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Am 12.06.2012 15:04, schrieb Jed Brown:
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cite="mid:CAM9tzSmEVam2LjBDywsi-4c+C=OrZrHXMfOJNfEdBo80R_+pOw@mail.gmail.com"
type="cite">
<div class="gmail_quote">On Tue, Jun 12, 2012 at 7:56 AM, Thomas
Witkowski <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:thomas.witkowski@tu-dresden.de" target="_blank">thomas.witkowski@tu-dresden.de</a>></span>
wrote:<br>
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There should be no null space from the Cahn-Hilliard equation.</blockquote>
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<div>You said all those boundary conditions are either Neumann
or periodic. I guess it couples to the fluid variables without
any null space?</div>
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yes.<br>
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cite="mid:CAM9tzSmEVam2LjBDywsi-4c+C=OrZrHXMfOJNfEdBo80R_+pOw@mail.gmail.com"
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<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex"> Is there
some black-box preconditioner that does not relay on LU
factorization at some point? I know that black-box approaches
are mostly not efficient, but I would have something I can
work with.</blockquote>
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<br>
<div>The SVD always works and will tell you about a null space,
but of course it's very expensive.</div>
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So assume I have a basis for the null space of the system that
should be solved. Is there any block-box solver/preconditioner
approach that does not make use of (I)LU factorization at any point?<br>
<br>
Thomas<br>
<br>
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