static IVector subtractVectors(IVector a, IVector b) {

        double vx = a.getVx() - b.getVx();
        double vy = a.getVy() - b.getVy();

        if(a instanceof Vector3D && b instanceof Vector3D) {
            double vz = ((Vector3D) a).getVz() - ((Vector3D) b).getVz();
            return new Vector3D(vx, vy, vz);
        }
        return new Vector(vx, vy);
    }