[petsc-dev] BlockGetIndices and GetBlockIndices

Smith, Barry F. bsmith at mcs.anl.gov
Sun Oct 20 23:39:33 CDT 2019

> On Oct 16, 2019, at 9:41 AM, Stefano Zampini via petsc-dev <petsc-dev at mcs.anl.gov> wrote:
> 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?

   I still don't understand why IS even has a layout so I was lost long ago.

   ISSetBlockSize_*() appear to be complete gibberish for ISGeneral, ISBlock, and ISStride! 

>> On Oct 16, 2019, at 4:37 PM, Jed Brown <jed at jedbrown.org> wrote:
>> Stefano Zampini via petsc-dev <petsc-dev at mcs.anl.gov> writes:
>>>> Thoughts and/or comments? Would it make sense to add an ISGetBlockIndices/ISRestoreBlockIndices or would that be too confusing for the user?

   Seems insane, ISGetBlockIndices/ISRestoreBlockIndices() should not only not exist the entire absurd SSetBlockSize() concept should be removed. 


>>> That would be more general and I think it makes sense, and should pair with  ISGetBlockSize
>> What happens if you call ISGetBlockIndices on an ISGeneral for which
>> blocks are not contiguous?

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