[petsc-dev] DMGetMatrix --> DMGetMatrices?

[Dmitry Karpeev]

On Fri, Feb 10, 2012 at 12:01 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> On Thu, Feb 9, 2012 at 23:55, Dmitry Karpeev <karpeev at mcs.anl.gov> wrote:
>
>> In a somewhat related matter, it appears that I cannot duplicate a
>> preallocated MATXXXAIJ until it has been assembled:
>> if my DM implementation keeps a preallocated MATSEQAIJ, which it wants to
>> duplicate on every call to DMGetMatrix,
>> it would have to put in fake entries before any duplication is possible.
>>
>
> Doesn't it already do this (inserting 0)?
>
I don't think so.  Preallocating doesn't set any values and seems to leave
the matrix marked !assembled.
MatDuplicate for such a matrix will fail.  Assemblying it before setting
values (just to force an assembled flag)
will squeeze out the extra values, won't it?  I think it would just be
reasonable to allow to duplicate unassembled
matrices, or, better yet, have a matrix be "assembled" by default until
MatSetValues has been called.
But I'm not sure whether either solution will break something else.

Dmitry.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20120210/90b2d398/attachment.html>