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<div class="moz-cite-prefix">On 11/13/25 19:48, Matthew Knepley
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAMYG4GntFkfE41HAne1r3P6yHtNZU0JzX96ETnT-TEHtAo-yBA@mail.gmail.com">
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<div dir="ltr">Sorry, I have been traveling. I just got back to
this.
<div><br>
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<div>The problem is that _everything_ that goes in the submesh
has to have the same label value. That way you can
distinguish exactly what you want in. However, the boundary
label has to make decisions about shared edges and vertices. I
am attaching a modified code that does what you want by making
a separate label for each side.</div>
<div><br>
</div>
<div>I apologize for the C. I am just not as quick in Fortran.</div>
<div><br>
</div>
<div> Thanks,</div>
<div><br>
</div>
<div> Matt</div>
</div>
<br>
<div class="gmail_quote gmail_quote_container">
<div dir="ltr" class="gmail_attr">On Thu, Nov 6, 2025 at 1:42 AM
Aldo Bonfiglioli <<a
href="mailto:aldo.bonfiglioli@unibas.it"
moz-do-not-send="true" class="moz-txt-link-freetext">aldo.bonfiglioli@unibas.it</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<p>Dear all,</p>
<p>I am having troubles in using DMPlexExtractSubMesh to
extract the different strata of the Face Sets of a given
mesh.</p>
<p>When run on the enclosed tetrahedral mesh of the unit
cube generated with gmsh</p>
<p> </p>
<blockquote type="cite"> <span
style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">Face Sets: 6
strata with value/size (1 (246), 2 (246), 3 (246), 4
(246), 5 (242), 6 (242))</span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
</span> </blockquote>
I would expect 246 "points" on stratum 3, but when I DMview
the subdm (and plot it) the surface mesh looks incomplete
<p> </p>
<blockquote type="cite"> <span
style="font-family:monospace"><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">DM Object:
patch_03 1 MPI process</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> type: plex</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">patch_03 in 2
dimensions:</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> Cells are
at height 1</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> Number of
0-cells per rank: 122</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> Number of
1-cells per rank: 325</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">Number of
2-cells per rank: 204</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">Number of
3-cells per rank: 204 [204]</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">Labels:</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">celltype: 4
strata with value/size (0 (122), 1 (325), 3 (204), 12
(204))</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">depth: 4
strata with value/size (0 (122), 1 (325), 2 (204), 3
(204))</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">Cell Sets: 1
strata with value/size (1 (204))</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">Face Sets: 1
strata with value/size (3 (204))</span><span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)">Edge Sets: 2
strata with value/size (1 (8), 5 (8))</span><br>
<span
style="color:rgb(0,0,0);background-color:rgb(255,255,255)"> </span><br>
</span> </blockquote>
see also patch_03.pdf
<p>What am I doing wrong?</p>
<p>A simple reproducer (compiles with petsc-3.24.0) and the
gmsh mesh are enclosed.</p>
<p>Thanks,</p>
<p>Aldo</p>
<pre cols="72">--
Dr. Aldo Bonfiglioli
Associate professor of Fluid Mechanics
Dipartimento di Ingegneria
Universita' della Basilicata
V.le dell'Ateneo Lucano, 10 85100 Potenza ITALY
tel:+39.0971.205203 fax:+39.0971.205215
web: <a
href="https://urldefense.us/v3/__http://docenti.unibas.it/site/home/docente.html?m=002423__;!!G_uCfscf7eWS!aMKmGG4aim9XcbNSnDyHUkDyhUkQHGZ-u-xX2C-sycYUMmtTij6AwqsQbZPXJSvPp9KUfgwRJK2Ok6Me2BLgO0en1w4QF2fHo7s$"
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<span class="gmail_signature_prefix">-- </span><br>
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<div>What most experimenters take for granted before
they begin their experiments is infinitely more
interesting than any results to which their
experiments lead.<br>
-- Norbert Wiener</div>
<div><br>
</div>
<div><a href="https://urldefense.us/v3/__http://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!abF6mWj2v5ivSvUET6QFY34S5Jw6daKMHiS5E9ztz2YbV2jQPr-0WGi09d7IEArZlAwqdLwjjsQeUl2PlNwJMcq6AAnRaIPU6qs$" target="_blank" moz-do-not-send="true">https://www.cse.buffalo.edu/~knepley/</a><br>
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</blockquote>
<p>Matthew,</p>
<p>thank you for providing the working C code.</p>
<p>I will ba back to you in case I need further advice.</p>
<p>Regards,</p>
<p>Aldo</p>
<pre class="moz-signature" cols="72">--
Dr. Aldo Bonfiglioli
Associate professor of Fluid Mechanics
Dipartimento di Ingegneria
Universita' della Basilicata
V.le dell'Ateneo Lucano, 10 85100 Potenza ITALY
tel:+39.0971.205203 fax:+39.0971.205215
web: <a class="moz-txt-link-freetext" href="https://urldefense.us/v3/__http://docenti.unibas.it/site/home/docente.html?m=002423__;!!G_uCfscf7eWS!abF6mWj2v5ivSvUET6QFY34S5Jw6daKMHiS5E9ztz2YbV2jQPr-0WGi09d7IEArZlAwqdLwjjsQeUl2PlNwJMcq6AAnRpMwHc3Q$">http://docenti.unibas.it/site/home/docente.html?m=002423</a></pre>
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