(defun m+ (a b) (mapcar* #'v+ a b)) (defun m- (a b) (mapcar* #'v- a b))と作ることができ,次のように実行できる.
> (setq a '(( 1 2 3 4)
( 5 6 7 8)
( 9 10 11 12)))
((1 2 3 4) (5 6 7 8) (9 10 11 12))
> (m+ a a)
((2 4 6 8) (10 12 14 16) (18 20 22 24))
> (m- a a)
((0 0 0 0) (0 0 0 0) (0 0 0 0))