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<div class="moz-cite-prefix">On 18.09.2012 20:14, Hong Zhang wrote:<br>
</div>
<blockquote
cite="mid:CAGCphBviX7x5qVb6m2kJYGKA-GSgrn4qiLYP=7MsUFzQF-LBfQ@mail.gmail.com"
type="cite">MatMatSolve_MUMPS() is never been supported.
<div>It seems mumps support multiple rhs now.<br>
<div>If you need it, we can implement MatSolve_MUMPS().</div>
</div>
</blockquote>
<br>
Hi Hong,<br>
<br>
Thanks for reply.<br>
<br>
Is MatSolve in any way more efficient than KSPSolve? <br>
As far as I understand for both cases one ends up with a loop over
RHS, <br>
but KSPSolve allows to use iterative solvers (I don't need them at
the moment though).<br>
I would then use latter option and do this loop myself.<br>
<br>
<blockquote
cite="mid:CAGCphBviX7x5qVb6m2kJYGKA-GSgrn4qiLYP=7MsUFzQF-LBfQ@mail.gmail.com"
type="cite">
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<div>
<div class="gmail_quote">
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<br>
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<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
There was one issue with it for sequential mode that has
been fixed here:<br>
<a moz-do-not-send="true"
href="http://petsc.cs.iit.edu/petsc/releases/petsc-3.3/rev/8badc49a596e"
target="_blank">http://petsc.cs.iit.edu/petsc/releases/petsc-3.3/rev/8badc49a596e</a></blockquote>
<div><br>
</div>
<div>This change prevents calling of MatMatSolve_Basic().</div>
<div>How many rhs vectors (or number of columns in your rhs
matrix)?</div>
<div>MUMPS only supports centralized rhs. Scattering many
rhs vectors to </div>
<div>a sequential dense matrix is non-scalable.</div>
</div>
</div>
</div>
</blockquote>
<br>
That is right. The request on that has recently appeared in the
mumps mailing list and they replied there are no plans to develop
it. <br>
I have usually < 10^3 and this is not a bottleneck, so I'm fine
with a "inefficient" loop over RHS. <br>
<br>
But, for those who are chasing performance and have many sprase RHS
(e.g., this is the case when one needs to solve many adjoint
problems with delta function as a RHS) I can say that using MUMPS'
multiple RHS mode is a way more efficient than solving them in a
loop. This is probably related to some internals where MUMPS is able
to take advantage of getting many RHS at once. <br>
<br>
<pre class="moz-signature" cols="72">--
Regards,
Alexander</pre>
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