X-Git-Url: https://git.jsancho.org/?a=blobdiff_plain;f=src%2Fgacela_misc.scm;h=6dd13b11a8acd7844c1943279b0c5f2aebc51ee1;hb=2dd62c9397803ff96e72f9e27f138b58273b5976;hp=9dc10aa6c9140dec198ca4d9079c001c0c55871d;hpb=e99551161b1199fcd068dce0f7b0fd2f3927e771;p=gacela.git

diff --git a/src/gacela_misc.scm b/src/gacela_misc.scm
index 9dc10aa..6dd13b1 100644
--- 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 +56,15 @@
 	  (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)))))
+
+(define (assoc-multiple-set! alist . pairs)
+  (define (amset! alist pairs)
+    (cond ((< (length pairs) 2)
+	   alist)
+	  (else
+	   (assoc-set! alist (car pairs) (cadr pairs))
+	   (amset! alist (cddr pairs)))))
+  (amset! alist pairs))