http://interfaces.gams-software.com/ 2008-08-28T05:36:04-04:00 http://interfaces.gams-software.com/ http://interfaces.gams-software.com/lib/images/favicon.ico text/html 2008-07-26T01:20:06-04:00 interfaces http://interfaces.gams-software.com/doku.php?id=gdx:gdxtools&rev=1217049606&do=diff A GDX (GAMS Data Exchange) file is a file that stores the values of one or more GAMS symbols such as sets, parameters variables and equations. GDX files can be used to prepare data for a GAMS model, present results of a GAMS model, store results of the same model using different parameters etc. A GDX file does not store a model formulation or executable statements. text/html 2008-07-22T06:12:53-04:00 interfaces http://interfaces.gams-software.com/doku.php?id=ext:external_functions_in_gams&rev=1216721573&do=diff Motivation Nonlinear models solved by (recent versions of) CONOPT, MINOS or SNOPT can contain socalled external functions. External functions are constraints of the form F(y) = 0 that are not specified in GAMS but in a separate subroutine. The subroutine needs to be packaged in a DLL (dynamic link library) for Windows, or shared object for Unix systems. A DLL can be written in most popular languages: C/C++, Delphi, Visual Basic, Fortran etc. text/html 2008-07-22T04:37:59-04:00 interfaces http://interfaces.gams-software.com/doku.php?id=env:spawning_gams_from_a_web_server&rev=1216715879&do=diff Running GAMS remotely using a Web based thin-client architecture requires that GAMS is executed directly or indirectly from the Web server or HTTP server. A simple way of doing this is via a CGI process. Common Gateway Interface (CGI) programs can be written in many languages such as C, Perl or Delphi. CGI is relatively slow, as for each interaction, even the most simple one, a process needs to be started. Alternatives exist in the form of CGI extensions such as FastCGI or using DLLs or shared … text/html 2008-07-22T03:41:36-04:00 interfaces http://interfaces.gams-software.com/doku.php?id=env:spawning_gams_from_excel&rev=1216712496&do=diff Background Calling GAMS out of Excel requires some more work than just exchanging data with Excel. The application has to: * Locate the GAMS system directory and adjust the system path accordingly. * Copy the GAMS model into a temporary directory (by default the temporary directory of Windows) * Extract the model data from the spreadsheet into a GAMS readable format (gdx) * Execute GAMS (solve the model, write the slution back to gdx file) * Import the model results back from the gd… text/html 2008-07-21T10:37:04-04:00 interfaces http://interfaces.gams-software.com/doku.php?id=env:gams_return_codes&rev=1216651024&do=diff When calling GAMS from a program one usually spawns gams.exe (Windows) or gams (Unix), located in the GAMS system directory. On UNIX the GAMS driver is a shell script. The following discussion can not be translated directly to that environment. Using the return codes allows the calling program to find out if there were any compilation or execution errors or other reasons why the GAMS job could not be completed. It is noted that return codes do not say anything about a model inside the GAMS job:… text/html 2008-07-21T08:44:57-04:00 interfaces http://interfaces.gams-software.com/doku.php?id=the_gams_grid_computing_facility&rev=1216644297&do=diff Note: This is copy of appendix J of the GAMS User's Guide. Introduction As systems with multiple CPUs and High Performance Computing Grids are becoming available more widely, the GAMS language has been extended to take advantage of these new environments. New language features facilitate the management of asynchronous submission and collection of model solution tasks in a platform independent fashion. A simple architecture relying on existing operating system functionality allows for rapid in… text/html 2008-07-18T07:10:27-04:00 interfaces http://interfaces.gams-software.com/doku.php?id=databases:oracle&rev=1216379427&do=diff The Oracle Database (commonly referred to as Oracle RDBMS or simply as Oracle) is a relational database management system (RDBMS) software product released by Oracle Corporation. Importing from Oracle SQL*Plus To export an Oracle table a simple solution is to write an SQL*Plus script. E.g. if our table looks like: text/html 2008-07-18T06:53:22-04:00 interfaces http://interfaces.gams-software.com/doku.php?id=databases:ms_access&rev=1216378402&do=diff Microsoft Office Access, previously known as Microsoft Access, is a relational database management system from Microsoft. It is a member of the Microsoft Office system. Importing from MS Access MDB2GMS MDB2GMS is a tool to convert data from an Microsoft Access database into GAMS readable format. The source is an MS Access database file (*.MDB) and the target is a GAMS Include File or a GAMS GDX File. MDB2GAMS is part of the Wtools, please consult the documentation for more information. text/html 2008-07-18T06:47:35-04:00 interfaces http://interfaces.gams-software.com/doku.php?id=databases:db2&rev=1216378055&do=diff DB2 is one of IBM's relational database management systems. Importing from DB2 DB2 has an EXPORT command that can be used to generate comma delimited files. An example of a DB2 session illustrating this is shown below: ------------------------------------- Command Entered ------------------------------------- describe table db2admin.dist ; ------------------------------------------------------------------------------------------- Column Type Type name … text/html 2008-07-18T02:07:41-04:00 interfaces http://interfaces.gams-software.com/doku.php?id=excel:excel&rev=1216361261&do=diff A tutorial on how to use the GDX facilities in GAMS to read data from Excel and to write data to Excel. This section gives a brief overview on how to use the GDX facilities in GAMS to read data from Excel and to write data to Excel. For more detailed information see the Appendix “GDX Facilities and Tools” of the GAMS User's Guide. text/html 2008-07-17T04:37:56-04:00 interfaces http://interfaces.gams-software.com/doku.php?id=gen:intro&rev=1216283876&do=diff Importing ASCII Files to GAMS Include without arguments All information in wp>ASCII format has to be available at compile time, and inserted into the compiler input stream. A basic task when importing data is to separate model specification and data input. The $include facility in GAMS is very helpful in this respect. For instance when the data for a table is actually coming from another environment, one could replace the TABLE statement by an include statement. A GAMS TABLE is in fact very we…