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Task/Averages-Root-mean-square/XLISP/averages-root-mean-square.xlisp

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+(defun quadratic-mean (xs)
+    (sqrt
+        (/
+            (apply +
+                (mapcar (lambda (x) (expt x 2)) xs))
+            (length xs))))
+
+; define a RANGE function, for testing purposes
+
+(defun range (x y)
+    (if (< x y)
+        (cons x (range (+ x 1) y))))
+
+; test QUADRATIC-MEAN
+
+(print (quadratic-mean (range 1 11)))