About the -pc_type tfs

[Matthew Knepley]

If you send the matrix in PETSc binary format we can check this.

  Matt

On Fri, May 15, 2009 at 12:20 PM, Ryan Yan <vyan2000 at gmail.com> wrote:

> Hi all,
> I am tring to use the tfs preconditioner to solve a large sparse mpiaij
> matrix.
>
> 11111111111111111111111111111111111111111
> It works very well with a small matrix 45*45(Actually a 9*9 block matrix
> with blocksize 5) on 2 processors; Out put is as follows:
>
>  0 KSP preconditioned resid norm 3.014544557924e+04 true resid norm
> 2.219812091849e+04 ||Ae||/||Ax|| 1.000000000000e+00
>   1 KSP preconditioned resid norm 3.679021546908e-03 true resid norm
> 1.502747104104e-03 ||Ae||/||Ax|| 6.769704109737e-08
>   2 KSP preconditioned resid norm 2.331909907779e-09 true resid norm
> 8.737892755044e-10 ||Ae||/||Ax|| 3.936320910733e-14
> KSP Object:
>   type: gmres
>     GMRES: restart=30, using Classical (unmodified) Gram-Schmidt
> Orthogonalization with no iterative refinement
>     GMRES: happy breakdown tolerance 1e-30
>   maximum iterations=10000, initial guess is zero
>   tolerances:  relative=1e-10, absolute=1e-50, divergence=10000
>   left preconditioning
> PC Object:
>   type: tfs
>   linear system matrix = precond matrix:
>   Matrix Object:
>     type=mpiaij, rows=45, cols=45
>     total: nonzeros=825, allocated nonzeros=1350
>       using I-node (on process 0) routines: found 5 nodes, limit used is 5
> Norm of error 2.33234e-09, Iterations 2
>
> 2222222222222222222222222222222222222222
>
> However, when I use the same code for a larger sparse matrix, a 18656 *
> 18656 block matrix with blocksize 5); it encounters the followins
> error.(Same error message for using 1 and 2 processors, seperately)
>
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> [0]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation,
> probably memory access out of range
> [0]PETSC ERROR: Try option -start_in_debugger or -on_error_attach_debugger
> [0]PETSC ERROR: or see
> http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#Signal[0]PETSC<http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#Signal%5B0%5DPETSC>ERROR: or try
> http://valgrind.org on linux or man libgmalloc on Apple to find memory
> corruption errors
> [0]PETSC ERROR: likely location of problem given in stack below
> [0]PETSC ERROR: ---------------------  Stack Frames
> ------------------------------------
> [0]PETSC ERROR: Note: The EXACT line numbers in the stack are not
> available,
> [0]PETSC ERROR:       INSTEAD the line number of the start of the function
> [0]PETSC ERROR:       is given.
> [0]PETSC ERROR: [0] PCSetUp_TFS line 116 src/ksp/pc/impls/tfs/tfs.c
> [0]PETSC ERROR: [0] PCSetUp line 764 src/ksp/pc/interface/precon.c
> [0]PETSC ERROR: [0] KSPSetUp line 183 src/ksp/ksp/interface/itfunc.c
> [0]PETSC ERROR: [0] KSPSolve line 305 src/ksp/ksp/interface/itfunc.c
> [0]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> [0]PETSC ERROR: Signal received!
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> [0]PETSC ERROR: Petsc Release Version 2.3.3, Patch 15, Tue Sep 23 10:02:49
> CDT 2008 HG revision: 31306062cd1a6f6a2496fccb4878f485c9b91760
> [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: ./kspex1reader_binmpiaij on a linux-gnu named
> vyan2000-linux by vyan2000 Fri May 15 01:06:12 2009
> [0]PETSC ERROR: Libraries linked from
> /home/vyan2000/local/PPETSc/petsc-2.3.3-p15//lib/linux-gnu-c-debug
> [0]PETSC ERROR: Configure run at Mon May  4 00:59:41 2009
> [0]PETSC ERROR: Configure options
> --with-mpi-dir=/home/vyan2000/local/mpich2-1.0.8p1/ --with-debugger=gdb
> --with-shared=0 --download-hypre=1 --download-parmetis=1
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> [0]PETSC ERROR: User provided function() line 0 in unknown directory
> unknown file
> application called MPI_Abort(MPI_COMM_WORLD, 59) - process 0[cli_0]:
> aborting job:
> application called MPI_Abort(MPI_COMM_WORLD, 59) - process 0
>
>
> 3333333333333333333333333333333333333333333333
>
> I have the exact solution x in hands, so before I push the matrix into the
> ksp solver, I did check the PETSC loaded matrix A and rhs vector b, by
> verifying Ax-b=0,  in  both cases of 1 processor and 2 processors.
>
> Any sugeestions?
>
> Thank you very much,
>
> Yan
>



-- 
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
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