Re: valarray

[Gabriel Dos Reis <Gabriel.Dos-Reis@dptmaths.ens-cachan.fr>]

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>>>>> «Nathan», Nathan Myers <ncm@cygnus.com> wrote:

Nathan> You should know that (as much as we appreciate Gabriel's contribution) 
Nathan> that valarray is generally a poor way to accomplish what it was intended 
Nathan> for.  A much better choice is something like Blitz++ or its kin, which you 
Nathan> can find at (or by following links from)

Nathan>   http://monet.uwaterloo.ca/blitz/

Nathan> To perform well, valarray really needs special compiler support, and because
Nathan> projects like Blitz++ have been so successful, valarray is unlikely ever to 
Nathan> get that support.


Any efficient C/C++ library in numerical computation *needs* some
support from the compiler (e.g. keyword "restrict" in C). I know (in
some extent) very well the blitz project. Todd is aware (at least it
was pointed to him when he visited CERN recently) that the blitz
project, as it is now, is not usable in real world scientific
computing (e.g. in finite elements, large linear systems, systems from
physics). Nevertheless it introduced new concepts which deserve new
ways of optimization. 

Actually (as Bjarne told me in Sophia last March), the sade state of
valarray is a consequence of a lack of numerical computation expert in
the committee. It's just recently that I gained interest in using C++
in scientific computing. Anyway, I would really like to support an
efficient, usable valarray but for that I *need* some support form
folks here. I'm not a compiler designer but I can spend time to
learn gcc internals in order to get an efficient valarray if there
guys to explain me how things are made up.

-- Gaby