On Wed, Apr 6, 2011 at 2:01 PM, Jed Brown <span dir="ltr"><<a href="mailto:jed@59a2.org">jed@59a2.org</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div dir="ltr"><div class="gmail_quote">2011/4/6 Gong Ding <span dir="ltr"><<a href="mailto:gdiso@ustc.edu" target="_blank">gdiso@ustc.edu</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>Ok, I will investigate matrix null space problem.<br>
The matrix comes from nonlinear problem, I wonder if I need to calculate the eigenvector each time.<br></div></blockquote><div><br></div><div>Possibly, but it is more likely that the null space is something simple like a constant.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>
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Several months ago, some one committed DGMRES implementation, which also dropped smallest eigen value.<br>
It it possible to use (slightly modified) DGMRES as flexable tool for sigular problem?</div></blockquote></div><br><div>I'm not familiar with DGMRES.</div></div>
</blockquote></div><br>Deflated GMRES will not help here. This is just the power method, and thus gets the large eigenvalues<div>first. You will not get the null space vector.</div><div><br></div><div> Matt<br clear="all">
<br>-- <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<br>
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