Creating a Parameter

Description

To create a new parameter in the Model Tree:

  1. Select the position in a Declaration Section where the new parameter should be inserted

  2. From the Edit menu select Insert – Parameter img_def_Identifier_Parameter_bmp

  3. Enter a name for the new parameter (if you are creating a multi-dimensional parameter, you can type the indices of each dimension as well)

  4. Press <Enter> to create the new parameter (or press <Esc> to abort the operation)

The newly created parameter is now ready for use, but you probably want to specify some additional attributes. To modify the attributes of the newly created parameter:

  • Press <Enter> or double click on the parameter node.

The most commonly used attributes of a parameter are discussed below.

  • INDEX DOMAIN : The INDEX DOMAIN attribute should be specified in order to declare indexed parameters. The img_def_Wizard_button_bmp wizard will display the Set Dependency Tree of your model and allows you to select one or more indices.

  • RANGE : The RANGE attribute should be specified in order to restrict the values to certain intervals. The img_def_Wizard_button_bmp wizard will let you either select one of the predefined ranges, like Real , Nonnegative , Nonpositive , Integer , or Binary , or specify a (parametric) interval range.

  • UNIT : The UNIT attribute is used to specify the unit in which the parameter value is measured. By specifying a unit, AIMMS is able to perform automatic unit conversions and unit consistency checks. The img_def_Wizard_button_bmp wizard will let you select a unit and quantity from the list made up from your model quantities and units together with the information in the AIMMS SI unit base.

  • DEFAULT : The DEFAULT attribute should be used in order to specify a nonzero default value for the parameter. Note that AIMMS will explicitly store all values that are non-default.

  • DEFINITION : The DEFINITION attribute can (and should) be used to specify the definition of an identifier by means of a global relationship. AIMMS stores the result of a definition and recomputes it only when necessary.

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