On Jul 17, 2010, at 9:46 PM, Isaac Hodes wrote:
> I did check out your response: it's rather fast on my machine. it's
> not really functional, though, as you use the `let` macro as a way of
> procedurally executing a lot of functions. This isn't bad at all, but
> you're not composing functions.
'Functional' means simply avoiding mutation and side-effects. How the code is
organized is a separate issue.
In case you're interested, I made a small change to the code I posted before
that makes it significantly faster. I don't know what you consider 'slow', but
it takes 2-3x as long as your imperative Python version on my hardware (less if
I replace the outermost map with pmap, depending on the input sizes). I think
that's quite acceptable, especially given Clojure's relative youth as a
language.
(defn convolve-indices [i max-m max-n]
"Lists all index pairs adding up to i, where the first index is less than
max-m and the second is less than max-n."
(map #(vector % (- i %))
(range
(max 0 (inc (- i max-n)))
(min (inc i) max-m))))
(defn convolve-1 [i ms ns]
"Returns the ith value of the convolution of ms with ns."
(reduce +
(map (fn [[m n]] (* (ms m) (ns n)))
(convolve-indices i (count ms) (count ns)))))
(defn convolve [ms ns]
"Convolves ms with ns."
(map #(convolve-1 % ms ns)
(range (dec (+ (count ms) (count ns))))))
--
You received this message because you are subscribed to the Google
Groups "Clojure" group.
To post to this group, send email to clojure@googlegroups.com
Note that posts from new members are moderated - please be patient with your
first post.
To unsubscribe from this group, send email to
clojure+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/clojure?hl=en
