[petsc-users] Coloring modifies user defined Jacobian at the first time step

[Juris Vencels]

Hello,

I am using such options:
    -ksp_type gmres -snes_monitor_short -snes_mf_operator -info

I construct Jacobian and pass it to SNES
SNESSetJacobian(snes,Jac,Jac,PETSC_NULL_FUNCTION,PETSC_NULL_OBJECT,ierr)

Jacobian is not changing during simulation.

At the first time step I get the following message
    [0] ISColoringCreate(): Number of colors 3
    [0] PetscCommDuplicate(): Duplicating a communicator 1 3 max tags = 
100000000
    [0] PetscCommDuplicate(): Using internal PETSc communicator 1 3
    [0] VecScatterCreate(): Special case: sequential vector general to 
stride
    [0] MatFDColoringSetUp_SeqXAIJ(): ncolors 3, brows 48 and bcols 1 
are used.

When I print Jacobian matrix after the first time step, it is different 
from one that I set at the beginning of simulation. Any ideas why 
coloring (which I am not using) changes user defined Jacobian?

Petsc Release Version 3.6.1 from Git
Configure options --with-cc=gcc --with-cxx=g++ --with-fc=gfortran 
--download-fblaslapack --with-fortran-kernels=generic 
--with-scalar-type=complex --with-debugging=0 COPTFLAGS="-O3 
-march=native -mtune=native" CXXOPTFLAGS="-O3 -march=native 
-mtune=native" FOPTFLAGS="-O3 -march=native -mtune=native" --with-mpi=0 
--with-openmp --with-threadcomm --with-pthreadclasses --with-openmpclasses

Thanks!