gams Namespace Reference


class  GAMSCheckpoint
class  GAMSDatabase
class  GAMSDatabaseDomainViolation
 This class describes a domain violation of a GAMSDatabase. More...
class  GAMSDatabaseIter
class  GAMSDomain
 This class represents a abstraction of GAMSSet objects and relaxed sets, i.e. strings. More...
class  GAMSEnum
 The collection of all common GAMS enumerations. More...
class  GAMSEquation
class  GAMSEquationRecord
 This class represents a single record of a GAMSEquation. More...
class  GAMSException
 Exception class thrown for GAMS exceptions. More...
class  GAMSExceptionExecution
 Exception class thrown for GAMS execution exceptions. More...
class  GAMSJob
class  GAMSModelInstance
class  GAMSModelInstanceOpt
 The GAMSModelInstanceOpt can be used to customize the GAMSModelInstance.solve() routine. More...
class  GAMSModifier
class  GAMSOptions
class  GAMSParameter
class  GAMSParameterRecord
 This is the representation of a single record of a GAMSParameter. More...
class  GAMSPath
 Represents the GAMS path to a specific file. More...
struct  GAMSPlatform
 Encapsulates all platform specific calls of the API. More...
class  GAMSSet
class  GAMSSetRecord
 This is the representation of a single record of a GAMSSet. More...
class  GAMSSymbol
class  GAMSSymbolDomainViolation
 This class describes a domain violation of a GAMSSymbol. More...
class  GAMSSymbolIter
class  GAMSSymbolRecord
class  GAMSVariable
class  GAMSVariableRecord
 This is the representation of a single record of a GAMSVariable. More...
class  GAMSVersion
 Represents the GAMS version information. More...
class  GAMSWorkspace
class  GAMSWorkspaceInfo
 The GAMSWorkspaceInfo can be used to input parameters for the GAMSWorkspace constructor. More...
class  GAMSWorkspacePool
 Manages a collection of all GAMS workspaces. More...
class  Logger
 Logging class used to get feedback about the API actions. More...
class  LoggerPool
 The class to manage all loggers used in an API instance. More...
class  SolverOptions
 Represents the solver options. More...

Detailed Description

The GAMS namespace provides objects to interact with the General Algebraic Modeling System (GAMS). Objects in this namespace allow convenient exchange of input data and model results (GAMSDatabase), help to create and run GAMS models (GAMSJob), that can be customized by GAMS options (GAMSOptions). Furthermore, it introduces a way to solve a sequence of closely related model instances in the most efficient way (GAMSModelInstance).

The underlying GAMS engine relies to some extent on file based communication (e.g. the listing file) and other low-level resources. A GAMS program can include other source files (e.g. $include), load data from GDX files (e.g. $GDXIN or execute_load), and create PUT files. All these files can be specified with a (relative) path and therefore an anchor into the file system is required. The base class GAMSWorkspace manages the anchor to the file system. If external file communication is not an issue in a particular application, temporary directories and files will be managed by objects within the library.

With the exception of GAMSWorkspace the objects in the GAMS namespace cannot be accessed across different threads unless the instance is locked. The classes themself are thread safe and multiple objects of the class can be used from different threads (see below for restrictions on solvers that are not thread safe within the GAMSModelInstance class).

Note: If you use multiple instances of the GAMSWorkspace in parallel, you should avoid using the same WorkingDirectory. Otherwise you may end up with conflicting file names.

This version of the GAMS namespace lacks support for the following GAMS components:

Acronyms, support for GAMS compilation/execution errors (GAMSJob.Run just throws an exception), structured access to listing file, and proper support for solver options.

Currently only CplexD and Gurobi fully utilize the power of solving GAMSModelInstances. Some solvers will not even work in a multi-threaded application using GAMSModelInstances. For some solvers this is unavoidable because the solver library is not thread safe (e.g. MINOS), other solvers are in principle thread safe but the GAMS link is not (e.g. Cplex, note there is a thread safe version of Cplex called CplexD which lack some minor features e.g. support for BCH framework). Moreover, GAMSModelInstances are not available for quadratic model types (QCP, MIQCP, RMIQCP).

There are examples in C++ using this API in [GAMS system]\apifiles.