Today the download odometer rolled past another milestone:
Thanks to all our users and our development team (and most recently Jack Dunn) for supporting OpenSolver for the last 6 years. None of this would have been possible without the solvers from COIN-OR; thanks to John Forrest and Ted Ralphs for the many years of CBC development, without which the OpenSolver project would never have started.
MIT have recently started a free Analytics MOOC, run by Jim Orlin, using OpenSover for Excel and OpenSolver for Google Sheets. (It also uses Julia and JUMP, which our SolverStudio system supports.) I recommend this course for all new users. Andrew
This blog by Derek Nelson shows how he built an OpenSolver model for fantasy football that worked well for him. “My optimizer was created using Excel with the Open Solver add-in. This worked for me and the results were good. Namely, I had the highest projected points for my teams at the start of the season in both leagues I played in (the best you can hope for in the draft, in my opinion), and I ended the season by winning one league and placing second in the other.”
Derek has now gone on to create a cloud-based version of this. This work is an interesting optimisation-based project.
I recently received a nice email from Andrew Trapp, Assistant Professor, School of Business, Worcester Polytechnic Institute. Andrew has been using OpenSolver and SolverStudio in his student projects. He writes:
I’m writing to first of all thank you for the excellent software tools that you make, OpenSolver and SolverStudio, that I have been using and featuring for 4 years now in my optimization courses. They have also been used in a number of “senior design” projects that I have advised (specifically, OpenSolver in conjunction with VBA…)
Andrew’s OpenSolver projects look very interesting, and show how OpenSolver can be used in practical applications. The reports are available online, as follows:
OpenSolver and COIN-OR are pleased to be part of the IFORS initiative to support operations research activities in developing countries, where access to specialist commercial software is often prohibited by licensing costs. For more on this initiative, see the IFORS Developing Countries OR Resources Website.
One of the features that we have enjoyed in SolverStudio is support for dynamic ranges, i.e. named ranges that are created using formulae. OpenSolver 2.8 and later now supports this, and so you can use formulae to define ‘dynamic’ named ranges that are then used for the left hand side and right hand side of constraints, for the decision cells and for the objective. So for example, instead of having a constraint left hand side of A1:A4, you can defined a named range Constraint1LHS with a formula such as “=offset($A$1, 0, 0, COUNTA($A:$A),1)”. This range is dynamic in that it automatically expands as more values are entered into the A column. You can then set up a constraint in which you enter Constraint1LHS for the left hand side range. This means your model automatically works as the user changes the data on the sheet. For more information on dynamic range, see excel-easy.com or ozgrid.com. We hope you find this useful.
This is a second attempt to work around the “Automation Error” bug that some users are seeing on some versions of Excel. (This appears to be caused by a VBA bug that is corrupting the cached code. We have now “cleaned” the code)
As always, please send us any feedback and let us know if you have any problems.