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<p>Hi Matthew and Barry,</p>
<p>Thanks for the quick response. <br>
</p>
<p>I also tried superlu and mumps, both work but it is about four
times slower than ILU(dt) prec through hypre, with 24 processors I
have tested. When I look into the convergence information, the
method using ILU(dt) still takes 200 to 3000 linear iterations for
each newton iteration. One reason is this equation is hard to
solve. As for the general cases, the same method works awesome and
get very good speedup. I also doubt if I use hypre correctly for
this case. Is there anyway to check this problem, or is it
possible to increase the factorization level through hypre?</p>
<p>Thanks,</p>
<p>Danyang<br>
</p>
<br>
<div class="moz-cite-prefix">On 17-05-24 04:59 AM, Matthew Knepley
wrote:<br>
</div>
<blockquote
cite="mid:CAMYG4GnTZChFxXgizw1edRtfNA==oOpeJFy57nzY1b-xkkPYbg@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">On Wed, May 24, 2017 at 2:21 AM,
Danyang Su <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:danyang.su@gmail.com" target="_blank">danyang.su@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">Dear All,<br>
<br>
I use PCFactorSetLevels for ILU and PCFactorSetFill for
other preconditioning in my code to help solve the
problems that the default option is hard to solve.
However, I found the latter one, PCFactorSetFill does not
take effect for my problem. The matrices and rhs as well
as the solutions are attached from the link below. I
obtain the solution using hypre preconditioner and it
takes 7 and 38 iterations for matrix 1 and matrix 2.
However, if I use other preconditioner, the solver just
failed at the first matrix. I have tested this matrix
using the native sequential solver (not PETSc) with ILU
preconditioning. If I set the incomplete factorization
level to 0, this sequential solver will take more than 100
iterations. If I increase the factorization level to 1 or
more, it just takes several iterations. This remind me
that the PC factor for this matrices should be increased.
However, when I tried it in PETSc, it just does not work.<br>
<br>
Matrix and rhs can be obtained from the link below.<br>
<br>
<a moz-do-not-send="true"
href="https://eilinator.eos.ubc.ca:8443/index.php/s/CalUcq9CMeblk4R"
rel="noreferrer" target="_blank">https://eilinator.eos.ubc.ca:8<wbr>443/index.php/s/CalUcq9CMeblk4<wbr>R</a><br>
<br>
Would anyone help to check if you can make this work by
increasing the PC factor level or fill?<br>
</blockquote>
<div><br>
</div>
<div>We have ILU(k) supported in serial. However ILU(dt)
which takes a tolerance only works through Hypre</div>
<div><br>
</div>
<div> <a moz-do-not-send="true"
href="http://www.mcs.anl.gov/petsc/documentation/linearsolvertable.html">http://www.mcs.anl.gov/petsc/documentation/linearsolvertable.html</a></div>
<div><br>
</div>
<div>I recommend you try SuperLU or MUMPS, which can both be
downloaded automatically by configure, and</div>
<div>do a full sparse LU.</div>
<div><br>
</div>
<div> Thanks,</div>
<div><br>
</div>
<div> Matt</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
Thanks and regards,<br>
<br>
Danyang<br>
<br>
<br>
</blockquote>
</div>
<br>
<br clear="all">
<div><br>
</div>
-- <br>
<div class="gmail_signature">
<div dir="ltr">
<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>
<div><br>
</div>
<div><a moz-do-not-send="true"
href="http://www.caam.rice.edu/%7Emk51/"
target="_blank">http://www.caam.rice.edu/~mk51/</a><br>
</div>
</div>
</div>
</div>
</div>
</blockquote>
<br>
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