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Ok, thank you for pointing me to this paper.<br>
<br>
On 21.03.2012 11:38, Jed Brown wrote:
<blockquote
cite="mid:CAM9tzS=6gimrbdGGaEyan3f_WOkFthdtP7uG4r=ENaFTgE3-Bw@mail.gmail.com"
type="cite">
<div class="gmail_quote">On Wed, Mar 21, 2012 at 04:03, Alexander
Grayver <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:agrayver@gfz-potsdam.de">agrayver@gfz-potsdam.de</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
Hello,<br>
<br>
Plotting values of relative residual norm versus iteration I
noticed that these curves have different behavior. For
instance, ones I got with BiCGStab are oscillatory and rather
noisy with large jumps within few iterations. Curves for QMR
are smooth, however it's usual that they stagnate for ~10-20
iterations and then go down further. Same preconditioner is
applied for both and both methods are Lanczos based, so I
don't understand this.<br>
I'm wondering is this just my specific case or there is
general explanation for that?<br>
</blockquote>
<div><br>
</div>
<div>This is normal.</div>
<div><br>
</div>
<div><a moz-do-not-send="true"
href="http://people.maths.ox.ac.uk/trefethen/publication/PDF/1992_52.pdf">http://people.maths.ox.ac.uk/trefethen/publication/PDF/1992_52.pdf</a></div>
</div>
</blockquote>
<br>
<br>
<pre class="moz-signature" cols="72">--
Regards,
Alexander</pre>
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