[R-SIG-Mac] Re : R 2.1.1 for optimized for G5+Tiger

[Simon Urbanek]

Hi Jörg,

On Jun 23, 2005, at 12:14 PM, joerg van den hoff wrote:

> I tried  a run of 1000 non-linear fits (i.e. all the time is spent  
> in "nls" and friends).
> I found no significant difference in the system.time() output  
> (2.1.1. seemed even a bit slower). both took about 22-24 sec. did a  
> miss something?

I didn't look at the implementation of nls, but If the time is spent  
mostly in vecLib or R code, there should be no difference. The  
optimization usually gains only a few percent. I suspect that Naji's  
speed up is due to the update of R.app, because it's running the  
event loop less frequently (there should be posts about that on the  
archives) - it used to slow down R. Unfortunately most of the really  
fast optimizations don't apply to R, because R uses doubles most of  
the time and they cannot be vectorized. Still, C/C++ code should  
benefit from the optimization (I wonder why it should run slower,  
that's really startling).

> a question on the side: would it be a bad idea to install the  
> R.framework with a name including the release (i.e. R. 
> 2.1.1.framework) and than use a place holder symlink R.framework?  
> in this way switching between releases would  be a bit easier.

The idea of the framework is actually to have support for multiple  
releases - just look in R.framework/Versions. If you want to switch  
versions, all you have to do is to change the "Current" symlink. This  
is the way frameworks work and I think it's really convenient. [BTW:  
if you set R_HOME to the full path including the version, you can  
actually run multiple R versions even without changing the symlink,  
because all packages and libraries are linked with the full path.]

> one more observation: the readline functionality is not complete,  
> i.e. ctr-R does not work for accessing the command history.

It's using libedit which comes with Tiger, not readline, so the  
differences are simply in what each library provides. Apple cannot  
ship the system with readline due to licensing issues (readline is  
not LGPL).

Cheers,
Simon