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<div class="moz-cite-prefix">On 05/01/2019 02:36, Matthew Knepley
wrote:<br>
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cite="mid:CAMYG4GngZgMPtcpjPfpxSQ66UEaFrXgSigi-bXa8OHF9Z_JkVg@mail.gmail.com">
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<div dir="ltr">On Fri, Jan 4, 2019 at 10:04 AM Yann Jobic via
petsc-users <<a href="mailto:petsc-users@mcs.anl.gov"
target="_blank" moz-do-not-send="true">petsc-users@mcs.anl.gov</a>>
wrote:<br>
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<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">Dear Petsc Users,<br>
<br>
I'm using DMPlexCreateFromCellList to create my DM. I would
like to have <br>
an order 2 geometry.<br>
<br>
It's working fine in 2D for elements of type Q9.<br>
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<div>I do not see how that is possible. The topology does not
work that way, and there</div>
<div>is no way a 9 vertex quad was interpolated, so something
else is happening.</div>
<div><br>
</div>
<div>Moreover, anything you input still has affine geometry.
Toby has been working on</div>
<div>non-affine geometry, and all the code is there, but right
now you have to build and</div>
<div>populate the coordinate space by hand. What this means is
that you create a</div>
<div>quadratic space for the coordinate DM (rather than the
default linear), get the</div>
<div>global coordinate vector out, and stick in the Q9
coordinates. The topology is still</div>
<div>the same no matter what coordinates you read in.</div>
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<p>I get the idea. So at the beginning i start with the Q4/H8
dmplex, then i fill from the global coordinate vector the missing
coordinates, and attach this new coordinate vector to the DM. Then
the interpolation will be correct ? Can i use DMproject and all
the petsc functions ? <br>
</p>
<p>In order to output the results, i've got to write my own vtk
interface no ? (by splitting the Q9/H27 in 4xQ4 or 8xH8).</p>
<p>Or is it working with the hdf5 one ?</p>
<p>Does the p4est interface work with this setup ?</p>
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cite="mid:CAMYG4GngZgMPtcpjPfpxSQ66UEaFrXgSigi-bXa8OHF9Z_JkVg@mail.gmail.com">
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<div>We will get around to making an interface for this soon.</div>
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<p>Great ! <br>
</p>
<p>Thanks,</p>
<p>Yann<br>
</p>
<blockquote type="cite"
cite="mid:CAMYG4GngZgMPtcpjPfpxSQ66UEaFrXgSigi-bXa8OHF9Z_JkVg@mail.gmail.com">
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<div><br>
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<div> Thanks,</div>
<div><br>
</div>
<div> Matt</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
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I checked that it's working correctly by using <br>
DMPlexComputeCellGeometryFEM, and compute the value of the
determinant <br>
(CheckMeshGeometry of
dm/impls/plex/examples/tutorials/ex2.c)<br>
<br>
I can import H8 elements, it's working fine.<br>
<br>
But for H27 element, it's not working. I really don't know
how to order <br>
my vertex in the cells array. So far, the determinant is
zero...<br>
<br>
I don't know where to look in order to find this
information. I tried <br>
the function DMPlexGetRawFaces_Internal of the file<br>
<br>
<a
href="https://www.mcs.anl.gov/petsc/petsc-current/src/dm/impls/plex/plexinterpolate.c.html#DMPlexGetRawFaces_Internal"
rel="noreferrer" target="_blank" moz-do-not-send="true">https://www.mcs.anl.gov/petsc/petsc-current/src/dm/impls/plex/plexinterpolate.c.html#DMPlexGetRawFaces_Internal</a><br>
<br>
but it didn't help me.<br>
<br>
Could you please point me where to look ?<br>
<br>
Thanks, and happy new year !<br>
<br>
Yann<br>
<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>
<div><br>
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<div><a href="http://www.cse.buffalo.edu/~knepley/"
target="_blank" moz-do-not-send="true">https://www.cse.buffalo.edu/~knepley/</a><br>
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