[petsc-users] MatLUFactorNumeric_SeqAIJ() consumes long runtime

[Debao Shao]

When will "PCSetUp" set up new PC?
1), PCSetUp(): Setting up PC with same nonzero pattern
2), [0] PCSetUp(): Setting up new PC

Thanks,
Debao
-----Original Message-----
From: petsc-users-bounces at mcs.anl.gov [mailto:petsc-users-bounces at mcs.anl.gov] On Behalf Of Barry Smith
Sent: Tuesday, October 25, 2011 9:04 PM
To: PETSc users list
Subject: Re: [petsc-users] MatLUFactorNumeric_SeqAIJ() consumes long runtime


  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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