Search found 137 matches
- 3 years ago
- Forum: GAMS-FAQ
- Topic: I know a better solution
- Replies: 1
- Views: 1940
I know a better solution
Is it possible that I found a better solution for my model than the optimal solution provided by the solver?
- 3 years ago
- Forum: GAMS-FAQ
- Topic: How do I write only the binding constraints to an external file?
- Replies: 1
- Views: 1887
Re: How do I write only the binding constraints to an external file?
To find out if a constraint is binding you just need to look at equation_name.slack . After solving you could selectively write only those instances of constraint e , which are binding: file fx /binding.txt/; put fx; loop((i,j)$(e.slack(i,j)<1e-6), put i.tl, j.tl, e.slack(i,j) / );
- 3 years ago
- Forum: GAMS-FAQ
- Topic: How do I write only the binding constraints to an external file?
- Replies: 1
- Views: 1887
How do I write only the binding constraints to an external file?
Say I have that constraint:
How do I write only the binding constraints to an external file?
Code: Select all
e(i,j).. ... =l= ...;
- 3 years ago
- Forum: GAMS-FAQ
- Topic: How do I model predecessor/successor relations?
- Replies: 1
- Views: 2088
Re: How do I model predecessor/successor relations?
The GAMS lingo for this is lag and lead operators : x(d,h-1) e.g. shows the previous hour. The - is not a numerical minus but a lag. Trouble is that the predecessor for x(d,'h1') is x(d-1,'h24') . You also have to decide what the predecessor of 'd1','h1' is. If you do a steady state model you could ...
- 3 years ago
- Forum: GAMS-FAQ
- Topic: How do I model predecessor/successor relations?
- Replies: 1
- Views: 2088
How do I model predecessor/successor relations?
I have variables with two indices, e.g. x(d,h) , where d and h are sets of days and hours. My problem is to make a predecessor/successor relation between those x variables. E.g. I have to model the difference between two neighboring x variables like: delta(d,h) =e= x(d,h) - x(pred(d,h)); delta(d,h) ...
- 3 years ago
- Forum: GAMS-FAQ
- Topic: How do I model that constraint: The sum of consecutive four elements in a vector should be less than 10?
- Replies: 1
- Views: 1990
Re: How do I model that constraint: The sum of consecutive four elements in a vector should be less than 10?
You can use the lag and lead operator as in the following example: Set i /1*10/; Alias (i,j); Set iconseq(i,j); Scalar cnt; loop(i, for(cnt=0 to 3, iconseq(i,i+cnt) = yes)); display iconseq; Variable x(i); Equation e(i); e(i).. sum(iconseq(i,j), x(i)) =l= 10; If you want your constraint to interpret...
- 3 years ago
- Forum: GAMS-FAQ
- Topic: How do I model that constraint: The sum of consecutive four elements in a vector should be less than 10?
- Replies: 1
- Views: 1990
How do I model that constraint: The sum of consecutive four elements in a vector should be less than 10?
Say a vector x has ten values (decision variables). Objective: Maximize the sum of x. How do I model this constraint: The sum of consecutive four elements in the vector should be less than 10.