Questions tagged [gams]

For questions related to GAMS (General Algebraic Modeling System), a high-level modeling system for mathematical optimization.

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2
votes
0answers
65 views

GAMS Sum over a subset

I have the following sets, variables, and parameters in a GAMS model. $set \quad h/1*3/;$ $alias (h,t);$ $positive \quad variables$ $p_d(h)$ $p_c(h)$ $e(h)$ ; $parameter$ $\eta = 0.9$; $e(0) =...
33
votes
13answers
8k views

Are Python and Julia used for optimization in industry?

I am giving a small computer exercise that aims at teaching students the basics of a modelling language to model small optimization problems. So far I have been using the modelling language GAMS as ...
9
votes
2answers
589 views

Modeling and solvers

I have just started to dive into OR world on my work. Currently we are using GAMS with Gurobi but some of us have strong programming background and would like to have more programmatic approach to OR. ...
5
votes
1answer
60 views

Tolerance for equality in GAMS/CPLEX

Is there an option in GAMS that sets the tolerance for declaring two real numbers to equal? For example, how can I tell GAMS or GAMS/CPLEX that $0.999100 = 0.99909$? Thank you for your help!
3
votes
0answers
63 views

How can I do this in GAMS?

I am mimicking a GAMS model that was introduced in Soler et al. (2013)1 to compare my new model with its results. In a nutshell, assume we have a variable $t$ that is supposed to only take certain ...
7
votes
1answer
146 views

Is this formulation linear or non-linear?

Can you help me figure out if this formulation constitutes a non-linear problem? I believe It is a linear problem but my solver (GAMS) is unable to produce a acceptable solution. $x,y$ and $\text{...
6
votes
1answer
59 views

Issue interpreting sets of constraints in AMPL

I'm new to AMPL and am trying to model the following constraints. \begin{align}y_{ij3}&\le\sum_\ell X_{j\ell2}\quad(m=2,k=3)\\y_{ijk}&\le\sum_\ell\sum_mx_{j\ell m},\quad\forall i\in I,\forall ...
7
votes
1answer
75 views

Get a MPS file using NEOS/GAMS web interface

I'm trying to use Neos/GAMS to solve an optimization problem. I will need to get a MPS file from the model. With using GAMS IDE it is easy to use an option file to get it but, it needs a licence file ...
10
votes
1answer
277 views

Comparison of Algebraic modelling languages and general programming languages

Some optimization software/frameworks (commercial or open-source) such as AMPL, GAMS, Cplex, ... have a specific Algebraic modelling language. Some of them have another type of programming that uses ...