Dear libmesh developers and users:
I'm not been able to solve ex11 or ex13 using LU factorization. I get the
error shown below. Does this means the matrix is singular?? PETSC
documentation states "If this error occurs in the *zeroth row * of the
matrix it is likely you have an error in the code that generates the
matrix". What's happening?. I'm trying to understand this because I think it
might be related to a problem I'm having with a 2-phased incompressible flow
simulation code I'm writing.
Many thanks for the help,
Nestor Solalinde
Output:
u...@server:/libmesh_3769/examples/ex13$ ./ex13-opt -ksp_type preonly
-pc_type lu
Mesh Information:
mesh_dimension()=2
spatial_dimension()=3
n_nodes()=1681
n_local_nodes()=1681
n_elem()=400
n_local_elem()=400
n_active_elem()=400
n_subdomains()=1
n_processors()=1
processor_id()=0
EquationSystems
n_systems()=1
System "Navier-Stokes"
Type "TransientLinearImplicit"
Variables="u" "v" "p"
Finite Element Types="LAGRANGE" "LAGRANGE" "LAGRANGE"
Approximation Orders="SECOND" "SECOND" "FIRST"
n_dofs()=3803
n_local_dofs()=3803
n_constrained_dofs()=0
n_vectors()=3
*** Solving time step 0, time = 0.01 ***
[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#ZeroPivot
!
[0]PETSC ERROR: Zero pivot row 0 value 0 tolerance 8.33333e-14 * rowsum
0.0833333!
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: Petsc Release Version 3.0.0, Patch 11, Mon Feb 1 11:01:51
CST 2010
[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: ./ex13-opt on a linux-gnu named ACARAY by manolo Tue Mar 30
17:21:07 2010
[0]PETSC ERROR: Libraries linked from
/opt/petsc/petsc-3.0.0-p11/linux-gnu-cxx-debug/lib
[0]PETSC ERROR: Configure run at Tue Mar 9 23:57:09 2010
[0]PETSC ERROR: Configure options --with-cc=gcc --with-fc=0 --with-cxx=g++
--download-c-blas-lapack=1 --download-mpich=1 --with-clanguage=cxx
--with-shared=0
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: MatLUFactorNumeric_SeqAIJ() line 581 in
src/mat/impls/aij/seq/aijfact.c
[0]PETSC ERROR: MatLUFactorNumeric() line 2396 in src/mat/interface/matrix.c
[0]PETSC ERROR: PCSetUp_LU() line 222 in src/ksp/pc/impls/factor/lu/lu.c
[0]PETSC ERROR: PCSetUp() line 794 in src/ksp/pc/interface/precon.c
[0]PETSC ERROR: KSPSetUp() line 237 in src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: KSPSolve() line 353 in src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: User provided function() line 495 in
unknowndirectory/src/solvers/petsc_linear_solver.C
application called MPI_Abort(comm=0x84000000, 71) - process 0
------------------------------------------------------------------------------
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