Data commit

Task/Average-loop-length/EchoLisp/average-loop-length.l

@@ -0,0 +1,29 @@
+(lib 'math) ;; Σ aka (sigma f(n)  nfrom nto)
+
+(define (f-count  N (times 100000))
+    (define count 0)
+    (for ((i times))
+
+    ;; new  random f mapping from  0..N-1 to 0..N-1
+    ;; (f n) is NOT (random N)
+    ;; because each call (f n) must return the same value
+
+    (define f (build-vector N  (lambda(i) (random N))))
+
+    (define hits (make-vector N))
+        (define n 0)
+        (while (zero? [hits n])
+            (++ count)
+            (vector+= hits n 1)
+            (set! n [f n])))
+    (// count times))
+
+(define (f-anal N)
+    (Σ  (lambda(i) (// (! N) (! (- N i)) (^  N i))) 1 N))
+
+(decimals 5)
+(define (f-print (maxN 21))
+	(for ((N (in-range 1 maxN)))
+	(define fc (f-count N))
+	(define fa (f-anal N))
+	(printf  "%3d %10d %10d  %10.2d %%" N fc fa (// (abs (- fa fc)) fc 0.01))))