<div class="gmail_quote">On Fri, Nov 18, 2011 at 07:53, Thomas Witkowski <span dir="ltr"><<a href="mailto:Thomas.Witkowski@tu-dresden.de">Thomas.Witkowski@tu-dresden.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Defining the sparsity pattern is no problem. But is there any documentation on MatFDColoringApply? The online function reference is quite short and is not mentioned in the manuel. So, I have no real idea how this is related to my question.</blockquote>
</div><br><div>You can find an example in snes/examples/tutorials/ex15.c</div><div><br></div><div>The point is that it can compute the Schur complement by coloring. In your case, you can do subdomain solves independently, so you can compute</div>
<div><br></div><div>S = K_PiPi - K_PiB inv(K_BB) K_BPi</div><div><br></div><div>on each subdomain using</div><div><br></div><div>Tmp = inv(K_BB) K_BPi (via MatMatSolve)</div><div><br></div><div>Tmp2 = K_PiB * Tmp (via MatMatMult)</div>
<div><br></div><div>S = K_PiPi - Tmp2 (via MatAXPY)</div><div><br></div><div><br></div><div>You would then assemble the resulting independent matrices into the global matrix.</div>