10 lines
372 B
Clojure
10 lines
372 B
Clojure
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(defn stateful-std-deviation[x]
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(letfn [(std-dev[x]
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(let [v (deref (find-var (symbol (str *ns* "/v"))))]
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(swap! v conj x)
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(let [m (/ (reduce + @v) (count @v))]
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(Math/sqrt (/ (reduce + (map #(* (- m %) (- m %)) @v)) (count @v))))))]
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(when (nil? (resolve 'v))
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(intern *ns* 'v (atom [])))
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(std-dev x)))
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