On 8/29/07, hui xie <[EMAIL PROTECTED]> wrote: > Thanks very much for all your advice. To be clear, my OS is window XP. I > bought this server last year. It's Dell Precision PWS690. THe processor is > Xeon(TM) CPU 3GHZ, 2G RAM. I am not sure how to check more details of > processor on my computer. But I went to Dell website and from what I can > recall, it seemed that I ordered a Dual-core Intel Xeon 5160 3GHz, 1333FSB, > 4MB L2 Cache, 80watts.
> I think from time to time, I will need linear algebra to do things such as > Choleskey Factorization, and matrix inverse etc... At the same time, I > considered myself quite unskilled on building R by myself. It seems there > were lots of details that I can get things wrong. So if there is an existing > ATLAS one on R website that I can use, I would be very happy to use it to > replace the default one. The reason why I would like to use ATLAS is that R > FAQ said : Rather than worrying about versions of ATLAS you may want to spend your time considering exactly how you are going about the calculations. A general result in numerical linear algebra is that if your algorithm involves computing the inverse of a matrix you have a sub-optimal algorithm. > "The savings can be appreciable: on a 2.6GHz P4 and a 1000 x 1000 matrix svd > took 16.2 sec with the standard BLAS and 7.8 sec with ATLAS. Because ATLAS > is tuned to a particular chip we can't use it generally: the optimal routines > for a P4 or an Athlon XP are quite different and neither will run at all on a > PII." > This seems to me an impressive gain to use the correct ATLAS instead of the > default BLAS. I guess my Xeon processor is either a P4 or Core2Duo, but I > am really not sure which one to use. Could you please offer me some > suggestions? > > Again, many thanks for all your advice! > > Best, > > Hui > > Uwe Ligges <[EMAIL PROTECTED]> wrote: > > Prof Brian Ripley wrote: > > On Tue, 28 Aug 2007, hui xie wrote: > > > >> hi everyone: > >> > >> I have a Dell Server that has a Xeon processor, and I would like to use > >> the best ATLAS posted in the R website. I find that R has ATLAS for > >> core2duo and P4. I am not sure which one of these two is best suited for > >> Xeon processor, or is that neither of these two is good and I should > >> stick with the default one that was installed originally? > > > > And your OS is? > > > > There are many different 'Xeon' processors with very different > > capabilities. > > ... the earlier similar to P4 and some similar to Core2Duo. You won't > make use of bigger L2/L3 caches in Xeon processors. > > > You really ought to build ATLAS for yourself if numerical > > linear algebra performance matters to you (and it makes little difference > > to most people: I think Uwe Ligges quoted 10% for testing all CRAN > > packages). > > > Right, it depends on what you are really doing. If most time is spend in > certain numerical matrix operations, ATLAS is your friend. In all other > cases, it does not matter so much, as Brian cited correctly. > > Uwe Ligges > > > > > >> Your advice is very much appreciated! > >> > >> Best, > >> > >> Hui > >> > >> > >> --------------------------------- > >> Park yourself in front of a world of choices in alternative vehicles. > >> > >> [[alternative HTML version deleted]] > >> > >> ______________________________________________ > >> R-help@stat.math.ethz.ch mailing list > >> https://stat.ethz.ch/mailman/listinfo/r-help > >> PLEASE do read the posting guide > >> http://www.R-project.org/posting-guide.html > >> and provide commented, minimal, self-contained, reproducible code. > > > > Please do! > > > > > > > > --------------------------------- > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
