[Scip] Optimal duals in *.sol returned by SCIPAMPL

[Vladimir VV]

Dear Stefan,
I tried to use SCIPAMPL as an "AMPL-interface" for SoPlex.

We did the same for CBC (Coin-Branch-and-Cut) MILP solver wich is
based on CLP (Coin-LP) solver, i.e. for "continues" LP-problem the
command
cbc stub.nl -AMPL wantsol=7
gives stub.sol with optimal duals "inside".

At https://github.com/ampl/coin/tree/master/Osi/src/OsiSpx
I see Coin_OSI-intrerface for SoPlex.
May be AMPL-interface for SoPlex exists somewhere ?

Vladimir.

On Tue, Aug 12, 2014 at 6:51 PM, Stefan Vigerske
<stefan at math.hu-berlin.de> wrote:
> Hi,
>
> Duals in terms of single values associated with variable bounds and
> constraints make only sense for convex problems, which isn't SCIPs domain.
> One could get them through the AMPL interface when solving a LP without
> presolving with SCIP, but I doubt the effort is worth it. Just use an LP
> solver for such cases.
>
> Stefan
>
>
> On 08/12/2014 04:10 PM, Vladimir VV wrote:
>>
>> Dear all,
>> Is it possible to get optimal dual variables by *.sol file returned by
>> SCIPAMPL ?
>> I see following operator
>> write_sol((char*)msg, x, NULL, NULL);
>> in line #1386 of
>> .../scip-3.1.0/interfaces/ampl/src/reader_nl.c
>>
>> So, nothing duals (the first NULL) nor "wantsol" options ?
>> What is the reason of that ?
>> BTW, the same was for scip-3.0.2...
>>
>> Thanks in advance.
>> Vladimir V. Voloshinov.
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