22.8.1 Major release (August 01, 2008)

Acknowledgements

We would like to thank all of our users who have reported problems and made suggestions for improving this release. In particular, we thank Wolfgang Britz, Andrea Consiglio, Anton Eremeev, Mustafa Esen,Josef Kallrath, Erwin Kalvelagen, Todd Munson, Rich Roberts, and Andres Ramos.

GAMS System

GAMS

GAMS scratch file extension: Starting with distribution 22.9 the default file extension of intermediate files located in the 225? directories will change from .scr to .dat. For distribution 22.8 it is still .scr. The scratch extension now is a parameter that can be changed with the GAMS option ScrExt, e.g gams trnsport scrext=tmp. Within GAMS code you get the scratch extension using %gams.scrext%.
Increased the maximum input line length to 40,000 characters and the maximum number of columns in a table to 10,000.
Checking for an interrupt is now also done inside a GAMS looping constructs.
The $LOAD directive can read the universe from a gdx file by specifying $LOAD id=*.
Certain gdx file read operations are now faster and use less memory.
GAMS parameters gdxcompress and gdxconvert
- Allow new gdx files to be written in an older format of the gdx file.
- Usage through an environment variables (valid for all gdx related operations): gdxconvert = <value> and gdxcompress = <value> or via GAMS command line parameters: gdxconvert = <value> and gdxcompress = <value>.
- Possible values for gdxcompress
  - 0 (or empty): no compression
  - 1: compression turned on
- Possible values for gdxconvert:
  - V7: version 7
  - V6: version 6
  - V5: version 5
- E. g. to get a compressed v6 gdx file enter: gams <model_name> gdxconvert=v6 gdxcompress=1 gdx=<gdx_file>.
- Note:
  - With GAMS 22.8 the default format for gdx files is V7 uncompressed.
  - Only V6 and V7 support compression.
  - V7 formatted files were introduced with version 22.6 of GAMS; V6 formatted files were introduced with version 22.3 of GAMS. GAMS platforms that were introduced after 22.3/22.6 (e.g. Mac Intel or SunSparc64) do not support V5/V6.
  - The command line options have a higher precedence as the environment variables with the same name.

Utilities

New
- gdx2xls: Converts an entire gdx data container to a Microsoft Excel spread sheet.
- invert: Calculates the inverse of a matrix provided as a gdx file (for more information see gdxutils documentation).
- msappavail: Checks which Microsoft Office programs are installed.
- xlstalk: Allows some interaction with Excel to open/close/save Excel files.
Extended/Updated
- gdxcopy: New option to replace existing gdx files.
- gdxdiff: New id option to compare specified ids only.
- gdxmerge: New optional output parameter to specify the name of the output file.
- gdxviewer: Fixed problem with cube view.

GAMSIDE

Fixed problem when moving a column to the plane in the gdx data viewer.

Model Libraries

GAMS Test Library

New models, including tests for
- invert utility
- ls solver
- poly function
- gdxconvert and gdxcompress parameters

GAMS Data Utilities

GAMS introduces the new model library 'GAMS Data Utilities' containing models that demonstrate the various utilities to interface GAMS with other applications.

PRACTICAL FINANCIAL OPTIMIZATION Models

The models of the forthcoming book PRACTICAL FINANCIAL OPTIMIZATION - A Library of GAMS Models by Andrea Coniglio, Soren Nielsen, and Stavros A. Zenios have been included in the GAMS distribution. It is a companion volume to the book Practical Financial Optimization by Stavros A. Zenios.

Solvers

BARON

New libraries 8.1.5 for Windows, Linux, and AIX

BDMLPD

GAMS 22.8 introduces a third experimental solver BDMLPD besides CONOPTD and CPLEXD. They are very similar compared to their professional brothers BDMLP, CONOPT and CPLEX. They lack some functionality (e.g. CPLEXD does not solve QCP models) but offer in-core communication between GAMS and the solver. No large model scratch files need to be written to disk which can save time if you solve many models in your GAMS program. This in-core execution is activated by setting <modelname>.solvelink=5; before the solve statement.

Coin-OR

CoinBonmin
- New libraries 0.99
- Support of user-defined cut generators and heuristics via BCH (Branch and Cut Heuristic)
CoinCbc new libraries 2.1
CoinScip supports user-defined cut generators, heuristics, and incumbent report callbacks via BCH

Convert

New option hessian to dump the Hessian matrix into a GDX file. Similar to the option jacobian.

Cplex

New libraries 11.1.1

Lindoglobal

New libraries 5.0.1.292. Sun Sparc Solaris 5.0.1.274.

LS

Linear Least Squares Solver

Mosek

New libraries 5 Rev 90

XA

New libraries for Windows

Solver/Platform Availability Matrix

Solver/Platform availability - 22.8 August 1, 2008
	x86 MS Windows	x86_64 MS Windows	x86 Linux	x86_64 Linux	Sun Sparc SOLARIS	Sun Sparc64 SOLARIS	Sun Intel SOLARIS	HP 9000 HP-UX 11¹	DEC Alpha Digital Unix 4.0³	IBM RS-6000 AIX 4.3	Mac PowerPC Darwin	Mac Intel32 Darwin	SGI IRIX²
ALPHAECP
BARON 8.1		32bit		32bit
BDMLP
COIN
CONOPT 3
CPLEX 11.1								10.0	8.1				9.1
DECIS						32bit
DICOPT
KNITRO 5.1		32bit				32bit
LINDOGLOBAL 5.0
LGO
MILES
MINOS
MOSEK 5								3.2
MPSGE
MSNLP						32bit
NLPEC
OQNLP		32bit		32bit
OSL V3		32bit		32bit		32bit		V2					V2
OSLSE		32bit		32bit		32bit
PATH
SBB
SNOPT
XA		32bit				32bit
XPRESS 18.00		32bit		32bit		32bit		16.10
¹⁾GAMS distribution for HP 9000/HP-UX is 22.1.
²⁾GAMS distribution for SGI IRIX is 22.3.
³⁾GAMS distribution for DEC Alpha is 22.7.

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