AIMMS Language

Hi all, i still need to implement a Minimax-Regret Function into Aimms. The Goal--Function is based on a deviation calculation by using the goal-programming approach. Therefore i added all the necessary constraints and variables. My main model looks like that: MathProgramm: Minimax_Regret Decision Variable Regret: max(k,sum(j,abs_Regret(j,k))) (k=scenarios and j= potential locations) MainExecution: myGmp := GMP::Instance::Generate(Minimax_Regret); GMPOuterApprox::CreateStatusFile :=1; GMPOuterApprox::UseMultistart :=1; GMPOuterApprox::DoOuterApproximation (myGmp); But my model still genereates the following error: GMP::Instance::CreateMasterMIP(): The objective column should be in the coefficient matrix exactly once. Does someone know how to fix this? Thank you very much! Alex

Hi Community, i have to build a robust optimization model for my masterthesis at the Technical University in Braunschweig. Therefore i choose the Minimax-Regret Function! These approach deals with different scenarios k. I need to implement this function in an existing basic model, which is a single factory location problem. The basic model calculates the minimal sum of all deviations "d" from target values (so it is a Goal Programming approach) and based on these deviations the output of the model is one compromise-optimal location solution (the basic model is based on one scenario). So first i implement a new index k for the scenarios to dealwith more than one scenario. How to deal with a minimax-obejctive function in AIMMS is already explained very well in one of the AIMMS Modeling Guides (https://download.aimms.com/aimms/download/manuals/AIMMS3OM_LinearProgrammingTricks.pdf). But i have some issues with the Regret. The definition of the regret is R = d - d*. Therefore, d is the de

Hello, At the moment I am performing a scheduling problem with time windows. The model is very similar to the second model which can be downloaded from the AIMMS website (see link) execpt from a number of elements: I try to minimize the sum of all the changeovers that are used. Base unit is in minutes. In total I have 3 datasets (one for each machine) that AIMMS can read in from an Excelfile, one at a time. Initially, my model is able to solve using CPOptimizer 12.8 for all machines, where each job has to be scheduled after the "StartTime" and finish before an "Endtime". After this solution I would like to decrease the StartTime by one week when a job meets a certain criteria and then solve it again. When I run the procedure that decreases the Startime by one week and try to solve it again it finds a solution for only one of the machines and for the other two AIMMS hasnt been able to find a solution yet after more than 9 hours. For the machine that could find a so

Dear, In the attached model, you should only run the procedure ReadFromExcel. This should load all the relevant sets and parameters. When I try to solve this model, I encounter different memory errors. I either see: Memory allocation error Memory allocation error: while assigning "xxx" bytes Are there any steps that I could take with regards to the index domain of some parameters, constraints or variables, such that this model becomes solvable? I think there are no other errors in my model, but would also like to double check this. Kind regards, Koen

Dear all, I have a few questions about my model, which I hope the AIMMS community can answer. Please bear with me, as I should be drawing to the conclusion of my thesis (when this model works). Sum and indices In the accompanied model, I am trying to add several constraints. However, when setting these constraints I often encounter errors like "the index (p) does not denote a subset of the domain of set "FactoryLines"" for instance. I often find that I make mistakes with the indices in the constraint itself and within the constraint definition. I have tried looking at the guides online, but with no effect. Could anyone explain to me (preferably in layman's terms) how the indices in constraints work as well as indices within a sum argument? I am encountering similar problems with the parameters "IncomingStock" and "OutgoingStock" Stock balancing One of the decision variables, StockAtWarehouse is made from the following definition: StockAtWarehouse(p,w,t-1) + sum(p, IncomingStock

When reading a table from an excel (and putting in wrong data) I get a pop-up in the UI stating what index it can't recognize and is therefore wrong, so something like this: "ReadTable : Cell A2 in 'Excelfile': 'Wrong element' is not an existing element in the set 'Technical name of set'" And I would like to use this information to make a specific pop-up for the end-user, so I can specify how to solve this error and also change the name of 'Technical name of set' to a name that they would recognize. So the exact element and index that are wrong, is stored somewhere, I would like to make use of this, but I can't find where to get this information.

Dear community, When I try to solve the attached model, I get the following errors: Warning: The columns "TransportToCustomer(Warehouse1,Customer5,038.001,1)" and "TransportToCustomer(Warehouse1,Customer399,038.001,1)" are equal in the generated mathematical program "LeastCostPlan". This may lead to non-unique solutions. For more information regarding potential causes and consequences, see the help associated with the option "Warning_duplicate_column". Warning: Only 3 out of 11565909 duplicate column warnings were reported. See also option limit_reported_duplicate_column_row_warnings. Warning: After zero iterations CPLEX 12.7.1 concluded that an integer solution to LeastCostPlan does not exist. Firstly, I don't really what this error means. In the example above, the shipping of product 038.001 to Customer5 on Period 1 and the shipping of product 038.001 to customer 399 on Period 1 do not have anything to do with each other, other than that they originate from the same warehouse an

Dear staff, I need your help with an objective function where I have the product of two variables. I have the following variables and parameters: y(i,j,c,a) binary variable x(a) continuous variable P(c) parameter How can I linearise the following objective function: MIN: sum((i,j,c,a), P(c) * y(i,j,c,a) - P(c) * y(i,j,c,a) * x(a)) Thank you

Hi, The CSV Export DLL does seem to export 0-dim identifiers. Therefore I would like to use put. However I can't figure out how to obtain the value of that 0-dim variable. I have the next snippet of code, which works fine, but the value of the variable is still missing. code:for (IndexVariables) do if (IdentifierDimension(IndexVariables)) then !do something else else csv_alt_name := FolderName + IndexVariables + ".csv"; put csv_alt; put IndexVariables + "\n"; put name_of_some_variable; putclose; endif;endfor; The line "put name_of_some_variable;" prints the value of a variable. But it should of course print the value referred to by IndexVariables. How to do that?

The WinUI has a super obvious tab for the Legend of a linechart. But there seems to be NO way whatsoever to display the legend (or anything that will work as a legend) on a WebUI linechart. I even tried the (seemingly obvious) solution of using a legend widget. If this will work, I can't figure out how. Is there a way to show the legend? And if you don't have on yet, is there a workaround and do you have it in the plans in the future?

This week I got the following request "Add functionality to 'watch' identifiers and view the data of all those watched items within a window panel". I did some probing with the requester to better understand the need for this and I learned it would help the developer to debug faster than using various data pages, or see values inline via the debugger. My thinking at this point is: - One would like to be able to watch the identifiers in the Developer IDE (something like you do in R Studio - see picture below) - One would be able to dive in details of the data via a DataPage option (only first items are shown; like x below in R Studio example) - One would select identifiers to watch from the model tree (or model) and not necessarily ALL identifiers that are touched (could be an extreme long list)? Wonder about your thoughts

Dear Staff, I need help writing the following constraint using the AIMMS language. I have two indexes: c a Where "a" indicates years. I have a variable y(c,a) I would like to define a summation over "c" and over "a" as less than or equal to a value. But the summation over "a" should be done only from the first year until the current year. I am trying this formulation but something is wrong with it: sum((c, a1|(a1="A01") and (a1=ord(a))), y(c,a1)) <= Value Can you please help me writing this correctly using the AIMMS syntax? Thank you,

Hi, is there a similar code that I can use if a project has set the option Data Management style to Disk files and folders? The below code was valid for projects using option Single Data Manager file. The code was available from https://techblog.aimms.com/2012/06/05/save-a-case-from-aimms-procedure/ (note this is blog is now not available) ************ !First try to find a case with the name indicated by CaseName. If AIMMS !can find this, it will store a reference to this case in the element !parameter CaseReference if ( not CaseFind( CaseName, CaseReference ) ) then !If no case with the name indicated by CaseName could be found, then !we try to create a case with this name. After creating the case, AIMMS !will store a reference in the CaseReference element parameter to the !newly created case if ( not CaseCreate( CaseName, CaseReference ) ) then !If there was an error while creating the case, notify the developer !by raising an error. If the raised error is not cau

Hi, When I run AIMMS, I’ve got this result in the progress window as shown in the picture attached, I wish to know what they are mean and how they work. Can anyone explain it to me? 1. infeasible 2. integer infeasible 3. intermediate infeasible 4. terminated by the solver 5. solution does not exist 6. solver not called 7. left 8. nodes 9. thread 10. nonzeroes 11. variables Thank you in advance.

Hi, I have an integer set, a parameter with filenames, and a parameters with Aimms'standard date/time. How do I select the newest file, or how to sort a parameter and select the first, or how to select the smallest, largest? Thanks!

Hi, I have a model that is indexed over N time periods, and each period is an independent problem. As a result, I want to solve N smaller optimization problems, instead of a big one. The way that I am currently doing it, is by restricting the domain of the calendar to one year in a loop and the optimization model automatically drops irrelevant variables and constraints. At the end I collect the data from the N optimizations, and create my results. Unfortunately, the above method is not bullet proof since, some of the optimization problems are falsely reported as infeasible. If I solve them manually for just 1 time period, then they get the correct optimal solution. The .lp files generated within the loop, are identical to the .lp files that I generate if I construct each model for just 1 time period, but in the first case I get infeasible statuses, whereas in the second everything is fine. The IIS of CPLEX gets into an infinite loop and cannot find the cause of infeasibility, and

Hi, I use the CSVExport DLLs to export data to CSV. How to set the unit? For example, [$/year] is converted to [$/second]. I would like to export using the unit [$/year]. Main problem here is that I loose accuracy when converting back to [$/year]. Thanks.

Dear all, In the accompanied model, I try to decrease the inter-facility transport flows between warehouses by changing the production allocation per factory. However, when I try to solve this model, after +- 20 seconds the solution comes back at '0', and I can see that nothing has changed. Could anyone point out to me why this is happening? Kind regards,

Hi, There are some changes I did on the setting before I run my MIP project in AIMMS. I wish to know what they mean and how they work. Can anyone explain it to me? 1. I change the ‘aggregrator’ to 0. 2. I change the ‘global thread limit’ to 1. Thank you in advance.

Hi, How to control/change the gap according to what we want? For example, I want to set the gap for 0.5% instead of 0.0%. Where should I insert the value? And how should I write the value in the AIMMS? Is it 5% or 0.5 or 0.05. Best regards, Zahidah Zaulir

I'm liking the group widget in WebUI, but I'd sure like to put more than a few buttons across it. I want to have a row of buttons all the way across the top of the page, and the only way I can get the buttons to not be 2 columns wide each is to use a group. But the group cuts off any buttons that exceed about 4 columns wide! How can I get either more buttons in a group all in a row or smaller buttons that I can place individually? Thanks!