v.normalise();
System.out.println(v);
Vector3 d=Vector3.of(10.0,0.0,0.0);
d.addMultiple(v, 5.0);
System.out.println(d);
Matrix33 m=Matrixx.createXAxisRotationMatrix(Math.PI);
Vector3 rotated=m.transform(d); // rotate 180 degrees around x axis
System.out.println(rotated);