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authorBryan Newbold <bnewbold@robocracy.org>2017-02-20 00:05:28 -0800
committerBryan Newbold <bnewbold@robocracy.org>2017-02-20 00:05:28 -0800
commit87b82b5822ca54228cfa6df29be3ad9d4bc47d16 (patch)
tree1eb4f87abd38bea56e08335d939e8171d5e7bfc7 /ratize.scm
parentbd9733926076885e3417b74de76e4c9c7bc56254 (diff)
downloadslib-87b82b5822ca54228cfa6df29be3ad9d4bc47d16.tar.gz
slib-87b82b5822ca54228cfa6df29be3ad9d4bc47d16.zip
Import Upstream version 2d2upstream/2d2
Diffstat (limited to 'ratize.scm')
-rw-r--r--ratize.scm26
1 files changed, 15 insertions, 11 deletions
diff --git a/ratize.scm b/ratize.scm
index d8cad11..9737934 100644
--- a/ratize.scm
+++ b/ratize.scm
@@ -1,13 +1,17 @@
-;;;; "ratize.scm" Convert number to rational number
+;;;; "ratize.scm" Find simplest number ratios
-(define (rational:simplest x y)
- (define (sr x y) (let ((fx (floor x)) (fy (floor y)))
- (cond ((not (< fx x)) fx)
- ((= fx fy) (+ fx (/ (sr (/ (- y fy)) (/ (- x fx))))))
- (else (+ 1 fx)))))
- (cond ((< y x) (rational:simplest y x))
- ((not (< x y)) (if (rational? x) x (slib:error)))
+(define (find-ratio-between x y)
+ (define (sr x y)
+ (let ((fx (inexact->exact (floor x))) (fy (inexact->exact (floor y))))
+ (cond ((>= fx x) (list fx 1))
+ ((= fx fy) (let ((rat (sr (/ (- y fy)) (/ (- x fx)))))
+ (list (+ (cadr rat) (* fx (car rat))) (car rat))))
+ (else (list (+ 1 fx) 1)))))
+ (cond ((< y x) (find-ratio-between y x))
+ ((>= x y) (list x 1))
((positive? x) (sr x y))
- ((negative? y) (- (sr (- y) (- x))))
- (else (if (and (exact? x) (exact? y)) 0 0.0))))
-(define (rationalize x e) (rational:simplest (- x e) (+ x e)))
+ ((negative? y) (let ((rat (sr (- y) (- x))))
+ (list (- (car rat)) (cadr rat))))
+ (else '(0 1))))
+(define (find-ratio x e) (find-ratio-between (- x e) (+ x e)))
+(define (rationalize x e) (apply / (find-ratio x e)))