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<div class="moz-cite-prefix">Abc is short for Aboca, which stands
for A Bit Of Clp Accelerated.<br>
<br>
In 2012 I decided to see if Simplex could be made faster by using
new instructions and by going parallel. I had some success going
parallel using an extension to C - cilk, which was originally from
MIT and eventually taken on by Intel. It is now in gcc 4.9. Abc
uses cilk to go parallel in classic sense (e.g. pricing matrix),
but also by doing part of factorization update at the same time as
the pricing. This leads to an interesting re-write of the dual
simplex method.<br>
<br>
This worked well and I gave a talk on it in 2012 at ISMP Berlin.
I still use it on some of my projects, but it's advantage over Clp
has diminished (and now can be negative on some problems).<br>
<br>
So clp model -abc four -dualsolve would use Abc to solve and then
hand back to Clp solve. This is only activated if Clp is
configured with --enable-aboca=4 and using -fcilkplus in compiler
options.<br>
<br>
I have recently realized that I have made some mistakes with #if
#else #endif constructs which I am going to fix this year. The
--enable-aboca version of Clp should behave in an identical
fashion to the ordinary version if aboca not switched on - but it
didn't. That should be easy to fix.<br>
<br>
I am in the process of revisiting Clp anyway - so I need to make
sure that Abc regains some of its former zing. <br>
<br>
If you need more information, do not hesitate to ask awkward
questions.<br>
<br>
John Forrest<br>
<br>
<br>
<br>
<br>
On 26/11/14 04:00, Babak Moazzez wrote:<br>
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cite="mid:CAEHJM4m7B8P7i605UKT-zSHUt5yk41A84zc0rzVQdHkuhhQ-RA@mail.gmail.com"
type="cite">
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<div dir="ltr">Hi<br>
<div><br>
What is the relation/difference between AbcSimplex and
ClpSimplex?<br>
<br>
</div>
<div>Thanks<br>
</div>
<div>
<div><br>
</div>
<div>B. M.<br>
</div>
</div>
</div>
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