[petsc-dev] Jed!!!

[Jed Brown]

Anton Popov <popov at uni-mainz.de> writes:

> The non-scalable conversion from MATNEST to AIJ is already implemented 
> in PETSc by Dmitry.
> The function is called MatConvert_Nest_AIJ. It is in the sources, but 
> not in documentation.
> I tried it ones, but it didn't work. So maybe it's time to look at it again.

We document interfaces rather than implementations, but I don't think
this function was ever finished.

> As far as I understand it is non-scalable because it exchanges the index 
> ranges between all the processors.
> Whereas a smart version would just exchange between the neighboring 
> processors in communication graph.
>
> But as Barry said, the scalability is not an issue for testing, so just 
> debugging this function would be enough.

The function can be implemented, and I think it's useful, but it doesn't
solve the problem of people using constraining interfaces to assemble
matrices.
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