Blog

New Support Site for CBC Solver

Most of our OpenSolver users choose the standard integer programming solver, CBC (which is the default option). COIN-OR, the non-profit who support and develop CBC, have just announced a new support forum for CBC users. (This is a beta test of the new GitHub discussion forums being developed.) This is the best place for advanced users to take technical questions, such as queries about CBC parameters (which OpenSolver supports). Andrew

OpenSolver 2.9.3 Beta Release

Hi everyone,

We have now released OpenSolver 2.9.3 for beta testing! You can download this new version of OpenSolver on https://sourceforge.net/projects/opensolver/files/. Below are the release notes that cover the changes made in this new version of OpenSolver:

v2.9.3 – 2020/03/02

  • Added support for using Gurobi 9.0
  • Added a temp fix for running consecutive operations on Excel64bit

v2.9.2 – 2019-02-04

  • Add support for NEOS CPLEX as a new solver.
  • Add import LP file feature.
  • Add Examples files and submenu.
  • Fix memory error when solving consecutive non-linear models in 64bit.

As always, we welcome any feedback! Please comment below if it works ok, or if there are any issues encountered, or if you have any questions regarding the new release. Thanks!

OpenSolver for Google Sheets currently down for new users

12 Feb 2020: It was raised to us that OpenSolver for GoogleSheets is still unaccessible to new users. We are now able to replicate this bug. From our tests, new user accounts are able to install OpenSolver for Google Sheets as an Add-on from Chrome Web Store. However, the “Sign in with Google is temporarily disabled for this app” screen will still show up when trying to open the sidebar from the ribbon. We are very sorry for the inconvenience and we have contacted Google regarding this issue. We need to wait for Google’s response on this, therefore we are unsure of when this problem will be fixed.

10 Feb 2020: This is no longer the case! OpenSolver for Google Sheets is now back online for new user installations. The “app isn’t verified” screen will no longer show up for new installations. We have also updated our privacy policy to align with Google’s requirements. For more information on the usage of Google OAuth scopes please visit our OpenSolver for Google Sheets page and our Privacy Policy page.

Original post: Changes made by Google mean that OpenSolver for Googlesheets is currently not working for new users who want to add it to their Googlesheets. (Apparently the first 100 users each month can sign in, but then further sign ins are blocked by Google.) We are working on fixing this, But we don’t know how long it will take, sorry. We suggest you use OpenSolver for Excel until we get it working properly for Googlesheets.

Sorry for the inconvenience.

Cheers,

Andrew

OpenSolver for Ecological Conservation

We justc ame across an interesting article using OpenSolver to help develop optimal policies for conservation.

https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.2596

Commonalities in stream connectivity restoration alternatives: an attempt to simplify barrier removal optimization

Ryan A. McManamayJoshuah S. PerkinHenriette I. Jager First published: 07 February 2019 https://doi.org/10.1002/ecs2.2596

https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.2596

Ecosphere banner


OpenSolver for Google Sheets 2.3.0 (2 April 2017)

Today we are releasing an update to OpenSolver for Google Sheets that includes a new solver: the SolveEngine from Satalia

The update will roll out over the next day or so, and you will then be able to access the SolveEngine in the list of available solvers. The first time you use the solver, you will be prompted to enter your SolveEngine API key, which you can obtain by creating an account using the link in the prompt. This is the beta version of the SolveEngine, which will be free during the beta period. After the beta has ended, users will receive 1 hour of free solving time per month. There will be no queuing during the beta, and after the beta there will be a short queuing time for free users.

The SolveEngine is a cloud-based system, similar to NEOS except with more powerful solvers and much shorter queue times. We hope that it will prove a useful and powerful alternative to the other solvers we offer, and have plans to also offer it in OpenSolver for Excel in the coming future.

SolveEngine Overview

The SolveEngine boasts many features that make it a powerful tool for solving a variety of optimisation problems, notably:

  • A single gateway to a portfolio of solvers;
  • Modern optimisation translators and encoding that give access to a wider range of algorithms;
  • No licence to manage and nothing to install;
  • Distributed cloud computation that enables dynamic resource allocation to accommodate complex and large problems;
  • Machine learning which matches the right algorithms to the problems it receives, improving itself over time.

Users of the SolveEngine benefit from :

  • Access to a constantly evolving portfolio of algorithms, designed to solve problems such as:
    • Boolean Satisfiability problem (SAT)
    • Linear programming (LP)
    • Mixed integer linear programming (MILP)
  • Free solving time (1 hour) after account creation;
  • Free Academic usage;
  • Access to cutting-edge algorithms from academia, and in doing so, supporting academics to commercialise and further develop their algorithmic innovations;
  • Direct access to time honored and also newly developed commercial algorithms;
  • Built-in translators, which means that there is no strict limit to the number of problem formats that can accepted by the SolveEngine and allows for human readable inputs such as GLPK to be submitted;
  • The capability of the SolveEngine to run many solvers in parallel using sophisticated pre-processing and pipelining techniques which identify the most promising routes through to solving the problem faster;
  • Submission of various problems and concurrency of problem solving in a scalable manner;
  • Access to a community of optimisation/modelling experts for support.

Optimisation problems exist across the entire spectrum of business, science and engineering. The SolveEngine has already been used to solve many hard computational problems in graph theory, logistics, system verification, BigData and cryptography.

Satalia Overview

Satalia is a spin-out from the UCL Department of Computer Science. Satalia’s team of academics and artificial intelligence experts harness a library of algorithms, hosted in the SolveEngine, to help companies and organisations solve the world’s most difficult problems. In 2016 Satalia was recognised in the elite Gartner Cool Vendors in Data Science list, the only UK company chosen.

Satalia’s commitment to continued innovation in algorithm development underpins the SolveEngine model through which academics and commercial solver developers can deploy their solvers to the SolveEngine to address the current and emerging requirements of industry and research communities. Providing access to state-of-the-art optimisation algorithms, Satalia enables the industry to analyse problems inputs more efficiently and thus to solve their problems more rapidly.

OpenSolver 2.8.6 (6 Mar 2017)

We have released OpenSolver version 2.8.6 which fixes various bugs:

  • We have updated the URL for NEOS so these solvers will work again
  • Made changes to support Gurobi v7
  • Set worksheet calculation in the OpenSolver file to automatic to avoid setting it to manual for the entire Excel session when OpenSolver is loaded. Thanks to the users that reported this issue.
  • Other minor bugfixes

You can get the new version here.

As always, please let us know about any issues you might have, or features you would like to see in future releases!

250k milestone

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.

Andrew

OpenSolver 2.8.5 (3 Nov 2016)

Today we are releasing OpenSolver version 2.8.5 which fixes a bug brought about by the October update to Excel 2016. This bug in Excel prevented clicks on the constraint section of the model creation form in OpenSolver, and there is a workaround in today’s update so that things work as intended.

You can get the new version here.

The release also includes a new feature that a number of users have asked for in the past, which is the ability to use the NOMAD solver to optimize models where the objective and constraints depend on the output of macros. For instance, one user wanted to use the results of a Pivot Table that depended on the variable values in their model, but Pivot Tables are not updated when the sheet is recalculated so this did not previously work with OpenSolver. Another example comes from Judd Larson at the University of Wyoming. Judd’s problem involved optimizing a function that depended on the solution to a series of differential equations, which he was solving using his VBA implementation of an ODE solver. This is not a problem that can be expressed and solved in the traditional way that OpenSolver supports, but is possible to solve now with the new ability to incorporate the macro into the solution process. We are very pleased to offer a solution to a tough problem like this! For more information on how this feature works, please see the new section in the documentation describing this feature.

As always, please let us know about any issues you might have, or features you would like to see in future releases!

OpenSolver 2.8.4 (12 Oct 2016)

We have just released OpenSolver 2.8.4 which fixes a bug in the 2.8.3 release that caused it to crash on the newest versions of Excel (in most cases the Office 365 versions). This release also fixes a bug where the saved solver choice could get corrupted and force you to re-select the solver.

You can download the 2.8.4 release here.

Don’t forget to enable the update checker in OpenSolver if you want to be notified automatically of new updates like this one.

As always, please let us know if you have any feedback or problems.

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.