[CIG-SHORT] PyLith problems

[Jiangning Lu]

Hi Brad,

I'm using the same boundary conditions in this model with the
example/3d/tet4/dislocation case.

Using the same mesh,I also run another problem successfully without a fault
specified. From this can I say that the material ids are correct? In other
words, specifying a fault will not change the material id settings?

Thanks,

Jiangning


Quoting Brad Aagaard <baagaard at usgs.gov>:

> Jiangning-
>
> The zero pivot suggests that you have a singular matrix. This usually means
> that the problem is not sufficiently constrained (some sort of rigid body
> motion is allowed). This is what why the asm preconditioner doesn't work for
> the two-cell examples. I think it would also show up if you have cells that
> are not associated with any material (i.e., the ids don't match), so that the
> stiffness matrix contains a bug of zeros.
>
> Brad
>
>
> On Thursday 06 December 2007, Jiangning Lu wrote:
>> Hi,
>>
>> When I tried to run one of my model by setting pc_type = asm, I got the
>> following error:
>> ......
>>  -- Solving linear equations.
>> [0]PETSC ERROR: --------------------- Error Message -------------
>> [0]PETSC ERROR: Detected zero pivot in LU factorization
>> see
>> http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#Ze
>> roPivot! [0]PETSC ERROR: Zero pivot row 61695 value 2.29519e-19 tolerance
>> 2.93442e-13 * rowsum 0.293442!
>> [0]PETSC ERROR: Petsc Development Version 2.3.3, Patch 8, unknown HG
>> revision: unknown
>> [0]PETSC ERROR: See docs/changes/index.html for recent updates.
>> [0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
>> [0]PETSC ERROR: See docs/index.html for manual pages.
>> [0]PETSC ERROR:
>> ------------------------------------------------------------------------
>> [0]PETSC ERROR:
>> /chandler/home/jlu/scratch1/pylith_workarea/nemesis/trunk/mpinemesis on a
>> linux-gnu named elsasser by jlu Thu Dec  6 12:50:16 2007
>> [0]PETSC ERROR: Libraries linked from
>> /chandler/home/jlu/scratch1/pylith_workarea/petsc-dev/lib
>> [0]PETSC ERROR: Configure run at Wed Nov 28 15:24:59 2007
>> [0]PETSC ERROR: Configure options --with-sieve=1 --with-clanguage=C++
>> --with-shared=1 --download-f-blas-lapack=1 --with-boost=1
>> --download-boost=1 --with-chaco=1 --download-chaco=1 --with-mpi=1
>> --download-mpich=1
>> --with-mpi-shared=1
>> [0]PETSC ERROR:
>> ------------------------------------------------------------------------
>> [0]PETSC ERROR: MatLUFactorNumeric_Inode() line 1495 in
>> src/mat/impls/aij/seq/inode.c
>> [0]PETSC ERROR: MatLUFactorNumeric() line 2276 in
>> src/mat/interface/matrix.c [0]PETSC ERROR: PCSetUp_ILU() line 564 in
>> src/ksp/pc/impls/factor/ilu/ilu.c [0]PETSC ERROR: PCSetUp() line 788 in
>> src/ksp/pc/interface/precon.c [0]PETSC ERROR: KSPSetUp() line 234 in
>> src/ksp/ksp/interface/itfunc.c [0]PETSC ERROR: PCSetUpOnBlocks_ASM() line
>> 224 in src/ksp/pc/impls/asm/asm.c [0]PETSC ERROR: PCSetUpOnBlocks() line
>> 821 in src/ksp/pc/interface/precon.c [0]PETSC ERROR: KSPSetUpOnBlocks()
>> line 158 in src/ksp/ksp/interface/itfunc.c [0]PETSC ERROR: KSPSolve() line
>> 347 in src/ksp/ksp/interface/itfunc.c [0]PETSC ERROR: preallocateOperator()
>> line 190 in
>> unknowndirectory/solver_embed.cpp
>>
>> When I changed the setting to pc_type = jacobi, the error did not show up,
>> but the result looks not right either.
>> Any thoughts?
>>
>> Thanks!!
>> Jiangning
>>
>> ---
>> Jiangning Lü
>> 54-521     x3-6389
>> Geophysics
>> EAPS, MIT
>> johnnylu at mit.edu (????
>> _______________________________________________
>> CIG-SHORT mailing list
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>
>
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---
Jiangning Lü
54-521     x3-6389
Geophysics
EAPS, MIT
johnnylu at mit.edu (????