Microsoft Solver Foundation 3.1 is now ready for download. Solver Foundation provides a complete system for optimization model specification, connection to data sources, and access to best-of-breed solvers for Excel users and .Net programmers. The Express version is available on the Solver Foundation site [click here], the MSDN and MSDNAA versions will be available soon, and the Enterprise version is available for purchase through Gurobi Optimization.

Here is a partial list of new features:

• New Solver Foundation Services APIs enable specification of large models with easier to use, faster data binding using LINQ.
• Improved SFS performance. Big models are processed in less time using less memory.
• A new nonlinear solver based on the Nelder-Mead method, comparable to methods provided in other environments.
• Improvements to the hybrid local search solver to support arbitrary goals and constraints.
• Numerous improvements to the Solver Foundation add-in for Excel:
  • Full support for commercial and open source solvers.
  • Sparse parameter support.
  • Warm start capabilities for performance and accuracy.
  • Better support for named ranges.
  • Complete control over all solver options – including third-party solvers.
  • Better control over logging and output.
  • Faster data binding.
• Solver Foundation Services improvements:
  • Inline Set definition.
  • New SetBinding overloads.
  • Support for multiple SolverContexts.
  • Better WCF and Windows service support.
• Logistic regression sample using the L-BFGS solver.

Solver Foundation also includes the Gurobi 4.5 solver, providing better MIP and MIQP performance. The Standard and Enterprise versions of this release are now permitted to be used in virtualized environments including Windows Azure.

Many of these improvements are based on feedback from the Solver Foundation community. Download the Express version and let us know what you think on the Solver Foundation forum.

- The Solver Foundation Team