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Date:Mon May 30 13:57:13 2001 
Subject:Re: GSL collaboration 
From:David Young 
Volume-ID:1010530.01 

A few thoughts about the GSL idea:

Poplog already has the vec_mat package which does some useful numerical
stuff. It was produced by Harry Barrow and Jim Stone some years ago. I
think it was funded by a research council and so ought to be freely
available, but it doesn't seem to be on the Birmingham web site, unless
I've missed it. For anyone who is looking for vector and matrix
operations now, it could be useful, though its scope is limited compared
to GSL, and I have found the odd bug. I seem to remember that they based
it on "Numerical Recipes" but I'm not certain. (Aaron: it's in the local
tree at Sussex.)

GSL looks like it has very good coverage, but I don't know anything
about the quality of the routines. I always think of the gold standard
as NAg (see http://www.nag.co.uk/) which pays huge attention to detailed
and subtle but vital numerical issues - stability and error propagation
and all that. If GSL can compete in that area, then it could be
extremely useful. Anyone know of a review or anything that looks at
their testing regime?

I started writing an interface for the NAg Fortran library years ago but
never had time to really follow it up. Drawbacks were that you have to
buy NAg, Fortran compilers became seen as rather esoteric things that
also needed special licences, and the NAg C library, when it became
available, didn't have the same coverage as the Fortran library. I think
this work did have some useful spin-offs in improving the interfaces for
external linking, which were used for some of the X-windows interface.

Anyway ...

If GSL is good, then I agree with Aaron about what would be useful, viz:

> I was thinking more of providing convenient pre-packaged interfaces
> with some limited documentation, which would point to the full GSL
> documentation.

and

> ... (A pop11 program reads the
> GSL documentation, and then genrates all the interface files ?????)

[Maybe it would be sufficient for it to read the header files?]

Ideally an installer ought to be able to download and compile GSL and
then generate the interface just by specifying a path and running a
procedure. After that, a user should be able to say "uses gsl" and then
be able to able to run gsl routines via Pop-11 routines, without ever
looking at HELP/REF EXTERNAL.

However, there are some hard bits. One is dealing with the GSL macros.
Another is deciding whether Pop-11 arrays can be passed to the gsl
procedures, or whether the user has to do some explicit translation.
There are, I suspect, quite a few similar major representation issues.

I'm not volunteering to do anything about it just yet, but I am
interested in the project.

David