[petsc-users] snes_type aspin without DA example

[Karin&NiKo]

Thanks Barry, I'll check it out.

Le ven. 23 juin 2023 à 18:57, Barry Smith <bsmith at petsc.dev> a écrit :

>
>   Take a look at setNestSubVecs()
> in /src/binding/petsc4py/src/petsc4py/PETSc/Vec.pyx it seems to deal with
> passing an array of PETSc objects. Likely there are additional instances
> where arrays of objects are passed between Python and C.
>
>   I do not understand this code, but the Python experts will. Perhaps this
> type of construct can be hoisted up into a petsc4py implementation utility
> useful for any place in PETSc where arrays of objects must be passed back
> and forth.
>
>   Barry
>
>
> On Jun 23, 2023, at 6:12 AM, Karin&NiKo <niko.karin at gmail.com> wrote:
>
> In order to transfer from Python to C a list of int, real or bool as an
> input, there are the functions iarray_i, iarray_r and iarray_b.
> In order to transfer from C to Python a list of int, real, bool or
> pointers as an output, there are the functions oarray_i, oarray_r, oarray_b
> and oarray_p.
> Nevertheless I do not find the function iarray_p which (I think) is
> required to transfer a list of Scatter when calling SNESNASMSetSubdomains.
> Am I right ?
>
> Le ven. 23 juin 2023 à 09:40, Karin&NiKo <niko.karin at gmail.com> a écrit :
>
>> Dear Barry,
>> I have started looking at the code but I miss an example using
>> SNESNASMSetSubdomains. In fact I do not even find a single use of the
>> function in PETSc.
>> Could someone provide me with an example ?
>> Thanks,
>> Nicolas
>>
>> Le ven. 23 juin 2023 à 02:17, Barry Smith <bsmith at petsc.dev> a écrit :
>>
>>>
>>>   A test would be great.
>>>
>>> On Jun 22, 2023, at 3:20 PM, Karin&NiKo <niko.karin at gmail.com> wrote:
>>>
>>> Thank you Barry. I will try this.
>>> Should I provide a test in src/binding/petsc4py/test/test_snes.py ?
>>>
>>> Le jeu. 22 juin 2023 à 20:41, Barry Smith <bsmith at petsc.dev> a écrit :
>>>
>>>>
>>>>   You are not missing anything. The petsc4py stub for
>>>> SNESNASMSetSubdomains() has not been written. You could add it by adding to
>>>> src/petsc4py/PETSc/SNES.pyx and src/petsc4py/PETSc/petscsnes.pxi and
>>>> then make a merge request
>>>> https://petsc.org/release/developers/contributing/ to get it into
>>>> PETSc.
>>>>
>>>> On Jun 22, 2023, at 1:54 PM, Karin&NiKo <niko.karin at gmail.com> wrote:
>>>>
>>>> Dear PETSc team,
>>>>
>>>> I would like to play with aspin-type nonlinear solvers. I have found
>>>> several tests like snes/tutorials/ex19.c but they all use DA, which I don't
>>>> want to use since I need to stick at the algebraic level.
>>>> Then, I started looking at petsc4py/demo/ode/heat.py and tried to set
>>>> up things.
>>>> Unfortunately, I get the error "DM has no default decomposition
>>>> defined.  Set subsolves manually with SNESNASMSetSubdomains()" which, I
>>>> think, I do understand.
>>>> But I do not find any implementation of the SNESNASMSetSubdomains in
>>>> petsc4py.
>>>> Am I missing something ?
>>>> Thanks,
>>>> Nicolas
>>>>
>>>>
>>>>
>>>
>
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