Search found 18 matches

by dirkse
1 month ago
Forum: Syntax
Topic: Single Element of a Set of a Parameter in a For Statement
Replies: 1
Views: 220

Re: Single Element of a Set of a Parameter in a For Statement

A common way to implement what you ask about - solves for different scenarios or data values - is to set up a loop over the scenarios you want to consider. In the loop, assign scenario values to the parameters used in the model, solve, and extract results to a parameter indexed by the scenario set. ...
by dirkse
1 month ago
Forum: API
Topic: metadata - keeping track of parameter descriptions
Replies: 2
Views: 334

Re: metadata - keeping track of parameter descriptions

Andy,

This metadata is called the explanatory text, or just text. It is part of the GamsSymbol class, accessible as a property called text.

https://www.gams.com/latest/docs/apis/p ... ymbol.html

-Steve
by dirkse
1 month ago
Forum: Bugs
Topic: RGDX compress issue
Replies: 3
Views: 596

Re: RGDX compress issue

Hermann, With GDXMRW, it is not possible to write a GDX file with domain information in it. The tools was developed prior to the advent of domain information in GDX files, and it hasn't been updated in this respect. If we did anything in this direction, we would probably write a file with relaxed do...
by dirkse
1 month ago
Forum: Bugs
Topic: RGDX compress issue
Replies: 3
Views: 596

Re: RGDX compress issue

Hermann, Your example is perfect for illustrating what compress is for. If I look at the domain info for your data, I see there is none: C:\support\mrw>gdxdump prices.gdx domaininfo SyNr Type DomInf Symbol 4 Par None AlP(*) 1 Par None DAP(*, *) 3 Par None PRLSP_Margin(*) 2 Par None PRLSP_Median(*) Y...
by dirkse
1 month ago
Forum: Modeling
Topic: Create all combinations of multiple parameters
Replies: 4
Views: 477

Re: Create all combinations of multiple parameters

Luis, Looks like you found what you need, but another way to do this that is also helpful is to use a map. In the example below, the mapping set matches each element of n with a different i,j,k tuple. It sometimes help to dump the entire thing to GDX and browse it in the IDE: that really helps to se...
by dirkse
1 month ago
Forum: Syntax
Topic: Cumulative sums
Replies: 5
Views: 412

Re: Cumulative sums

Hermann, To be precise, GAMS displays the linearization of the expression. Since you have multiplication, that linearization will involve the level values for some variables, but that's only because of the product rule for derivatives. If you have exp(2*x) + exp(3*y) =L= 10; you will not see anythin...
by dirkse
2 months ago
Forum: Syntax
Topic: Beginner Question: Using csv as an input
Replies: 4
Views: 461

Re: Beginner Question: Using csv as an input

If you want to use CSV files with headers and not change them at all, you could use the GAMS utility csv2gdx. The datalib model csv2gdx1 gives you a working example: there's a call to csv2gdx in that model, and also some error checking. To read your file, I did: csv2gdx param.csv output=param.gdx ID...
by dirkse
3 months ago
Forum: Announcements
Topic: GAMS Studio
Replies: 3
Views: 757

GAMS Studio

We’ve received some user feedback recently that went like this: “I am confused. Rumor has it that the GAMS folks are working on a new IDE. Is GMS-Manager the new GAMS-supported IDE?” This is an important question that deserves a good answer. GMS-Manager is software developed by Ingo Huck and is dist...
by dirkse
4 months ago
Forum: Solvers
Topic: CPU time for large-scale instances
Replies: 2
Views: 367

Re: CPU time for large-scale instances

Moosavi, I would not call the problem size you mention - 23k vars and 4k constraints - large-scale. If this is an LP, there is nothing remarkable about solving such a problem in seconds. You say it is a MIP, but you don't say how many of these 23k vars are discrete. And even if many are discrete, th...
by dirkse
4 months ago
Forum: Syntax
Topic: Edist Function
Replies: 1
Views: 245

Re: Edist Function

Bilal, I tried out the search function within our documentation on our Web site (not the Web site search, but the search within the documentation) . I could search just within model libraries and found a nice example where the edist function is used in the the relief model: https://www.gams.com/late...