On Fri, Nov 11, 2011 at 2:11 PM, <a href="mailto:markus.sons@gmail.com">markus.sons@gmail.com</a> <span dir="ltr"><<a href="mailto:markus.sons@gmail.com">markus.sons@gmail.com</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;">Thanks for the quick answer. We already have a wrapper class for BLAS/Lapack and it's currently being used for small problems as well as solving the - possibly huge - equation system.<div>
We want to use PETSc to solve this problem in parallel and would have hoped to be able to simultaneously drop the wrapper. I guess a mixed approach would be perfect then?<br></div></blockquote><div><br></div><div>You can certainly use Vec for small vectors. The overhead is minimal. However, it will not optimize these operations (neither does BLAS)</div>
<div>in the same way as Eigen. BLAS is optimized for vectors of length 10000+.</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;">
<div><div class="gmail_quote">On Fri, Nov 11, 2011 at 3:05 PM, Jed Brown <span dir="ltr"><<a href="mailto:jedbrown@mcs.anl.gov" target="_blank">jedbrown@mcs.anl.gov</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div class="gmail_quote">On Fri, Nov 11, 2011 at 03:35, <a href="mailto:markus.sons@gmail.com" target="_blank">markus.sons@gmail.com</a> <span dir="ltr"><<a href="mailto:markus.sons@gmail.com" target="_blank">markus.sons@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">So, what do you recommend? Using PETSc for the large-scale computations and some simple Vec and Mat class for small, local stuff?</blockquote>
</div><br></div><div>Don't use PETSc Mat/Vec for very small local problems like the 3x3 or 4x4 matrices. If you are already addicted to templates and overloading, you might check out a library like Eigen which is competitive with BLAS/Lapack for some problems on some architectures.</div>
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</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>