[petsc-dev] Problem with GAMG

[Barry Smith]

  Mark,

    If I use the hem coarsen type I get this error. Note that I am setting the -pc_gamg_sym_graph true flag   I the debugger I do see that PCGAMGFilterGraph() has the 
sym flag set so it seems to me either

1) the symmetrizer doesn't actually make it symmetric or
2) the detector of lack of symmetry thinks it is not symmetric when it is.

   Thoughts on how to debug this?

Thanks

   barry



$ petscmpiexec -n 2 ./ex19 -pc_type gamg -da_refine 3 -mat_coarsen_type hem -pc_gamg_sym_graph true
lid velocity = 0.0016, prandtl # = 1., grashof # = 1.
[1]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
[1]PETSC ERROR: Petsc has generated inconsistent data
[1]PETSC ERROR: Have un-symmetric graph (apparently). Use '-pc_gamg_sym_graph true' to symetrize the graph or '-pc_gamg_threshold -1.0' if the matrix is structurally symmetric.
[0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
[0]PETSC ERROR: Petsc has generated inconsistent data
[0]PETSC ERROR: Have un-symmetric graph (apparently). Use '-pc_gamg_sym_graph true' to symetrize the graph or '-pc_gamg_threshold -1.0' if the matrix is structurally symmetric.
[0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
[0]PETSC ERROR: Petsc Development GIT revision: v3.7.2-596-g05491f7  GIT Date: 2016-06-22 13:31:47 -0500
[0]PETSC ERROR: ./ex19 on a arch-single named Barrys-MacBook-Pro.local by barrysmith Wed Jun 22 16:24:13 2016
[0]PETSC ERROR: [1]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
[1]PETSC ERROR: Petsc Development GIT revision: v3.7.2-596-g05491f7  GIT Date: 2016-06-22 13:31:47 -0500
[1]PETSC ERROR: ./ex19 on a arch-single named Barrys-MacBook-Pro.local by barrysmith Wed Jun 22 16:24:13 2016
[1]PETSC ERROR: Configure options --with-mpi-dir=/Users/barrysmith/libraries --with-precision=single
[1]PETSC ERROR: #1 smoothAggs() line 463 in /Users/barrysmith/Src/petsc/src/ksp/pc/impls/gamg/agg.c
Configure options --with-mpi-dir=/Users/barrysmith/libraries --with-precision=single
[0]PETSC ERROR: #1 smoothAggs() line 463 in /Users/barrysmith/Src/petsc/src/ksp/pc/impls/gamg/agg.c
[1]PETSC ERROR: #2 PCGAMGCoarsen_AGG() line 1021 in /Users/barrysmith/Src/petsc/src/ksp/pc/impls/gamg/agg.c
[1]PETSC ERROR: [0]PETSC ERROR: #2 PCGAMGCoarsen_AGG() line 1021 in /Users/barrysmith/Src/petsc/src/ksp/pc/impls/gamg/agg.c
[0]PETSC ERROR: #3 PCSetUp_GAMG() line 524 in /Users/barrysmith/Src/petsc/src/ksp/pc/impls/gamg/gamg.c
#3 PCSetUp_GAMG() line 524 in /Users/barrysmith/Src/petsc/src/ksp/pc/impls/gamg/gamg.c
[1]PETSC ERROR: #4 PCSetUp() line 968 in /Users/barrysmith/Src/petsc/src/ksp/pc/interface/precon.c
[0]PETSC ERROR: #4 PCSetUp() line 968 in /Users/barrysmith/Src/petsc/src/ksp/pc/interface/precon.c
[0]PETSC ERROR: #5 KSPSetUp() line 390 in /Users/barrysmith/Src/petsc/src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: #6 KSPSolve() line 599 in /Users/barrysmith/Src/petsc/src/ksp/ksp/interface/itfunc.c
[1]PETSC ERROR: #5 KSPSetUp() line 390 in /Users/barrysmith/Src/petsc/src/ksp/ksp/interface/itfunc.c
[1]PETSC ERROR: [0]PETSC ERROR: #7 SNESSolve_NEWTONLS() line 230 in /Users/barrysmith/Src/petsc/src/snes/impls/ls/ls.c
[0]PETSC ERROR: #8 SNESSolve() line 4008 in /Users/barrysmith/Src/petsc/src/snes/interface/snes.c
#6 KSPSolve() line 599 in /Users/barrysmith/Src/petsc/src/ksp/ksp/interface/itfunc.c
[1]PETSC ERROR: #7 SNESSolve_NEWTONLS() line 230 in /Users/barrysmith/Src/petsc/src/snes/impls/ls/ls.c
[0]PETSC ERROR: #9 main() line 159 in /Users/barrysmith/Src/petsc/src/snes/examples/tutorials/ex19.c
[0]PETSC ERROR: [1]PETSC ERROR: #8 SNESSolve() line 4008 in /Users/barrysmith/Src/petsc/src/snes/interface/snes.c
[1]PETSC ERROR: PETSc Option Table entries: