Search found 1033 matches
- 3 years ago
- Forum: Modeling
- Topic: VAR operands relational or boolean
- Replies: 11
- Views: 6584
Re: VAR operands relational or boolean
I don't think that you logic is correct also you if logic looks flawed, but I guess you mean if(DU(t)-(DIP(t)- DIN(t))-CU(t))>=0, DD(t)=DU(t)-(DIP(t)- DIN(t))-CU(t); else DD(t)=0; ) or easier DD(T) = max(0,DU(t)-(DIP(t)- DIN(t))-CU(t)). I would do it like this: set s /slack1, slack2/; SOS1 variable ...
- 3 years ago
- Forum: Syntax
- Topic: dollar sign ($) in macro
- Replies: 2
- Views: 2222
Re: dollar sign ($) in macro
Macros are expanded by the GAMS compiler. The expanded text is not scanned for compile time commands (anything that starts with a $, like $call) by the compiler, so you can't have a $ command inside a macro. You will need to use a batinclude for this: $set Filaname xxx $set Path abc/ $set SpecKey $e...
- 3 years ago
- Forum: Announcements
- Topic: Webinar: GAMS MIRO Engine - running GAMS in the cloud! Announcement
- Replies: 0
- Views: 77070
Webinar: GAMS MIRO Engine - running GAMS in the cloud! Announcement
I want to let you know about an upcoming webinar next Tuesday (5/5/20).
Please find details at https://www.gams.com/news-events/detail ... the-cloud/
-Michael
Please find details at https://www.gams.com/news-events/detail ... the-cloud/
-Michael
- 3 years ago
- Forum: Modeling
- Topic: Defining a SOS1-Variable as binary, where not all Sets must contain a non-Zero Value
- Replies: 4
- Views: 2931
Re: Defining a SOS1-Variable as binary, where not all Sets must contain a non-Zero Value
Just turn your x(i,l) into a binary variable and your equality constraint into a less-or-equal: defx(i).. sum(l, x(i,l)) =l= 1 ; That's it. Don't worry about x being binary instead of SOS 1. Most solvers will turn them into binary inside anyway, because nowadays modern MIP solvers prefer to work wit...
- 3 years ago
- Forum: Modeling
- Topic: VAR operands relational or boolean
- Replies: 11
- Views: 6584
Re: VAR operands relational or boolean
I did not check your logic, but a few comments: Don't use arbitrary large numbers for bigM. They mess up the numerics of your model. Find out from your understanding of model and data what's the maximum/minimum value a variable can take. If that's not possible, bigM is not possible and you need to g...
- 3 years ago
- Forum: GAMS-FAQ
- Topic: How do I export only rounded numbers from GAMS to Excel?
- Replies: 1
- Views: 2121
Re: How do I export only rounded numbers from GAMS to Excel?
There is no explicit option to round numbers when writing to an Excel file, but you can round within GAMS before writing the data to GDX. You could also use cell formatting in Excel to instruct Excel to show you a certain number of digits. The following will round the parameter abc to two decimal pl...
- 3 years ago
- Forum: GAMS-FAQ
- Topic: How do I export only rounded numbers from GAMS to Excel?
- Replies: 1
- Views: 2121
How do I export only rounded numbers from GAMS to Excel?
When unloading data from GAMS to Excel with GDX, is it possible to round numbers or choose the number of decimal to be included in the Excel files?
- 3 years ago
- Forum: Modeling
- Topic: VAR operands relational or boolean
- Replies: 11
- Views: 6584
Re: VAR operands relational or boolean
You can't model this as an LP. You can model this with some binary variables and make a MIP out of it. You need a binary variable that is 0 if DU(t)-(DIP(t)- DIN(t))-CU(t) <= 0 and 1 otherwise. Search the forum for logical constraint and HP Williams (that is an author of a book that describes such r...
- 3 years ago
- Forum: Modeling
- Topic: Error: Endogenous operands for * not allowed in linear models
- Replies: 4
- Views: 9897
Re: Error: Endogenous operands for * not allowed in linear models
Look at r1 and o1. The supply capacity from s1, s2, and s3 is 8+6+0=14. The demand is o1.r1 is 18. No way to make it, so the model is infeasible. How did I get there? Again, I removed the unhelpful and superfluous supplier variables, get an LP and solved with e.g. Cplex, now I get a infeasible solut...
- 3 years ago
- Forum: GAMS-FAQ
- Topic: How do I compute the Kronecker product in GAMS FAQ
- Replies: 1
- Views: 4895
Re: How do I compute the Kronecker product in GAMS FAQ
The Kronecker products, see https://en.wikipedia.org/wiki/Kronecker_product can easily computed with the matching operator (see https://www.gams.com/latest/docs/UG_SetDefinition.html?search=matching ). See details in the following example: $onText Kronecker product of two matrices A and B A is of di...