On Wed, 16 Oct 2019 at 15:54, Jed Brown via petsc-dev <petsc-dev@mcs.anl.gov> wrote:
> Stefano Zampini <stefano.zamp...@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. We use it for this purpose (certainly ISStride, I think ISGeneral) LAWRENCE
