[petsc-users] ex12 poisson solver

[David Fuentes]

Hi,

I'm trying to use petsc 3.8.0 with ex12.c example to setup a poisson
solver:
http://www.mcs.anl.gov/petsc/petsc-current/src/snes/examples/tutorials/ex12.c.html

I seem to be getting zeros in my jacobian with this example?
I attached a debugger and the assembly routines seems ok... but am getting
zero jacobian somewhere along the way to the MatAssembly...
Am I missing something with the command line arguments ?



$ ./ex12 -snes_type ksponly  -snes_monitor -snes_converged_reason
-ksp_converged_reason -ksp_monitor -ksp_rtol 1.e-6 -pc_type jacobi -info
-info_exclude null,pc,vec
--------------------------------------------------------------------------
[[55310,1],0]: A high-performance Open MPI point-to-point messaging module
was unable to find any relevant network interfaces:

Module: OpenFabrics (openib)
  Host: SCRGP2

Another transport will be used instead, although this may result in
lower performance.
--------------------------------------------------------------------------
[0] MatAssemblyEnd_SeqAIJ(): Matrix size: 8 X 8; storage space: 0
unneeded,8 used
[0] MatAssemblyEnd_SeqAIJ(): Number of mallocs during MatSetValues() is 0
[0] MatAssemblyEnd_SeqAIJ(): Maximum nonzeros in any row is 1
[0] MatCheckCompressedRow(): Found the ratio (num_zerorows
0)/(num_localrows 8) < 0.6. Do not use CompressedRow routines.
[0] MatSeqAIJCheckInode(): Found 8 nodes out of 8 rows. Not using Inode
routines
[0] DMGetDMSNES(): Creating new DMSNES
[0] DMGetDMKSP(): Creating new DMKSP
  0 SNES Function norm 1.414213562373e+00
[0] MatAssemblyEnd_SeqAIJ(): Matrix size: 8 X 8; storage space: 0
unneeded,8 used
[0] MatAssemblyEnd_SeqAIJ(): Number of mallocs during MatSetValues() is 0
[0] MatAssemblyEnd_SeqAIJ(): Maximum nonzeros in any row is 1
[0] MatCheckCompressedRow(): Found the ratio (num_zerorows
0)/(num_localrows 8) < 0.6. Do not use CompressedRow routines.
[0] SNESComputeJacobian(): Rebuilding preconditioner
    0 KSP Residual norm 1.414213562373e+00
    1 KSP Residual norm 1.414213562373e+00
[0] KSPGMRESBuildSoln(): Likely your matrix or preconditioner is singular.
HH(it,it) is identically zero; it = 0 GRS(it) = 1.41421
  Linear solve did not converge due to DIVERGED_BREAKDOWN iterations 1
[0] SNESSolve_KSPONLY(): iter=0, number linear solve failures 1 greater
than current SNES allowed, stopping solve
Nonlinear solve did not converge due to DIVERGED_LINEAR_SOLVE iterations 0
Number of SNES iterations = 0
L_2 Error: 0.751285


configured with: ./config/configure.py --with-shared-libraries
--with-clanguage=c++ --CFLAGS='-g -O0' --CXXFLAGS='-g -O0'
--download-ctetgen  --download-triangle --with-debugging=yes
--with-exodusii-lib=[/usr/lib/x86_64-linux-gnu/libexoIIv2.so]
--with-netcdf-lib=[/usr/lib/libnetcdf.so]
--with-netcdf-include=/usr/include
--with-hdf5-include=/usr/include/hdf5/serial/
--with-hdf5-lib=[/usr/lib/x86_64-linux-gnu/hdf5/serial/libhdf5.so]
--with-c2html=0 --with-exodusii-include=/usr/include


thanks!
David
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