Re: [Fwd: Re: Is it possible to feed glpsol with a feasible initial solution to a MIP problem?]
João Flávio de Freitas Almeida <[email protected]>
| Newsgroups | gmane.comp.gnu.glpk |
|---|---|
| Message-ID | <CABroSTaeJWQ2CXuiRk8TF_ChYEYUHC8PDf2u6vFaN3X_NFor+A@mail.gmail.com> |
Dear Alejandro, 1 - Call glpsol to generate a solution of the *LP* problem and save it using "-w file.sol" 2 - The file.sol file must have a solution line (first) named "s" "bas", ie a basic solution 3 - Call glpsol by disabling LP (--nopresol) and MILP preprocessing (--nointopt) and include the base file (--ini file.sol) $ glpsol -m localiz.mod -d localiz.dat --nopresol --nomip -w file.sol $ glpsol -m localiz.mod -d localiz.dat --nopresol --nointopt --cuts --ini file.sol Andrew, for MIP problems I had the same problem: a file.sol with "mip" solution, but Glpk display an error message: "error: wrong solution designator; 'bas' expected" Bests, -- João Flávio de Freitas Almeida Professor Adjunto Departamento de Engenharia de Produção Universidade Federal de Minas Gerais 30.310-290 Belo Horizonte MG Brasil Em sáb, 7 de abr de 2018 às 11:07, Alejandro Pascual <[email protected]> escreveu: > Hello Chris, > > Thank you very much for your concern. > > I tried the --nopresol --nointopt options following your suggestion, > but I got the following error message (I attach the log file): > > localiz0.sol:8: error: wrong solution designator; 'bas' expected > Unable to read initial basis > > Best regards, > Alejandro > > On 7 April 2018 at 10:12, Chris Matrakidis <[email protected]> wrote: > > Hi Alejandro, > > > >> > >> Anyway, I can't get glpsol to use the feasible solutition fed with > >> --ini. > > > > > > I think you need to disable the presolver with options --nopresol > --nointopt > > to use a given solution. The presolver generates a new problem, for which > > the given solution is no longer valid. > > > > Best Regards, > > > > Chris Matrakidis > _______________________________________________ > Help-glpk mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/help-glpk > _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk