converting a lingo model to lp format

Question

I have written a program using LINGO but the trial version has constraints of 30 nonlinear variables and 30 integer variables, putting me over the limit. Before I decide I might want to buy the next version, I thought I would see how my program would perform on free software. I downloaded LPSolve IDE 5.5 and I am trying to manually convert it, but I am running into problems such as not being able to use parenthesis to influence order of operations and not being able to divide. Is there an easier way to convert a lingo program? I tried exporting it to a MPS file but that gave me errors.

Answer 1

This may not be what you want to hear, but oftentimes you are better off trying to create the entire LP/IP in MPS format from scratch. You might actually end up saving time over converting from Lingo.

If you do want to convert, I suggest that you first load a much smaller problem onto LINGO and see if you are able to convert that first. Then incrementally keep increasing the size of your LP to see where you are getting the errors. This document has instructions on converting an existing problem to the MPS format.

In addition to LPSolve, you might want to try other open-source/free solvers. Some of the common ones include GLPK, SCIP, Google-OR Tools. If you know R, then optim and several other options are available. Finally, I've found that Excel's Solver is quite good as well.

Hope this helps you move forward.