接下来的代码:
(ns clojure101.series)
(defn avg [[x y]] (/ (+ x y) 2))
(defn avg-damp
[seq]
(map avg (partition 2 seq)))
(defn avg-damp-n
[n]
(apply comp (repeat n avg-damp)))
(defn sums
[seq]
(reductions + seq))
(defn Gregory-Leibniz-n
[n]
(/ (Math/pow -1 n) (inc (* 2 n))))
(def Gregory-Leibniz-pi
(map #(* 4 (Gregory-Leibniz-n %)) (iterate inc 0)))
(println (first ((avg-damp-n 10) (sums Gregory-Leibniz-pi))))
当n=20时,我遇到了"gc overhead limit exceeded"错误。该怎么解决呢?
更新:我已更改avg-damp-n函数。
(defn avg-damp-n
[n seq]
(if (= n 0) seq
(recur (dec n) (avg-damp seq))))
现在我可以得到n=20的数字
(time
(let [n 20]
(println n (first (avg-damp-n n (sums Gregory-Leibniz-pi))))))
20 3.141593197943081
"Elapsed time: 3705.821263 msecs"
更新2 我修复了一些错误,现在它可以正常工作:
(ns clojure101.series)
(defn avg [[x y]] (/ (+ x y) 2))
(defn avg-damp
[seq]
(map avg (partition 2 1 seq)))
(defn avg-damp-n
[n]
(apply comp (repeat n avg-damp)))
(defn sums
[seq]
(reductions + seq))
(defn Gregory-Leibniz-n
[n]
(/ (int (Math/pow -1 n)) (inc (* 2 n))))
(def Gregory-Leibniz-pi
(map #(* 4 (Gregory-Leibniz-n %)) (range)))
; π = 3.14159265358979323846264338327950288419716939937510...
(time
(let [n 100]
(println n (double (first ((avg-damp-n n) (sums Gregory-Leibniz-pi)))))))
输出:
100 3.141592653589793
"Elapsed time: 239.253227 msecs"
(partition 2 1 ...)
后,上面的代码就不再适用了。) - kotarak