Thank you very much for the quick fix Lawrence.

What is Firedrake's policy with respect to PETSc versioning ? To make it clear, when will your fix be available through "firedrake-update" ?

Thanks,

Nicolas

Le jeu. 18 juin 2020 à 18:04, Lawrence Mitchell <wence@gmx.li> a écrit :

Hi,

> On 18 Jun 2020, at 15:15, Karin&NiKo <niko.karin@gmail.com> wrote:
>
> Dear Firedrakers,
>
> I am solving a 3 fields coupled problem with Firedrake. I would like to use a multiplicative block-preconditioner but PETSc complains about a local size not being correct.
> [0] Arguments are incompatible
> [0] Local size 9 not compatible with block size 2
>
> I have noticed that the use of a MatAij solves the problem (see comment in line 132) but I am afraid this is just a side effect.
>
> Am I missing something?

It looks like this is a bug inside PETSc. I have a proposed a fix here: https://gitlab.com/petsc/petsc/-/merge_requests/2883

With that change, your code runs fine in both nest and aij mode.

Lawrence