On Wed, Feb 8, 2012 at 12:35 AM, Jed Brown <span dir="ltr">&lt;<a href="mailto:jedbrown@mcs.anl.gov">jedbrown@mcs.anl.gov</a>&gt;</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">
<div dir="ltr"><div class="im"><div class="gmail_quote">On Wed, Feb 8, 2012 at 08:57, Matthew Knepley <span dir="ltr">&lt;<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">

<div>I just want to point out that Jed envisions that coefficients (and maybe subproblems, etc) cannot be accommodated on the</div><div>same DM. I agree. However, this silly idea that we can make DMs all over the place with no cost, like DAs, if they contain</div>


<div>all the mesh information, is just wrong. I think this is a good argument for having both a topology object and a DM handling</div><div>layout/solver information. What is the counter-argument?</div></blockquote></div>

<br></div><div>Why can&#39;t we have multiple DMs that internally share topology? Then each implementation can share or not share as much as they like. Some DMs might also share topological information between levels. I don&#39;t think it makes sense to encode a specific sharing model into the type system.</div>

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</blockquote></div><br>So you would have some weird call to that DM that says &quot;make another DM and share the internal state&quot;? That sounds<div>error prone and hard to inspect from outside. Things we complain about when other people do them.</div>
<div><br></div><div>   Matt<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>
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