On Wed, Jun 22, 2011 at 10:37 AM, John Mousel <span dir="ltr"><<a href="mailto:john.mousel@gmail.com">john.mousel@gmail.com</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;">
I'm using ML as a preconditioner, and I want to get an estimate of the spectral radius of my preconditioned matrix. I see a flag -pc_ml_SpectralNormScheme_Anorm. Does this need to be set in conjunction with another flag like -ksp_compute_eigenvalues or something cool I don't know about?</blockquote>
<div><br></div><div>I do not see a way to pull out the estimate from ML. However, you can easily replicate their estimate using</div><div><br></div><div> -ksp_monitor_singular_values</div><div><br></div><div>and run GMRES with -pc_type none. If you run with ML, it will estimate the extreme values for the preconditioned operators.</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;"><font color="#888888"><br>John<br>
</font></blockquote></div><br><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>