[R] Switching to Mac, suggestions? (was switching to linux)

[Jari Oksanen]

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 <jarioksa at sun3.oulu.fi>