Emmanuel,
On 30 August 2008 at 00:04, Emmanuel Charpentier wrote:
| Dear list, | | Setup : Ubuntu Hardy + updates + backports + security + R repository on | a 3.2 GHz PIV dual-core processor. | | Bitten (again...) by the "I'll optimize my setup" bug, I tried to test | atlas. Following Dirk's advice on a not-so-recent post to R-help, I | tried "apt-get install -s atlas3-doc atlas3-base-dev" (I tend to | recompile some packages, so I need r-base-dev and I *think* I need | atlas3-base-dev to allow the recompiled packages to use it, but I might | be completely wrong...). Ahem ... : | | [ Snip... ] | | Les paquets suivants seront ENLEV?S : | libblas-dev liblapack-dev r-base-dev | | [ Snip again ... ] | | (for non-francophones : "The following packages will be REMOVED : ..."). | | However, atlas3-base *is* currently installed, and I never had problems | recompiling packages. Quick guess: you have the old atlas-* packages instead of the new libatlas-* packages. Try $ sudo apt-get install libatlas3gf-base libatlas-base-dev | So, my (first) question is : what would be the benefits of installing | atlas3-base-dev ? Isn't that necessary for recompiling packages ? [Make that libatlas-base-dev] So that you can compile against Atlas and get the 'automatically tuned linear algebra system' for better performance on linear algebra. | Second question : what would be the benefits/drawbacks of "apt-get | install atlas3-sse2 lapack3" ? A brief test seems to hint to limited | benefits... [Make that libatlas3gf-sse2] Faster performance for binary code tuned to your process. Atlas actually provides lapack, and replace it in use. | Last but not least : Atlas does not seem to exist on other architectures | (I'm interested in amd64, of course...), at least in Debian and Ubuntu. | Are there similar projects for amd64 I'm not aware of ? Are you sure? This has built on many architectures for many years, and the reason it took so long to get to libatlas [ie the new build with the new Fortran compuler] was as far as I know the darn portability. All this works on my Debian (which gets R from my Debian packages) and Ubuntu (which gets R from CRAN) machines. Hope this helps, Dirk
Three out of two people have difficulties with fractions.