[petsc-users] ex12 poisson solver

[Justin Chang]

You need this additional command line argument: -petscspace_order 1



On Mon, Oct 9, 2017 at 9:02 AM, David Fuentes <fuentesdt at gmail.com> wrote:

>
> 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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