Return c;

}

V_3d V_3d:: operator =(V_3d t)

{

x=t.x; y=t.y; z=t.z;

return *this;

}

ostream &operator <<(ostream &stream,V_3d t)

{

stream<<"x="<<t.x<<",";

stream<<"y="<<t.y<<",";

stream<<"z="<<t.z<<"n";