<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Thu, May 19, 2016 at 7:43 AM, Elias Karabelas <span dir="ltr"><<a href="mailto:elias.karabelas@medunigraz.at" target="_blank">elias.karabelas@medunigraz.at</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
Well I don't bother to much about which PC is use. I just wanted to
look what's possible. One can of course come up with some kind of
augmented Lagrange formulation, but then you end up with a saddle
point problem.<br></div></blockquote><div><br></div><div>We do understand PCs for saddle point problems, but I do not know of anything for A+rank 1, except updated factorizations.</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 text="#000000" bgcolor="#FFFFFF">
<div>On 19.05.2016 14:41, Matthew Knepley
wrote:<br>
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<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">On Thu, May 19, 2016 at 7:39 AM,
Elias Karabelas <span dir="ltr"><<a href="mailto:elias.karabelas@medunigraz.at" target="_blank"></a><a href="mailto:elias.karabelas@medunigraz.at" target="_blank">elias.karabelas@medunigraz.at</a>></span>
wrote:<br>
<blockquote class="gmail_quote">
<div> Ok maybe I should go a little bit more into detail.
I have some stokes problem in a bifurcating Y-tube. Now
I would like to enforce some prescribed flux splits at
the outlets. After some literature research i found a
Nitsche method to do that. And if you consider the
additional billinear forms you end up with some nonlocal
coupling terms at the outlets (which are those vectors I
talked earlier)<br>
</div>
</blockquote>
<div><br>
</div>
<div>Keep the Cc.</div>
<div><br>
</div>
<div>I can see that you might have that formulation, but how
you would incorporate that into AMG, I have no idea.</div>
<div><br>
</div>
<div> Matt</div>
<div> </div>
<blockquote class="gmail_quote">
<div> <br>
<div>On 19.05.2016 14:31, Matthew Knepley wrote:<br>
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<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">On Thu, May 19, 2016 at
7:29 AM, Elias Karabelas <span dir="ltr"><<a href="mailto:elias.karabelas@medunigraz.at" target="_blank"></a><a href="mailto:elias.karabelas@medunigraz.at" target="_blank">elias.karabelas@medunigraz.at</a>></span>
wrote:<br>
<blockquote class="gmail_quote">
<div> maybe something with PCSHELL?</div>
</blockquote>
<div><br>
</div>
<div>No, I mean that I do not understand what
algorithm you might use (apart from the
implementation).</div>
<div><br>
</div>
<div> Matt</div>
<div> </div>
<blockquote class="gmail_quote">
<div>
<div>
<div> <br>
<div>On 19.05.2016 14:28, Matthew
Knepley wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">On Thu,
May 19, 2016 at 2:48 AM, Elias
Karabelas <span dir="ltr"><<a href="mailto:elias.karabelas@medunigraz.at" target="_blank"></a><a href="mailto:elias.karabelas@medunigraz.at" target="_blank">elias.karabelas@medunigraz.at</a>></span>
wrote:<br>
<blockquote class="gmail_quote">Dear
all,<br>
<br>
I have a question about
preconditioned solvers. So, I
have a Sparsematrix, say A,
and now for some reason I
would like to add some
rank-one term u v^T to that
matrix.<br>
As far as I know about Petsc,
I can define the action of
this matrix with MatShell. But
is it possible to adapt the
preconditioner (like a AMG) of
my KSP to handle that kind of
MatShell?<br>
</blockquote>
<div><br>
</div>
<div>I do not know how you would
do that. Its possible other
people have ideas.</div>
<div><br>
</div>
<div> Thanks,</div>
<div><br>
</div>
<div> Matt</div>
<div> </div>
<blockquote class="gmail_quote">
Kind Regards<span><br>
Elias<br>
<br>
-- <br>
Dr Elias Karabelas<br>
<br>
Medical University of Graz<br>
Institute of Biophysics<br>
Harrachgasse 21/IV<br>
8010 Graz, Austria<br>
<br>
Phone: <a href="tel:%2B43%20316%20380%207759" value="+433163807759" target="_blank">+43 316
380 7759</a><br>
Email: <a href="mailto:elias.karabelas@medunigraz.at" target="_blank"></a><a href="mailto:elias.karabelas@medunigraz.at" target="_blank">elias.karabelas@medunigraz.at</a><br>
Web : <a href="http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas" rel="noreferrer" target="_blank"></a><a href="http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas" target="_blank">http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas</a><br>
<br>
</span></blockquote>
</div>
<br>
<br>
<div><br>
</div>
-- <br>
<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>
</div>
</blockquote>
<br>
<pre cols="72">--
Dr Elias Karabelas
Medical University of Graz
Institute of Biophysics
Harrachgasse 21/IV
8010 Graz, Austria
Phone: <a href="tel:%2B43%20316%20380%207759" value="+433163807759" target="_blank">+43 316 380 7759</a>
Email: <a href="mailto:elias.karabelas@medunigraz.at" target="_blank">elias.karabelas@medunigraz.at</a>
Web : <a href="http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas" target="_blank">http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas</a> </pre>
</div>
</div>
</div>
</blockquote>
</div>
<br>
<br>
<span>
<div><br>
</div>
-- <br>
<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>
</span></div>
<span> </span></div>
<span> </span></blockquote>
<span> <br>
<pre cols="72">--
Dr Elias Karabelas
Medical University of Graz
Institute of Biophysics
Harrachgasse 21/IV
8010 Graz, Austria
Phone: <a href="tel:%2B43%20316%20380%207759" value="+433163807759" target="_blank">+43 316 380 7759</a>
Email: <a href="mailto:elias.karabelas@medunigraz.at" target="_blank">elias.karabelas@medunigraz.at</a>
Web : <a href="http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas" target="_blank">http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas</a> </pre>
</span></div>
</blockquote>
</div>
<br>
<br><span class="HOEnZb"><font color="#888888">
<div><br>
</div>
-- <br>
<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>
</font></span></div><span class="HOEnZb"><font color="#888888">
</font></span></div><span class="HOEnZb"><font color="#888888">
</font></span></blockquote><span class="HOEnZb"><font color="#888888">
<br>
<pre cols="72">--
Dr Elias Karabelas
Medical University of Graz
Institute of Biophysics
Harrachgasse 21/IV
8010 Graz, Austria
Phone: <a href="tel:%2B43%20316%20380%207759" value="+433163807759" target="_blank">+43 316 380 7759</a>
Email: <a href="mailto:elias.karabelas@medunigraz.at" target="_blank">elias.karabelas@medunigraz.at</a>
Web : <a href="http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas" target="_blank">http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas</a> </pre>
</font></span></div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature">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></div>