Re: [pooma-dev] Some special needs for Lattice Gauge Theory

[Norbert Nemec]

On Tue, Sep 03, 2002 at 12:00:11PM +0200, Richard Guenther wrote:
> On Tue, 3 Sep 2002, Norbert Nemec wrote:
> > The things I need are:
> > * 4 dimensional fields in euclidean space-time (I assume that's just gonna
> >   be some copy-and-paste work)
> 
> This should be supported by POOMA already.

In 2.4.0, fields are limited to 3 dimensions. Necessary changes are spread over
a number of spots in the sources.

> > * extensive use of random-number-generators (RNGComponent fits most of my 
> > needs)
> 
> Didnt look into the RNGComponent class yet.

It is quite straigtforward and simple. Anyhow, there is only one very simple 
RNG to use. Shouldn't be a problem though to add more elaborate ones.

> > * some kind of stencils with more than one input field (to allow the use of
> >   per-site-RNG within the stencil)
> 
> You mean a stencil that has an operator() like
> 
>   A& operator()(const B&, const C&) const;
> 
> this would be useful for me, too. It seems the FieldStencil(Simple) needs
> some work - at least in documentation.

Well, yes, documentation is somewhat minimalistic in some areas, but that's ok.
I have no idea how much time I'm can spend on that. I know that many of my own 
troubles
would have been solved by adequate documentation, but since I'm not a very 
literate
programmer myself I'm not in the position to criticise...

> But multi-input stencils are possible.

??? Could you give details on that? What do you mean with "multi-input" if not 
one
with an "A& operator()(const B&, const C&) const;" ?


> 
> > Much of the stuff would probably be implementable without any changes to the
> > POOMA sources, but the kind of work I'm preparing for demands some kind of 
> > abstraction
> > of different field types (U(1), SU(N), gaugefields, scalar fields, vector 
> > fields) and
> > algorithms (Metropolis, and more specialized Monte Carlo methods)
> 
> Hmm - can you elaborate more on these "field types"? What fundamental
> properties do they share/differ in? How would you use them?

Well, in general I'm focusing on Monte-Carlo simulations. I'm pretty new to 
that area 
myself, so my ideas are still somewhat vague.

Anyhow, there are several kinds of particle fields (real, complex, scalar, 
multi-component,
and so on) as well as their gauge fields. Some having several ways for 
discretization.

On the other hand, there are several methods for Monte Carlo simulation 
(Metropolis,
Langevin, Molecular Dynamics and hybrid types)

I still have some way to go before I understand all the details, and especially 
how
they can be implemented and how their common properties can be pulled together
and abstracted.

There is a long way to go, but I know it will be more revarding to go that way 
instead
of implementing each combination from scratch...

> > Any ideas and cooperation are very welcome. I'm pretty serious about 
> > investing some
> > time and others will hopefully have some profit from it, too.
> 
> Contributing is very well needed. I'm trying to do this myself, but be
> prepared to be confronted with some legal issues from the CodeSourcery if
> you want to contribute. I hope I get positive feedback from our local
> legal department after I return from vacation.

Thanks for the hint. Haven't sent much thought on that, yet, but I guess, it 
might be 
a good idea...

Ciao,
Nobbi

-- 
-- _____________________________________Norbert "Nobbi" Nemec
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