[petsc-users] PETSC ERROR: Petsc has generated inconsistent data with PCGAMG and KSPGRMES

[Smith, Barry F.]

  Most preconditioners don't care if the matrix has non-symmetric non-zero structure. GAMG requires it have a symmetric nonzero structure. It lists some options you can try to make it symmetric.


> [2]PETSC ERROR: Have un-symmetric graph (apparently). Use '-(null)pc_gamg_sym_graph true' to symetrize the graph or '-(null)pc_gamg_threshold -1' if the matrix is structurally symmetric.



> On Jul 9, 2019, at 8:30 AM, 我 via petsc-users <petsc-users at mcs.anl.gov> wrote:
> 
> Hello all,
> I set PCGAMG and KSPGRMES to solve the matrix which is formed by a particle method such as SPH. But when there is always a PETSC ERROR: 
> [2]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
> [2]PETSC ERROR: Petsc has generated inconsistent data
> [2]PETSC ERROR: Have un-symmetric graph (apparently). Use '-(null)pc_gamg_sym_graph true' to symetrize the graph or '-(null)pc_gamg_threshold -1' if the matrix is structurally symmetric.
> [2]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
> [2]PETSC ERROR: Petsc Release Version 3.9.1, Apr, 29, 2018 
> [2]PETSC ERROR: ./MPS on a arch-linux2-cxx-debug named daye-Precision-7920-Tower by daye Tue Jul  9 20:59:39 2019
> [2]PETSC ERROR: Configure options --with-cc=gcc --with-cxx=g++ --with-fc=gfortran --download-mpich --download-fblaslapack --download-hypre --with-clanguage=cxx
> [2]PETSC ERROR: #1 smoothAggs() line 418 in /home/daye/PETSC/petsc-3.9.1/src/ksp/pc/impls/gamg/agg.c
> [2]PETSC ERROR: #2 PCGAMGCoarsen_AGG() line 970 in /home/daye/PETSC/petsc-3.9.1/src/ksp/pc/impls/gamg/agg.c
> [2]PETSC ERROR: #3 PCSetUp_GAMG() line 518 in /home/daye/PETSC/petsc-3.9.1/src/ksp/pc/impls/gamg/gamg.c
> [2]PETSC ERROR: #4 PCSetUp() line 923 in /home/daye/PETSC/petsc-3.9.1/src/ksp/pc/interface/precon.c
> [2]PETSC ERROR: #5 KSPSetUp() line 381 in /home/daye/PETSC/petsc-3.9.1/src/ksp/ksp/interface/itfunc.c
> [2]PETSC ERROR: #6 KSPSolve() line 612 in /home/daye/PETSC/petsc-3.9.1/src/ksp/ksp/interface/itfunc.c
> ^C[mpiexec at daye-Precision-7920-Tower] Sending Ctrl-C to processes as requested
> [mpiexec at daye-Precision-7920-Tower] Press Ctrl-C again to force abort
> 
> This matrix can be solved when I use PCHYPRE and KSPGRMES. But when I change the pre-condition to PCGAMG, this error always occurs. Any suggestions about that?
> Thank you at first!
> 
> Daye
> 
> 
>