<div class="gmail_quote">On Mon, Jun 20, 2011 at 16:26, Gianluca Meneghello <span dir="ltr"><<a href="mailto:gianmail@gmail.com">gianmail@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div id=":1cp">My goal is to perform some relaxation sweeps for each ordering at each<br>
level of a multigrid process, probably using ksptype PREONLY and<br>
pctype ILU.<br>
Is that possible?</div></blockquote><div><br></div><div>Yes, but you would need to perform a separate factorization for each ordering. Also, the orderings that are not aligned with the grid in memory will have poor performance. This is a general problem with using different orderings.</div>
<div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div id=":1cp"> Is there the equivalent of -pc_sor_its with ILU<br>
(-pc_ilu_its maybe)?<br></div></blockquote><div><br></div><div>-ksp_type richardson is the same thing, put it inside -pc_type bjacobi for -pc_sor_lits. (-pc_sor_its is just a lower overhead way to do that cycling).</div>
<div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div id=":1cp">
<br>
I also have the problem that in order to build the ordering I would<br>
need to have access to a structure containing some grid informations,<br>
and it seems I cannot pass that structure to the YourOrdering function<br>
you suggested.<br></div></blockquote><div><br></div><div>You can PetscObjectCompose() your structure to the Mat. You might need PetscContainerCreate() to wrap your struct.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div id=":1cp">
<br>
I guess a solution for me could be to build the IS from an external<br>
function (not used by petsc) and then attach them directly to the mat<br>
structure. I also guess that the one to use are the ones at line 36 of<br></div></blockquote><div><br></div><div>No, those slots are not public. Use PetscObjectCompose().</div></div>