Import Upstream version 2d2upstream/2d2

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)))