I tried the --fpump option, and it still ran slow. By the way, I am writing in mathprog, converting to LP format, and then solving in Gurobi. Is there an easier way? I guess I can write some python scripts to get the variables into a post solver program, but I would think there is a simpler solution?
On Wed, Sep 7, 2016 at 10:55 AM, Giorgio Sartor <[email protected]> wrote: > Have you tried option --fpump? > The heuristic part of GLPK (the one able to find feasible solutions > quickly) is not as strong as the MIP engine. We are working on that. ;-) > > - G. S. - > > On 7 Sep 2016, at 9:44 PM, Joshua Friedman <[email protected]> wrote: > > I am working on a bit integer program and my data has 45000 variables (see > below). I am basically just looking for a feasible solution, my objective > is constant. > > My question: it took 10 minutes to run using the glpk solver. I converted > to a CBC form and it solved it in 1 minute, and using Gurobi it took about > 1 second (but it used all 8 threads). Am I doing something wrong with glpk > for bit integer programs? Is there an option that is more efficient? > > Model has been successfully generated > GLPK Integer Optimizer, v4.60 > 68514 rows, 45040 columns, 372605 non-zeros > 45040 integer variables, all of which are binary > Preprocessing... > 9020 hidden covering inequaliti(es) were detected > 1397 constraint coefficient(s) were reduced > 15253 rows, 29410 columns, 161743 non-zeros > 29410 integer variables, all of which are binary > Scaling... > A: min|aij| = 1.000e+00 max|aij| = 1.000e+01 ratio = 1.000e+01 > Problem data seem to be well scaled > Constructing initial basis... > Size of triangular part is 15253 > Solving LP relaxation... > GLPK Simplex Optimizer, v4.60 > 15253 rows, 29410 columns, 161743 non-zeros > 0: obj = 0.000000000e+00 inf = 6.040e+02 (247) > 500: obj = 0.000000000e+00 inf = 3.980e+02 (115) 1 > 837: obj = 0.000000000e+00 inf = 0.000e+00 (0) 1 > OPTIMAL LP SOLUTION FOUND > Integer optimization begins... > + 837: mip = not found yet >= -inf (1; 0) > + 1389: mip = not found yet >= 0.000000000e+00 (30; 0) > + 2309: mip = not found yet >= 0.000000000e+00 (50; 7) > + 2835: mip = not found yet >= 0.000000000e+00 (77; 14) > + 3106: mip = not found yet >= 0.000000000e+00 (113; 14) > > > -- > Joshua Friedman PhD > > [email protected] > http://www.math.sunysb.edu/~joshua > > _______________________________________________ > Help-glpk mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/help-glpk > > -- Joshua Friedman PhD [email protected] http://www.math.sunysb.edu/~joshua
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