On Mon, 2004-12-13 at 19:53, doktora v wrote: > I'm looking to switch to Mac platform. Anyone had any experience > with that? I'm expecting on a power G4 laptop later this week.... hope > R behaves... > Still one comment on speed. I once (and, actually, just now) had to analyse a big data set of some 1100 observations using various multivariate methods, among them isoMDS of MASS and eigenvector methods in vegan library. I made a testsuite of typical analysis sequence for this very special data set. So it is non-general, but something that matters to me. I have run this data set on crippled (=Celeron) i686 under Linux and Windows, and on G4 (iBook and iMac) under MacOS X, Yellowdog Linux 3 and Ubuntu GNU/Linux 4.10. It may be daring to say something about G4 performance based on this special case, but this doesn't stop me from saying. For my all sequence, G4 with MacOS X is somewhat faster compared to cpu speed than Celeron, but not nearly as much as advertised. There were some procedures that run slower per MHz than Celeron (isoMDS). However, MacOS X comes with G4-optimized blas, so that eigenvector based analysis was faster: 800 MHz iBook run like 1400 MHz Celeron, and 1000MHz iMac run like 1700 MHz Celeron. I guess the boost depends on time you spend in blas. Otherwise you may count that your G4 cpu cycles equal i686 cpu cycles, and you are slower since you can get faster Intel chips. Vector processor (AltiVec) may be handy, but most functions can't use without very tedious and ugly code optimized by hand. I've seen claims that gcc 3.4 has some automatic G4 optimization. If this is true, you may get some advantage with G4.
G5 is a different issue. Yellowdog Linux 3 didn't have G4-optimized blas, and it was really slow. Actually, 800 MHz iBook run like a 500 MHz Celeron in a blas-heavy analysis. YD3 was so old that I couldn't build an optimized blas without extensive upgrading (gcc, glibc etc), and I really wasn't motivated for that. You can get a G4-optimized blas for Ubuntu GNU/Linux and with that it runs just as fast as MacOS X. BTW, this test matter in the sense that I have to run these analyses, and they take an observable amount of time. The test suite run in 800MHz iBook in 1600 secs, and in in 2GHZ Celeron in 700 secs. We are not talking about millisecond boosts but about going to lunch or sitting by your computer. Another efficiency issue in Mac is that graphics are superb in Mac. The default plot (quartz) is small but sharp. It used to scale instantly when you changed its size, but this deteriorated in 2.0 series. cheers, jari oksanen -- Jari Oksanen <[EMAIL PROTECTED]> ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html