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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Hello<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>I want to know whether is it possible that a specific field in the section have been defined at some time on edges and other times on the vertices. This change in the dof , I think, may cause problem, especially in the global vector size of the dm. At times when the field changes to be defined on the edges, I think, I need to reset the dof with routine. I know how to do this, thanks to Matt. But, how I can deal with the global vector. At first, the global vector was defined on the vertices, but by this change. How would the global vector would response? Do I need to change the global vector?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Thanks<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Amir<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><div><div><p class=MsoNormal><o:p> </o:p></p><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><p class=gmail-msonormal>Hello<o:p></o:p></p><p class=gmail-msonormal>I am using the DMPlex interface for the solving PDEs.<o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Great. What discretization are you using?<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><p class=gmail-msonormal>A part of mesh, considering, is staggered grid, at the location of middle of each edge.<o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>So you would like to put variables at each edge midpoint?<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><p class=gmail-msonormal>After generation of main grid points, I find it hard to have the staggered grid at the prescribed location.<o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>In Plex, the topology is specified by the DMPlex, but the dof layout is specified by a PetscSection. To put<o:p></o:p></p></div><div><p class=MsoNormal>variables on edges, you could use:<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>DMGetDefaultSection(dm, &s);<o:p></o:p></p></div><div><p class=MsoNormal>DMPlexGetDepthStratum(dm, 1, &eStart, &eEnd);<o:p></o:p></p></div><div><p class=MsoNormal>for (e = eStart; e < eEnd; ++e) {<o:p></o:p></p></div><div><p class=MsoNormal> PetscSectionAddDof(s, e, 1);<o:p></o:p></p></div><div><p class=MsoNormal>}<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>and of course any other dofs you are using.<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><p class=gmail-msonormal>I want to know how to deal with the staggered besides of main grid. Is it better to have another DM for the staggered?<o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Another option is to use several DMDA. This has its own drawbacks.<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><p class=gmail-msonormal>Is it possible to extend the DMChart and inserting the points.<o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>If the chart does not have edges, it is because it has not been interpolated. Either pass the PETSC_TRUE, or call<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> <a href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/DMPLEX/DMPlexInterpolate.html">http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/DMPLEX/DMPlexInterpolate.html</a><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> Thanks,<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> Matt<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><p class=gmail-msonormal>I would really appreciate for your time.<o:p></o:p></p><p class=gmail-msonormal>Amir <o:p></o:p></p></div></div></blockquote></div><p class=MsoNormal><br><br clear=all><o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>-- <o:p></o:p></p><div><div><div><div><div><p class=MsoNormal>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<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><a href="http://www.caam.rice.edu/~mk51/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><o:p></o:p></p></div></div></div></div></div></div></div></div></body></html>