New platforms supported

• 64 bit Windows (aka Windows 64-Extended, Windows EM64T) version introduced. Windows licensing includes both 32 and 64 bit systems at a single platform cost. Some solvers exist only in 32 bit mode and are included as such on the 64 bit version. See the solver platform matrix.

Updated build for the Linux platform

• Previous 32-bit Linux GAMS Distributions (e.g. 21.X) were built using only an older Linux machine with version 2.2 of the GNU C Library. This distribution is compatible with both older and newer Linux systems. The installer for this software is located in the systems/lnx/lnx2.2 directory of the CD. The build code for this software is LXI (displayed on the solver audit lines, etc). This build is included in the current CD as it was before.
• This distribution includes a new 32-bit Linux build (build code LX3) that parallels the previously-existing LXI build. The LX3 system is built on a newer Linux machine with version 2.3 of the GNU C Library, and is not compatible with older systems using GNU LIBC 2.2. The installer for this software is located in the systems/lnx/lnx2.3 directory of the CD.
• Consider the following when choosing which Linux build to install:
  • Most Linux users will be using a system with GNU LIBC 2.3 and should use the newer build. You can check your LIBC version by running it. On my machine, I do "/lib/libc.so.6" but be aware your version number may vary.
  • These are builds of the same source, using different compilers. The "older" build uses older compilers, not older source. In cases where different vendor libraries are required, the same comment applies.
  • The different builds use a common GAMS license file.
  • While there is no scheduled end-of-life for the older build we expect that our algorithm vendors will stop supporting it at some point. When this happens, we can only ship updated versions of the new build.
  • If you wish to install both versions, install them in separate directories.

GAMS System

GDX Utilities

GDXDIFF

• Modified the comparison routine that determines if two numbers are equal wrt. an absolute or relative tolerance.

GAMS IDE

• Added option to save a file in Unix format.
• Added option to save and email the current file.
• Added option to launch Windows Explorer showing directory of the current file with the current file selected.
• gamsdir is now a sub-directory of 'My documents'. gamside.ini file now stored in the gamsdir directory.
• Reload file now also works for GDX files and RefFiles (in addition to regular source files).
• When starting the IDE or opening a project, a scan is made for GAMS temporary directories which can be deleted. This option was also added under the Utilities menu.
• Pressing F1 for help was broken.
• $ONECHO/$OFFECHO work now like $OFFTEXT/$ONTEXT for syntax coloring.

Solvers

CPLEX

• New libraries (version 9.1)
  • Option mipstart: It is no longer necessary to provide a compete integer solution as the starting point.
  • Option fraccuts: Settings of 1 or 2 will cause Gomory cuts to be generated for MIQCP models.
  • New Option lbheur: When set to 1 (default is 0), CPLEX will use a local branching heuristic to try to improve new incumbents.

KNITRO

• New libraries are included which address minor fixes.

XA

• New libraries are included which address minor fixes.

XPRESS

• New libraries are included which address minor fixes.