Improvement of SignRank functions

Hi Ivo,

"IU" == Ivo Ugrina <ivo at iugrina.com>
    on Sat, 15 Dec 2007 14:13:10 +0100 writes:

   IU> Martin Maechler wrote:

   >> do you have evidence for your belief?
   >> i.e. a set of  system.time(.) calls where you see the
   >> difference?

   IU> system.time(dsignrank(17511, 400))
   IU> user  system elapsed
   IU> 1.010   0.120   1.145
   IU> system.time(dsignrank((0:17511), 400))
   IU> user  system elapsed
   IU> 1.25    0.13    1.40
   IU> system.time(dsignrank((0:17511), 500))
   IU> user  system elapsed
   IU> 2.040   0.220   2.296
   IU> system.time(psignrank((0:17511), 600))
   IU> user  system elapsed
   IU> 20.670   0.580  21.403
   IU> system.time(qsignrank(0.56, 300))
   IU> user  system elapsed
   IU> 0.700   0.050   0.753
   IU> ======================================
   IU> system.time(dsignrank(17511, 400))
   IU> user  system elapsed
   IU> 0.070   0.000   0.078
   IU> system.time(dsignrank((0:17511), 400))
   IU> user  system elapsed
   IU> 0.100   0.000   0.104
   IU> system.time(dsignrank((0:17511), 500))
   IU> user  system elapsed
   IU> 0.160   0.000   0.164
   IU> system.time(psignrank((0:17511), 600))
   IU> user  system elapsed
   IU> 16.330   0.370  16.729
   IU> system.time(qsignrank(0.56, 300))
   IU> user  system elapsed
   IU> 0.020   0.010   0.029



   IU> system.time(dsignrank((0:20000), 600))
   IU> user  system elapsed
   IU> 3.470   0.280   3.745
   IU> RAM: ~130MB
   IU> ======================================
   IU> system.time(dsignrank((0:20000), 600))
   IU> user  system elapsed
   IU> 0.250   0.010   0.26
   IU> RAM: ~1MB

that's quite convincing; thank you!
and I can verify part of it on my computer.

I think I'd just commit your signrank.c
(with a few cosmetic changes) to the sources, right?

*Not* using a static with all the previously computed counts
is probably not possible without a (CPU time) efficiency loss;
and to make this thread-safe one could use a "thread-global"
array, but how to do that would really depend on the threading
system used, and that's not at all given.

Thank you for your contribution!
Martin

   >> BTW: If you had a smart idea to *not* use a static 'w' and still
   >> be memory efficient,
   >> that could lead to make that code "thread-safe", but I am
   >> not at all sure this is possible without using
   >> "thread-library C code".

   IU> I'll look into it.


   IU> With respect,
   IU> --
   IU> Ivo Ugrina
   IU> ICQ: 47508335 | www.iugrina.com
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