[petsc-dev] why does MatCreate_MPIDense still exist?

[Barry Smith]

On Aug 13, 2012, at 11:50 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> On Mon, Aug 13, 2012 at 10:40 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> Should I remove all the MPIDense stuff from PETSc now?   It is uses PLAPACK which is buggy and unsupported.
> 
> That is still a good distribution for MxN matrices with M>>N. We can do them with Elemental, but that would use a different distribution so it will be more complicated to interact with. (The current Elemental interface uses a squarish distribution, but we can tell Elemental to use the [VC,*] distribution (for which fewer operations are supported).
> 
> The main thing I care about for that distribution is QR. The best format is dense and row-aligned. I don't care whether it uses MPIDense or a new "multi-vector" thing, but that concept should be somewhere.


  My main concern is that MPIDense is rickety and relays on broken stuff. I hate to keep crappy stuff in PETSc that haunts us on a regular basis.

   What would break today if I strip out MPIDense? 

    Barry