Hi,
I proceeded as Matt suggested. I am running without nullspace
(Dirichlet's BCs) with the following options:
-pc_type gamg -pc_mg_cycle_type v -pc_gamg_agg_nsmooths 1
-mg_coarse_sub_pc_factor_shift_type NONZERO -ksp_view -options_left
The results are fine and the run finishes. The output of -ksp_view does
not say anything about the coarse solver being shifted.
In fact the option -mg_coarse_sub_pc_factor_shift_type NONZERO is not used:
#PETSc Option Table entries:
-ksp_view
-mg_coarse_sub_pc_factor_shift_type NONZERO
-options_left
-pc_gamg_agg_nsmooths 1
-pc_mg_cycle_type v
-pc_type gamg
#End of PETSc Option Table entries
There is one unused database option. It is:
Option left: name:-mg_coarse_sub_pc_factor_shift_type value: NONZERO
Michele
On 05/24/2013 03:20 PM, Matthew Knepley wrote:
On Fri, May 24, 2013 at 5:18 PM, Michele Rosso <[email protected]
<mailto:[email protected]>> wrote:
Using
-pc_type gamg -pc_mg_cycle_type v -pc_gamg_agg_nsmooths 1
-mg_coarse_sub_pc_factor_shift_type NONZERO -option_left -ksp_view
This is what debugging is about. We are not running your problem. How
could this be debugged?
1) Run the problem w/o a null space so that it finishes
2) Look at the output for -ksp_view
3) Does the coarse solver say that it is shifted?
4) Are there options which were unused?
Matt
still produces the same error:
[0]PCSetData_AGG bs=1 MM=131072
[0]PETSC ERROR: --------------------- Error Message
------------------------------------
[0]PETSC ERROR: Detected zero pivot in LU factorization:
see http://www.mcs.anl.gov/petsc/documentation/faq.html#ZeroPivot!
[0]PETSC ERROR: Zero pivot row 280 value 6.56964e-17 tolerance
2.22045e-14!
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: Petsc Release Version 3.3.0, Patch 3, Wed Aug 29
11:26:24 CDT 2012
[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: ./hit on a named nid15363 by Unknown Fri May 24
17:06:50 2013
[0]PETSC ERROR: Libraries linked from
[0]PETSC ERROR: Configure run at
[0]PETSC ERROR: Configure options
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: MatPivotCheck_none() line 583 in
src/mat/impls/aij/seq//ptmp/skelly/petsc/3.3.03/cray_interlagos_build/real/src/include/petsc-private/matimpl.h
[0]PETSC ERROR: MatPivotCheck() line 602 in
src/mat/impls/aij/seq//ptmp/skelly/petsc/3.3.03/cray_interlagos_build/real/src/include/petsc-private/matimpl.h
[0]PETSC ERROR: MatLUFactorNumeric_SeqAIJ() line 585 in
src/mat/impls/aij/seq/aijfact.c
[0]PETSC ERROR: MatLUFactorNumeric() line 2803 in
src/mat/interface/matrix.c
[0]PETSC ERROR: PCSetUp_LU() line 160 in
src/ksp/pc/impls/factor/lu/lu.c
[0]PETSC ERROR: PCSetUp() line 832 in src/ksp/pc/interface/precon.c
[0]PETSC ERROR: KSPSetUp() line 278 in src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: PCSetUpOnBlocks_BJacobi_Singleblock() line 715 in
src/ksp/pc/impls/bjacobi/bjacobi.c
[0]PETSC ERROR: PCSetUpOnBlocks() line 865 in
src/ksp/pc/interface/precon.c
[0]PETSC ERROR: KSPSetUpOnBlocks() line 154 in
src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: KSPSolve() line 403 in src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: PCSetUpOnBlocks_BJacobi_Singleblock() line 715 in
src/ksp/pc/impls/bjacobi/bjacobi.c
[0]PETSC ERROR: PCSetUpOnBlocks() line 865 in
src/ksp/pc/interface/precon.c
[0]PETSC ERROR: KSPSetUpOnBlocks() line 154 in
src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: KSPSolve() line 403 in src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: PCMGMCycle_Private() line 20 in
src/ksp/pc/impls/mg/mg.c
[0]PETSC ERROR: PCMGMCycle_Private() line 49 in
src/ksp/pc/impls/mg/mg.c
[0]PETSC ERROR: PCMGMCycle_Private() line 49 in
src/ksp/pc/impls/mg/mg.c
[0]PETSC ERROR: PCMGMCycle_Private() line 49 in
src/ksp/pc/impls/mg/mg.c
[0]PETSC ERROR: PCApply_MG() line 326 in src/ksp/pc/impls/mg/mg.c
[0]PETSC ERROR: PCApply() line 384 in src/ksp/pc/interface/precon.c
[0]PETSC ERROR: KSPSolve_CG() line 139 in src/ksp/ksp/impls/cg/cg.c
[0]PETSC ERROR: KSPSolve() line 446 in src/ksp/ksp/interface/itfunc.c
On 05/24/2013 02:51 PM, Jed Brown wrote:
Michele Rosso<[email protected]> <mailto:[email protected]> writes:
With petsc-3.4 (which you should upgrade to), use
-mg_coarse_sub_pc_factor_shift_type NONZERO
Actually, use this with petsc-3.3 also (and please upgrade to
petsc-3.4).
The option you were passing was not being used.
--
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which
their experiments lead.
-- Norbert Wiener
