<html>
  <head>
    <meta content="text/html; charset=utf-8" http-equiv="Content-Type">
  </head>
  <body 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>
    <br>
    <div class="moz-cite-prefix">On 19.05.2016 14:41, Matthew Knepley
      wrote:<br>
    </div>
    <blockquote
cite="mid:CAMYG4G=xkxTX1A=-JsQGWAmcoxrBPXt9PwC4E5p7wW7FUKzvBA@mail.gmail.com"
      type="cite">
      <meta http-equiv="Context-Type" content="text/html; charset=UTF-8">
      <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
                moz-do-not-send="true"
                href="mailto:elias.karabelas@medunigraz.at"
                target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:elias.karabelas@medunigraz.at">elias.karabelas@medunigraz.at</a></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>
                </div>
                <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
                            moz-do-not-send="true"
                            href="mailto:elias.karabelas@medunigraz.at"
                            target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:elias.karabelas@medunigraz.at">elias.karabelas@medunigraz.at</a></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
                                            moz-do-not-send="true"
                                            href="mailto:elias.karabelas@medunigraz.at"
                                            target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:elias.karabelas@medunigraz.at">elias.karabelas@medunigraz.at</a></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
                                              moz-do-not-send="true"
                                              href="tel:%2B43%20316%20380%207759"
                                              value="+433163807759"
                                              target="_blank">+43 316
                                              380 7759</a><br>
                                            Email: <a
                                              moz-do-not-send="true"
                                              href="mailto:elias.karabelas@medunigraz.at"
                                              target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:elias.karabelas@medunigraz.at">elias.karabelas@medunigraz.at</a></a><br>
                                            Web  : <a
                                              moz-do-not-send="true"
                                              href="http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas"
                                              rel="noreferrer"
                                              target="_blank"><a class="moz-txt-link-freetext" href="http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas">http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas</a></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 moz-do-not-send="true" href="tel:%2B43%20316%20380%207759" value="+433163807759" target="_blank">+43 316 380 7759</a>
Email: <a moz-do-not-send="true" href="mailto:elias.karabelas@medunigraz.at" target="_blank">elias.karabelas@medunigraz.at</a>
Web  : <a moz-do-not-send="true" 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 class="HOEnZb">
                        <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 class="HOEnZb"> </span></div>
                  <span class="HOEnZb"> </span></blockquote>
                <span class="HOEnZb"> <br>
                  <pre cols="72">-- 
Dr Elias Karabelas

Medical University of Graz
Institute of Biophysics
Harrachgasse 21/IV
8010 Graz, Austria

Phone: <a moz-do-not-send="true" href="tel:%2B43%20316%20380%207759" value="+433163807759" target="_blank">+43 316 380 7759</a>
Email: <a moz-do-not-send="true" href="mailto:elias.karabelas@medunigraz.at" target="_blank">elias.karabelas@medunigraz.at</a>
Web  : <a moz-do-not-send="true" 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>
          <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>
    </blockquote>
    <br>
    <pre class="moz-signature" cols="72">-- 
Dr Elias Karabelas

Medical University of Graz
Institute of Biophysics
Harrachgasse 21/IV
8010 Graz, Austria

Phone: +43 316 380 7759
Email: <a class="moz-txt-link-abbreviated" href="mailto:elias.karabelas@medunigraz.at">elias.karabelas@medunigraz.at</a>
Web  : <a class="moz-txt-link-freetext" href="http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas">http://forschung.medunigraz.at/fodok/staff?name=EliasKarabelas</a> </pre>
  </body>
</html>