fenics team mailing list archive

["Theodore Omtzigt" <tomtzigt@xxxxxxxxxxx>]

Anders:

 I had to adjust to the new build process of 0.5.11, but I got everything
wiggling again. This time I get a different convergence failure:

*** Error: Krylov solver did not converge. [KrylovSolver.cpp:104: solve()]

Remember, this is with a PETSc that does not use the Fortran BLAS libs, but
uses a downloaded c-blas-lapack. I haven't figured out what that actually
means, but it does seem to have a profound impact on the sw stack.

Let me rebuild with a PETSc that uses the Fortran BLAS and see what I get:
................
Arggggh, boogers, now I get the same error message with that version as
well..... so my comment above is not proven yet. I need to figure out what
all these messages imply and how to root cause them. Anyone have experience
with that?

Theo

P.S. I see that the build process is moving further away from what is
customary in the Windows world. I need to redo most of the build process
anyway to get it included in a .NET world, so I don't know yet if this is
problematic, but tricks like `dolfin-config --cflags` are just not very
Windows friendly, nor are lots of shell scripted conditionals or pre and
post build file moves like the "make install" target.

  I am a big fan of the jam/bjam cross platform build tools, mostly because
I think Perforce and BOOST are well done, and these tools are very light
weight and comprehend the windows world natively. Something that autoconf
just doesn't. So for now, I'll hold of judgment until I get more familiar
with the environment.



-----Original Message-----
From: fenics-dev-bounces@xxxxxxxxxx [mailto:fenics-dev-bounces@xxxxxxxxxx]
On Behalf Of Anders Logg
Sent: Monday, December 19, 2005 5:26 PM
To: Garth N. Wells; Discussion of FEniCS development
Subject: Re: [fenics-dev] two questions

On Tue, Dec 20, 2005 at 12:38:01AM +0100, Garth N. Wells wrote:
> On Mon, 2005-12-19 at 17:07 -0600, Anders Logg wrote:
> > > 
> > > Setting up PETSc GMRES solver: (rtol, atol, dtol, maxiter) = (1.0e-05,
1.0e-50,
> > > 1.0e+04, 10000).
> > > 
> > > *** Error: GMRES solver did not converge. [GMRES.cpp:71: solve()]
> > > 
> > >  
> > > 
> > > My postulate would be that PETSc with the above configuration somehow
gets put
> > > into single precision mode and the atol=1.0e-50 doesn't stand a
change.
> > > However, I can't find this information (yet) in the PETSc log.
> > > 
> > >  
> > > 
> > > So, any known issues that explain the two issues here?
> > 
> 
> At one stage, not so long ago, the preconditioner was turned off (it's
> on again).
> This lead to a some of the demos not converging, particularly
> when the mesh was refined. Could be an explanation.
> 
> Garth 

Make sure you use the latest version (0.5.11) which should work.

/Anders

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