28 Distribution

28.1.0 Major release (August 02, 2019)


We would like to thank all of our users who have reported problems and made suggestions for improving this release. In particular, we thank Johan Löfberg, Hans Mittelmann, and José Luis Vilar Zanón.


  • We plan to drop support for Mac OS X 10.12 (Sierra) with the next GAMS major release.

GAMS System



  • Improved ranking of results in offline search by minimizing the effect of the length of a document on the importance of a search term in that document.
  • When searching the index, only relevant results are shown for subcategories as well.
  • The full-text search now shows also results for a search in the index.


ANTIGONE, Bonmin, Couenne, Ipopt, SCIP

  • Downgraded Intel MKL libraries to version 2018.3 on Windows 64-bit.


  • The timelimit is now applied to the wallclock time and wallclock time is reported in the log and back to GAMS.


  • New libraries 19.7.13.
    • New relaxations and branching rules for nonconvex mixed-integer quadratic programs, leading to significant speedups for this class of problems.
    • Increased robustness in various range reduction routines.
    • Increased solvability of large-scale problems by BARON's cut generators.
    • Enhanced convexity recognition routines.
    • Updated to IPOPT 3.12.13 and CBC 2.10.1.
  • Fixed passing constant equations to BARON.



  • CONOPT3 accepts models with empty rows. The GAMS/CONOPT3 link sets the hidden option LSAZRW to true.



  • Fixed handling of Ipopt's feasible-point-found status.




  • New libraries 6.0 (f79421d).


GAMS Studio

  • New version 0.12.3.
    • Stability and performance improvements.
    • Added GAMS Solver Option Editor to view and edit a solver-specific option file.
    • Renamed Option Editor to Parameter Editor to better distinguish solver options and GAMS parameters.
    • Added menu entry GAMS -> Delete scratch directories to delete all scratch directories in current working directory. A similar dialog will also be triggered if GAMS returns 110 ("Too many scratch directories").
    • Added file associations and icons for .gms and .gdx files on Mac OS X.
    • Changed shortcut to focus Main widget from Ctrl+H to CTRL+E (there was a collision on Mac OS X).
    • Improved keyboard navigation between files and widgets.
  • We plan to drop Studio for 32 bit Windows with the next major release.


  • As announced, dropped support for Python 2.6.
  • We plan to increase the minimum version requirement of the Java Runtime Environment to Java SE 8 with the next major release.

Model Libraries

GAMS Model Library

  • Changed model sigma in immun to minimize standard-deviation instead of variance.
  • Added missing nonnegativity requirement on variables in model wall.

28.2.0 Minor release (August 19, 2019)


We would like to thank all of our users who have reported problems and made suggestions for improving this release. In particular, we thank Nayeem Chowdhury, Salvador Doménech Martínez, Michael Ferris, Antti Lehtila, Evangelos Panos, Jochen Uhrich, and Alexey Ziuzin.

GAMS System


  • Setting $onMultiR allows the redefinition of macros as well now.
  • Fixed a problem finding the Python interpreter, that comes with GAMS, in certain cases.
  • Fixed a bug in the model generation, which could have caused a crash or wrong results in some cases.



  • Corrected reporting of solution for (MI)QCP problems when using feasopt.
  • CplexD now reports the objective of the feasible relaxation in the solution summary when using feasopt.


GAMS Studio

  • New version 0.12.4
    • Stability and performance improvements.
    • Improved robustness of glb file parser (see User Libraries).
    • Added "What's new" menu entry to show latest changes of Studio.

Object Oriented APIs

  • Fixed a problem, where GAMSDatabase.Export triggered an exception because of domain violations, even if only relaxed domains were used.


  • Added new method GAMSSymbolRecord.dispose() for on-demand release of external resources hold by non-java library.