public class vector2{

       public double x,y,z;


       public vector2 productocruz(vectorv){  //este me manda el error

           double i=y*v.z-z*v.y;
           double j=z*v.x-x*v.z;
           double k=x*v.y-y*v.x;

           vector2 aux= new vector2(i,j,k);

           return aux;

       }
   }