<div dir="ltr"><div>The sequential SuperLU has ILUTP implementation, not in parallel versions. PETSc already supports the option of using SuperLU. <br><br>In SuperLU distribution:<br></div><div> EXAMPLE/zitersol.c : an example to use GMRES with ILUTP preconditioner (returned from driver SRC/zgsisx.c)<br>
</div><div> SRC/zgsitrf.c : the actual ILUTP factorization routine<br><br></div><div>Sherry Li<br><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Oct 30, 2013 at 8:48 AM, Matthew Knepley <span dir="ltr"><<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">On Wed, Oct 30, 2013 at 8:58 AM, Torquil Macdonald Sørensen <span dir="ltr"><<a href="mailto:torquil@gmail.com" target="_blank">torquil@gmail.com</a>></span> wrote:<br>
<div class="gmail_extra"><div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div></div><div>Thanks Matthew!<br><br>The problem I'm working on is the Dirac equation, in various number of dimensions. I'm going to take a stab at multigrid preconditioning.</div>
</div></blockquote><div><br></div><div>My limited knowledge of the Dirac Equation tells me that it is a relativistic wave equation, and thus hyperbolic, which is quite difficult for</div><div>MG (but doable with a bunch of work). How do you have this formulated?</div>
<div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">
<div>Best regards<br>Torquil Sørensen<br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On 27 October 2013 14:48, Matthew Knepley <span dir="ltr"><<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">On Sat, Oct 26, 2013 at 3:05 PM, Torquil Macdonald Sørensen <span dir="ltr"><<a href="mailto:torquil@gmail.com" target="_blank">torquil@gmail.com</a>></span> wrote:<br>
<div class="gmail_extra"><div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div>Hi!<br><br></div>I have a linear problem Ax=b, with complex values, that is solved very well using the ILUTP and GMRES implementations in GMM++. None of the other preconditioners available in GMM++ would work (e.g. ILU and ILUT) for this problem.<br>
<br></div>Then I tried the same problem using ILU and GMRES in PETSc, with no success, despite a lot of attempts at adjusting ILU settings. I always end up with gigantic residual norm values. The same PETSc program works well when I apply it to a different matrix A.<br>
<br></div><div>I'm now suspecting that the ILU options cannot be set so as to obtain ILUTP behaviour.<br></div><div><br></div><div>What would be the recommended method to access an ILUTP preconditioner from PETSc?<br>
<br>According to the PETSc website, a preconditioner named ILUDT is available by using the external package Hypre, but I had to deselect Hypre during the PETSc build due to my use of complex numbers... So do you guys think that I should transform everything to a real representation and try Hypre/ILUDT?<br>
</div></div></blockquote><div><br></div><div>I suggest you look for a different preconditioner. The fact that you have so much trouble reproducing the behavior shows</div><div>you just how fragile the performance of ILU is. It may work for a certain size, but fail for larger or smaller problems, or slightly</div>
<div>different parameters. What problem are you solving? Usually the best option is to consult the literature for preconditioners</div><div>tailored to your problem, and then reproduce them.</div><div><br></div><div> Matt</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div></div><div>Best regards<span><font color="#888888"><br>Torquil Sørensen<br>
<br></font></span></div></div><span><font color="#888888">
</font></span></blockquote></div><span><font color="#888888"><br><br clear="all"><span class="HOEnZb"><font color="#888888"><span><font color="#888888"><div><br></div>-- <br>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
</font></span></font></span></font></span></div></div><span class="HOEnZb"><font color="#888888">
</font></span></blockquote></div><span class="HOEnZb"><font color="#888888"><br></font></span></div><span class="HOEnZb"><font color="#888888">
</font></span></blockquote></div><span class="HOEnZb"><font color="#888888"><br><br clear="all"><div><br></div>-- <br>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
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