My guess is that the code is repeatedly trying larger and large shifts to get
a nonzero pivot as it factors. If you run with -info and let it run to
completion it will print some information about the shifts it has tried.
Barry
On Oct 25, 2011, at 3:45 AM, Debao Shao wrote:
> DA,
>
> I?m using PETSc ILU(1)+GMRES to solve an QP problem. But the job may hang at
> ?MatLUFactorNumeric_SeqAIJ()? for long time.
>
> (gdb) bt
> #0 0x0000000002284520 in MatLUFactorNumeric_SeqAIJ ()
> #1 0x0000000002265f89 in MatLUFactorNumeric ()
> #2 0x0000000002342ff3 in PCSetUp_ILU ()
> #3 0x00000000024f8d65 in PCSetUp ()
> #4 0x0000000002362964 in KSPSetUp ()
> #5 0x0000000002363455 in KSPSolve ()
>
> Do you have idea for such phenomenon?
>
> Thanks,
> Debao
>
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