8 Debugging Tutorials¶
This collection of tutorials contains basic techniques for debugging optimization problems using tools available in MOSEK: optimizer log, solution summary, infeasibility report, command-line tools. It is intended as a first line of technical help for issues such as: Why do I get solution status unknown and how can I fix it? Why is my model infeasible while it shouldn’t be? Should I change some parameters? Can the model solve faster? etc.
The major steps when debugging a model are always:
Consult the log output. It is enabled by default, but if neccessary switch it on explicitly with:
r <- mosek(prob, list(verbose=10))
Run the optimization and analyze the log output, see Sec. 8.1 (Understanding optimizer log). In particular:
check if the problem setup (number of constraints/variables etc.) matches your expectation.
check solution summary and solution status.
Dump the problem to disk if necessary to continue analysis. See Sec. 7.3.3 (Saving a problem to a file).
use a human-readable text format, preferably
*.ptfif you want to check the problem structure by hand. Assign names to variables and constraints to make them easier to identify.
r <- mosek_write(prob, "dump.ptf");
use the MOSEK native format
*.task.gzwhen submitting a bug report or support question.
r <- mosek_write(prob, "dump.task.gz");
Fix problem setup, improve the model, locate infeasibility or adjust parameters, depending on the diagnosis.
See the following sections for details.