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[gacela.git] / src / gacela_misc.scm

diff --git a/src/gacela_misc.scm b/src/gacela_misc.scm
index a9393ca89607d52e3d75ea42700753ec9f6c44d6..6dd13b11a8acd7844c1943279b0c5f2aebc51ee1 100644 (file)
--- a/src/gacela_misc.scm
+++ b/src/gacela_misc.scm
@@ -26,6 +26,28 @@
 (define *pi* (* (asin 1) 2))
 
 
+;;; Geometry
+
+(define (degrees-to-radians angle)
+  (/ (* angle *pi*) 180))
+
+(define (radians-to-degrees angle)
+  (/ (* angle 180) *pi*))
+
+(define (distance-between-points p1 p2)
+  (define (add-power-of-two p1 p2)
+    (cond ((null? p1)
+          0)
+         (else
+          (+ (expt (- (car p1) (car p2)) 2)
+             (add-power-of-two (cdr p1) (cdr p2))))))
+
+  (cond ((not (= (length p1) (length p2)))
+        #f)
+       (else
+        (sqrt (add-power-of-two p1 p2)))))
+
+
 ;;; Functions
 
 (define (nearest-power-of-two n)
@@ -34,12 +56,6 @@
          (else (power (* p 2) n))))
   (power 1 n))
 
-(define (degrees-to-radians angle)
-  (/ (* angle *pi*) 180))
-
-(define (radians-to-degrees angle)
-  (/ (* angle 180) *pi*))
-
 (define-macro (pushnew elem list)
   `(cond ((not (find (lambda (e) (eq? e ,elem)) ,list))
          (set! ,list (cons ,elem ,list)))))