Dear libMesh team,

It seems as if the thing is now running quite well for me.  (I fixed 
some bugs in the meantime, all of which were all on the application 
side.)  I've still not been able to test it in parallel though, since 
the cluster is still making trouble.  I hope this will be repaired 
soon (altough I've been hoping this since several weeks now).

There is one weakness of my implementation: If you have A = B + v*w' 
(as I have) and want to use B as the preconditioning matrix (to be 
able to use ILU) (as I am doing now), you have to store two sparse 
matrices although there is only one.  That is because 
LinearImplicitSystem::solve() calls have_matrix("Preconditioner") to 
find out whether the preconditioning matrix differs from the system 
matrix.  So I have to add a preconditioning matrix manually.  On the 
other hand, LinearImplicitSystem::matrix exists nevertheless.  I think 
I don't have to put too much effort now in solving this problem since 
you will restructure the implementation anyway and your restructuring 
is likely to resolve this problem "on the fly".

Another issue is a sensible example program that uses the shell matrix 
concept.  I think it should be sensible to have one since there are 
some pitfalls (such as the correct constraining methods I mentioned 
last week).  Unfortunately, I cannot think of a sensible, simple 
example application.  (The one I'm working on is far too complicated 
for that purpose.)  Does anyone have a sensible idea?

Best Regards,

Tim

-- 
Dr. Tim Kroeger                                        Phone +49-421-218-7710
[EMAIL PROTECTED], [EMAIL PROTECTED]  Fax   +49-421-218-4236

MeVis Research GmbH, Universitaetsallee 29, 28359 Bremen, Germany

Amtsgericht Bremen HRB 16222
Geschaeftsfuehrer: Prof. Dr. H.-O. Peitgen

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