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Thanks, Matt. That works now. </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> Thursday, January 21, 2021 9:29 AM<br>
<b>To:</b> Tang, Qi <tangqi@msu.edu><br>
<b>Cc:</b> PETSc users list <petsc-users@mcs.anl.gov><br>
<b>Subject:</b> Re: [petsc-users] MatCreateSchurComplementPmat to create a Schur complement</font>
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<div dir="ltr">On Thu, Jan 21, 2021 at 2:52 AM Tang, Qi <<a href="mailto:tangqi@msu.edu">tangqi@msu.edu</a>> wrote:<br>
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Hi,</div>
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When I use the MatCreateSchurComplementPmat to create a Schur complement for my own usage, I do not understand the logic when preuse=MAT_INITIAL_MATRIX. If all the matrixes are not empty, the first thing it did is</div>
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809: MatDestroy(Spmat);<br>
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So that means I cannot pass in an empty matrix. It works if I first do MatCreate a dummy matrix and then pass in. Is that just some inconsistency or is there something I misunderstood?</div>
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<div>Yes, it wants you to pass &Sp with Sp == NULL. Sorry this is not more clear.</div>
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<div> Thanks,</div>
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<div> Matt</div>
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Qi</div>
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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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