<div>Hi Jed,</div>
<div>Thanks a lot, it works after switching to the right .</div>
<div> </div>
<div>But can you say a little more about what happened in the first scenario, I did not quite fellow you. Let's say, If I set -ksp_rtol 1e-2, what does this mean in the left PC case. More specifically, which term will be considered as a stop creteria for the KSP solve.</div>
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<div>Yan</div>
<div><br><br> </div>
<div class="gmail_quote">On Tue, Sep 15, 2009 at 6:27 PM, Jed Brown <span dir="ltr"><<a href="mailto:jed@59a2.org">jed@59a2.org</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">
<div class="im">Ryan Yan wrote:<br>> How can I explain the relative tolerance is function correctly? as you can<br>> see from the term ||Ae||/||Ax||, neither of my testruns seems to stop at the<br>> right place(should be 10^(-2), 10^(-3) respectively).<br>
<br></div>The ||Ae||/||Ax|| column is not the preconditioned norm. You are using<br>left-preconditioned GMRES (the default) which uses the preconditioned<br>norm. Use<br><br> -ksp_right_pc -ksp_norm_type unpreconditioned<br>
<br>for the behavior you seem to expect.<br><font color="#888888"><br>Jed<br><br></font></blockquote></div><br>