• Gurobi Staff

Just looking at the first lines of the log files, I would guess that you are solving two different models.

For the web tool, you get this:

Optimize a model with 2475 rows, 66689 columns and 355340 nonzeros

For the development tool, you get this:

Optimize a model with 2472 rows, 81930 columns and 442513 nonzeros

thanks yes they are slightly different in the way the original points have been clustered. I hadn't thought this would make such a significant difference

• Gurobi Staff

It can happen sometimes that small changes in the model make a big difference...

The web tool returns a solution with a MIP gap of 4% though. Are you sure you correctly set the MIP gap to the same value in both setups? After what time did the solver reach 4% with the development tool? (Could you share complete log files?)

Could you try running exactly the same model with both tools? Could you also try running with different random seeds?

This is the log from the web tool - it seems to be repeated probably due to the developers saving the AMPL log to the same location as the Gurobi log.

It appears to me to be exiting optimization at mipgap = 4% rather than 2%. But looking at the log output seems like it is implemented properly.

we have altered the problem slightly to improve the runtime in the development tool, so now my focus is trying to determine why the webtool stops at mipgap=4%

• Gurobi Staff

Looking at the log you have attached, the  final mip gap is not displayed.  The final objective is 9.9741019e+07.  Gurobi Optimizer is reducing the gap between the best bound and the best objective.  The last best bound is 9.7378e+07.  This is approximately 2% mip gap.

If the log file above is no longer current, please post the current log file.

thanks Jennifer for pointing out that the achieved mipgap is close to 2% - I can see that now.

This is the most current log, I am not sure why the last line and final mipgap is not displaying. There is something strange happening with the way the webtool captures the log. thanks again for your help.