T9 - zad.2.

#include <iostream>
#include <cmath>

class Vektor3d
{
    double koordinate[3];
    public:
     void Postavi(double x, double y, double z)
     {
         koordinate[0] = x;
         koordinate[1] = y;
         koordinate[2] = z;
     }

     void Ocitaj(double &x, double &y, double &z) const
     {
         x = koordinate[0];
         y = koordinate[1];
         z = koordinate[2];
     }

     void Ispisi() const
     {
         std::cout << "{" << koordinate[0]<< "," <<
            koordinate[1]<< "," << koordinate[2]<< "}";
     }

     double DajX() const { return koordinate[0];}

     double DajY() const { return koordinate[1];}

     double DajZ() const { return koordinate[2];}

     double DajDuzinu() const
     {
         return std::sqrt(koordinate[0]*koordinate[0]+koordinate[1]*
                     koordinate[1]+koordinate[2]*koordinate[2]);
     }

     Vektor3d &PomnoziSaSkalarom(double s)
     {
         koordinate[0]*= s;
         koordinate[1]*= s;
         koordinate[2]*= s;
     }

     friend Vektor3d ZbirVektora(const Vektor3d &v1,const Vektor3d &v2);

     void PostaviX(double x){ koordinate[0]=x;}

     void PostaviY(double y){ koordinate[1]=y;}

     void PostaviZ(double z){ koordinate[2]=z;}
};

Vektor3d ZbirVektora (const Vektor3d &v, const Vektor3d &v2)
{
    Vektor3d v3;
    v3.koordinate[0]=v.koordinate[0]+v2.koordinate[0];
    v3.koordinate[1]=v.koordinate[1]+v2.koordinate[1];
    v3.koordinate[2]=v.koordinate[2]+v2.koordinate[2];
    return v3;
}

int main()
{
    Vektor3d vektor,vektor2, vektor3;
    vektor.Postavi(2,3,4);
    vektor.Ispisi();
    std::cout<<std::endl;
    vektor.PostaviX(6);
    vektor.Ispisi();
    std::cout<<std::endl<<vektor.DajX()<<std::endl;
    vektor2.Postavi(4,5,6);
    vektor2.Ispisi();
    std::cout<<std::endl;
    vektor.Ispisi();
    vektor3=ZbirVektora(vektor, vektor2);
    vektor3.Ispisi();

return 0;
}