On Aug 13, 2012, at 12:05 PM, Hong Zhang <hzhang@mcs.anl.gov> wrote:

> Barry,
> Elemental interface is not well tested yet.
> I would wait for few months to remove PLAPACK stuff.

PLAPACK stuff is (and never was) well tested. Does anyone rely on it? I hope not. And I hate to have someone new come along and rely on it.

I am for removing it. I wrote it, and so I can guarantee that it is not maintained. We should

just fix anything that comes up rather than fooling ourselves that this current stuff works.

Matt

Barry

>
> Hong
>
> On Mon, Aug 13, 2012 at 11:50 AM, Jed Brown <jedbrown@mcs.anl.gov> wrote:
> On Mon, Aug 13, 2012 at 10:40 AM, Barry Smith <bsmith@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.
>