[petsc-users] Petsc ILU PC Change between 3.6.4 and 3.7.x?

Klaij, Christiaan C.Klaij at marin.nl
Tue Aug 22 08:49:01 CDT 2017

We also faced this problem in our code. So I've added:

CALL PetscOptionsSetValue(PETSC_NULL_OBJECT,"-sub_pc_factor_shift_type","nonzero",ierr)

since there seems to be no setter function for this (correct me
if I'm wrong). Then everythings fine again.

Out of curiosity, what was the reason to change the default
behaviour? It seems to have really reduced the robustness of

> Message: 2
> Date: Fri, 11 Aug 2017 12:28:43 -0500
> From: Barry Smith <bsmith at mcs.anl.gov>
> To: Gaetan Kenway <gaetank at gmail.com>
> Cc: petsc-users <petsc-users at mcs.anl.gov>
> Subject: Re: [petsc-users] Petsc ILU PC Change between 3.6.4 and
>         3.7.x?
> Message-ID: <E09F4C23-527D-4F48-A2E9-BA6B338D36CE at mcs.anl.gov>
> Content-Type: text/plain; charset="us-ascii"
>    Run with the additional option
>  -sub_pc_factor_shift_type nonzero
> does this resolve the problem. We changed the default behavior for ILU when it detects "zero" pivots.
> Please let us know if this resolves the problem and we'll update the changes file.
>    Barry

dr. ir. Christiaan Klaij  | Senior Researcher | Research & Development
MARIN | T +31 317 49 33 44 | mailto:C.Klaij at marin.nl | http://www.marin.nl

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