OpenSolver 2.8.3 (05 Oct 2016)

We are happy today to announce the release of OpenSolver 2.8.3! This is a bugfix release for the 2.8.2 release, but we are also using the occasion to mark the 2.8.x releases as stable. This means 2.8.3 will become the default download for all users and is the recommended version for everyone.

You can download OpenSolver 2.8.3 here.

This update is primarily a bugfix release (the changelog lists around 20 significant fixes) as well as two new features.

The first new feature is extended support for using the solution on the sheet as the starting point for the solver. Passing the solution as a “warm start” to the solver in this way is now supported by all solvers except CBC. This functionality is enabled automatically – if the initial solution on the sheet is feasible, it will be sent to the solver. This can give significant reductions in solve time when solving tough integer problems.

The other big change in this release is our first partial support for Excel 2016 for Mac. This version should work if your version of Excel is at least 15.28. Unfortunately, the VBA support on this version of Excel is very limited, and so it has been very difficult to get OpenSolver working. We do not yet have the full range of functionality running, but we do have some core features working for those that need to use Excel 2016 for Mac or want to help with testing. Right now, the features that we know are working are model creation and manipulation, and solving using the linear solvers (CBC and Gurobi).

There are some major changes in the way Excel 2016 for Mac works that have made our life difficult. The most important of these is that Excel is now sandboxed for security reasons, which makes it harder for us to run the optimization solvers. Currently, the only workaround we have come up with requires you to run an installer after you download OpenSolver that installs the solvers we use on your system so that they can be used by Excel. Unfortunately this means that you will need administrative privileges on your computer to set up OpenSolver if you want to use Excel 2016 on Mac. Please see the installation page for more information about this.

It seems that Excel 2016 for Mac is significantly slower than any other Excel release, which leads to much slower OpenSolver solve times. We can only hope that Microsoft improve its speed in future releases.

We appreciate any feedback you might have on the release, especially in regards to Excel 2016 for Mac. If you do encounter any problems, please either use the “Report Issue” button from inside OpenSolver, or leave a comment here so that we can address the problem.

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