<div dir="ltr"><div class="gmail_quote">On Wed, Apr 6, 2011 at 05:27, Matthew Knepley <span dir="ltr"><<a href="mailto:knepley@gmail.com">knepley@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
There should be no difference since direct solves take so long.</blockquote></div><br><div>That is, solves are very fast compared to factorization.</div><div><br></div><div>If you just want to check the residual, Richardson is cheaper than GMRES because it will require one fewer preconditioner/matrix applications.</div>
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