Search found 372 matches

by Fred
3 years ago
Forum: Modeling
Topic: Variable Start-up cost in the Unit Commitment Problem
Replies: 4
Views: 3400

Re: Variable Start-up cost in the Unit Commitment Problem

When you run set i / -2, -1, 0, 1, 2 /; you should get the following error which is very explicit about UNQUOTED elements having to start with a letter or digit. 1 set i / -2, -1, 0, 1, 2 /; **** $338$338 $172$172 **** 172 Element is redefined **** 338 Unique element expected - symbol was not an ele...
by Fred
3 years ago
Forum: Archive Google Group
Topic: GAMS Studio dark mode
Replies: 2
Views: 12156

Re: GAMS Studio dark mode

Yes, see https://www.gams.com/latest/docs/T_STUD ... O_SETTINGS

For Windows the dark theme was introduced in Studio version 0.14.6.
If you download the latest GAMS from https://www.gams.com/download/ you get Studio version 1.1.0 and should be good.

I hope this helps!

Fred
by Fred
3 years ago
Forum: Tools
Topic: International characters
Replies: 1
Views: 2704

Re: International characters

Hi, I guess that you are executing GAMS in a directory with non-ASCII characters. GAMS has trouble with this. Please run GAMS in a directory that does only contain [a-zA-Z] characters. If this is not possible (because your home directory already has non-ASCII characters in it) choose a solveLink opt...
by Fred
3 years ago
Forum: Modeling
Topic: Warehouse Problem with minimizing the net present value of the cost
Replies: 2
Views: 7855

Re: Warehouse Problem with minimizing the net present value of the cost

Hi, Problem is how you use set t at the end of equation cost.. TC =e= sum[t, [{SP(t)*(buy(t)-sell(t))+SC*stock(t)}/((1+i)**t)]]; While you use set elements 1,2,3,4, set elements can in general be strings (e.g. apple, orange, cherry, ...) which is why you cannot make calculations with set elements li...
by Fred
4 years ago
Forum: Syntax
Topic: Run a program
Replies: 4
Views: 3232

Re: Run a program

What I suggested was a way to get your own license, free of charge, that allows you to solve the model yourself. The license type is called a community license (https://www.gams.com/latest/docs/UG_License.html#GAMS_Community_Licenses). I thought that you would probably prefer being able to solve you...
by Fred
4 years ago
Forum: Syntax
Topic: Run a program
Replies: 4
Views: 3232

Re: Run a program

Your model fits in the community license limits (https://www.gams.com/latest/docs/UG_Lic ... y_Licenses)
You can contact sales@gams.com to request such a license.

I hope this helps!

Fred
by Fred
4 years ago
Forum: Modeling
Topic: Questions about the Results
Replies: 4
Views: 2739

Re: Questions about the Results

Actually, the output was right. Your idea of what the output should be like was wrong. Hard to have this fixed by a debugging tool ;-) When facing a problem as the one described in your initial post, it is often a good idea to have a look at the equation listing and column listing to check whether t...
by Fred
4 years ago
Forum: Modeling
Topic: Cplex generates optimal solution but then declares it to infeasible
Replies: 3
Views: 2474

Re: Cplex generates optimal solution but then declares it to infeasible

Hi Nikou,

Can you share an example, so other forum users can reproduce the observed behavior.
Would also be interesting to know which version you are using.

Best,
Fred
by Fred
4 years ago
Forum: Syntax
Topic: Infeasibilities in loop solve using CPLEX
Replies: 3
Views: 8140

Re: Infeasibilities in loop solve using CPLEX

Hi Petros, Happy to read that you solved your problem. However, to avoid confusion, I would like to mention that that the mipstart option has little to do with your initial problem. You wrote that Cplex returns infeasible for your model. Instructing Cplex to use a starting point (which is what you d...
by Fred
4 years ago
Forum: Syntax
Topic: BCH | Cplex | Branch and Cut
Replies: 6
Views: 4407

Re: BCH | Cplex | Branch and Cut

Hi Jonathan, To avoid confusion, let's call your first approach "BCH approach" and the second approach "loop approach". I get your idea but there is no such syntax that allows you to do something like =*sense_c(allcuts)*= with the loop approach. The sense_c and rhs_c stuff is des...