2007-11-08 問題2-10 SICP こんなかんじ? (define (div-interval x y) (let ((l-div (/ 1.0 (upper-bound y))) (r-div (/ 1.0 (lower-bound y)))) (if (and (<= l-div 0) (=> r-div 0)) (error "invalid interval") (mul-interval x (make-interval l-div r-div))))) 今日朝いそいでて確かめてない><