double gammq(const double, const double);
double gser(double&, const double, const double, double&);
double gcf(double&, const double, const double, double&);
double erfcc(double);
double gammq(const double, const double);
double gser(double&, const double, const double, double&);
double gcf(double&, const double, const double, double&);
double erfcc(double);