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So DM_BOUNDARY_GHOSTED values are not updated then in the DMDALocalToLocal routines. I should instead use DM_BOUNDARY_NONE and make the domain larger by 2 elements if I need those values to be shared between processes then? Is that the best approach?</div>
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Thanks,</div>
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Lucas</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Matthew Knepley <knepley@gmail.com><br>
<b>Sent:</b> Friday, May 22, 2020 8:03 PM<br>
<b>To:</b> Lucas Banting <bantingl@myumanitoba.ca><br>
<b>Cc:</b> PETSc <petsc-users@mcs.anl.gov><br>
<b>Subject:</b> Re: [petsc-users] Question about DMLocalToLocal for DM_BOUNDARY_GHOSTED conditions</font>
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<div dir="ltr">On Fri, May 22, 2020 at 4:34 PM Lucas Banting <<a href="mailto:bantingl@myumanitoba.ca">bantingl@myumanitoba.ca</a>> wrote:<br>
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Hello,</div>
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I am converting a serial code to parallel in fortran with petsc. I am using the DMDA to manage communication of the information that used to be in old two-dimensional fortran arrays.</div>
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I noticed when using DMLocalToLocalBegin/End, not all the ghost values in the array at the DM_BOUNDARY_GHOSTED area is updated. Is this expected behaviour?</div>
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<div>I believe so. GHOSTED is user managed space. We do not touch it.</div>
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I read through this thread: <a href="https://lists.mcs.anl.gov/mailman/htdig/petsc-users/2016-May/029252.html" id="x_gmail-m_-7081108383524483544LPlnk791893" target="_blank">
https://lists.mcs.anl.gov/mailman/htdig/petsc-users/2016-May/029252.html</a> and saw someone had a similar question, but the answer was not clear to me.</div>
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If this is expected behaviour, how should I instead update these values in my arrays? I was using DM_BOUNDARY_GHOSTED as I needed the extra ghost cells for some subroutines, but I do not need them in my matrix from DMCreateMatrix.</div>
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<div>You fill them in the local vector.</div>
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<div> Thanks,</div>
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<div> Matt</div>
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I am using Petsc 3.12.4 and open MPI 3.1.4.</div>
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Thanks,</div>
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Lucas Banting<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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<div><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br>
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