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    <div class="moz-cite-prefix">Le 05/01/2019 à 13:23, Matthew Knepley
      a écrit :<br>
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cite="mid:CAMYG4G==s1+9o3Eto08g-hF7JgwVLnxovMzs_t_Tpp44b4k9OQ@mail.gmail.com">
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          <div dir="ltr">On Sat, Jan 5, 2019 at 4:04 AM Yann Jobic <<a
              href="mailto:yann.jobic@univ-amu.fr"
              moz-do-not-send="true">yann.jobic@univ-amu.fr</a>>
            wrote:<br>
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              <div class="gmail-m_-6168566035861119409moz-cite-prefix">On
                05/01/2019 02:36, Matthew Knepley wrote:<br>
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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>
                    </div>
                    <blockquote class="gmail_quote" style="margin:0px
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                      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><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>
                  </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.</p>
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          <div>Yes. <br>
          </div>
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    In order to set up a quadratic space for my DM, i should use
    PetscDualSpaceSetOrder no ?
    <p>And then attach this space to my DM ?</p>
    <p>When i add the missing vertex coordinates, the order should not
      matter no ? (it should at the next step with the
      DMPlexVecSetClosure)</p>
    <p>I'll try to build a laplacian test case, with analytical solution
      in FEM in order to test it.<br>
    </p>
    <p>Thanks,</p>
    <p>Yann<br>
    </p>
    <blockquote type="cite"
cite="mid:CAMYG4G==s1+9o3Eto08g-hF7JgwVLnxovMzs_t_Tpp44b4k9OQ@mail.gmail.com">
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              <p>Then the interpolation will be correct ?</p>
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          <div>This is the tricky part. What you likely have to do is:</div>
          <div><br>
          </div>
          <div>  1) Build the topology</div>
          <div>  2) Run over the cells</div>
          <div>  3) For each cell, put in the coordinates using
            DMPlexVecSetClosure(). This is redundant, but the only way<br>
          </div>
          <div>      you can connect with the Q9 format.</div>
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              <p> Can i use DMproject and all the petsc functions ? <br>
              </p>
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          <div>This is the idea. The amount of testing is so far almost
            nothing. </div>
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              <p> </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>
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          <div>That is a good question. Right now, it will just output
            Q4. However, compared to everything else, writing Q9 should</div>
          <div>be comparatively easy. </div>
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              <p>Or is it working with the hdf5 one ?</p>
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          <div>I would probably write code to to Xdmf through HDF5
            rather than straight VTK, but we will end up having both.</div>
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              <p>Does the p4est interface work with this setup ?</p>
            </div>
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          <div>It will. I do not know if it currently does. We have to
            check.</div>
          <div><br>
          </div>
          <div>  Thanks,</div>
          <div><br>
          </div>
          <div>    Matt </div>
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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>
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                    <div>  Thanks,</div>
                    <div><br>
                    </div>
                    <div>     Matt</div>
                    <div> </div>
                    <blockquote class="gmail_quote" style="margin:0px
                      0px 0px 0.8ex;border-left:1px solid
                      rgb(204,204,204);padding-left:1ex"> 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>
                              </div>
                              <div><a
                                  href="http://www.cse.buffalo.edu/~knepley/"
                                  target="_blank" moz-do-not-send="true">https://www.cse.buffalo.edu/~knepley/</a><br>
                              </div>
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        <div><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>
                    </div>
                    <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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    <pre class="moz-signature" cols="72">-- 
___________________________

Yann JOBIC
HPC engineer
IUSTI-CNRS UMR 7343 - Polytech Marseille
Technopôle de Château Gombert
5 rue Enrico Fermi
13453 Marseille cedex 13
Tel : (33) 4 91 10 69 43
Fax : (33) 4 91 10 69 69
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