Topics started by Zahidah Mohd Zaulir
Hi, My model took more than 14 days to run on i7 core computer with 16GB RAM. And it still does not give an optimal solution yet. What will happen if we stop AIMMS during the middle of running a model when the solution is not optimal yet? The gap in progress window shows 38.2% for 10 days (see attached picture), then it drops to 38.1% on day-13. From what I understand, the gap is the difference between a best known solution and the best bound. If I set the gap to certain values, which part of the model will be affected? Will all the constraints be satisfied/evaluate? Or will AIMMS only satisfied half of the constraints? For your information, my objective is to maximize the preferences of the lecturer. My preferences parameter has the range values from 1 to 5, where 1 is least preferred while 5 is the most preferred. Can anyone help me? Thank you in advance! Gap on Day-12
Hi. I tried to follow the tutorial to read the data from excel. I have manually inserted the data for the sets of the index c,t and r in AIMMS. Then, I must set a 3-dimensional parameter, e.g. waste(c,t,r) as shown in the picture below. I wish to insert the data for the parameter by using the axll function in AIMMS. I put the excel sheet in the AMMS data folder. I tried using this coding: WorkBookName := "roomWaste.xlsx"; if axll::WorkBookIsOpen(WorkBookName) then axll::SelectWorkBook(WorkBookName); else axll::OpenWorkBook(WorkBookName); endif; axll::SelectSheet(SheetName : "Waste"); axll::ReadTable( IdentifierReference : waste(c,t,r), RowHeaderRange : "A5:A2890", ColumnHeaderRange : "B2:KLH3", DataRange : "B5:KLH2890"); axll::CloseWorkBook(WorkBookName); However, when i tried to run the procedure, there is warning/error as shown below: Can anyone help me with this problem? Thank you in advance!
Hi. I have a few questions to ask: In the progress window, what exactly is means by (Gap = 0.04%)? is it 0.04% of optimality gap, or 4% of optimality gap, or something else? and if it is 4% of optimality gap, does it means that 96% of it is the best solution, meanwhile 4% of it is the less best solution?
Hi,I am working on 2 multi-objective problem with two objective functions (one is to maximize the lecturers’ preference and the other is to maximize students’ preference). I have many constraints and only one decision variable (for the first problem) while many decision variables for the second problem.The tutorial that AIMMS provided is for CPLEX 12.9. Can it still be used for CPLEX 12.8? If not, is there any tutorial that can be used for CPLEX 12.8?Thank you in advance.
Hi, In the Options Tree, I have been changing the MIP Relative Optimality Tolerance to 0.5%, 1.0%, 5.0% and 10.0% to analyse the performance of the solution, gap and solving time. I wish to change the gap to 0.5%, 1.0%, 5.0% and 10.0% to analyse whether the solving time can be reduce by changing the gap. However, the CPLEX always stop at either 0.04%, 0.12% or 0.00% of gap. Is there any way to stop the CPLEX at 10% of gap?
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, 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.
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