Symbol listing

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The next output item is called the "symbol listing" and contains a classified list of all the named items along with their explanatory text.  The classification is by the main object types (Sets, Parameters, Equations, Variables, and Models) is a useful way of obtaining information on item definitions provided explanatory names and explanatory text has been used as argued in the Writing Models and Good Modeling Practices chapter.

The symbol listing for the shortmodel.gms example is

 

SETS

   PROCESS     PRODUCTION PROCESSES

   RESOURCE    TYPES OF RESOURCES

ACRONYMS

   ite         test an acronym

PARAMETERS

   PRICE       PRODUCT PRICES BY PROCESS

   PRODCOST    COST BY PROCESS

   RESORAVAIL  RESOURCE AVAILABLITY

   RESOURUSE   RESOURCE USAGE

   solprod     report of production

   Yield       yields per unit of the process

VARIABLES

   PRODUCTION  ITEMS PRODUCED BY PROCESS

   PROFIT      TOTALPROFIT

EQUATIONS

   AVAILABLE   RESOURCES AVAILABLE

   OBJT        OBJECTIVE FUNCTION ( PROFIT )

MODELS

   RESALLOC

FILES

   putfile     test a file statement

Notes:

•The symbol list does not always appear.  In particular, it is suppressed in the IDE and, if desired, needs to be requested by using the command $Onsymlist.
•In GAMS runs outside the IDE the symbol list always appears and if one wishes to suppress it one uses $Offsymlist.
•The symbol list is useful in model comprehension and documentation preparation.
•The capitalization in the symbol list is controlled by the rules explained in the Rules for Item Capitalization and Ordering chapter.
•Again long explanatory names and explanatory text really improve the utility of this list (see the Writing Models and Good Modeling Practices chapter for more on this point).