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SICP/exercise_1_44.janet

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+(defn compose [f g]
+  (fn [x] (f (g x))))
+
+(defn repeated [f n]
+  (defn iter [inner_f k]
+    (cond
+      (= k 1) inner_f
+      (iter (compose f inner_f) (- k 1))))
+  (iter f n))
+
+(def dx 0.01)
+(defn smooth [f]
+  (fn [x] (let [c (f x)
+                p (f (- x dx))
+                n (f (+ x dx))]
+            (/ (+ c p n) 3))))
+
+(defn n-smooth [f n]
+  ((repeated smooth n) f))
+
+(defn cubic [a b c] (fn [x] (+ (* x x x) (* a x x) (* b x) c)))
+(def abs-cube (compose math/abs math/sin))
+(def smooth-abs (smooth abs-cube))
+
+(def n-smooth-abs (n-smooth abs-cube 5))
+
+(var i 0)
+(while (< i 400000)
+  (printf "%f,%f,%f,%f"
+          (* i 0.00001)
+          (abs-cube (* i 0.00001))
+          (smooth-abs (* i 0.00001))
+          (n-smooth-abs (* i 0.00001)))
+  (set i (+ i 1)))