Hi, While solving a MIP problem, I got the following terminal output and I need help to interpret it. See my comments below.
> GLPK Integer Optimizer, v4.47 > 3781 rows, 26950 columns, 90897 non-zeros > 26950 integer variables, 26680 of which are binary > Preprocessing... > 3520 rows, 25184 columns, 84631 non-zeros > 25184 integer variables, all of which are binary > Scaling... > A: min|aij| = 1.000e+00 max|aij| = 1.000e+00 ratio = 1.000e+00 > Problem data seem to be well scaled > Constructing initial basis... > Size of triangular part = 3520 > Solving LP relaxation... > GLPK Simplex Optimizer, v4.47 > 3520 rows, 25184 columns, 84631 non-zeros > 16213: obj = 0.000000000e+00 infeas = 3.870e+02 (0) > 16500: obj = 0.000000000e+00 infeas = 3.810e+02 (0) > 17000: obj = 0.000000000e+00 infeas = 3.480e+02 (0) > 17500: obj = 0.000000000e+00 infeas = 2.980e+02 (0) > 18000: obj = 0.000000000e+00 infeas = 2.540e+02 (0) > 18500: obj = 6.500000000e+00 infeas = 2.290e+02 (0) > 19000: obj = 1.200000000e+01 infeas = 1.730e+02 (0) > 19500: obj = 1.075000000e+01 infeas = 1.260e+02 (0) > 20000: obj = 8.000000000e+00 infeas = 1.040e+02 (0) > 20500: obj = 1.100000000e+01 infeas = 7.825e+01 (0) > 21000: obj = 1.250000000e+01 infeas = 7.150e+01 (0) > 21500: obj = 1.333333333e+01 infeas = 6.083e+01 (0) > 22000: obj = 1.064864865e+01 infeas = 4.914e+01 (0) > 22500: obj = 1.119493671e+01 infeas = 1.729e+01 (0) > * 22919: obj = 1.431795314e+01 infeas = 2.932e-15 (0) > * 23000: obj = 9.703296703e+00 infeas = 7.096e-15 (0) > * 23500: obj = 2.714285714e+00 infeas = 2.817e-14 (0) > * 23721: obj = 1.000000000e+00 infeas = 1.486e-12 (0) > OPTIMAL SOLUTION FOUND As I understand, at this point the simplex algorithm is done finding an optimal solution for my problem. The objective value found is 1. >From this point, I'm expecting the branch-and-bound algorithm to start. > Integer optimization begins... > + 23721: mip = not found yet >= -inf (1; 0) > | 34000: obj = 1.000000000e+00 infeas = 1.058e-12 (0) Reading the GLPK documentation the symbol "|" means the dual simplex algorithm is running. Why are we running simplex again? I'm expecting the branch-and-bound to run or the Fpump heuristic since I enabled it. > | 34500: obj = 1.000000000e+00 infeas = 6.092e-12 (0) > | 35000: obj = 1.000000000e+00 infeas = 7.244e-12 (0) > | 35500: obj = 1.000000000e+00 infeas = 3.837e-12 (0) > | 36000: obj = 1.000000000e+00 infeas = 5.162e-12 (0) > | 36500: obj = 1.000000000e+00 infeas = 2.919e-12 (0) > | 37000: obj = 1.000000000e+00 infeas = 3.240e-12 (0) > | 37500: obj = 1.000000000e+00 infeas = 2.045e-12 (0) > | 38000: obj = 1.000000000e+00 infeas = 4.419e-12 (0) > | 38500: obj = 1.000000000e+00 infeas = 8.190e-13 (0) > | 39000: obj = 1.000000000e+00 infeas = 3.498e-12 (0) > | 39500: obj = 1.000000000e+00 infeas = 1.208e-24 (0) > | 40000: obj = 1.000000000e+00 infeas = 4.321e-12 (0) > | 40500: obj = 1.000000000e+00 infeas = 5.864e-12 (0) > | 41000: obj = 1.000000000e+00 infeas = 1.950e-13 (0) > | 41500: obj = 1.000000000e+00 infeas = 3.029e-12 (0) > | 42000: obj = 1.000000000e+00 infeas = 1.799e-12 (0) > | 42500: obj = 1.000000000e+00 infeas = 4.196e-12 (0) > | 43000: obj = 1.000000000e+00 infeas = 1.802e-12 (0) > | 43500: obj = 1.000000000e+00 infeas = 1.449e-12 (0) > | 44000: obj = 1.000000000e+00 infeas = 3.356e-12 (0) > | 44500: obj = 1.000000000e+00 infeas = 4.529e-13 (0) > | 45000: obj = 1.000000000e+00 infeas = 2.765e-12 (0) > | 45500: obj = 1.000000000e+00 infeas = 2.123e-12 (0) > | 46000: obj = 1.000000000e+00 infeas = 1.775e-12 (0) > | 46500: obj = 1.000000000e+00 infeas = 4.873e-12 (0) > | 47000: obj = 1.000000000e+00 infeas = 6.158e-12 (0) > | 47500: obj = 1.000000000e+00 infeas = 2.211e-12 (0) > | 48000: obj = 1.000000000e+00 infeas = 6.426e-12 (0) > | 48500: obj = 1.000000000e+00 infeas = 1.391e-11 (0) > | 49000: obj = 1.000000000e+00 infeas = 3.064e-12 (0) > | 49500: obj = 1.000000000e+00 infeas = 2.130e-11 (0) > | 50000: obj = 1.000000000e+00 infeas = 1.447e-12 (0) > | 50500: obj = 1.000000000e+00 infeas = 6.791e-12 (0) > | 51000: obj = 1.000000000e+00 infeas = 3.456e-12 (0) > | 51500: obj = 1.000000000e+00 infeas = 9.451e-13 (0) > | 51714: obj = 1.000000000e+00 infeas = 2.042e-13 (0) > Applying FPUMP heuristic... > Pass 1 > Solution found by heuristic: 1 > + 51714: mip = 1.000000000e+00 >= tree is empty 0.0% (0; 1) > INTEGER OPTIMAL SOLUTION FOUND Patrik Dufresne _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk
