<div class="gmail_quote">On Thu, Apr 5, 2012 at 08:22, Abdul Hanan Sheikh <span dir="ltr"><<a href="mailto:hanangul12@yahoo.co.uk">hanangul12@yahoo.co.uk</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>For the system Au = f, I want to apply a multilevel preconditioner with a KSP (say FGMRES) . The preconditioner<br>reads as<br><br>Prec = C + M^-1 (I - A*C) , where<br><br></div><ul><li> C reads coarse grid correction operator i.e. <span style="background-color:rgb(64,255,255)">C = P*A_2h\R</span> [ R restriction, A_2h coarse operator, P interpolation] </li>
<li>M is say some sparse matrix (resembling to A) <br></li></ul><div>What makes it multilevel is I have to approximate coarse operator <span>"A_2h" with few KSP iterations preconditioned by the above defined</span></div>
<div><span>preconditioner "Prec" , but off course at the level 2h and hence at every coarse level until coarsest.
</span></div></blockquote><div><br></div><div>Hmm, if you use a constant number of iterations in C at each level, the number of coarsest grid iterations will grow exponentially in the number of levels. Is that really what you want?</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><span></span></div><div><span>I
only know, it can be implemented with PCMG. I am little afraid of DMMG. <br></span></div></blockquote><div><br></div><div>Don't use DMMG, it is being removed.</div></div>