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Dear PETSc Team:</div>
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I have a question about <span style="font-family: "Courier New", monospace;">DM</span> and
<span style="font-family: "Courier New", monospace;">PetscSection</span>. Say I import a mesh (for FEM purposes) and create a
<span style="font-family: "Courier New", monospace;">DMPlex</span> for it. I then use
<span style="font-family: "Courier New", monospace;">PetscSections </span>to set degrees of freedom per "point" (by point I mean vertices, lines, faces, and cells). I then use
<span style="font-family: "Courier New", monospace;">PetscSectionGetStorageSize</span><span style="font-family: "Courier New", monospace;">()</span> to get the size of the global stiffness matrix (K) needed for my FEM problem. One last detail, this K I populate
inside a rather large loop using an element stiffness matrix function of my own. Instead of using
<span style="font-family:"Courier New", monospace">DMCreateMatrix()</span>, I manually created a
<span style="font-family:"Courier New", monospace">Mat</span> using <span style="font-family:"Courier New", monospace">
MatCreate()</span>, <span style="font-family:"Courier New", monospace">MatSetType()</span>,
<span style="font-family:"Courier New", monospace">MatSetSizes()</span>, and <span style="font-family:"Courier New", monospace">
MatSetUp()</span>. I come to find that said loop is painfully slow when I use the manually created matrix, but 20x faster when I use the Mat coming out of
<span style="font-family:"Courier New", monospace">DMCreateMatrix()</span>.<br>
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My question is then: Is the manual <span style="font-family: "Courier New", monospace;">
Mat</span> a noob mistake and is it somehow creating a memory leak with K? Just in case it's something else I'm attaching the code. The loop that populates K is between lines 221 and 278. Anything related to DM, DMPlex, and PetscSection is between lines 117
and 180.<br>
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<span style="font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);">Machine Type: HP Laptop</span>
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C-compiler: Gnu C<br>
OS: Ubuntu 20.04</div>
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PETSc version: 3.16.0</div>
<span style="font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);">MPI Implementation: MPICH</span><br>
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Hope you all had a Merry Christmas and that you will have a happy and productive New Year. :D<br>
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<span style="margin: 0px; color: black; font-family: "Times New Roman", Times, serif; font-size: 12pt;">Sincerely:</span></p>
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<span style="margin: 0px; color: red; font-family: "Courier New", monospace; font-size: 14pt;"><b style=""><span style="font-family: "Courier New", monospace;">J.A. Ferrand</span></b></span><u><span style="margin: 0px; color: red; font-family: "Swis721 BlkCn BT", sans-serif; font-size: 12pt;"></span></u></p>
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<span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;">Embry-Riddle Aeronautical University - Daytona Beach FL</span></p>
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<span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;">M.Sc. Aerospace Engineering | May 2022</span></p>
<p style="background: white none repeat scroll 0% 0%; margin: 0px; line-height: normal;">
<span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;">B.Sc. Aerospace Engineering</span></p>
<p style="background: white none repeat scroll 0% 0%; margin: 0px; line-height: normal;">
<span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;">B.Sc. Computational Mathematics</span></p>
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<span style="margin: 0px; color: rgb(0, 0, 0); font-family: Courant; font-size: 12pt;"> </span></p>
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<span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;"><span style="color: rgb(0, 0, 0); font-family: Courant; font-size: 12pt; display: inline !important; font-size-adjust: none; background-color: rgb(255, 255, 255);">Sigma Gamma Tau</span><span style="color: rgb(0, 0, 0); font-family: Courant; font-size: 12pt; display: inline !important; font-size-adjust: none; background-color: rgb(255, 255, 255);"> </span><br>
</span></p>
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<span style="margin: 0px; color: rgb(0, 0, 0); font-family: Courant; font-size: 12pt;">Tau Beta Pi</span></p>
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<span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;"><span style="margin: 0px; color: rgb(0, 0, 0); font-family: Courant; font-size: 12pt;">Honors Program</span></span></p>
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<span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;"> </span></p>
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<u><span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;">Phone:</span></u><span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;"> (386)-843-1829</span></p>
<p style="background: white none repeat scroll 0% 0%; margin: 0px; line-height: normal;">
<u><span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;">Email(s):</span></u><span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;"> ferranj2@my.erau.edu</span></p>
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<span style="margin: 0px; color: black; font-family: Courant; font-size: 12pt;"><span style="margin:0px">
</span>jesus.ferrand@gmail.com</span></p>
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