On Tue, Jan 18, 2011 at 2:06 AM, Kathrin Burckhardt <span dir="ltr"><<a href="mailto:burckhardt@itis.ethz.ch">burckhardt@itis.ethz.ch</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;">
Dear all,<br>
<br>
I have a problem using BiCGStab with right preconditioning.<br>
<br>
Solving my system using gmres everything looks ok:<br>
<br>
0 KSP preconditioned resid norm 4.490868831255e-04 true resid norm 4.490868831255e-04 ||Ae||/||Ax|| 6.402973612108e-01<br>
1 KSP preconditioned resid norm 2.641616638766e-04 true resid norm 2.641616638766e-04 ||Ae||/||Ax|| 3.766353965541e-01<br>
<br>
<br>
Solving it with bcgs, however, I got:<br>
<br>
0 KSP preconditioned resid norm 4.490868831255e-04 true resid norm 1.222737120188e+01 ||Ae||/||Ax|| 1.743349407273e+04<br>
1 KSP preconditioned resid norm 1.801799542022e-04 true resid norm 1.222736696074e+01 ||Ae||/||Ax|| 1.743348802582e+04<br></blockquote><div><br></div><div>The first one is the most disturbing since the initial residual should be the true residual with right preconditioning. Can</div>
<div>you run with -ksp_view -ksp_monitor and send it just to make sure you are running with what you think.</div><div><br></div><div> Thanks,</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;">
What could be wrong?<br>
<br>
Looking forward to your help,<br><font color="#888888">
Kathrin<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>