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oj! Algorithms v51.2.0 Release Notes

Release Date: 2022-04-20 // about 2 years ago

  • ➕ Added

    org.ojalgo.function

    • ✅ MissingMath can now find the greatest common denominator of multiple int:s or long:s.

    org.ojalgo.matrix

    • ➕ Added support for creating diagonal matrices in MatrixFactory.

    org.ojalgo.optimisation

    • ✅ There is now a new solver, GomorySolver, for (mixed) integer models. It implements Gomory's cutting plane method. This solver is primarily used to test the cut generation feature used in IntegerSolver, which is the solver to use for (mixed) integer problems. The real news here is that IntegerSolver now generates GMI cuts as part of the solve process.
    • Utilities in Expression (actually in ModelEntity) to simplify creating Expression:s from combinations of other Expression:s (ModelEntity.s).

    org.ojalgo.type

    • ➕ Additional utilities in NumberContext like isInteger(double), isSmall(BigDecimal,BigDecimal) and more.

    🔄 Changed

    org.ojalgo.optimisation

    • The IntegerSolver is no longer a pure branch-and-bound algorithm. It now also generates GMI cuts.
    • 🔨 A whole lot of refactoring to enable cut generation for the IntegerSolver. This touches almost everything in the optimisation package, but the public API:s for normal/recommended usage should be unchanged.

    🗄 Deprecated

    org.ojalgo.optimisation

    • 🗄 Deprecated the separation between preferred and fallback solver integrations in ExpressionsBasedModel. Instead, if you want add a solver integration, you simply call addIntegration(Integration<?>).

    🛠 Fixed

    org.ojalgo.optimisation

    • 🔨 The MPS file parser of ExpressionsBasedModel has been refactored and can now handle more format variants. In particular some instances from MIPLIB2017 had problems.

    ✂ Removed

    • 🗄 The methods isMinimisation() and isMaximisation() from ExpressionsBasedModel. They've been deprecated for a while and are replaced by getOptimisationSense(). There is no way to set the optimisation sense – you simply call minimise() or maximise();