In response to a user request, OpenSolver has been upgraded to version 0.982. This new version can handle larger problems with more than 32,000 variables and/or constraints. However, such models will be very slow to build. Andrew
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
Mike Trick, who visited New Zealand a few years ago, has blogged about OpenSolver. This has generated an interesting discussion about the GPL license, and whether this will limit what people want to do with OpenSolver. I’ve been having similar discussions with Ted Ralphs, the CBC maintainer, and Stu Mitchell of PULP fame. If anyone wants OpenSolver to be available under another license, then please let me know.
As well as all the contributions Mike made to OR in New Zealand during his stay, I also have to thank him for his Travelling Umpire Problem (TUP) which kept my Heuristics class very busy.
I hadn’t come across Larry’s IEOR Tools site before following the link on his OpenSolver comment. He too has written about OpenSolver. He’s created an interesting site with a good open source emphasis that I’ll be visiting more often.
Some of you may have arrived at this site by clicking on a Google ad. This is an experiment that’s possible thanks to the free Google credits provided by our GoDaddy hosting plan. On our first day we’ve had 5 click-thru’s, all for a total cost of nz$1.20 a day!
OpenSolver has now moved from wordpress.com over to our GoDaddy hosted site. It took a while (longer than I’d expected, and with too many GoDaddy hiccups), but it is now up and running. Enjoy. Andrew
Better checking of parameters; better handling of Escape during long CBC runs (no DoEvents now, and a new dialog). Fixed bug in the “Last open model in CBC” where OpenSolver was waiting for CBC to close (but still allowing events to be handled, including sheet edits etc.)
Updated OpenSolver. Added a fix for sheet names with spaces, and for the definition of parameters. Added new commands to (1) Solve LP relaxation, and (2) to open CBC command line. Also added improved support for cancelling long CBC runs. A new .zip file has been uploaded. Enjoy. Andrew
Welcome to OpenSolver, the Open Source linear and integer optimizer for Microsoft Excel. This is our first release of OpenSolver.