//  Force class 
//  -----------

#ifndef FORCE
#define FORCE const Force
class Mass;                     //  Interacting     
class Acceleration;             //    classes

//  This class supports 3-dimensional force quantities

#include <math.h>                  /*  (for sqrt)                        */

 class Force {

   double value[3];                //   Dynes in 3-dimensions

 public:
   
//  Constructors and accessors
//  --------------------------

  Force(DOUBLE x=0, DOUBLE y=0, DOUBLE z=0)  //  Parameters in dynes
    {value[0]=x; value[1]=y; value[2]=z;}       

//  The compiler will provide an acceptable copy constructor,
//  destructor, and assignment operator.

  double magnitude() const 
    {return sqrt(value[0]*value[0] + value[1]*value[1] + value[2]*value[2]);}

  double x()       const {return value[0];}
  double y()       const {return value[1];}
  double z()       const {return value[2];}
  double dynes()   const {return magnitude();}
  double newtons() const {return magnitude() / 10000;}
  double pounds()  const {return magnitude() / 2248.2014;}

//  Operations on Force operands

#define  Class Force
#include "Additive.hpp"
  
 bool operator==(FORCE rs) const;
 bool operator< (FORCE rs) const; 
     
//  Arithmetic operations on mixed operands (Newton's law)
//  ---------------------------------------

    Acceleration operator/(const Mass         rs) const; 
    Mass         operator/(const Acceleration rs) const;


};                          //  *****  End of class definition


 ostream& operator<<(ostream& ls, FORCE rs); // Output stream insertion
    

#undef Class
#endif