You could use (-1)^{i+1}, which would be a bit more mathy but it may not be
efficient.
(defn altsum [n]
(->>
(range 1 (inc n))
(map #(* % (Math/pow -1 (inc %))))
(reduce +)))
On Nov 13, 2014, at 6:31 PM, Andy L <core.as...@gmail.com> wrote:
> Hi,
>
> All I was able to come up with was this
>
> (defn altsum[n] (reduce + (map * (range 1 (inc n)) (interpose -1 (repeat
> 1)))))
>
> ... works quite well, however I was wondering if there is more idiomatic way
> to write that.
>
> Thanks,
> Andy
>
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