 
 #include <iostream>
 #include <fstream>
-#include <cmath>
 #include <vector>
 //6 analytical quantities
 namespace dg

    double lnN_inner_;
    Psip psip_;
};
/**
 * @brief testfunction to test the parallel derivative
 */ 

    }     
    double operator()( double R, double Z)
    {
       return invB_(R,Z)*invB_(R,Z)/R*(bR_(R,Z) *psipZ_(R,Z) - bZ_(R,Z)* psipR_(R,Z)) ;
    }
    double operator()( double R, double Z, double phi)
    {
       return invB_(R,Z,phi)* invB_(R,Z,phi)/R*(bR_(R,Z,phi) *psipZ_(R,Z,phi) - bZ_(R,Z,phi)* psipR_(R,Z,phi)) ;
    }
    private:
//     InvB invB_; 
