Problem description: It only allows you to select: - less or equal - equal - more or equal - "Integer" - "Binary" (see the attached screenshot) Is there some problem with allowing "not equal"? I would need this condition in my task sheet :( Steps to reproduce: Menu -> Tools -> Solver ...> Limiting conditions I reported this on launchpad: https://bugs.launchpad.net/ubuntu/+source/libreoffice/+bug/1336763 , but they redirected me here, so here I am :) Operating System: Linux (Other) Version: 4.2.4.2 release
Non-linear solvers are pretty complicated and that is why the interface is simplified. Not equal condition can be implemented in the model with the usage of IF and NOT functions. Yes, it requires a little bit more efforts in building of the model, but the final goal can be achieved.
> Is there some problem with allowing "not equal"? I would need this condition > in my task sheet :( Linear and non-linear solvers only work with "=", "<=" and ">=" operators. The explanation is a bit complicated, but it comes from the standard representation of mathematical programming models. For instance, Excel solver, OpenSolver for Excel and professional solvers as Gurobi only accept constraints of "=", "<=" and ">=" types. Mathematically you can approximate "<>" constraints adapting your model using the explanation in [1] given by Kuifje, but you'd have first to estimate M. So it is not trivial. [1] https://math.stackexchange.com/questions/37075/how-can-not-equals-be-expressed-as-an-inequality-for-a-linear-programming-model/1517850 Closing this as NOTABUG.