Desired behavior of Sliced

[Barry Smith]

On Apr 10, 2009, at 11:50 AM, Jed Brown wrote:

> I have run into some issues with Sliced for bs!=1.

   What's this "sliced" beasty you are talking about :-)

> I have mostly fixed
> them and can push a patch after testing, but had a couple questions
> about the desired behavior.
>
> First, matrix preallocation cannot pass the same d_nnz,o_nnz for AIJ  
> and
> BAIJ.  I think the user should provide the BAIJ version and Sliced
> should generate the AIJ version if necessary.  This should respect
> (something like) DASetBlockFills.

    Sounds ok.

>  Do you think DMSetBlockFills is a
> good idea, or just SlicedSetBlockFills?

    just SlicedSetBlockFills

>
>
> Also, with SlicedSetGhosts, we have a few choices for the arguments
>
>  nlocal
>  Nghosts
>  ghosts
>
> Should nlocal be the number of blocks or the total number of entries?
> The latter is consistent with VecCreateGhostBlock, but I'm not  
> convinced
> it's most natural since other block operations are indexed by block.
> Certainly Nghosts should be the number of blocks, and then ghosts can
> either be indexed by block or by first entry of each block (again, the
> latter is consistent with VecCreateGhostBlock).
>
    At this time I would say everything in terms of blocks.

> Presumably in SlicedGetMat, we should set both the block and scalar
> local-to-global map.

    Yes

>  My patch fixes preallocation (minus block fills)
> and provides both local-to-global maps, while staying consistent with
> VecCreateGhostBlock.  Unless I hear otherwise, I'll push it after some
> testing.

    OK

>
>
> Jed