xpress version and options

[edward.thomas]

Hello,

We are running Xpress 8.12 and an older version of Xpress from 2008. With the newer version of Xpress 8.12, the run crashes since the Xpress solver reaches the maximum iterations, whereas the older Xpress works fine. We are being directed by our IT to upgrade our Xpress so that the old one will no longer be an option going forward.

Is there a version of Xpress that you recommend? Also, what are the options that are recommended in the Xpress.opt file? We have tried different options and while some work, when there is a price change it can break. Note: This does not happen in the older version of Xpress from 2008.

Thank you for your help,
Ed Thomas

Xpress Options

DEFAULTALG = 4
BARTHREADS = 16
presolve = 1
Crossover = 1
barstart = 2
scaling = 5

[Antti-L]

It seems there a not so many Xpress users around; I think most ETSAP partners are using the GAMS/Cplex solver.

I have no experience with Xpress either, but wonder whether the Xpress solver you are using is the one that comes with GAMS, or a standalone Xpress solver with a separate license and linked to GAMS?  If the former, note that you can well keep many GAMS installations on your computer, and any newer GAMS licenses do keep working with older versions as well.  Therfeore, unless you have a separate license to a standalone Xpress, I would suggest to keep the old GAMS installation with the well-working older Xpress version, in order to have a backup plan if running with the new version fails.

But otherwise, I would suggest to contact the Xpress support, or community forum, and describe your problem.
https://community.fico.com/s/ask-a-question/xpress-optimization