    # File lib/facets/more/quaternion.rb, line 360
      def - (other)
        if other.kind_of?(Quaternion)
          Quaternion(@re-other.re,@im-other.im,@jm-other.jm,@km-other.km)
        elsif other.kind_of?(Complex)
          Quaternion(@re-other.real,@im-other.image, @jm, @km)
        elsif Complex.generic?(other)
          Quaternion(@re-other.real,@im, @jm, @km)
        else x , y = other.coerce(self); x - y
        end
      end