On Wed, Jun 8, 2011 at 7:34 AM, Klaus Zimmermann <span dir="ltr"><<a href="mailto:klaus.zimmermann@physik.uni-freiburg.de">klaus.zimmermann@physik.uni-freiburg.de</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;">
Hi Jed, Hi Matthew,<br>
<br>
thanks for your quick responses!<br>
<br>
On 06/08/2011 02:23 PM, Jed Brown wrote:<br>
> On Wed, Jun 8, 2011 at 14:17, Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a><br>
> <mailto:<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>>> wrote:<br>
><br>
> However, you might look at Elemental<br>
> (<a href="http://code.google.com/p/elemental/" target="_blank">http://code.google.com/p/elemental/</a>) which solves the complex<br>
> symmetric eigenproblem and is very scalable.<br>
><br>
><br>
> Note that Elemental is for dense systems.<br>
><br>
><br>
> To solve your problem, it's important to know where it came from. The<br>
> average number of nonzeros per row doesn't tell us anything about it's<br>
> mathematical structure which is needed to design a good solver.<br>
<br>
We are doing quantum mechanical ab initio calculations. The Matrix stems from a two particle Hamiltonian in a product basis. Thus we have basis vectors S_{nm}. The sparseness is now due to the fact that the matrix element <S_{nm}|H|S_{n'm'}> can only be non-zero if |n-n'|<4 and |m-m'|<4.<br>
<br>
Does this help or do you need more information? Like the matrix construction code?<br></blockquote><div><br></div><div>This does not just sound sparse, it sounds banded. Is this true? If so, you can use dense, banded solvers instead.</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;">
Thanks,<br><font color="#888888">
Klaus<br>
<br>
<br>
</font></blockquote></div><br><br clear="all"><br>-- <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>