2018 October 17 CPLEX
Understand the output from CPLEX solver
Understand the output from CPLEX solver
Ref: https://www.ibm.com/support/knowledgecenter/SSSA5P_12.6.3/ilog.odms.cplex.help/CPLEX/UsrMan/topics/discr_optim/mip/para/52_node_log.html
Solver Output
MIP search method: dynamic search.
Parallel mode: none, using 1 thread.
Root relaxation solution time = 0.00 sec (0.00 ticks)
Nodes Cuts/
Node Left Objective IInf Best Integer Best Bound ItCnt Gap
* 0+ 0 0.0000 3261.8212 8 ---
* 0+ 0 3148.0000 3261.8212 8 3.62%
0 0 3254.5370 7 3148.0000 Cuts: 5 14 3.38%
0 0 3246.0185 7 3148.0000 Cuts: 3 24 3.11%
* 0+ 0 3158.0000 3246.0185 24 2.79%
0 0 3245.3465 9 3158.0000 Cuts: 5 27 2.77%
0 0 3243.4477 9 3158.0000 Cuts: 5 32 2.71%
0 0 3242.9809 10 3158.0000 Covers: 3 36 2.69%
0 0 3242.8397 11 3158.0000 Covers: 1 37 2.69%
0 0 3242.7428 11 3158.0000 Cuts: 3 39 2.68%
0 2 3242.7428 11 3158.0000 3242.7428 39 2.68%
10 11 3199.1875 2 3158.0000 3215.1261 73 1.81%
* 20+ 11 3168.0000 3215.1261 89 1.49%
20 13 3179.0028 5 3168.0000 3215.1261 89 1.49%
30 15 3179.9091 3 3168.0000 3197.5227 113 0.93%
* 39 3 integral 0 3186.0000 3197.3990 126 0.36%
40 3 3193.7500 1 3186.0000 3197.3990 128 0.36%
Cover cuts applied: 9
Zero-half cuts applied: 2
Gomory fractional cuts applied: 1
Solution pool: 5 solutions saved.
MIP-Integer optimal solution: Objective = 3.1860000000e+03
Solution time = 0.01 sec. (0.00 ticks) Iterations = 131 Nodes = 44
Column Meaning
- (1st) : * - integer-feasible solution (new incumbent) is found
- Node : current node number
- Nodes Left : number fo nodes left to explore
- Objective :
- Objective value at the node; or
- Reason to fathom the node, because
- Subproblme at the node is infeasible; or
- Value of the objective function at the node is worse that the cutoff value for branch & cut; or
- LP relaxation of the node supplies an integer solution
- (Note: blank means CPLEX found a new incumbent by primal heuristics – a plus(+) appears after node number)
- IInf : number of integer-infeasible variables and special ordered sets
- Best Integer : the objective value of the best integer solution found so far (blank if no solution found)
- Cuts/Best Bound : the best objective function vallue achievable
- Cuts : means various cuts generated
- <particular name of a cut> (e.g., Covers) : only that kind of cut was generated
- ItCnt : cumulative iteration count when solving the subproblems
- Gap : relative gap value
- hyphen (-) : gap > 999.99%
- blank : no solution so far
- gap := (best integer - best node) * objsen / (abs(best ineger) )