[Scip] Dive

[Timo Berthold]

Hi Jonas,

please try the following:
SCIP_CALL( SCIPtransformProb(subscip) );
SCIP_CALL( SCIPsetLongintParam(subscip, "limits/nodes", 1LL) );
SCIP_CALL( SCIPsetIntParam(subscip, "lp/solvefreq", -1) );
SCIP_CALL( SCIPsetPresolving(subscip, SCIP_PARAMSETTING_OFF, TRUE) );
SCIP_CALL( SCIPsetHeuristics(subscip, SCIP_PARAMSETTING_OFF, TRUE) );
SCIP_CALL( SCIPsetSeparating(subscip, SCIP_PARAMSETTING_OFF, TRUE) );
SCIP_CALL( SCIPsolve(subscip) );
SCIP_CALL( SCIPconstructLP(subscip, &cutoff) );
SCIP_CALL( SCIPflushLP(subscip) );

Cheers,
Timo

Am 06.05.2013 16:45, schrieb Jonas Witt:
> Hi Ambos,
>
> thanks for your help, I will try to implement the SCIPaddColDive() function.
>
> I have another question:
> I have a SCIP instance in SCIP_STAGE_PROBLEM and I just want to 
> construct the root lp (without solving it) to start a dive. How can I do 
> this?
>
> I tried to turn presolving off and set lp/iterlim as well as 
> limits/nodes to 0 (I also tried 1). Then I called SCIPsolve(), but it 
> sometimes still solved the SCIP instance or left the SCIPsolve() in 
> SCIP_STAGE_PRESOLVING. After the dive I would like to return to the 
> SCIP_STAGE_PROBLEM, because I need to solve and modify this problem later.
>
>
> Best regards,
> Jonas
>
>
>
> Am 06.05.2013 15:02, schrieb Ambros Gleixner:
>> Hi Jonas,
>>
>> yes, this is possible.  I cannot think of any big problems.  The most
>> important issue is that the already existing columns are not modified
>> (except for bounds and objective coefficients, of course) and that the
>> LP is shrunk to the initial size when calling SCIPendDive().  This
>> should be completely parallel to SCIPaddRowDive().
>>
>> I do not see another possibility except for expensive ways such as using
>> a sub-SCIP.
>>
>> You can ask me any questions if you run into problems during the
>> implementation.  We would be happy to include such an extension into the
>> next release.
>>
>> Ambros
>>
>>
>> Am 06.05.2013 10:03, schrieb Jonas Witt:
>>> Hi all,
>>>
>>> I use the diving mode and I would like to add columns to the diving lp.
>>> Is it possible to write a SCIPaddColDive()-function which is similar to
>>> the SCIPaddRowDive()-function? What problems might occur? Or is there
>>> another possibility to do this?
>>>
>>> Best regards,
>>> Jonas
>>> _______________________________________________
>>> Scip mailing list
>>> Scip at zib.de
>>> http://listserv.zib.de/mailman/listinfo/scip
>>>
> _______________________________________________
> Scip mailing list
> Scip at zib.de
> http://listserv.zib.de/mailman/listinfo/scip