Search found 1047 matches
- 9 months ago
- Forum: Syntax
- Topic: the uncertain wrong of minimizing
- Replies: 6
- Views: 12348
Re: the uncertain wrong of minimizing
Jim, Don't put your code in a regular text. The topic editor gives you code markdown to put code in mono-spaced font. This way, the formatting of table sam survives and we know where what number goes. BTW, this might all be related to non-convexity. But without running the model it's hard to say. -M...
- 9 months ago
- Forum: Modeling
- Topic: How to obtain the marginal of equality constraints in nlp
- Replies: 1
- Views: 4450
Re: How to obtain the marginal of equality constraints in nlp
Conopt delivers fine marginals. Nothing wrong with 0 or EPS marginals. If you want more detailed information, you might want to share your model.
-Michael
-Michael
- 9 months ago
- Forum: Modeling
- Topic: Modeling Question
- Replies: 1
- Views: 3658
Re: Modeling Question
That is super straight forward equation and its realization in GAMS is
-Michael
Code: Select all
$set M 5
$set F 3
$set L 7
set m / 1*%M%/, f / 1*%F%/, l / 1*%L% /, ps / 1*2 /;
variable z(l,m), x(f,l), conv(ps);
equation e(l);
e(l).. sum(m, z(l,m)) =e= sum(f, x(f,l))*prod(ps, conv(ps));
- 9 months ago
- Forum: API
- Topic: Python API ignores default Solver?
- Replies: 4
- Views: 6920
Re: Python API ignores default Solver?
There are many ways to change options in GAMS, changing optgams.def is not one of them. Please read this part of the docs: https://www.gams.com/44/docs/UG_GamsCal ... Precedence
-Michael
-Michael
- 9 months ago
- Forum: Modeling
- Topic: limiting a variable with a lower boundary
- Replies: 3
- Views: 3871
Re: limiting a variable with a lower boundary
You have implemented a semicont variable (https://www.gams.com/44/docs/UG_Languag ... sVariables). Many solvers do support them natively. But performance is usually comparable to your own binary reformulation (if your bigM is small enough).
-Michael
-Michael
- 9 months ago
- Forum: Syntax
- Topic: how to use a single subscript variable
- Replies: 4
- Views: 6621
Re: how to use a single subscript variable
If each stock belongs exactly to one sector, you can change SC(s,i) to SC(i) because the sector is implicit for a given i. You can work with a map si(s,i) that tells GAMS about what stocks belong to what sector. In your algebra, you can use the map to access the sector (and it's data) if you iterate...
- 9 months ago
- Forum: Solvers
- Topic: SBB Scaling
- Replies: 2
- Views: 6363
Re: SBB Scaling
SBB itself dooes not do any scaling, but it runs NLP solvers to solve the relaxed model, these solvers, e.g. Conopt, will do scaling.
-Michael
-Michael
- 9 months ago
- Forum: Solvers
- Topic: Full CPLEX license issue
- Replies: 1
- Views: 5659
Re: Full CPLEX license issue
I suggest you contact sales or support at gams.com. Too many things depend on you license and the forum won't be able to fix this.
-Michael
-Michael
- 9 months ago
- Forum: API
- Topic: Java Api - change set entries in ModelInstance via Modifier or else
- Replies: 2
- Views: 5195
Re: Java Api - change set entries in ModelInstance via Modifier or else
No, this is not possible. GAMSModelinstance only works with a fixed model rim. Sets change the model rim. The solution to this is to initiate the GAMSModelinstance with the full set of a possible subsets and use 0 (actually EPS) in the equation aalgebra (via some modifiable parameter) when you don't...
- 9 months ago
- Forum: Syntax
- Topic: how to use a single subscript variable
- Replies: 4
- Views: 6621
Re: how to use a single subscript variable
Hi, I don't know what you mean by this But now, having to write it professionally Almost all GAMS model have multiple indexes, this is as professional as it gets. There are ways to ""flatten" the index space, but that looks very ugly, so before suggesting ways to do this, I would like...