This page is for an old version of Hexaly Optimizer. We recommend that you update your version and read the documentation for the latest stable release.

Quick tour of LocalSolver’s modeler¶

The best way to discover LocalSolver is to use the built-in modeling language. It provides many mathematical operators and facilitates goal programming. The language itself, called LSP (for LocalSolver Programming language) can be both used for programming and modeling: in the same LSP program it is possible to manipulate data structures as in an imperative language and define the optimization model.

As a result, models written in LSP language are really concise and readable. They are structured around 5 predefined functions: input(), model(), param(), display(), output(). These functions, called in this order, induce the flow of the program launched by the LocalSolver executable:

  • input: for declaring your data or reading them from files.
  • model: for declaring your optimization model.
  • param: for parameterizing the local-search solver before running.
  • display: for displaying some info in console or in some files during the resolution.
  • output: for writing results in console or in some files, once the resolution is finished.

The quick tour of LocalSolver’s modeler covers the following main topics: the basics of mathematical modeling, the programming style, and the list of all built-in variables and functions. For more details on the modeling language, see LSP Reference Manual.

We start this tour by solving a celebrated problem of the operations research literature: the knapsack problem.