GAMS World Forum

Hi, I don't understand your question completely but some things look fishy to me. You say yR(r) is a binary variable to choose one number out of 95. So this looks like you want to write binary expansion for integer variables. But you don't have a constraint saying only one yR(r) can be 1 and rest sh...

In the following, we will give an overview of the different ways to increase solver performance, mainly by considering hardware upgrading. Note that not all solvers have all capabilities and that the feature naming may differ, therefore, we explain a capability by taking a particular solver, as an e...

Using GAMS with cloud storage services (e.g., dropbox, onedrive, google drive) requires some caution and especially it is not recommended to place a GAMS working directory in such a synchronized cloud storage folder. A user can run into issues when a cloud storage service such as Dropbox has locked ...

I only provided the part that needs to be corrected. Of course you need the full equation constraint(k,i,ii)$(ord(i)<>ord(ii)).. r(k,i)) * x(k,i) =g= r(k,ii) )*x(k,i) ; I don't know what you are trying to solve, but this constraint itself does not make sense to me. there is x(k, i) on both sides of ...

You are missing "alias" https://www.gams.com/latest/docs/UG_SetDefinition.html#UG_SetDefinition_TheAliasStatementMultipleNamesForASet All you need to do is create an alias for set i. (say ii) alias(i, ii); now you can define your constraint constraint(k, i, ii) (ord(i) <> ord(ii)).. Hope t...

https://www.gams.com/38/docs/RN_cmex226 ... ch=$ifthen
$ifthen was introduced in 22.6. So you cannot use it. I am not sure what you can do and I can't test nor point you to documentation of such an old version.

- Atharv

I think it is also important to know which version of GAMS you are using.

- Atharv

Please show how you are using it (i.e., copy the line where you get this error from as it is). There is clearly some error in your syntax.

One possible reason is you have an unnecessary space $ ifthen instead of $ifthen

- Atharv

That's a vague question. It is also a completely different question. Unfortunately, there is no answer without looking at your model. In fact, your model could actually be very difficult and lowering gap is not in your hands. If you need further help, provide your entire code (may be in a separate t...

optcr and optca are tolerances that tell the solver when to stop. This has nothing to do with the absolute gap that solver achieves. You can set the tolerance however low you want, if the solver does not reach it, you will get bad results. The answer lies in reformulating your problem and doing othe...