Re: Fibonacci function performance compare between clojure and scala
On Oct 19, 7:49 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
Clojure's
(defn fib [n]
(if (or (zero? n) (= n 1))
1
(+ (fib (dec n) ) (fib (- n 2)
(time (fib 36))
Elapsed Time: 10475.325226 msecs
24157817
Scala's
def fib(n:Int):Int=if (n==0||n==1)1 else fib(n-1)+fib(n-2)
def time(cal: =Int)={
val beginTime=System.currentTimeMillis
cal
val endTime=System.currentTimeMillis
println(endTime-beginTime)}
fib(36)
res70:Int=24157817
time(fib(36))
263
I am not a scala expert but I suspect scala Int maps directly to
java ints.
In clojure, the number are boxed and checked by default IIRC.
This would roughly correspond to BigInt in scala.
For clojure, you could coerce ints to native java types using
(int ..).
Also, unchecked-dec could be used.
Doing this should make the code as fast as java or scala.
There was some discussion along these lines here:
http://groups.google.com/group/clojure/browse_thread/thread/4274ce8bd44664ef#
That said, for most practical uses the default behavior
should be fast enough. Its not considered idiomatic to
use coersion and unchecked operation unless absolutely
necessary.
Parth
Both not tail recursive,both running on Repl (scala's interpreter),but
the difference between two is huge
10475~263
My box : Intel core2 cpu 1.86G，2G mem
Clojure and scala both latest build from svn
any ideas?
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Re: Fibonacci function performance compare between clojure and scala
Scala is sure to use java primitive int type underline, i.e value type and boxed to java Integer when necessarily But why not Clojure auto make this ? gerry On Oct 19, 11:31 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: Here is coersion version for Clojure (defn fib [n] (let [n (int n)] (if (or (zero? n) (= n 1)) 1 (+ (fib (dec n) ) (fib (- n 2)) (time (fib 36)) Elapsed time 8848.865149 not much better and how to type hint for a int type? --~--~-~--~~~---~--~~ 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 To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Fibonacci function performance compare between clojure and scala
There is also a faster way to calculate fibonacci numbers in Clojure
(code taken from from
http://en.wikibooks.org/wiki/Clojure_Programming#Lazy_Fibonacci):
(defn fib-seq []
((fn rfib [a b]
(lazy-cons a (rfib b (+ a b
0 1))
user= (time (take 38 (fib-seq)))
Elapsed time: 0.032965 msecs
(0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765
10946 17711 28657 46368 75025 121393 196418 317811 514229 832040
1346269 2178309 3524578 5702887 9227465 14930352 24157817)
Lauri
2008/10/19 [EMAIL PROTECTED] [EMAIL PROTECTED]:
Clojure's
(defn fib [n]
(if (or (zero? n) (= n 1))
1
(+ (fib (dec n) ) (fib (- n 2)
(time (fib 36))
Elapsed Time: 10475.325226 msecs
24157817
Scala's
def fib(n:Int):Int=if (n==0||n==1)1 else fib(n-1)+fib(n-2)
def time(cal: =Int)={
val beginTime=System.currentTimeMillis
cal
val endTime=System.currentTimeMillis
println(endTime-beginTime)
}
fib(36)
res70:Int=24157817
time(fib(36))
263
Both not tail recursive,both running on Repl (scala's interpreter),but
the difference between two is huge
10475~263
My box : Intel core2 cpu 1.86G，2G mem
Clojure and scala both latest build from svn
any ideas?
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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
To unsubscribe from this group, send email to [EMAIL PROTECTED]
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Re: Fibonacci function performance compare between clojure and scala
This lazy cached calculate is wonderful ,but i think the benefit from
it mostly due to cache .
On Oct 19, 11:56 pm, Lauri Oherd [EMAIL PROTECTED] wrote:
There is also a faster way to calculate fibonacci numbers in Clojure
(code taken from
fromhttp://en.wikibooks.org/wiki/Clojure_Programming#Lazy_Fibonacci):
(defn fib-seq []
((fn rfib [a b]
(lazy-cons a (rfib b (+ a b
0 1))
user= (time (take 38 (fib-seq)))
Elapsed time: 0.032965 msecs
(0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765
10946 17711 28657 46368 75025 121393 196418 317811 514229 832040
1346269 2178309 3524578 5702887 9227465 14930352 24157817)
Lauri
2008/10/19 [EMAIL PROTECTED] [EMAIL PROTECTED]:
Clojure's
(defn fib [n]
(if (or (zero? n) (= n 1))
1
(+ (fib (dec n) ) (fib (- n 2)
(time (fib 36))
Elapsed Time: 10475.325226 msecs
24157817
Scala's
def fib(n:Int):Int=if (n==0||n==1)1 else fib(n-1)+fib(n-2)
def time(cal: =Int)={
val beginTime=System.currentTimeMillis
cal
val endTime=System.currentTimeMillis
println(endTime-beginTime)
}
fib(36)
res70:Int=24157817
time(fib(36))
263
Both not tail recursive,both running on Repl (scala's interpreter),but
the difference between two is huge
10475~263
My box : Intel core2 cpu 1.86G，2G mem
Clojure and scala both latest build from svn
any ideas?
--~--~-~--~~~---~--~~
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
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/clojure?hl=en
-~--~~~~--~~--~--~---
Re: Fibonacci function performance compare between clojure and scala
Hello, Am 19.10.2008 um 17:56 schrieb Lauri Oherd: There is also a faster way to calculate fibonacci numbers in Clojure (code taken from from http://en.wikibooks.org/wiki/Clojure_Programming#Lazy_Fibonacci): (defn fib-seq [] ((fn rfib [a b] (lazy-cons a (rfib b (+ a b 0 1)) user= (time (take 38 (fib-seq))) Elapsed time: 0.032965 msecs (0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765 10946 17711 28657 46368 75025 121393 196418 317811 514229 832040 1346269 2178309 3524578 5702887 9227465 14930352 24157817) This timing is wrong. Since take returns a lazy sequence you only get the timing for the call to take. The sequence is forced later on when the Repl prints it. The correct way is to force the evaluation with doall. user= (time (take 38 (fib-seq))) Elapsed time: 0.055 msecs ... user= (time (doall (take 38 (fib-seq Elapsed time: 0.3 msecs ... Sincerely Meikel smime.p7s Description: S/MIME cryptographic signature
