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    <div class="moz-cite-prefix">Matt<br>
      <br>
      The analytical (Okada) solution is wrong at the fault. PETSc is
      right. It is a strike slip fault and constraints are being
      enforced correctly.<br>
      <br>
      Tabrez<br>
      <br>
      <br>
      On 10/28/2014 11:57 AM, Matthew Knepley wrote:<br>
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cite="mid:CAMYG4GmD539m8kVCEZ2s6WZnBPuGqRO0pY6ZraLi3epqM+nC2Q@mail.gmail.com"
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          <div class="gmail_quote">On Tue, Oct 28, 2014 at 11:56 AM,
            Tabrez Ali <span dir="ltr"><<a moz-do-not-send="true"
                href="mailto:stali@geology.wisc.edu" target="_blank">stali@geology.wisc.edu</a>></span>
            wrote:<br>
            <blockquote class="gmail_quote" style="margin:0 0 0
              .8ex;border-left:1px #ccc solid;padding-left:1ex">Jed<br>
              <br>
              You're right and it is precisely what I am trying to
              understand as well. I am attaching the comparison to the
              analytical solution. As you can see the agreement is
              almost perfect, except at the discontinuity (y=0 in the
              analytical solution).<br>
              <br>
              So why am I getting the correct solution when according to
              true residuals I should not?</blockquote>
            <div><br>
            </div>
            <div>The discontinuty is generating the large residuals.
              Your saddle is not actually enforcing</div>
            <div>the discontinuty, so you get the bulk mostly right by
              solving the (1,1) block, but not</div>
            <div>the slip. At least it looks that way to me.</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"><span
                class="HOEnZb"><font color="#888888"><br>
                  Tabrez</font></span>
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                <div class="h5"><br>
                  <br>
                  On 10/28/2014 11:18 AM, Jed Brown wrote:<br>
                  <blockquote class="gmail_quote" style="margin:0 0 0
                    .8ex;border-left:1px #ccc solid;padding-left:1ex">
                    Tabrez Ali <<a moz-do-not-send="true"
                      href="mailto:stali@geology.wisc.edu"
                      target="_blank">stali@geology.wisc.edu</a>>
                    writes:<br>
                    <br>
                    <blockquote class="gmail_quote" style="margin:0 0 0
                      .8ex;border-left:1px #ccc solid;padding-left:1ex">
                      Matt and Jed<br>
                      <br>
                      But it does appear to work well in practice (as in
                      I get the correct<br>
                      solution).<br>
                    </blockquote>
                    Your "correct" solution has a residual seven orders
                    of magnitude bigger<br>
                    than the initial guess.  Does that not give you
                    pause?<br>
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          <br clear="all">
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          -- <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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