Re: Nonlinear CG

Peter,
Interesting. I'll start thinking about it.

I think most nonlinear CG flavors require one additional concept: a
function,
  func(const vector& x, scalar& result, vector& result_gradient),
which computes f(x) and f'(x).

I actually don't want to use PETSc data. My state vector represents atom
positions as well as continuum displacements, stored separately, so
basically it's a heterogeneous mess. (This is part of the reason a generic
approach seems so appealing – I should be able to abstract that
heterogeneity away.)

Do you know where I might find pseudocode (or just Free code) for of
algorithm?

—Ben


On 1/9/07, Peter Gottschling <[email protected]> wrote:
>
> Dear Ben,
>
> As far as I know, non-linear solvers does not exist in ITL.  It is an
> excellent idea and we will likely work on it in the future.  If you
> want to work on this, I'd be happy to support you.
>
> I don't know if that helps you, I've written an interface between PETSc
> and parallel BGL so that one can read out parallel PETSc matrices from
> generic libraries and also access to distributed PETSc vector without
> copying them.  However, it sounds more that you want to use PETSc data
> with in a clearer way than I did. ;-)
>
> Best Regards,
> Peter
>
> On 09.01.2007, at 18:01, Ben FrantzDale wrote:
>
> > Dear ITL-devel,
> > I'm glad I finally found ITL. It looks like it could be the Right Way
> > to solve a bunch of problems that various closed-source Fortran
> > libraries have attempted.
> >
> > I am interested in solving large nonlinear minimization problems in
> > parallel. Presently we are experimenting with several CG solvers. The
> > work, but all of them want to see the state vector as a single
> > contiguous array of doubles. The ITL example using PETSc in parallel
> > makes me think there are interesting possibilities for large nonlinear
> > problems as well.
> >
> > The ITL distribution includes two nonlinear examples, but all of the
> > solvers appear to be linear. Has anyone extended ITL to do nonlinear
> > minimization?
> >
> > Again, great work.
> >
> > Thanks,
> > Ben FrantzDale_______________________________________________
> > This list is archived at http://www.osl.iu.edu/MailArchives/mtl-devel/
> ------------
> Peter Gottschling, Ph.D.
> Research Associate
> Open Systems Laboratory
> Indiana University
> 135 Lindley Hall
> Bloomington, IN 47405
> Tel.: +1-812-855-3608   Fax: +1-812-856-0853
> http://www.osl.iu.edu/~pgottsch
>
>
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