<div class="gmail_extra">On Wed, Apr 25, 2012 at 2:19 PM, Dominik Szczerba <span dir="ltr"><<a href="mailto:dominik@itis.ethz.ch" target="_blank">dominik@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">
> Notice that there is no increase in the residual as is required. Notice also<br>
> that<br>
> there is no decrease. This must mean that the preconditioner is rank<br>
> deficient,<br>
> and I think it probably means that it is 0 since I find it hard to believe<br>
> that P x<br>
> produces no component in the b direction.<br>
<br>
Should this be the case, how would I get correct results for several<br>
benchmarks without using the option?</blockquote><div><br></div><div>This is not what I said. Look closely at the above. I said the preconditioner you give</div><div>back when using -snes_mf_operator is not right. This has nothing to do with normal</div>
<div>operation.</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"><span class="HOEnZb"><font color="#888888"><br>
Dominik<br>
</font></span></blockquote></div><br><br clear="all"><div><br></div>-- <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>
</div>