OpenSolver 2.5.1 alpha (25 Jun 2014)

Today we are releasing OpenSolver 2.5.1 alpha, which builds on the 2.5 alpha release from last week.

The main addition in this release is the option to use the non-linear solvers Couenne and Bonmin through the cloud-based NEOS servers.

We have also included a 64-bit version of CBC that is used automatically on 64-bit systems.

There are also stability fixes for the non-linear NOMAD solver that was included in the 2.5 release, and other bug fixes.

You can download it here. Like 2.5, this is an experimental alpha release, and we are looking for feedback on the new features, as well as any problems you might run into while using them.

OpenSolver 2.5 alpha (20 Jun 2014)

We have just released OpenSolver 2.5 alpha, which has a number of fixes and improvements. It also has some new experimental features.

You now have the ability to select from number of different solvers:

  • CBC (included and upgraded to version 2.8.8 in this release)
  • Gurobi LP/IP solver (if this is installed on your machine)
  • NOMAD non-linear solver (included, supported in 32-bit Office only for now)
  • Solvers on the cloud-based NEOS servers – CBC (linear) is supported now, and we hope to offer Couenne and Bonmin (both non-linear) in a future release.

This release also adds reporting of dual variables and sensitivity analysis, and as well as many small bug fixes and feature enhancements. Many thanks to students Matt, Kris, and Jack for their work on these enhancements.

You can download it here. All feedback is welcome, particularly regarding the new experimental features.


OpenSolver 2.1 (6 Sept 2012)

OpenSolver 2.1 is now released, and has a number of fixes and improvements. These include a newer version of the optimiser CBC, a bug fix for handling multiple cell blocks as decision cells on non-English systems, more robust non-linearity checking, and the ability to turn off this non-linearity checking if you know your model is linear. We now also display ≥ instead of > in our on-sheet constraints. All feedback is welcome.

OpenSolver 1.9 (5 Dec 2011)

Fixed some display issues in the model dialog to give more compact displays, and force formulae RHS to be in absolute terms
Fixed a bug that saw models being wrongly built and then reported as non-linear (incorrectly) for some complex models if Excel calculation mode was set to manual.
Fixed passing of multiple parameters to CBC if the user defines a parameter table on the sheet; previously only the last parameter was passed.
Deleted the DLL’s downloaded in the .zip file which don’t seem to be needed now that we statically link everything in CBC.

OpenSolver 1.8 (5 Dec 2011)

Version 1.8 fixes a problem that prevented OpenSolver 1.7 loading on 64 bit systems, and improves handling of models that have decision variables and constraints on multiple sheets. Note that Excel does not allow ranges to contain arbitrary cells from many sheets, and so all the decision variables must be on the same sheet.

OpenSolver 1.7 (11 November 2011)

OpenSolver 1.7 has been released. (OpenSolver 1.6 was an internal release only.) Changes include:

Version 1.7 beta
Added controls in the About box to allow easy installation and uninstallation
Added code to interact nicely with the forthcoming OpenSolver Studio
Improved OpenSolver for use from VBA:
– Build and Solve operations now throw errors (instead of popping up dialogs), allowing dialog-free usage from VBA
– Return codes are better handled (and Solver compatible)
– A new optional parameter has been added to RunOpenSolver to avoid dialogs even if infeasible/unbounded solutions are generated

Version 1.6 beta
Fixed display and editting of an objective target value in the Model dialog.
Modified the Open Last Model in CBC functionality so that it passes any Solver options and any CBC solve parameters to CBC if they are available in any current worksheet
Fixed a minor issue in Model dialog where a RHS could be entered for a new constraint if the user had previously had a Bin or Int constraint selected
Fixed a redim bug in the quick non-linearity checker for models with no constraints (which can happen if there is only a target objective value)
Added “Show optimisation progress while solving”  (being Solver’s “Show Iteration Results”) to the OpenSolver options dialog
Improved operation of Options dialog, including proper sycnronisation of values when opened from the Model dialog
Better handling of the Excel 2010 “Simplex engine” option as used in parallel with “Assume linear model”
Fixed an error in the full non-linearity checker
Added output of dual prices onto the sheet; this is set using the Model dialog
Rearranged Model dialog to better fit new Duals option, and better use space around constraint listing
Better handling of the Excel solver options – OpenSolver now sets all these to sensible defaults
Better handling of users entering formulae in the Model dialog for a constraint RHS in terms of non-English localisation issues, but this still needs work
Fixed a size limitation in Quick Solve, and converted Quick Solve to sparse matrix handling for better memory usage.

OpenSolver 1.5 (9 August 2011)

We are pleased to announce the release of OpenSolver 1.5!

This is a bug-fix release:

  • Re-compiled CBC so that it does not have any external dependencies.
  • Fixed an error with cells formatted as currency or date.
  • Fixed some localisation-related issues with tolerance/ratio gap.

Thank you for submitting bug reports – they are very handy in solving problems. With so many different system configurations out there, it can be tricky to test even a fraction!

OpenSolver 1.4 (31 July 2011)

We are pleased to announce the release of OpenSolver 1.4!

For a full changelog, please see the document in the download.

  • Fixed 2003 menus – version 1.3 had some issues remaining.
  • Fixed some issues with and streamlined AutoModel
  • Fixed a ref-edit related focus bug in Model tool that was causing some strange behaviour.
  • Added partial locale support to Model. Entering number like 180,2 will work, but will display as 180.2
  • Added an Options window, available under Model in menu, and from a button on the Model form.
  • Added error catching in int/bin constraints on non-decision variable cells.
  • Updated CBC to version 2.7
  • Added custom icons for toolbar!

As always, please report any bugs via email or as comments.

OpenSolver 1.3 beta (7 July 2011)

We are pleased to announce the release of OpenSolver 1.3 beta!

Big features in this release are:

  • Excel 2003 menu support, thanks to Paul at Eclipse Engineering. Eclipse Engineering provide high-end CFD and FEA analysis along with a host of highly specialized CAE-based automation and integration solutions.
  • Support for 64-bit Excel 2010 has been added.
  • Removed last dependence on the built-in Solver: you can now build a model in the OpenSolver Model window!
A screenshot of the new Model tool
The new Model tool in OpenSolver 1.3

Bug reports are very welcome.

OpenSolver 1.2 is now the official stable version of OpenSolver.

OpenSolver 1.1beta released (4 March 2011)

OpenSolver 1.1beta is now available for download. OpenSolver can now run in Excel 2010 as well as 2007, and solves much larger problems and does so more quickly. (We tested on a problem with 70,000 variables and 70,000 constraints sent in by a user!) There are lots of little bug fixes and big improvements, including an AutoModel feature that provides an optional alternative to the Solver dialog; many thanks to my student Iain Dunning for coding this up. We now also check that the model is linear, and highlight any problems. Thanks to Kathleen Gilbert for working over her holidays to make these improvements. You can download the beta here. We look forward to your feedback.

OpenSolver 0.98 beta (Jul 16, 2010)

OpenSolver has been upgraded to version 0.98 (still beta). This version includes bug fixes associated with quick solves (one GUI related, one that fixes the handling of multi-area ranges, and checks that the user is on the same sheet and workbook as that used to initialise the quick solve), and also improvements so that OpenSolver dynamically resizes its arrays to handle large problems (assuming everything fits in memory). All feedback appreciated… Andrew