[Couenne] Question about "display" the results
Pietro Belotti
pbelott at clemson.edu
Thu Dec 23 10:15:22 EST 2010
Dear Nathalie,
this is most probably an issue with the interface between Cbc (the
branch-and-bound solver used by Couenne) and the Couenne wrapper for
Cplex. The former might not be able to access the right data and end up
with the wrong (-326) value.
You may want to post the model you have used, so that one can replicate
the problem. Also, if total_income is the name of the objective function
as specified in the AMPL model, I assume it is associated with an
expression. What happens when you display that expression instead of
total_income?
Thanks,
Pietro
--
Pietro Belotti
Dept. of Mathematical Sciences
Clemson University
email: pbelott at clemson.edu
phone: 864-656-6765
web: myweb.clemson.edu/~pbelott
On Thu, 23 Dec 2010, njamett at uantof.cl wrote:
>
> Hi
>
> I'm working with couenne and cplex as a subsolver. I found an optimal, but when I try to display the results, it shows a different solution.
>
> CPX0000 CPLEX Error 1217: No solution exists.
> CPX0000 CPLEX Error 1217: No solution exists.
> CPX0000 CPLEX Error 1217: No solution exists.
> CPX0000 CPLEX Error 1217: No solution exists.
> Cbc0001I Search completed - best objective -12707779302.36208, took 557444 iterations and 10274 nodes (275.85 seconds)
> Cbc0032I Strong branching done 0 times (285622 iterations), fathomed 13 nodes and fixed 185 variables
> Cbc0035I Maximum depth 282, 4 variables fixed on reduced cost
> CPX0000 CPLEX Error 1217: No solution exists.
> CPX0000 CPLEX Error 1217: No solution exists.
> CPX0000 CPLEX Error 1217: No solution exists.
> CPX0000 CPLEX Error 1217: No solution exists.
> CPX0000
> CPX0000 Iteration Objective In Variable Out Variable
> CPX0000 1 sI 4645.972072 x78 x77
> CPX0000 2 sI 4645.970457 x63 x62
> Couenne convexifier cuts was tried 34282 times and created 845177 cuts of which 30323 were active after adding rounds of cuts
>
> "Finished"
>
> couenne: Optimal
>
> ampl: display total_income,w,vr,vs,vc,or,os,oc,nr,ns,nc,s1,s2,aj,ak;
> total_income = -362.768 (best objective)
>
> w [*,*]
> : 1 2 :=
> 1 1250 2500
> 2 1250 2500
> 3 0 0
> 4 226.445 1755.75
> 5 0 0
> 6 0 0
> 7 0 0
> 8 0 0
> 9 0 0
> 10 226.445 1755.75
> 11 57.2661 1590.52
> 12 0 0
> 13 0 0
> 14 0 0
>
> I solved the same problem using Couenne without Cplex and I got almost the same result ( total income-12E-10). I when i did the display i didn't have any problem. Do
> you know why I have troubles in display when I use Couenne with Cplex?
>
> Thank you
>
> Best regards.
>
> Nathalie Jamett
> PhD Student
> University of Antofagasta
> Chile.
>
>
>
>
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