Re: [ROOT] How to Call CERNLIB routines from the interpreter

From: Dave Morrison (dave@bnl.gov)
Date: Wed Dec 20 2000 - 18:59:45 MET


Christian Holm Christensen wrote:

> I'd like to direct your attention to the "GNU Scientific Library"
> (GSL) developed, among others, by people from Los Alamos. This is a
> very general library with many many features aimed for scientific
> use. It's written in ANSI C, and is very portable. Also, it's released
> under GPL, making it truely OpenSource. No wrappers in C++ exist, but
> as far as I can tell, it should be fairly easy to do. For a more
> complete description of the features in GSL, please look at

Hi,

I'd second this idea - at least as something to investigate.  We've had
GSL available in PHENIX for about a year and it seems to work well.  One
of the nice things about GSL is that it's being written by people with
knowledge of numerical computing; it's not trivial to write good
numerical software.  I mean, I can write a series expansion for a Bessel
function as well as the next guy, but I'd have a hard time guaranteeing
the results are correct out to the least-significant digit.  

(Prof. Kahan at Berkeley has some nice papers about the myriad ways in
which numerical implementations go awry:
http://www.cs.berkeley.edu/~wkahan/ )

GSL also has a extensive test suite to spot check the behavior of the
library.  

It's also not quite true that there are _no_ C++ wrappers for GSL.  The
Fermilab folks have wrappers for the special functions part of GSL:

http://www.fnal.gov/docs/working-groups/fpcltf/Pkg/SpecialFunctions/doc/SpecialFunctions.html

Whether the particular way they've chosen to do things is the best way
or not is a different question, but it's at least a place to start.

Cheers,
Dave

-- 
David Morrison  Brookhaven National Laboratory  phone: 631-344-5840
                Physics Department, Bldg 510 C    fax: 631-344-3253
		          Upton, NY 11973-5000  email: dave@bnl.gov



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