;;;;

;; Issues
;;
;; - `bigO' "near" 1. should be rounded for comparisons

(module bigO

(;export
  bigO bigO= bigO< bigO> bigO-compare)

(import scheme)

;;;

(define (log-with-base b)
  (let ((lnb (log b)))
    (lambda (n)
      (/ (log n) lnb) ) ) )

(define log10 (log-with-base 10))

;;;

;;

;#; ;over fit?
(define (bigO a) (inexact->exact (round (log10 a))))
#; ;power 10 boundary issue - bigO 1000 3.0 floor -> 2.0
(define (bigO a)
  (import (only (chicken base) print))
  (print "bigO " a " " (log10 a) " " (floor (log10 a)) " " (inexact->exact (floor (log10 a))) )
  (let* ((a1 (log10 a))
         (a2 (floor (log10 a)))
         (a3 (inexact->exact (floor (log10 a)))) )
    (print "bigO " a " " a1 " " a2 " " a3) )
  (inexact->exact (floor (log10 a))))

(define (bigO-compare a b) (- (bigO a) (bigO b)))

(define (bigO< a b) (negative? (bigO-compare a b)))
(define (bigO= a b) (zero? (bigO-compare a b)))
(define (bigO> a b) (positive? (bigO-compare a b)))

) ;module bigO