List of Contributions

Xavier Nodet

IBM

Contact Details

IBM

My Content

1 to 20 of 50+ total
Posted By Xavier Nodet Tue August 23, 2022 03:26 AM
Found In Egroup: Decision Optimization
\ view thread
MIP starts and solutions found by heuristics are two different things. A MIP start is a set of values that CPLEX will try to use, at the beginning of a search, to derive a feasible solution to the problem it starts to solve. A MIP start doesn't need to be a feasible solution (the assignment of values ...
Posted By Xavier Nodet Tue June 21, 2022 09:38 AM
Found In Egroup: Decision Optimization
\ view thread
When you updated from 12.9 to 12.10, what did you do related to the Python modules? Did you run python [path-to-COS12.10-install]/python/setup.py install already? If doing so doesn't solve the issue, please let us know your Python version, and the versions of the cplex and docplex packages in your ...
Posted By Xavier Nodet Wed June 08, 2022 05:25 PM
Found In Egroup: Decision Optimization
\ view thread
Dear Andy, The situation has not changed: there is not a CPLEX release that uses GPUs, and we don't discuss future plans for our products. Each CPLEX release comes with release notes. The last ones are available at https://www.ibm.com/docs/en/icos/22.1.0?topic=2210-release-notes-cplex. Rest assured ...
Posted By Xavier Nodet Tue June 07, 2022 04:18 AM
Found In Egroup: Decision Optimization
\ view thread
Hi Shahrooz, Seeing that the first error refers to Python 3.8, but the other refers to 3.9, I very much suspect that you have multiple versions of Python installed, and that `python` and `python3` don't refer to the same versions. You can check with `python --version` and `python3 --version`. If both ...
Posted By Xavier Nodet Thu May 19, 2022 02:52 AM
Found In Egroup: Decision Optimization
\ view thread
Did you consider the symmetry parameter? https://www.ibm.com/docs/en/icos/20.1.0?topic=parameters-symmetry-breaking-mip-models ------------------------------ Xavier ------------------------------
Posted By Xavier Nodet Mon May 16, 2022 02:44 PM
Found In Egroup: Decision Optimization
\ view thread
Hi Andrada, There are a number of examples for DOcplex, and they are referred to from the documentation at http://ibmdecisionoptimization.github.io/docplex-doc/index.html#mathematical-programming-modeling-for-python-using-docplex-mp-docplex-mp. Did you study the examples in the section examples/mp/modeling ...
Posted By Xavier Nodet Thu April 28, 2022 03:11 AM
Found In Egroup: Decision Optimization
\ view thread
Hi Anil, The product IBM ILOG ODM Enterprise has been withdrawn on 2020-09-30: https://www.ibm.com/support/pages/node/1200874. It has been superseded with IBM Decision Optimization Center (aka DOC): https://www.ibm.com/cloud/decision-optimization-center. The section 'Optimization Server' from the ...
Posted By Xavier Nodet Tue March 29, 2022 11:41 AM
Found In Egroup: Decision Optimization
\ view thread
I suggest you try to remove _DEBUG from your preprocessor definitions and rebuild all. This symbol is used in Debug builds, but we don't ship Debug versions of our libraries. Does this help? ------------------------------ Xavier ------------------------------
Posted By Xavier Nodet Mon March 14, 2022 01:00 PM
Found In Egroup: Decision Optimization
\ view thread
I'm afraid the answer is no: there is no API to gain access to the cuts, whether when they are generated or when they are actually added to the model. ------------------------------ Xavier ------------------------------
Posted By Xavier Nodet Tue March 08, 2022 12:16 PM
Found In Egroup: Decision Optimization
\ view thread
Thanks for the details. The reason why you don't get a solution has nothing to do with limitations of the Community Edition version. The issue is: Primal unbounded due to dual bounds, variable 'ELbuy#2257'.​ This means that your model is unbounded: solutions exist with arbitrarily large (or small, ...
Posted By Xavier Nodet Tue March 08, 2022 11:34 AM
Found In Egroup: Decision Optimization
\ view thread
It will be much easier to help if you can describe in details what exactly you do, and the output that you get. - What Operating System does your computer use? - How exactly do you define the model to solve? Are you using a programming language such as Java, Python or C++? Are you using OPL in the ...
Posted By Xavier Nodet Thu December 09, 2021 01:42 PM
Found In Egroup: Decision Optimization
\ view thread
There is unfortunately no way for CPLEX to give you more details directly. What I can suggest, first and foremost, to run with 'read datacheck' set to 1, so that if there is an issue with the inputs, you will learn about it. Then you can try to save the instance as an LP or MPS file (if it's not already ...
Posted By Xavier Nodet Tue December 07, 2021 03:28 AM
Found In Egroup: Decision Optimization
\ view thread
Hi Roshan, I'm afraid this group is decicated to Decision Optimization (the product line based on CPLEX and CP Optimizer) rather than the 'Rules' product line. I think what you're looking for is at https://community.ibm.com/community/user/automation/home. ------------------------------ Xavier ...
Posted By Xavier Nodet Tue November 30, 2021 03:53 AM
Found In Egroup: Decision Optimization
\ view thread
The way to formulate such a constraint is to use an intermediary object to hold the expression that you want to build, before you can put it in a constraint. Such objects are of type IloNumExpr. You will find examples of using such objects in the directory `cplex/examples/src/java` in your installation ...
Posted By Xavier Nodet Mon November 29, 2021 02:56 AM
Found In Egroup: Decision Optimization
\ view thread
Hi Saumya, It seems to me that the following pseudo-code should work: for i ... for j ... if !is_adjacent(i,j) ( for k ... cplex.add(y[i][j][k] <= 0); ) ​ ------------------------------ Xavier ------------------------------
Posted By Xavier Nodet Mon November 15, 2021 02:53 PM
Found In Egroup: Decision Optimization
\ view thread
As I don't know anything about power flow network, I can't really give you a specific advice. All I can suggest is the following... If you have an issue with bus 7 and its children, you may want to remove from your data everything but these three buses and the two corresponding lines. This allows ...
Posted By Xavier Nodet Fri October 29, 2021 10:24 AM
Found In Egroup: Decision Optimization
\ view thread
Hi Yiran, According to https://www.ibm.com/docs/en/icos/20.1.0?topic=api-cpxerr-not-benders, you can't use control callbacks during a Benders solve. From this, I would say that you can use informational callbacks, and the newer generic callbacks. ------------------------------ Xavier ------- ...
Posted By Xavier Nodet Fri October 22, 2021 03:24 AM
Found In Egroup: Decision Optimization
\ view thread
Do you mean that you see the CPLEX log, but you don't see the results of the print statements? That seems very strange to me... With respect to the 'logging' statements, I can't say much. I'd be happy to look into this, but I would need a complete code that reproduces the issue, rather than a screenshot ...
Posted By Xavier Nodet Thu October 21, 2021 02:22 AM
Found In Egroup: Decision Optimization
\ view thread
You need to set the CPLEX parameter multiobjective.display to value 2, instead of the default value 1. https://www.ibm.com/docs/en/icos/20.1.0?topic=parameters-level-display-during-multiobjective-optimization Here's an example: model = Model() model.context.cplex_parameters.multiobjective.display ...
Posted By Xavier Nodet Thu October 21, 2021 02:17 AM
Found In Egroup: Decision Optimization
\ view thread
Hi Anilkumar, In order for docplex to print the CPLEX log, you need to set the 'log_output' parameter in the Model constructor to 'True'. The documentation is at http://ibmdecisionoptimization.github.io/docplex-doc/mp/docplex.mp.model.html, and here's an example: mdl = Model(name='my_model', l ...