[Couenne] couenne doesn't write solution file

[Pietro Belotti]

Francois,

I can reproduce the behaviour you describe. It is the Bonmin interface 
with AMPL that takes care of writing the .sol file. However, I believe it 
is reasonable that if a problem is found infeasible, a .sol file should 
not be written.

Note that the .sol file is supposed to contain the best feasible solution 
found so far, and not whether a solution was found or how much time was 
taken, etc.

Hope this helps.

Regards,
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, 8 Sep 2011, Francois Dionne wrote:

> Dear mailing list,
>
> I wrote a model and a script in AMPL, which then calls Couenne. I don't
> think Couenne writes a ".sol" file. This is the output of "ampl
> myscript":
>
> Couenne 0.4 --  an Open-Source solver for Mixed Integer Nonlinear
> Optimization
> Mailing list: couenne at list.coin-or.org
> Instructions: http://www.coin-or.org/Couenne
> couenne:
> ANALYSIS TEST:  Couenne: Warning, tightened NLP is infeasible
> problem infeasible
> Error at _cmdno 2 executing "solve" command
> (file myscript.txt, line 4, offset 60):
> can't open /tmp/at28498.sol
>
> This is the output of "ampl -v":
>
> AMPL Student Version 20110813 (Linux x86_32)
>
> I wrote a stub which I then used directly on Couenne. It reports that
> the problem is unfeasible, which is possible. However, I don't think it
> writes a solution file with that either.
>
> I'm using Ubuntu Linux Lucid Lynx 32 bit. The only thing I did
> differently in the compilation of Couenne is the use of "--prefix="
> during the "configure" step. A stub is included with this message. Any
> ideas on what I'm doing wrong?