From: rearman <rearman@r717.net>
Date: Mon, 13 Apr 2026 19:57:33 +0000 (-0400)
Subject: Make average-of-points length agnostic
X-Git-Url: https://git.earman.xyz/?a=commitdiff_plain;h=e301d5489aef2fbbf85f38278ebb3ccf72171270;p=lisp%2Fworkenv.git

Make average-of-points length agnostic

Drop cond for length of one, calculate average based on length of list of
points.
---

diff --git a/math.lisp b/math.lisp
index 31f2ded..70099e8 100644
--- a/math.lisp
+++ b/math.lisp
@@ -25,18 +25,19 @@
 If a 2d point is given, it is converted to 3d with z=0."
   (cond ((numberp (first points))
 	 points)
-	((= (length points) 1)
-	 (first points))
-	(t (mapcar #'/
-		   (list (apply #'+ (mapcar #'first points))
-			 (apply #'+ (mapcar #'second points))
-			 (apply #'+
-				(mapcar #'(lambda (x)
-					    (if (null (third x))
-						0
-						(third x)))
-					points)))
-		   '(2 2 2)))))
+	(t (let ((numpoints (length points)))
+	     (mapcar #'/
+		     (list (apply #'+ (mapcar #'first points))
+			   (apply #'+ (mapcar #'second points))
+			   (apply #'+
+				  (mapcar #'(lambda (x)
+					      (if (null (third x))
+						  0
+						  (third x)))
+					  points)))
+		     (list numpoints
+			   numpoints
+			   numpoints))))))
 
 (defun dot-product-points (apoint bpoint)
   "Return the dot-product of 3d vectors a and b.