; sicp-lib.scm ; 共通関数群 (define (abs x) (if (< x 0) (- x) x)) (define (square x) (* x x)) (define (cube x) (* x x x)) (define (sqrt x) (define (sqrt-iter old new x) (if (good-enough? old new) new (sqrt-iter new (improve new x) x))) (de…