[petsc-users] strange FPE divide by zero

[Randall Mackie]

I’ve run into a strange error, which is that when I compile my Fortran code with -ffpe-trap=invalid it bombs out and gives the backtrace below. If I don’t include the ffpe-trap switch, the code runs fine and gives the expected results.

I’ve even run the code through Valgrind, and no issues were found.

I don’t know if this is just something strange with my matrix, or this is a bug somewhere in the PETSc code.

I do have a small test program and a large binary matrix and vector file if you want to test.


Randy


[9]PETSC ERROR: ------------------------------------------------------------------------
[9]PETSC ERROR: Caught signal number 8 FPE: Floating Point Exception,probably divide by zero
[9]PETSC ERROR: Try option -start_in_debugger or -on_error_attach_debugger
[9]PETSC ERROR: or see http://www.mcs.anl.gov/petsc/documentation/faq.html#valgrind
[9]PETSC ERROR: [0]PETSC ERROR: or try http://valgrind.org on GNU/linux and Apple Mac OS X to find memory corruption errors
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] LAPACKgesvd line 44 /state/std2/FEMI/PETSc/petsc-3.6.1/src/ksp/ksp/impls/gmres/gmreig.c
[0]PETSC ERROR: [0] KSPComputeExtremeSingularValues_GMRES line 24 /state/std2/FEMI/PETSc/petsc-3.6.1/src/ksp/ksp/impls/gmres/gmreig.c
[0]PETSC ERROR: [0] KSPComputeExtremeSingularValues line 51 /state/std2/FEMI/PETSc/petsc-3.6.1/src/ksp/ksp/interface/itfunc.c
[2]PETSC ERROR: likely location of problem given in stack below
[2]PETSC ERROR: ---------------------  Stack Frames ------------------------------------
[2]PETSC ERROR: Note: The EXACT line numbers in the stack are not available,
[2]PETSC ERROR:       INSTEAD the line number of the start of the function
[2]PETSC ERROR:       is given.
[2]PETSC ERROR: [2] LAPACKgesvd line 44 /state/std2/FEMI/PETSc/petsc-3.6.1/src/ksp/ksp/impls/gmres/gmreig.c
[2]PETSC ERROR: [2] KSPComputeExtremeSingularValues_GMRES line 24 /state/std2/FEMI/PETSc/petsc-3.6.1/src/ksp/ksp/impls/gmres/gmreig.c
[2]PETSC ERROR: [2] KSPComputeExtremeSingularValues line 51 /state/std2/FEMI/PETSc/petsc-3.6.1/src/ksp/ksp/interface/itfunc.c
[2]PETSC ERROR: [2] PCGAMGOptProlongator_AGG line 1187 /state/std2/FEMI/PETSc/petsc-3.6.1/src/ksp/pc/impls/gamg/agg.c
[2]PETSC ERROR: [2] PCSetUp_GAMG line 468 /state/std2/FEMI/PETSc/petsc-3.6.1/src/ksp/pc/impls/gamg/gamg.c
[2]PETSC ERROR: [2] PCSetUp line 944 /state/std2/FEMI/PETSc/petsc-3.6.1/src/ksp/pc/interface/precon.c
[2]PETSC ERROR: [2] KSPSetUp line 247 /state/std2/FEMI/PETSc/petsc-3.6.1/src/ksp/ksp/interface/itfunc.c
[2]PETSC ERROR: [2] KSPSolve line 510 /state/std2/FEMI/PETSc/petsc-3.6.1/src/ksp/ksp/interface/itfunc.c
[2]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
[2]PETSC ERROR: Signal received
[5]PETSC ERROR: [2]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.


This happens using either mpich or mvapich. The mvapich backtrace shows this:

[compute-1-11.local:mpi_rank_6][print_backtrace]   5: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(+0x268d24) [0x2ba2fac58d24]
[compute-1-11.local:mpi_rank_6][print_backtrace]   6: /lib64/libc.so.6() [0x38af6329a0]
[compute-1-11.local:mpi_rank_6][print_backtrace]   7: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(ieeeck_+0x1e9) [0x2ba2fc0e7b55]
[compute-1-11.local:mpi_rank_6][print_backtrace]   8: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(ilaenv_+0x1b17) [0x2ba2fc0baa77]
[compute-1-11.local:mpi_rank_6][print_backtrace]   9: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(dlasq2_+0x9a2) [0x2ba2fc0dd53e]
[compute-1-11.local:mpi_rank_6][print_backtrace]  10: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(dlasq1_+0x45d) [0x2ba2fc0dc941]
[compute-1-11.local:mpi_rank_6][print_backtrace]  11: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(zbdsqr_+0x33e) [0x2ba2fc0bb42a]
[compute-1-11.local:mpi_rank_6][print_backtrace]  12: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(zgesvd_+0x9091) [0x2ba2fc089445]
[compute-1-11.local:mpi_rank_6][print_backtrace]  13: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(KSPComputeExtremeSingularValues_GMRES+0x7e0) [0x2ba2fbcf77fd]
[compute-1-11.local:mpi_rank_6][print_backtrace]  14: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(KSPComputeExtremeSingularValues+0x4ec) [0x2ba2fbd78ea6]
[compute-1-11.local:mpi_rank_6][print_backtrace]  15: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(PCGAMGOptProlongator_AGG+0x111a) [0x2ba2fbbb28f9]
[compute-1-11.local:mpi_rank_6][print_backtrace]  16: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(PCSetUp_GAMG+0x1565) [0x2ba2fbb9995b]
[compute-1-11.local:mpi_rank_6][print_backtrace]  17: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(PCSetUp+0xc6b) [0x2ba2fbcb06b3]
[compute-1-11.local:mpi_rank_6][print_backtrace]  18: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(KSPSetUp+0x14e5) [0x2ba2fbd7bac3]
[compute-1-11.local:mpi_rank_6][print_backtrace]  19: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(KSPSolve+0xc31) [0x2ba2fbd7d70a]
[compute-1-11.local:mpi_rank_6][print_backtrace]  20: /state/std2/FEMI/PETSc/petsc-3.6.1/linux-gfortran-debug/lib/libpetsc.so.3.6(kspsolve_+0x3e) [0x2ba2fbdbba40]
[compute-1-11.local:mpi_rank_6][print_backtrace]  21: ./test() [0x401425]
[compute-1-11.local:mpi_rank_6][print_backtrace]  22: ./test() [0x4014ca]