I believe glpk is too slow for timetable problems like yours. Try Gurobi. On Tue, Jun 12, 2018, 8:05 PM João Pedro de Sá Moreira < jopmoreir...@gmail.com> wrote:
> I’m currently working on a timetable model that is supposed to deal if a > pretty big number of variables. > > > > On initial tests i can see it takes a fair time to get to a LP solution > (about 30m) and then it starts to work on finding the optimal integer > solution. > > > > The problem is that in this part, it takes about 5h working on analyzing > the whole tree, but the strange thing is that it keeps showing the same > value every iteration it does until it gets to the end of the tree. The > value it shows is the same value that can be seen when it finds the lp > solution, does it means that the LP solution was the optimal since the > beginning? Am i able to interrupt the execution and take a look at this > solution? Or is there a way to speed it up a little bit? > > > > I’ve alreay tried –tmlim and it worked but the solution couldn’t be > returned. Then i tried –nopresol and –output but the problem is that the > output returned a “INTEGER UNDEFINED” status. > > > > That’s the part of the model where it finds the optmial LP solution: > > > > Solving LP relaxation... > > GLPK Simplex Optimizer, v4.65 > > 15202 rows, 138924 columns, 555696 non-zeros > > 0: obj = -0.000000000e+00 inf = 3.194e+03 (620) > > Perturbing LP to avoid stalling [401]... > > 2722: obj = 8.750000000e+02 inf = 1.930e+02 (52) 2 > > 4678: obj = 8.951560756e+02 inf = 1.026e+01 (9) 11 > > 4915: obj = 9.000461789e+02 inf = 8.944e-06 (0) 1 > > * 6780: obj = 9.391853182e+02 inf = 7.886e-06 (49431) 11 > > Removing LP perturbation [8499]... > > * 8499: obj = 9.680000000e+02 inf = 1.588e-14 (0) 10 > > OPTIMAL LP SOLUTION FOUND > > > > Then it begins the integer optmization and keeps on working and 5 hours > later: > > > > . > > . > > . > > + 86591: mip = not found yet <= 9.680000000e+02 (1184; 0) > > + 86616: mip = not found yet <= 9.680000000e+02 (1187; 0) > > + 86651: mip = not found yet <= 9.680000000e+02 (1191; 0) > > + 86727: mip = not found yet <= 9.680000000e+02 (1195; 0) > > + 86818: mip = not found yet <= 9.680000000e+02 (1205; 0) > > Time used: 18130.5 secs. Memory used: 313.8 Mb. > > + 86874: >>>>> 9.680000000e+02 <= 9.680000000e+02 0.0% (1213; 0) > > + 86874: mip = 9.680000000e+02 <= tree is empty 0.0% (0; 2425) > > INTEGER OPTIMAL SOLUTION FOUND > > Time used: 18154.2 secs > > Memory used: 413.6 Mb (433691909 bytes) > > > > Then the timetable is shown. > > > > Any tips? Thanks in advance. > > > > > > > > > > > > > > Enviado do Email <https://go.microsoft.com/fwlink/?LinkId=550986> para > Windows 10 > > > > > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> > Livre > de vírus. www.avast.com > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient>. > <#m_-3075016419714778253_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > _______________________________________________ > Help-glpk mailing list > Help-glpk@gnu.org > https://lists.gnu.org/mailman/listinfo/help-glpk >
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