[R-SIG-Mac] R 2.10.0

[Simon Urbanek]

On Oct 27, 2009, at 11:11 , Luca Scrucca wrote:

> Dear Simon,
>
> first of all I would like to thank you for providing the Mac binary  
> package for the latest version of R.
> It works ok on my two years old MBP with OSX 10.5.8.
> As mentioned in the web page the GUI installed are two, 32-bit GUI  
> (R.app) and 64-bit GUI (R64.app).
> I noticed that running a simple loop in the two GUI I got different  
> values. For example, having defined the function
>
> fun <- function(n)
> { for(i in 1:n)
>     median(rnorm(100000))
> }
>
> I obtained the following typical timings:
>
> [R.app GUI 1.30 (5511) i386-apple-darwin9.8.0]
> > system.time(fun(1000))
>   user  system elapsed
> 30.131   2.460  32.506
>
> [R.app GUI 1.30 (5511) x86_64-apple-darwin9.8.0]
> > system.time(fun(1000))
>   user  system elapsed
> 24.927   2.151  26.957
>
> The second is always smaller, although my MBP is not 64 bit. Can you  
> comment on that? I'm just curious.
>

Your MBP *is* 64-bit capable otherwise you couldn't run the 64-bit GUI  
at all (there are very few Apple machines that had the early ICD/ICS  
without 64-bit support - they are rather rare, all other machines  
starting with IC2D are 64-bit capable).

On Intel machines the 64-bit instruction set is different form the 32- 
bit instruction set since it didn't have to follow the legacy baggage  
from 16-bit times of x86. As a result code using the 64-bit  
instruction set can be more efficient than its 32-bit (ix86)  
counterpart. This is counterbalanced by the fact that all pointers  
have double the size in 64-bit and thus you have to use double the  
memory and associated speed penalty, so depending on the task (yours  
is trivial enough to not involve too many pointer operations) the net  
result is speed-up or slow-down.


> I also noticed that running R64.app the X11 environment is also  
> started (the graphical device is the default, i.e. quartz). This  
> does not happen with R.app.
>

At a first glance I see no difference between those and neither of  
them starts X11 on my machine ...


> Aside, there is a broken link in the web page http://cran.r-project.org/bin/macosx/ 
> , namely the link to the tools directory for R-2.10.0.pkg (there is  
> a missing 's' in the URL).
>

Thanks, that was reported and fixed already.

Cheers,
Simon