chibi-scheme/lib/scheme/division.scm
2011-11-10 05:34:20 +09:00

43 lines
1.4 KiB
Scheme

(define truncate-quotient quotient)
(define truncate-remainder remainder)
(define (truncate/ n m)
(values (truncate-quotient n m) (truncate-remainder n m)))
(define floor-remainder modulo)
(define (floor-quotient n m)
(quotient (- n (floor-remainder n m)) m))
(define (floor/ n m)
(values (floor-quotient n m) (floor-remainder n m)))
(define (round-quotient n m)
(inexact->exact (round (/ n m))))
(define (round-remainder n m)
(- n (* m (round-quotient n m))))
(define (round/ n m)
(values (round-quotient n m) (round-remainder n m)))
(define (ceiling-quotient n m)
(inexact->exact (ceiling (/ n m))))
(define (ceiling-remainder n m)
(- n (* m (ceiling-quotient n m))))
(define (ceiling/ n m)
(values (ceiling-quotient n m) (ceiling-remainder n m)))
(define (euclidean/ n m)
(if (> n 0) (ceiling/ n m) (floor/ n m)))
(define (euclidean-quotient n m)
(if (> n 0) (ceiling-quotient n m) (floor-quotient n m)))
(define (euclidean-remainder n m)
(if (> n 0) (ceiling-remainder n m) (floor-remainder n m)))
(define (centered-remainder n m)
(let ((r (euclidean-remainder n m))
(m/2 (abs (/ m 2))))
(cond ((< r (- m/2)) (+ r (abs m)))
((>= r m/2) (- r (abs m)))
(else r))))
(define (centered-quotient n m)
(quotient (- n (centered-remainder n m)) m))
(define (centered/ n m)
(values (centered-quotient n m) (centered-remainder n m)))