On Wed, Sep 5, 2012 at 12:25 PM, Tobin Isaac <span dir="ltr"><<a href="mailto:tisaac@ices.utexas.edu" target="_blank">tisaac@ices.utexas.edu</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">
<br>
What's the difference between "-pc_type sor -pc_sor_local_symmetric"<br>
and "-pc_type asm -sub_pc_type sor -sub_pc_sor_local_symmetric"?<br></blockquote><div><br></div><div>The ASM version sticks a Krylov iteration in these by default.</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">
Specifically, this converges in 30 iterations:<br>
<br>
./ex49 -mx 100 -my 100 -elas_ksp_view -elas_ksp_monitor -elas_ksp_type<br>
cg -elas_pc_type gamg -elas_pc_gamg_verbose 10 -elas_pc_gamg_threshold<br>
0. -elas_mg_coarse_pc_type cholesky -elas_pc_mg_smoothup 1<br>
-elas_pc_mg_smoothdown 1 -elas_mg_levels_ksp_type richardson<br>
-elas_mg_levels_pc_type asm -elas_ml_levels_1_sub_pc_type sor<br>
<br>
While this iterates forever:<br>
<br>
./ex49 -mx 100 -my 100 -elas_ksp_view -elas_ksp_monitor -elas_ksp_type<br>
cg -elas_pc_type gamg -elas_pc_gamg_verbose 10 -elas_pc_gamg_threshold<br>
0. -elas_mg_coarse_pc_type cholesky -elas_pc_mg_smoothup 1<br>
-elas_pc_mg_smoothdown 1 -elas_mg_levels_ksp_type richardson<br>
-elas_mg_levels_pc_type sor<br>
<br>
Thanks,<br>
Toby<br>
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<br></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>