1 665c255d 2023-08-04 jrmu (defun sub-interval (x y)
2 665c255d 2023-08-04 jrmu   (make-interval
3 665c255d 2023-08-04 jrmu    (- (lower-bound x) (upper-bound y))
4 665c255d 2023-08-04 jrmu    (- (upper-bound x) (lower-bound y))))