Ivan,
On Mar 13, 2010, at 7:04 AM, Ivan Calandra wrote:
Dear Mac Users,
New on R Mac (MacOS X 10.6), I've used up to now R.app [R.app GUI 1.31 (5537) i386-apple-darwin9.8.0].
But I've tried R64 [R.app GUI 1.31 (5537) x86_64-apple-darwin9.8.0] and it also works.
If both work, which one should I use? Is there any difference in terms of speed for example (which would not be really critical for me since I don't really handle large datasets) or anything else.
There is no clear answer to that. In general, using 32-bit R is a bit safer because not all packages support 64-bit. The main advantage of 64-bit is that you can use more memory (>4GB). Historically, 64-bit R was used only on machines a lot of RAM. As of speed, on the one hand 64-bit instruction set is faster as it can take advantage of new features, but on the other hand it uses twice as much memory for pointers which is slows it down. I have posted some info on the list here a while ago
http://www.mail-archive.com/r-sig-mac at stat.math.ethz.ch/msg04244.html
there is no clear winner - there are tasks where one is faster than the other either way.
In OS X 10.6 all applications are now by default 64-bit so in fact the command line R is 64-bit so Apple's suggestion is to use the R64.app in Snow Leopard -- but it's more about technology than real benefits I think...
Cheers,
Simon