Re: Why is this code so slow?

2013-02-03 Thread Alexandros Bantis
yes, I believe I can just make a list of the greatest common factors and 
then multiply them out to get the number rather than iterating through 2 
through n. Still, I'm curious about the performance difference, since 
all three are running on the same JVM and ultimately are all compiled 
down to java byte code, you would expect that a similar algorithm would 
produce similar results across the three.


On 02/03/2013 07:29 AM, Jules wrote:

If your goal is just to make it fast, then you should use a different
 algorithm, e.g.

(defn bump-up Bump up n by a multiple of x until greater than or
equal to k. [n x k] (if (= n k) n (recur (+ n x) x k)))

(defn bump-up-fast Bump up n by a multiple of x until greater than
or equal to k in O(1). [n x k] exercise for the reader)

(defn lcm Compute the least common multiple of a and b. [a b] (loop
[n a k b] (cond ( n k) (recur (bump-up n a k) k) ( n k) (recur n
(bump-up k b n)) (= n k) n)))

(defn smallest-multiple-of-1-to-n [n] (reduce lcm (range 1 (+ n
1

On Sunday, February 3, 2013 3:28:09 AM UTC+1, Alexandros Bantis
wrote:

Hello all. I'm working through the Project Euler problems in Java,
Scala,  Clojure (trying to learn all three?!?). I notice that for
one particular problem, I use--more or less--a similar algorithm for
all three, but the clojure code runs about 20-30 times slower than
the java/scala versions. Does anyone have any idea why this might be?
It strikes me that it might have something to do with every? but I
don't know because I'm a newbie with Clojure.

http://stackoverflow.com/questions/14668272/what-can-i-do-to-speed-up-this-code



http://stackoverflow.com/questions/14668272/what-can-i-do-to-speed-up-this-code



thanks,

alex

-- -- 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 --- You received this
message because you are subscribed to the Google Groups Clojure
group. To unsubscribe from this group and stop receiving emails from
it, send an email to clojure+unsubscr...@googlegroups.com. For more
options, visit https://groups.google.com/groups/opt_out.




--
--
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
--- 
You received this message because you are subscribed to the Google Groups Clojure group.

To unsubscribe from this group and stop receiving emails from it, send an email 
to clojure+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.




Why is this code so slow?

2013-02-02 Thread Alexandros Bantis
Hello all. I'm working through the Project Euler problems in Java, 
Scala,  Clojure (trying to learn all three?!?). I notice that for one 
particular problem, I use--more or less--a similar algorithm for all 
three, but the clojure code runs about 20-30 times slower than the 
java/scala versions. Does anyone have any idea why this might be? It 
strikes me that it might have something to do with every? but I don't 
know because I'm a newbie with Clojure.


http://stackoverflow.com/questions/14668272/what-can-i-do-to-speed-up-this-code

thanks,

alex

--
--
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
--- 
You received this message because you are subscribed to the Google Groups Clojure group.

To unsubscribe from this group and stop receiving emails from it, send an email 
to clojure+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.