Originally posted by: hzy_cims

I wrote a piece of code which solves LP problem with C#. I split the constraints and variables to two parts, and ordered theirs sequence number from 1 to the last in theirs own function. But when I use the ILPMatrix like this:
IEnumerator matrixEnum = cplex.GetLPMatrixEnumerator();
matrixEnum.MoveNext();

ILPMatrix lp = (ILPMatrix)matrixEnum.Current;
the result of the variables going to be mass on the sequence. In other words, in lp, the NumVars is the result of the variables which had been separated to two parts, theirs sequence is not from 1 to the last. How can I make them ordered by 1 to the last?
Thanks!
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Originally posted by: SystemAdmin

Did you create and add an instance of IloLPMatrix to your problem yourself or did this get created automatically when you read in an LP file?
Do I understand correctly that your problem is that your variables are re-numbered? Does this renumbering only happen when you write and read back a file or does it happen without any file interaction as well?
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Originally posted by: hzy_cims

I guess it may created and added the instance.
There's INumVar][ in the cplex with C# language. And what I did is name it too two dimensions of the first "[]", so when I use ILPMatrix, the variables will get together, and then theirs sequence numbers what I have named before in the subfunction are being massed.
This problem may also because of my personal mistakes, so if you have some suggestion, that will be very nice!If you don't, I will thank you all the same!
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Originally posted by: hzy_cims

Addtional question: when I use ILPMatrix, why did the variables lose? My code contains 259 variables, but it left 239 remaining after using ILPMatrix.
Please help me, thanks!
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Originally posted by: SystemAdmin

Sorry for the long delay.
Actually, I don't really understand what you are trying to do, what behavior you are observing and what behavior your are expecting.
Is it possible to write some sample code that illustrates what you want to do and what does not work?
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Originally posted by: hzy_cims

Sorry, it is all my fault, and I solved those problems.
Thank you so much!
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Originally posted by: SystemAdmin

If you are referring to the number of variables left after presolving, it just means that the presolver was able to eliminate 20 variables (meaning that those 20 variables are either expressible as a function of the surviving variables or have optimal values known at the outset). Variables eliminated during presolve will have values in the optimal solution; they just don't need to be part of the actively solved model.

Paul

Mathematicians are like Frenchmen: whenever you say something to them, they translate it into their own language, and at once it is something entirely different. (Goethe)
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Originally posted by: hzy_cims

Sorry, it is all my fault, and I solved those problems.
Thank you so much!
#CPLEXOptimizers
#DecisionOptimization