<div dir="ltr">Hi Gerald and Stefan,<div><br></div><div>Thanks a bunch for the quick response! You are correct, it is not a true LP. The reason I tried to run it through a different solver is that scip is not finding the optimal solution, one that I don't think is "hard" to intellectual find, but may for some reason be hard to solve for? It has solved 10/10 tests I created for it (some of which are harder), but 1 of these tests it does not find the optimal solution.</div>
<div><br></div><div>In my optimization, I am trying to find the optimal wireless frequency for each network. I give it the possible set of frequencies for each radio:</div><div><div> set FR[R] :=<br></div><div> <1> { 2412 },</div>
<div> <2> { 2412 },</div><div> <3> { 2437 },</div><div> <4> { 2437 },</div><div> <5> { 2412, 2437 },</div><div> <6> { 2412, 2437 };</div></div><div><br></div><div>By putting {2412,2437} for <5> and <6>, I allow for the optimization to choose between those two frequencies for those two radios (that belong to the same network -- they must end up on the same frequency). When solving through scip, it will choose 2412 for these radios which produces an objective value of 2.40163428660051. </div>
<div><br></div><div>If I force the two radios to 2437 by removing 2412 from both's set (such that there is no choice in the optimization problem), then the objective value of 2.73735205292492 will be produced because the radios receive less interference on 2437.</div>
<div><br></div><div>Intellectually, this is not hard for me to solve in my head. Of course, with 387 and 794 constraints, I know that what goes on in my head is not what happens in the optimization. But, the only "choices" in the optimization are these frequencies and there are only 2. So, I'm not sure why it misses the optimal solution.</div>
<div><br></div><div>Does anyone have any suggestions when running through scip to try and find the optimal solution? </div><div><br></div><div>I have included the ZIMPL file with a matching data.zpl that forces the optimal solution. You can change FR[R] in data.zpl to match what I pasted in this e-mail and if you run it through scip it will find the non-optimal solution. Thanks for any help. This is my first attempt at mixed integer programming, so this is all extremely new to me, and I appreciate all the work you've all done the optimization suite.</div>
<div><br></div><div>- George</div><div><br></div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Fri, Jul 26, 2013 at 4:34 AM, Stefan Vigerske <span dir="ltr"><<a href="mailto:stefan@math.hu-berlin.de" target="_blank">stefan@math.hu-berlin.de</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi,<br>
<br>
your model is not an LP, but a quadratic program. SCIP can handle this, but SoPlex cannot.<span class="HOEnZb"><font color="#888888"><br>
<br>
Stefan</font></span><div><div class="h5"><br>
<br>
On 07/26/2013 10:13 AM, George Nychis wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
I am trying to run an LP file through soplex that was generated by zimpl.<br>
However, when I try to I get:<br>
<br>
Loading LP file spectrum_optimization.lp<br>
ELPFRD15 Syntax error in line 205<br>
error while reading file "spectrum_optimization.lp"<br>
<br>
This points to the following lines:<br>
<br>
airtime_eq_re@19:<br>
- RadioAirtime#1 + GoodAirtime#1<br>
+ [ + RadioAirtime#1 * RadioLossRate#1 ] <--- line 205<br>
= 0<br>
<br>
I've attached the zmpl files and the lp output. I am able to run this<br>
through scip using both of these commands:<br>
scip -f spectrum_optimization.zpl<br>
scip -f spectrum_optimization.lp<br>
<br>
So, something seems to be wrong when parsing with soplex. I'd greatly<br>
appreciate any help.<br>
<br>
Thanks!<br>
George<br>
<br>
<br>
<br></div></div><div class="im">
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