-- Since the norm is defined on a vector space, we should be able to
-- add and subtract anything on which a norm is defined. Of course
-- 'Num' is a bad choice here, but we really prefer to use the normal
-- addition and subtraction operators.
-- Since the norm is defined on a vector space, we should be able to
-- add and subtract anything on which a norm is defined. Of course
-- 'Num' is a bad choice here, but we really prefer to use the normal
-- addition and subtraction operators.