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<div class="moz-cite-prefix">Thanks!</div>
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<div class="moz-cite-prefix">On 02/05/2022 18:07, Matthew Knepley
wrote:<br>
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<div dir="ltr">On Mon, May 2, 2022 at 11:25 AM Matteo Semplice
<<a href="mailto:matteo.semplice@uninsubria.it" moz-do-not-send="true" class="moz-txt-link-freetext">matteo.semplice@uninsubria.it</a>>
wrote:<br>
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0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">Hi.<br>
<br>
I am facing a PDE with 2 dofs per node in which one dof has
periodic <br>
b.c. in the x direction and the other one periodic b.c. in
the y <br>
direction. Is there a (possibly quick-and-dirty) solution to
represent <br>
this in a DM (not necessarily a DMDA)?<br>
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<div>I am trying to understand what this means. </div>
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<p>It comes from a toy model for more complicated quantum field
theory model that's hard for me to understand.<br>
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<blockquote type="cite" cite="mid:CAMYG4GkS1aCjYPynuNhiiiAdg82Y_Dtm6_BrUDV4AQS6v4hfnQ@mail.gmail.com">
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<div>Usually we think of periodicity as arising from the
domain, not the field.</div>
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<div>I think it would be easiest to:</div>
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<div> a) Use two different DMDA for the fields that "match
up" where needed</div>
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<p>This is kind of what I was thinking at. So I would create two
DMDA, then a DMComposite with the two and finally create Vecs and
Matrices from the DMComposite?<br>
</p>
<p>If so, then how do I assemble matrices for linear systems? If I
extract submatrices, I could use MatSetValuesStencil on diagonal
blocks, but how about the off-diagonal ones? These latter would
have rows/cols indexed by different DMDAs.<br>
</p>
<p>Matteo<br>
</p>
<p><br>
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<blockquote type="cite" cite="mid:CAMYG4GkS1aCjYPynuNhiiiAdg82Y_Dtm6_BrUDV4AQS6v4hfnQ@mail.gmail.com">
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<div>or</div>
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<div> b) Use a DMStag since it sounds like these should live
on horizontal and vertical edges</div>
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<div> Thanks,</div>
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<div> Matt</div>
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<blockquote class="gmail_quote" style="margin:0px 0px 0px
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I understand the request it's strange, but I should add that
we are <br>
experimenting numerically with this toy model, so in fact
the b.c. may <br>
change in the future... just to stress once more that I am
not after a <br>
perfect solution, but anything that would at least allow
parallel runs <br>
with few processors would do for now.<br>
<br>
Thanks in advance<br>
<br>
Matteo<br>
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-- <br>
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<div>What most experimenters take for granted before
they begin their experiments is infinitely more
interesting than any results to which their
experiments lead.<br>
-- Norbert Wiener</div>
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<pre class="moz-signature" cols="72">--
Prof. Matteo Semplice
Università degli Studi dell’Insubria
Dipartimento di Scienza e Alta Tecnologia – DiSAT
Professore Associato
Via Valleggio, 11 – 22100 Como (CO) – Italia
tel.: +39 031 2386316</pre>
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