[petsc-dev] Problem with GAMG

[Mark Adams]

On Wed, Jun 22, 2016 at 11:27 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   Mark,
>
>     If I use the hem coarsen type I get this error.


Does this go away with mis? Don't bother testing, it probably does.


> 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
>

It should be symmetric, even with roundoff, I think.

You have an unsymmetric matrix structurally?


> 2) the detector of lack of symmetry thinks it is not symmetric when it is.
>

The edge weights are used to drop edges and if there is an error then you
can get a structurally unsymmetric graph. Then the parallel graph
algorithms barf (they assume if I know you, you know me, symmetric).


>
>    Thoughts on how to debug this?
>

Try with a threshold of 0.  I need to take a look at it.  Can I run it?

I have to run for the night (in Vienna)




>
> 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:
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20160623/3173190b/attachment.html>