30 Distribution

30.1.0 Major release (January 10, 2020)

Acknowledgments

We would like to thank all of our users who have reported problems and made suggestions for improving this release. In particular, we thank Todd Munson, Suguru Otani, Nick Sahinidis, and Dimitri Tomanos.

Platforms

Licensing and Demo Limits

  • The GAMS demo limits have been increased. GAMS will generate linear (LP, RMIP, MIP) models up to 2000 constraints and 2000 variables and up to 1000 constraints and 1000 variables for all other model types. No other limits apply (e.g. non-zeros or discrete variables). Some solvers (e.g., the global solvers ANTIGONE, BARON, and LindoGlobal) might enforce additional restrictions.
  • GAMS provides a free community license for users on request. This community license allows generating even larger models: up to 5000 constraint and variables for linear and 2500 constraints and variables for other model types. These free licenses are for demonstration and evaluation but not for commercial and production work, see the GAMS End User License Agreement.
  • Starting with this release, GAMS requires a valid license even for the free demo system. Free demo licenses (time-limited for 12 months) can be generated at the download page. The free demo and community licenses require also a recent version (not older than 18 months) of GAMS to run. Please check the license documentation for details.
  • GAMS Beta versions will stop working 90 days after their release. This is to prevent accidental use of beta software.

GAMS System

GAMS

  • Added system suffix MACAddress, which contains the MAC address of the first network adapter.
  • Allow to declare more than one parameter as table on a single line.
  • Added new dollar control options $[on][off]Filtered: These control how GAMS loads data from GDX with $load, $loadR, and $loadM as well as from $offEmbeddedCode.
  • Added new dollar control options $loadFiltered, $loadFilteredM, and $loadFilteredR to load data from GDX in filtered mode explicitly.
  • Added new dollar control options $[on][off]ExternalInput to load data implicitly from an external source and $[on][off]ExternalOutput to save data implicitly to an external target.
  • Added new command line parameters IDCGDXInput, IDCGDXOutput, IDCGenerateGDX, IDCGenerateGDXInput, IDCGenerateGDXOutput, IDCGenerateJSON, and IDCJSON.
  • Embedded Python Code:
    • Changed the optional boolean argument domCheck to an enumerated option DomainCheckType in the gams.set method in embedded code. This might break existing code. Even if the domCheck argument was not used, the default behavior at execution time changes. In previous versions the content was domain checked, now it is read filtered.
    • The argument mergeType was documented incorrectly. With type MergeType.DEFAULT (or no argument given) GAMS merged the content, in contrast to what the documentation said (here replace was mentioned).
  • Terminate with a proper error message if lines in the EMP info file exceed the maximum line length of 1020 characters.
  • Fixed a problem where the order of a semicolon and certain dollar control options changed the behavior of the compiler.

Installer

  • In addition to .gms files, the Windows installer also associates .gdx files with either the GAMS IDE or GAMS Studio.

Solvers

BARON

  • New libraries 19.12.7.
    • Performance improvements for large-scale and mixed-integer quadratic problems.
    • Improvements in interface to IPOPT.

CBC

  • New libraries.

CONOPT

  • New library 4.16 with bug fixes.
    • Improvement in the transition from Phase 0 to Phase 1 and in the one-dimensional search close to optimality.

CPLEX

GUROBI

JAMS/LogMIP

  • New option userPFFile to provide additional GAMS command line parameters for the GAMS run of the reformulated model.

LocalSolver

  • New libraries 9.0 (20191219).

MOSEK

  • New libraries 9.1.9.

ODHCPLEX

  • New libraries 4.3.2 with bug fixes and performance improvements.

PATH

  • New library 5.00.01 with bug fixes.
    • Fix seg fault when using the hidden option output_hidden_options.

SCIP

Tools

GAMS Studio

  • New version 0.14.1.
    • Stability improvements.
    • Added GDX Diff dialog to compare two GDX files. It can be opened by choosing Tools > GDX Diff from the menu or through the context menu off a GDX file in the Project Explorer.
    • Allow to open OS specific terminal in current working directory (Tools > Terminal) or in working directory of a specific group (using the context menu in the Project Explorer)
      • Note: This feature does not work on all Linux distributions, e.g., Ubuntu, yet.
    • Added basic integration of GAMS MIRO .
      • Note: This requires a separate installation of the GAMS MIRO package.
    • Improved GDX Viewer layout to optimize used screen space.
    • Adjusted layout of Reference File Viewer.
    • Added clear button to filter input field in GDX Viewer and Reference File Viewer.

Object Oriented APIs

C++

  • We plan to drop support for Microsoft Visual Studio 2013 and maybe also 2015 with the next major release.

Python

  • Added support for Python 3.8.
  • As announced, dropped support for Python 3.4.

Expert Level APIs

  • Added support for Python 3.8.
  • As announced, dropped support for Python 3.4.

Model Libraries

GAMS Data Library

New models:

GAMS Test Library

New models: