Release Notes

Major releases contain substantial changes to the GAMS system. The License Check date is set to the release date of the major release.

Minor releases are mainly issued to provide bug fixes, performance improvements, and maintenance releases of solver libraries. Additionally, they can provide a few new features that do not change existing behavior. The License Check Date remains the same as for the prior major release. This means that any license file that worked with the prior major release will also work with this minor release.

Maintenance releases do not provide any new features. They are issued to provide bug fixes, performance improvements, and maintenance releases of solver libraries. The License Check Date remains the same as for the prior major release. This means that any license file that worked with the prior major release will also work with this maintenance release.

GAMS Distribution 20.3 - December 24, 2001

This is a Major release.

GAMS System

  • GAMS
    Restrictions of number of symbols, set elements and execution code size have been completely removed.

    Performance enhancements for very large models with millions of rows and columns.

    Minor language enhancements: $on/offecho copies a block of lines to a file. The text is subject to string macro processing as well as inline and eol comment removal.
    For example:

    $onecho > myfile
    ...
    $offecho
    To append to a file use ">>".

  • IDE
    Contributed solver installation files (e.g. QPWRAP, DEA, ... see http://www.gams.com/contrib/contrib.htm) can now be installed using the IDE. Place the installation file (file extension *.zip or *.pck) in the GAMS system directory and click on the "Update" button in File->Options->Execute

Solvers

  • Uniform Solver Naming Conventions
    Since solvers are distributed with past, production, and beta versions (e.g. OSL, CONOPT, ...) a consistent naming convention has been adoped.
    The following simple rules apply:
    1. The base name of the solver does not change (e.g. CPLEX, OSL, CONOPT, ...) and refers to the current production version.
    2. Past and beta versions have names derived from the base name. For example, in this release we distribute CONOPT1 (past), CONOPT2 (production), and CONOPT3 (future). The base name CONOPT refers to CONOPT2.
    If you select the base name of a solver from now on you will get the most recent production version of the solver.

    For the following solvers the naming convention has changed:

    New Name (20.3-) Old Name (-20.2)
    CONOPT or CONOPT2 CONOPT2
    CONOPT3 CONOPT3
    CONOPT1 CONOPT
    OSL or OSL2 OSL2
    OSL3 OSL3
    OSL1 OSL
    MINOS or MINOS55 MINOS
    MINOS5 MINOS5
    PATH or PATHC PATHC
    PATHOLD PATH
    MILES or MILESE MILESE
    MILESOLD MILES

  • CONOPT
    The future version CONOPT3 is also available on Linux.

  • CONVERT
    For BARON and AMPL output GAMS/CONVERT eleminates the objective variable and uses a "true" objective function.

  • SBB
    NLP solvers sometimes have difficulties solving particular nodes and using up all the resources in this node. SBB provides options (see subres, subiter) to overcome these instances, but options have to be set in advance. Now, SBB keeps track of how much time is spend in the nodes, builds an average over time, and automatically controls the time spend in each node. The option avgresmult allows the user to customize this new feature.

  • XPRESS
    The XPRESS licensing for Windows, Linux, and Solaris is now much simplified; there is no XPRESS-specific licensing procedure for the user to follow. The GAMS/XPRESS solver takes care of licensing the XPRESS DLL, and does this automatically. Of course, as with other solvers, the GAMS/XPRESS must be licensed with your GAMS system.