[petsc-dev] BlockGetIndices and GetBlockIndices

Jed Brown jed at jedbrown.org
Wed Oct 16 09:54:22 CDT 2019

Stefano Zampini <stefano.zampini at gmail.com> writes:

> I just took a look at the ISGENERAL code. ISSetBlockSize_General just sets the block size of the layout (??)
> ISGetIndices always return the data->idx memory.
> So, a more profound question is: what is the model behind setting the block size on a ISGENERAL? And on a IS in general?

My recollection is that it was added to support MatNest and
MatGetLocalSubMatrix preserving block sizes so that MatSetValuesBlocked
could be used.

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