Search found 372 matches

by Fred
1 week ago
Forum: Syntax
Topic: GAMS/CPLEX Model Creation Time
Replies: 3
Views: 738

Re: GAMS/CPLEX Model Creation Time

Hi Gabriel, Adam already shared a link to some hints on how to formulate a model efficiently. If this did not help, I suggest you share your code and data, such that other forum user can analyze and provide help. If this cannot be shared publicly (e.g. due to confidentiality), feel free to reach out...
by Fred
2 weeks ago
Forum: Modeling
Topic: How can I get very old GAMS version?
Replies: 1
Views: 642

Re: How can I get very old GAMS version?

Please reach out to sales@gams.com with your license and ask for a download link.

Best,
Fred
by Fred
2 weeks ago
Forum: Modeling
Topic: Performance Difference between LP and MIP with fixed integer variables
Replies: 1
Views: 568

Re: Performance Difference between LP and MIP with fixed integer variables

Usually, there shouldn't be a big difference in performance. But I guess in some corner cases solver behavior might be different. Fixing a variable means setting upper and lower bound to the same value. But it is still a variable and feasibility and integrality may be violated within the tolerances....
by Fred
2 weeks ago
Forum: Syntax
Topic: error 198
Replies: 1
Views: 926

Re: error 198

I guess you are running into a problem with an unordered set. Looking at this example may help.

When sharing code, please use code tags or attach a gms file. Just pasting code as text breaks the alignment which is especially annoying when using table statements.

I hope this helps!

Fred
by Fred
2 weeks ago
Forum: Modeling
Topic: Binary variable to count other variable within model
Replies: 1
Views: 537

Re: Binary variable to count other variable within model

Hi, It would be easier to help, if you could share the files requored to run your code. Just from looking at it, it is quite challenging to say why the model is integer infeasible without having access to the date that goes into the model. On a side note, constraints like eq_ELECTROLYSER_Trans1(E).....
by Fred
3 weeks ago
Forum: Modeling
Topic: Need for help
Replies: 3
Views: 1305

Re: Need for help

Hi, Then I do not understand the model. Look for example at free variable d1. It occurs with coefficient 1 in the objective which is minimized. Other than that it occurs only in constraint "Tracking", also with coefficient 1. This is a "=L=" constraint. So the solver will make d1...
by Fred
3 weeks ago
Forum: Syntax
Topic: gdxxrw error 343 in
Replies: 4
Views: 728

Re: gdxxrw error 343 in

Hi,

I cannot reproduce the issue mentioned in the initial post. Please note that Excel has to be installed and activated for gdxxrw to work.

I hope this helps!

Fred
by Fred
1 month ago
Forum: Modeling
Topic: Need for help
Replies: 3
Views: 1305

Re: Need for help

It seems that your model is unbounded. You might want to set proper lower bounds on variables d1,d2,d3,d4.

I hope this helps.

Fred
by Fred
1 month ago
Forum: API
Topic: Error reading config file
Replies: 3
Views: 1187

Re: Error reading config file

Seems that you are using a rather old GAMS system with Python 3.12? I suggest you get the latest GAMS from https://www.gams.com/download/ and then follow the tutorial . In general, please make sure to use the documentation that matches your installed version. Especially in the installation process o...