<div dir="ltr"><div class="gmail_quote">On Thu, Mar 31, 2011 at 07:59, Gong Ding <span dir="ltr"><<a href="mailto:gdiso@ustc.edu">gdiso@ustc.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div>No, not a singular system. Just bad conditioned.<br>I mean if I can eliminate the bad conditioned rows by building schur complement?<br></div></blockquote></div><br><div>How are you enforcing the integral constraint in the boundary conditions? There is probably a way to write your boundary condition so that it is well scaled.</div>
<div><br></div><div>The Schur complement of your strip is an awkward thing to compute and will significantly affect sparsity unless that part of the matrix is already diagonal in which case there are good ways to scale correctly during assembly or eliminate a-priori, or have PCREDISTRIBUTE do it automatically.</div>
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