[R-sig-Debian] Special BLAS and explcit parallel code

[Matthieu Stigler]

Hi

I just read the thread on gotoBLAS, as well as the excellent vignette of 
gcbd. I still have some confusion and would like to ask very basic 
questions, hope I am not taking too much of your time.

The point that retained my attention was the question of using implicit 
(multi-threaded blas) versus explicit (parallel code) optimisation. As I 
understood, the ideal would be to use a multi-threaded BLAS for simple 
code, and restrict it to use one core when parallel R code is used? Do 
you agree? I could not find the presentation of R Bivand on this... Any 
other references on this question?

Secondly, I am a little bit confused about how this is done on Ubuntu. 
First of all.... I am not sure of which BLAS is actually being used... a 
dpkg -l indicated me that both liblas (-dev and 3gf) and libatlas 
(3gf-base) are installed... Doing:

$ ls -n /usr/lib/R/lib/
total 2528
-rw-r--r-- 1 0 0 2583076 2011-02-26 04:21 libR.so

I don't see which one is used actually... how can I figure out?

Thanks!

Matthieu