[petsc-dev] major changes to DA in PETSc-dev

[Jed Brown]

On Mon, Oct 18, 2010 at 15:23, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>  You are both wrong on this issue. In 1995 most people thought the
> flexibility was totally unneeded and actually harmful for matrices; they
> were wrong. In five years you will realize that you were wrong on the issue
> for DMs in 2010. Just wait, this is going to be damn powerful.


To elucidate this power, can you explain what benefit *user code* obtains
from having a DM while still calling DMGetLocalInfo and rolling loops over
the structured local ranges?

I fully understand the need for DM to be flexible from the solver
perspective, in its uses for multigrid and such.  But that's what the
interface in _DMOps is for.  Do you really envision user code that provides
a discretization on an arbitrary DM (same code works with a DA, Sieve-mesh,
particle DM)?  What might that look like?

Jed
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