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<p class="MsoNormal"><span lang="EN-US">Thank you very much for the input. I will test this approach. I have some reading (about the numerical techniques that you have implemented) to do as well, so it might take some time for me, but I’ll be back…<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">What does NV abbreviate?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Mahir<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Mark Adams [mailto:mfadams@lbl.gov]
<br>
<b>Sent:</b> den 26 juli 2015 15:41<br>
<b>To:</b> Jed Brown<br>
<b>Cc:</b> Ülker-Kaustell, Mahir; Matthew Knepley; petsc-users<br>
<b>Subject:</b> Re: [petsc-users] SuperLU MPI-problem<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal">Coming in late to this thread but you are doing frequency domain NV.<o:p></o:p></p>
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<p class="MsoNormal">Start by getting your time domain (definite, no omega shift) solves working. This can be a challenge for NV. There are techiques for this but we do not have them. Start with plane aggregation (-pc_gamg_nsmooths 0), this should be able
to work OK, then try smoothing, this will probably not work.<o:p></o:p></p>
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<p class="MsoNormal">Now add the shift. If you are shifting to high frequency then there is no hope w/o very special methods so use a direct solver.<o:p></o:p></p>
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<p class="MsoNormal">Mark<o:p></o:p></p>
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<p class="MsoNormal">On Wed, Jul 22, 2015 at 5:29 PM, Jed Brown <<a href="mailto:jed@jedbrown.org" target="_blank">jed@jedbrown.org</a>> wrote:<o:p></o:p></p>
<p class="MsoNormal">"<a href="mailto:Mahir.Ulker-Kaustell@tyrens.se">Mahir.Ulker-Kaustell@tyrens.se</a>" <<a href="mailto:Mahir.Ulker-Kaustell@tyrens.se">Mahir.Ulker-Kaustell@tyrens.se</a>> writes:<br>
> I am solving Ax = b with a sparse, indefinite, symmetric, complex<br>
> matrix, can anything be said about the chances of success in using an<br>
> iterative method?<br>
<br>
Not without more information/experimentation. You should check the<br>
literature for your problem domain to see what people claim is<br>
successful or does not work.<o:p></o:p></p>
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