Search found 132 matches

by aileen
3 months ago
Forum: GAMS-FAQ
Topic: GAMS User Groups
Replies: 0
Views: 1248

GAMS User Groups

Besides GAMS World Forum, there are other user groups that allow GAMS users worldwide to exchange information about GAMS:
by aileen
3 months ago
Forum: Tools
Topic: The good source for learning ScenRed
Replies: 1
Views: 1118

Re: The good source for learning ScenRed

Hi, If you want to learn the tool SCENRED/SCENRED2 for scenario reduction take a look at the documentation of the tool (see SCENRED documentation and SCENRED2 documentation ). The documentation also provides you with a short description of the algorithms used and references of papers the tool is bas...
by aileen
3 months ago
Forum: GAMS-FAQ
Topic: How do I formulate logical expressions in equations?
Replies: 0
Views: 1602

How do I formulate logical expressions in equations?

GAMS does not reformulate logical expressions. You need to do this by hand. A common way to model logical expressions is using the so-called big-M method. The interested reader is referred to the book by H.P. Williams on Model Building in Mathematical Programming. It explains how to use the big-M me...
by aileen
3 months ago
Forum: GAMS-FAQ
Topic: Linearize a nonlinear function using piecewise linear approximation
Replies: 0
Views: 1173

Linearize a nonlinear function using piecewise linear approximation

Find below some approaches to linearize the cubic function y =e= x*sqr(x) - 7*sqr(x) + 14*x - 8 using piecewise linear approximation. In general, piecewise linear functions can be modeled using binary variables, SOS1 type formulations or SOS2 type formulations. Check textbooks like Nemhauser and Wol...
by aileen
3 months ago
Forum: GAMS-FAQ
Topic: GAMS Related References
Replies: 0
Views: 1043

GAMS Related References

This post contains a list of some GAMS related scientific papers. Please email suggestions for additions to this list to support@gams.com. Johannes Bisschop and Alexander Meeraus. On the Development of a General Algebraic Modeling System in a Strategic Planning Environment. In Applications, volume 2...
by aileen
3 months ago
Forum: GAMS-FAQ
Topic: How to reference GAMS in a paper?
Replies: 0
Views: 985

How to reference GAMS in a paper?

This post contains some information on how to give a proper reference to the GAMS software and the GAMS documentation in a (scientific) paper. Since the software and the documentation changes with every release, it is a good idea to include the release number XX.Y.Z. A particular release has a publi...
by aileen
3 months ago
Forum: Syntax
Topic: Domain violation for set
Replies: 3
Views: 1521

Re: Domain violation for set

Looking at your .gms file I see that you declared IOT30 over the domains (RIOT, CIOT ). PS1 is an alias to PS which is a subset of RIOT not CIOT, therefore the domain violation occurs for xx(PS,PS1) = IOT30(PS, PS1 ); and VI(FI,PS1) = IOT30(FI, PS1 ); (PS1 is the wrong domain here given how you decl...
by aileen
3 months ago
Forum: GAMS-FAQ
Topic: How do I implement a "lookup-table"? FAQ
Replies: 1
Views: 766

Re: How do I implement a "lookup-table"? FAQ

Please have a look at the code below. The second model requires a decent GAMS/CPLEX license: set i / 1*4 / s / 1*5 / table data(s,*) 1 2 3 4 val 1 0 1 1 0 23 2 1 0 0 1 -5 3 1 0 1 0 16 4 0 1 0 1 4 5 1 1 1 0 111 ; parameter c(i) "cost of i when on"; c(i) = -uniformInt(1,10); display c; variable b(i) "...
by aileen
3 months ago
Forum: GAMS-FAQ
Topic: How do I implement a "lookup-table"? FAQ
Replies: 1
Views: 766

How do I implement a "lookup-table"? FAQ

In my case the determinant is the summation of the variables from U1 to Ux that have been introduced as a binary variable to GAMS. In each iteration during the optimization these variables are set to 0 or 1 but the structure of these variables should be considered in the optimization process, for ex...
by aileen
3 months ago
Forum: Syntax
Topic: Scenario Reduction
Replies: 5
Views: 2623

Re: Scenario Reduction

Hi paganini, Can you say more specifically where you got confused reading the documenation of SCENRED2 and what it is you are confused about? You might want to check out the simplified interface to SCENRED2 . You need to specify n the set of nodes in the tree, tree the set of ancestor relations desc...