GAMS World Forum

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...

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

That is super straight forward equation and its realization in GAMS is

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));

-Michael

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

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

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...

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

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

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...

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...

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