[Scip] Set a primal solution

[Rostislav Stanek]

Dear Gregor,
thank you for your response. I have then a theoretical question: If I 
add after the freeing process a new global constraint and the solution 
gets infeasible, will it be dropped automatically before starting the 
solving process again? This is not my situation (my solution remains 
feasible), but it could be useful to know it in the future.
Thank you again.
Best regards,
Rostislav Stanek


Dne 11.7.2013 13:17, Gregor Hendel napsal(a):
> Hi Rotislav,
>
> when you invoke SCIPfreeTransform(), found solutions are retransformed 
> and thus "lifted" to the original space, so that they survive
> the freeing process.
>
> regards,
> Gregor
>
> Am 11.07.2013 11:58, schrieb Rostislav Stanek:
>> Dear Michael,
>> excuse me, that I am writing again, but I have a small additional 
>> question: If I use the second proposed option (I do not want that the 
>> heuristic runs more times) and then call “SCIPfreeTransform” and 
>> after that add some global constraints, do I have to set the solution 
>> again also if I know that the solution remains feasible? Or do I have 
>> to check the solution again via “SCIPtrySol()” / “SCIPtrySolFree()”?
>> Thank you again in advice.
>> Best regards,
>> Rostislav Stanek
>>
>> Dne 10.7.2013 17:30, michael.winkler at zib.de napsal(a):
>>> Hi Rostislav,
>>>
>>> you can write a heuristic plugin setting the timing to
>>> SCIP_HEURTIMING_BEFOREPRESOL. This heuristic will then be called only
>>> before presolving of the whole problem (might be multiple times when a
>>> restart happens).
>>> Take a look at the heur_trivial.c for further details.
>>>
>>> When creating a solution via SCIPcreateSol() the solution vector will
>>> contain zero values for all variables implicitly.
>>>
>>> You then need to use SCIPsetSolVal()/SCIPsetSolVals() to set solution
>>> values for the variables.
>>>
>>> Afterwards please use SCIPtrySol()/SCIPtrySolFree() which will check 
>>> the
>>> correctness of the solution and if so SCIP will store the solution and
>>> also update the primalbound and cutoffbound. (So, there is no need 
>>> to add
>>> you extra "bound constraint" anymore, when adding a solution.)
>>>
>>> Please take a look at:
>>> http://scip.zib.de/doc/html/HEUR.shtml
>>> http://scip.zib.de/doc/html/scip_8h.shtml#a03da404f4153d8f673e87fb28bc7d552 
>>>
>>> http://scip.zib.de/doc/html/scip_8h.shtml#adbb9f3c0c0b462481fe5eff677463258 
>>>
>>> http://scip.zib.de/doc/html/scip_8h.shtml#ab4007453cafad788430c2ad55129479f 
>>>
>>> http://scip.zib.de/doc/html/scip_8h.shtml#ae4041777d638e0bcbbb592946b520f15 
>>>
>>> http://scip.zib.de/doc/html/scip_8h.shtml#af00de2379f996445b4497db79e7449f0 
>>>
>>>
>>> Best, Michael
>>>
>>>> Dear SCIP community,
>>>> I excuse me for this question which should be clear for me, but how
>>>> should I correctly set a primal solution before starting the solving
>>>> process? I solve an ILP using the SCIP solver and before starting the
>>>> process I would like to set a heuristical primal solution which would
>>>> also define a bound (this heuristic should not be called during the
>>>> solving process more). I set the bound as a global constraint, but 
>>>> I do
>>>> not know how to set the solution. Can I use “SCIPcreateSol”? 
>>>> And what
>>>> does it mean “creates a primal solution, initialized to zero”?
>>>> Thank you very much in advance.
>>>> Yours faithfully,
>>>> Rostislav Stanek
>>>> _______________________________________________
>>>> 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
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://listserv.zib.de/mailman/private/scip/attachments/20130711/80ab3598/attachment.html