Dear Forumers,
I have encountered a small problem with the expected OPTCR default values. I know that the default used to be 0.1, until GAMS 32.0 I guess, when it was changed to 0.0001 (1e-4). The online documentation also still gives these two values: Under latest/docs/UG_LanguageFeatures.html, the default value is still being stated as 0.1, and under latest/docs/UG_GamsCall.html#GAMSAOoptcr the default value is still being stated as 1.0e-4. On this Forum, the Global Moderator has moreover mentioned that “Nowadays, it is 1e-6”, and I wonder if that is the correct value for the latest versions?
Anyway, I am trying to help a GAMS user, who is using version GAMS 39 and who is seeing from the CPLEX log the that GAMS/Cplex is still setting the epgap value as 0.1. The user is himself not defining OPTCR anywhere at all, and so I think the epgap value should be set equal to the GAMS default, which I think should not be 0.1 under GAMS v39. Therefore, what could be the reason for Cplex getting the value 0.1?
I note additionally that the user is using a restart file created by GAMS 29 (which includes only some declarations). As that appears to be the only explanation that I have been able to imagine for the anomaly, my question is now: Does the GAMS version used for creating a restart file in fact determine the default values for GAMS options? And if this is so, which all defaults would the restart file affect? Or is there indeed some other explanation?