The Model Specification Module

In this module the objects are created and the model is specified using TGIF [#!tgif!#]; see Figure .

Figure: TGIF - TANGRAM Graphic Interface Facility

To create a new object type, the tool displays a template as shown in Figure . The template shows the state variable and all parameter types that can be defined by the user, and displays a set of fields to be filled in by the user indicating the events and messages of the object type and the associated conditions and actions. The object also may have an attribute called ``rewards'' that can be used to obtain reward measures using appropriate analytical or simulation solution methods. The box in the left-hand corner of the template can be modified to create an icon for the object type being defined.

Figure: Template to define a new object type.

After all objects are created, it is necessary to interconnect them using ports. Through these ports, messages are exchanged between objects. All variables are either state variables, constants or parameters. State variables are of type integer or integer-valued vector. Constants can be of type integer, float, object, or port. All state variables and constants must be initialized before the mathematical model is generated. Parameters need be initialized only before the analytical solution (they are not used in simulation).