Does multiple matrix free from one tria gives out the same cell batch id

[Chengjiang Yin]

Hi all,

I'm now using MatrixFree to solve a multi-component problem. It contains a scalar and a vector and the equations couple to each other.

I plan to use two DofHandler (FESystem + FE_Q) and two MatrixFree to split the variables and I'm wondering if the cell batch ids are the same between these two MatrixFree? To be more straightforward, does MatrixFree give out the same partition once the tria is given and is independent of the FE?

If not, does this mean I can only use one MatrixFree but with multiple components? Is this better or with some extra optimization?

Regards,

Chengjiang Yin

[subramanya gautam]

Hi ChengJiang ,

Martin answered this same question, when I asked this recently.

https://groups.google.com/g/dealii/c/OWd7QsSSR18/m/q0j08zwLCQAJ?utm_medium=email&utm_source=footer

Cheers,

Subramanya

[Chengjiang Yin]

Hi  Subramanya,

Thanks for the quick reply! So, the cell batch id does change between different dof_handlers. I think that's a caveat worth mentioning in the tutorial.

Also, I'm curious about the partition algorithm, what is actually related to the cell partition, the Mesh, the FE, the partition_scheme (none/color/parallel etc.)? I didn't find the explicit initialization in `matrix_free.templates.h`. It should within the function `compute_dof_info`.

Regards,

Chengjiang Yin