stirling-naive.clj

(use '(incanter core charts io latex))

(defn stirling [#^Integer n]
  (* (Math/sqrt (* 2 n Math/PI))
     (Math/pow n n)
     (Math/pow Math/E (* -1 n))))

(defn fact [#^Integer n]
  (reduce * (range 2 (inc n))))

(let [n-vals (range 5 1000)]
  (view
   (xy-plot n-vals
            (map #(- (/ (fact %) (stirling %)) 1.0) n-vals)
            :x-label "n"
            :y-label "factorial(n)/stirling(n) - 1")))