Re: [Gurobi] Can't give a solution, all variables' values are 0
Renan Garcia
On May 28, 2015, at 10:43 PM, peng yang <pengy...@gmail.com> wrote:When I use AMPL+gurobi to solve my MIP, about a supply network. I built some instances with different size to try it. It can solve the instance with 20 customers (_solve_time = 39.3435), 25 customers(_solve_time = 134.847). When the customer number is 30, it can give a solution after a long time. But when the customer number is 100, it can't give any solution after the limited time, all the values of variables are 0.
I use the option outlev to find some information.Who can explain what happened to me?what shall I do?
Thank you for any help!
Here is the logfile for 100 custommers.
Gurobi 6.0.2: mipgap=0.01
timelim=5000
outlev=1
Optimize a model with 2059748 rows, 823371 columns and 8944463 nonzeros
Coefficient statistics:
Matrix range [3e-01, 1e+06]
Objective range [1e-01, 2e+03]
Bounds range [1e+00, 5e+03]
RHS range [1e+00, 1e+06]
Presolve removed 1234480 rows and 0 columns (presolve time = 12s) ...
Presolve removed 1234480 rows and 0 columns (presolve time = 15s) ...
Presolve removed 1234480 rows and 0 columns (presolve time = 20s) ...
Presolve removed 1234480 rows and 0 columns (presolve time = 25s) ...
Presolve removed 1234480 rows and 0 columns (presolve time = 32s) ...
Presolve removed 1234480 rows and 0 columns (presolve time = 36s) ...
Presolve removed 1234480 rows and 0 columns (presolve time = 48s) ...
Presolve removed 1234480 rows and 0 columns (presolve time = 50s) ...
Presolve removed 1234480 rows and 0 columns (presolve time = 55s) ...
Presolve removed 1234480 rows and 0 columns (presolve time = 60s) ...
Presolve removed 1234480 rows and 0 columns (presolve time = 65s) ...
Presolve removed 1234480 rows and 0 columns
Presolve time: 68.21s
Presolved: 825268 rows, 823371 columns, 6475503 nonzeros
Variable types: 8800 continuous, 814571 integer (814571 binary)
Root simplex log...
Iteration Objective Primal Inf. Dual Inf. Time
0 2.8299000e+04 1.033163e+02 0.000000e+00 146s
4295 2.9767993e+04 1.767151e+03 0.000000e+00 151s
6831 2.9804305e+04 5.520752e+02 0.000000e+00 159s
7648 2.9816707e+04 5.519845e+02 0.000000e+00 161s
8457 2.9825406e+04 4.768371e+02 0.000000e+00 166s
9788 2.9833806e+04 4.945867e+02 0.000000e+00 173s
10366 2.9837104e+04 3.891660e+02 0.000000e+00 178s
10831 2.9838507e+04 6.811148e+02 0.000000e+00 182s
11220 2.9840606e+04 2.219199e+03 0.000000e+00 187s
12403 2.9841390e+04 6.392823e+03 0.000000e+00 191s
13485 2.9862132e+04 6.147623e+03 0.000000e+00 196s
15273 2.9899214e+04 8.712195e+03 0.000000e+00 200s
17190 2.9947859e+04 2.050172e+04 0.000000e+00 205s
20469 3.0078828e+04 1.098573e+04 0.000000e+00 210s
22500 3.0193675e+04 3.341815e+04 0.000000e+00 215s
26429 3.0479412e+04 1.337392e+04 0.000000e+00 221s
29413 3.0819329e+04 9.001763e+03 0.000000e+00 226s
31713 3.1140239e+04 1.316501e+04 0.000000e+00 231s
33553 3.1358846e+04 1.409499e+04 0.000000e+00 236s
35571 3.1541877e+04 3.789451e+04 0.000000e+00 241s
37910 3.1855688e+04 4.154797e+04 0.000000e+00 246s
40728 3.2507709e+04 1.495933e+04 0.000000e+00 251s
43028 3.2930836e+04 3.414223e+04 0.000000e+00 256s
45788 3.3562856e+04 3.805219e+04 0.000000e+00 261s
48696 3.4076243e+04 1.217141e+05 0.000000e+00 265s
51916 3.6550039e+04 6.764694e+05 0.000000e+00 270s
54216 3.7178535e+04 1.236746e+05 0.000000e+00 276s
56056 3.7676201e+04 4.100928e+04 0.000000e+00 282s
58356 6.3587150e+04 4.181625e+04 0.000000e+00 286s
60196 6.5171878e+04 1.773320e+04 0.000000e+00 291s
61576 6.5260813e+04 4.210748e+03 0.000000e+00 297s
62956 6.5666478e+04 1.341276e+04 0.000000e+00 301s
64336 6.5822156e+04 6.182792e+03 0.000000e+00 305s
65256 6.5878867e+04 4.312729e+03 0.000000e+00 310s
66636 6.5911414e+04 1.493711e+03 0.000000e+00 319s
67096 6.6290477e+04 1.030092e+03 0.000000e+00 322s
67556 6.6299129e+04 1.105604e+03 0.000000e+00 325s
68476 6.6588907e+04 9.632499e+02 0.000000e+00 335s
69396 6.7057698e+04 9.517664e+02 0.000000e+00 341s
69856 6.7062092e+04 7.091900e+02 0.000000e+00 346s
70316 6.7251983e+04 8.135377e+02 0.000000e+00 352s
70776 6.7269315e+04 1.807602e+03 0.000000e+00 359s
71236 6.7272188e+04 1.030165e+03 0.000000e+00 366s
71696 6.7278640e+04 2.630213e+03 0.000000e+00 371s
72852 6.7294197e+04 6.452606e+02 0.000000e+00 380s
73414 6.7299385e+04 6.728824e+02 0.000000e+00 387s
74134 6.7304551e+04 1.010013e+03 0.000000e+00 394s
74968 6.7307885e+04 9.414837e+02 0.000000e+00 403s
75434 6.7311542e+04 6.530876e+02 0.000000e+00 408s
76066 6.8023513e+04 3.618974e+02 0.000000e+00 418s
76546 6.8029069e+04 8.125808e+02 0.000000e+00 424s
77006 6.8031568e+04 7.348432e+02 0.000000e+00 429s
77466 6.8035312e+04 6.378018e+02 0.000000e+00 433s
77926 6.8036517e+04 3.176099e+02 0.000000e+00 440s
78386 6.8040017e+04 2.994573e+02 0.000000e+00 445s
78982 6.8043366e+04 1.588299e+02 0.000000e+00 456s
79641 6.8047119e+04 4.333188e+02 0.000000e+00 471s
80101 6.8052919e+04 1.123385e+02 0.000000e+00 477s
80693 6.8054319e+04 1.861776e+02 0.000000e+00 491s
81306 6.8056117e+04 1.002897e+02 0.000000e+00 506s
82049 6.8057616e+04 8.927126e+01 0.000000e+00 528s
82801 6.8058716e+04 5.133443e+01 0.000000e+00 552s
83615 6.8059516e+04 0.000000e+00 0.000000e+00 580s
root relaxation: objective 6.805951e+04, 83615 iterations, 434.87 seconds
Total elapsed time = 580.10s
Total elapsed time = 591.17s
Total elapsed time = 600.70s
Total elapsed time = 608.15s
Nodes | Current Node | Objective Bounds | Work
Expl Unexpl | Obj Depth IntInf | Incumbent BestBd Gap | It/Node Time
0 0 68059.5050 0 203 - 68059.5050 - - 611s
0 0 68061.6135 0 325 - 68061.6135 - - 845s
0 0 68065.8179 0 330 - 68065.8179 - - 1022s
0 0 68065.8179 0 328 - 68065.8179 - - 1091s
0 0 68065.8179 0 317 - 68065.8179 - - 1168s
0 0 68065.8179 0 337 - 68065.8179 - - 1255s
0 0 68065.8179 0 237 - 68065.8179 - - 1373s
0 0 68065.8179 0 262 - 68065.8179 - - 1504s
0 0 68065.8179 0 247 - 68065.8179 - - 1642s
0 0 68065.8179 0 232 - 68065.8179 - - 1773s
0 0 68065.8179 0 245 - 68065.8179 - - 1899s
0 0 68065.8179 0 245 - 68065.8179 - - 3418s
Cutting planes:
Gomory: 21
Cover: 5
Implied bound: 1226
Clique: 1
MIR: 4
Flow cover: 2
Explored 0 nodes (124547 simplex iterations) in 5000.13 seconds
Thread count was 2 (of 4 available processors)
Time limit reached
Best objective -, best bound 6.806581793006e+04, gap -
Gurobi 6.0.2: time limit
124547 simplex iterations
No basis.
No primal or dual variables returned.
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