zero pivot

[billy at dem.uminho.pt]

I am getting zero pivot errors. I know the matrix has a high condition number.


see
http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#ZeroPivot!
[12]PETSC ERROR: Zero pivot row 3556 value 6.56537e-13 tolerance 1e-12 * rs
0.727229!
[12]PETSC ERROR: MatLUFactorNumeric() line 2212 in src/mat/interface/matrix.c
[12]PETSC ERROR: PCSetUp_ILU() line 551 in src/ksp/pc/impls/factor/ilu/ilu.c
[12]PETSC ERROR: PCSetUp() line 798 in src/ksp/pc/interface/precon.c
[12]PETSC ERROR: KSPSetUp() line 234 in src/ksp/ksp/interface/itfunc.c
[12]PETSC ERROR: PCSetUpOnBlocks_ASM() line 224 in src/ksp/pc/impls/asm/asm.c
[12]PETSC ERROR: PCSetUpOnBlocks() line 831 in src/ksp/pc/interface/precon.c
[12]PETSC ERROR: KSPSetUpOnBlocks() line 158 in src/ksp/ksp/interface/itfunc.c
[12]PETSC ERROR: KSPSolve() line 335 in src/ksp/ksp/interface/itfunc.c


When I use -sub_pc_factor_shift_nonzero and -pc_factor_zeropivot 1E-18 I get:


[10]PETSC ERROR: Caught signal number 8 FPE: Floating Point Exception,probably
divide by zero
[10]PETSC ERROR: Try option -start_in_debugger or -on_error_attach_debugger
[10]PETSC ERROR: or try http://valgrind.org on linux to find memory corruption
errors
[10]PETSC ERROR: likely location of problem given in stack below
[10]PETSC ERROR: --------------- Stack Frames ---------------
[10]PETSC ERROR: Note: The EXACT line numbers in the stack are not available,
[10]PETSC ERROR:       INSTEAD the line number of the start of the function
[10]PETSC ERROR:       is given.
[10]PETSC ERROR: [10] VecDot_MPI line 25 src/vec/vec/impls/mpi/pbvec.c
[10]PETSC ERROR: [10] VecDot line 86 src/vec/vec/interface/rvector.c
[10]PETSC ERROR: [10] KSPSolve_BCGS line 29 src/ksp/ksp/impls/bcgs/bcgs.c
[10]PETSC ERROR: --------------------------------------------
[10]PETSC ERROR: User provided function() line 0 in unknown directory unknown file
[10]PETSC ERROR: Signal received!
[10]PETSC ERROR:  !

Is there anyway to solve this?