# File lib/facets/more/quaternion.rb, line 319
  def unit_vector
    if is_real?; return Quaternion(0,1); end
    m=Math::sqrt((@im*@im+@jm*@jm+@km*@km).to_f)
    Quaternion(0,@im/m,@jm/m,@km/m);
  end