text: #include "geo_vector.h"
  
  #include<iostream>
  
  int main(void) {
  
    //Defining a 3D point of force type
  
    typedef point< quantity<force>, 3 , cartesian >  Point3D; 
  
    //Creating Two points of force type 
  
    Point3D P( 3 * newton , 2 * newton , 4 * newton);
    Point3D Q( 5 * newton , 4 * newton , -3 * newton);
  
    //creating two position vectors of force type to above points 
  
    geo_vector<force> f1(P);
  
    geo_vector<force> f2(Q);
  
    //creating a zero vector of force type
  
    geo_vector<force> Resultant;
  
    // f1 + f2 returns a resultant addition vector and we store it in Resultant  
  
    Resultant = f1 + f2;
  
    std::cout<<"f1 : "<< f1 <<std::endl
             <<"f2 : "<< f2 <<std::endl
  
             <<"\nResultant : "<< Resultant<<std::endl;
  
    return 0;
  }
  
  
  /* *  * OUTPUT * * * * * * * * * * *
  
  f1 : (3 N)i + (2 N)j + (4 N)k
  f2 : (5 N)i + (4 N)j + (-3 N)k
  
  Resultant : (8 N)i + (6 N)j + (1 N)k
  
  
  * * * * * * * * * * * * * * * * 
  */
  
  
  
  
  
  
  
  