Is GSL a single or multi-threaded math library?

[Charlie Zender]

Hi, 

The sysadmin on our IBM supercomputers (8-node and 128-node)
does not want to install GSL there because:

> As per my voicemail response: In general, SCD doesn't support 
> single-threaded math libraries on our IBMs.  That is why you 
> don't see familiar libraries like slatec or fftpack there.  
> 
> We do this for efficiency reasons.  We prefer that users use the
> vendor library ESSL if possible.  However, sometimes that is not
> possible.

I'm not sure how to respond to this.
I'm not a computer scientist, so I don't even know if GSL
is single or multi-threaded, or if the question means anything.
I know that the C/C++ codes that I write use OpenMP (when the
compiler supports OpenMP) to enable multi-threaded computations.
Is there a distinction between this and GSL itself being
multi-threaded? In case it matters, the specific GSL routines I use
are gsl_complex and about 6 routines in the gsl_sf_erf and
gsl_sf_gamma families. Does anyone know whether GSL would be
superior or inferior to the "vendor library ESSL" (I have
no idea what ESSL means) for the IBM AIX platform?

Any clues appreciated,
Charlie
-- 
Charlie Zender zender@uci.edu (949) 824-2987/FAX-3256, Department of
Earth System Science, University of California, Irvine CA 92697-3100
Visiting NCAR CGD Jul 1-Aug 31: Room ML-304A (303) 497-1738/FAX-1324
Work Address: NCAR CGD, 1850 Table Mesa Dr., Boulder, CO, 80303-5602