code: public Vector3d sub(double x, double y, double z) {
          return sub(x, y, z, thisOrNew());
      }
docs: Subtract <code>(x, y, z)</code> from this vector.
  
  @param x
  the x component to subtract
  @param y
  the y component to subtract
  @param z
  the z component to subtract
  @return a vector holding the result