Retrieve Solver Log Files in AIMMS Developer¶
Solvers can share information about the solution process up to a very detailed level. To avoid overhead in generating information that is not inspected anyway, the AIMMS IDE defaults to not sharing any information.
Get started with log files¶
The first option is to set the option solver_listing_messages to all.
By just setting this option, a solver will generate a small log file with the name <solver name>.sta in the folder log.
The first solve of an AIMMS session will create the file, subsequent solves will append to the file.
To generate a log file, I used the Flow Shop problem with 14 jobs and 20 machines and solved it using CPLEX 12.8 on my desktop.
1
2Solve problem 'FlowShopModel' with 554 rows, 476 columns (196 binaries, 0 generals), and 8808 nonzeros.
3
4MIP - Integer optimal solution: Objective = 3.8900000000e+002
5Solution time = 71.72 sec. Iterations = 6163443 Nodes = 101990
6
Additional information and example¶
For a MIP problem, a typical first setting to add is the option MIP display to Display each nth node.
Thus I obtained a 95 line log file log\cplex 12.8.sta.
For the sake of brevity, I only show the first and last five lines here.
1Solve problem 'FlowShopModel' with 554 rows, 476 columns (196 binaries, 0 generals), and 8808 nonzeros.
2Tried aggregator 3 times.
3MIP Presolve eliminated 0 rows and 1 columns.
4MIP Presolve modified 7561 coefficients.
5Aggregator did 25 substitutions.
Last five lines:
90 ------------
91Total (root+branch&cut) = 72.72 sec. (45534.38 ticks)
92
93MIP - Integer optimal solution: Objective = 3.8900000000e+002
94Solution time = 72.72 sec. Iterations = 6163443 Nodes = 101990
Overview of options to try out first for logging¶
This section presents, based on problem type and solver, a list of first options to be set for more information. This is not a list of options to improve performance, but a first step to obtain more information about the solution process so analysis of the solution process can be started.
LP Problems solved using Barrier¶
Solver |
Option |
Value |
|---|---|---|
CPLEX |
Barrier display |
Normal |
GUROBI |
Output file |
yes |
CBC |
Status File |
File |
LP Problems solved using SIMPLEX¶
Solver |
Option |
Value |
|---|---|---|
CPLEX |
Simplex display |
At refactorizations |
GUROBI |
Output file |
yes |
CBC |
Status File |
File |
MIP Problems¶
Solver |
Option |
Value |
|---|---|---|
CPLEX |
MIP display |
Display each nth node |
GUROBI |
Output file |
yes |
CBC |
Status File |
File |
NLP Problems¶
Solver |
Option |
Value |
|---|---|---|
BARON |
Keep results file |
On |
CONOPT |
Status file display |
Iteration log |
IPOPT |
Status file |
Yes |
KNITRO |
Status file display |
Summary |
SNOPT |
Print output file |
On |