[petsc-users] Use Vectors and Scalars in MatNest matrices

[Thomas Hisch]

On Mon, Nov 14, 2022 at 3:06 PM Matthew Knepley <knepley at gmail.com> wrote:
>
> On Mon, Nov 14, 2022 at 8:59 AM Thomas Hisch <t.hisch at gmail.com> wrote:
>>
>> Hi!
>>
>> I would like to ask if it is possible to create a MatNest matrix that
>> contains matrices, vectors and scalars.
>
>
> No, You would turn everything into a type of matrix, but you can get the effect you want.
> Vectors can be easily used to create dense matrices, or vice versa. The scalars would also
> be dense matrices (and can share storage). Sparse vectors are just sparse matrices in
> PETSc.

Good. I'll work on an example and will then ask you if I'm using the
api in the correct way.

Thx

>
>   Thanks,
>
>      Matt
>
>>
>> My (jacobian) matrix looks like the following
>>
>> [[A, B, a, b],
>>  [C, D, c, d],
>>  [e, f, g, h]]
>>
>> where A-D are sparse square matrices, a-d are dense column vectors, e,
>> f are sparse row vectors and g,h are just scalars.
>>
>> Is there also a petsc4py example that shows how nest objects should be
>> created and how they should be used?
>>
>> Best regards
>> Thomas
>
>
>
> --
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener
>
> https://www.cse.buffalo.edu/~knepley/