const HepVector *x, void *data, HepVector *f){
    cout << "resid called\n";
    cout << "params: " << *x << endl;
    double a = (*x)(1);
    double b = (*x)(2);
    double c = (*x)(3);
    double xthis;
    for (unsigned int i = 0; i < n; i++) {
      xthis = xdata[i];
      (*f)[i] = a*xthis*xthis + b*xthis + c - ydata[i];
    }
  };
  void deriv(const HepVector *x, void *data, HepMatrix *J){
    cout << "deriv called\n";
    cout << "params: " << *x << endl;
    double a = (*x)(1);
    double b = (*x)(2);
    double c = (*x)(3);
    double xthis, dfda, dfdb, dfdc;
    for (unsigned int i = 0; i < n; i++) {
      xthis = xdata[i];
      dfda = xthis*xthis;
      dfdb = xthis;
      dfdc = 1.0;
      (*J)((int)i + 1, 1) = dfda;
      (*J)((int)i + 1, 2) = dfdb;
      (*J)((int)i + 1, 3) = dfdc;
    }
  };
  void residAndDeriv(const HepVector *x, void *data, HepVector *f, HepMatrix *J){};
  unsigned int getn() {return n;};
  unsigned int getp() {return p;};
 private:
  unsigned int n, p;
};