Creating an Arc

Description

To create a new arc in the Model Tree:

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

  2. From the Edit menu select Insert – Other (or press the <Insert> key)

  3. In the dialog box select img_def_Identifier_Arc_bmp Arc and press OK

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

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

The newly created arc is not yet ready for use, because you should at least specify some mandatory attributes. To modify the attributes of the newly created arc:

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

The most commonly used attributes of an arc are discussed below.

  • INDEX DOMAIN : The INDEX DOMAIN attribute should be specified in order to declare indexed arcs. 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 arc’s 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.

  • FROM : The FROM attribute is mandatory an should contain a node reference specifying the start node of the arc. The img_def_Wizard_button_bmp wizard will display an Identifier Selection Dialog box that helps you select the appropriate node.

  • TO : The TO attribute is mandatory an should contain a node reference specifying the end node of the arc. The img_def_Wizard_button_bmp wizard will display an Identifier Selection Dialog box that helps you select the appropriate node.

  • COST : The COST attribute is used to specify the cost coefficient that will be used to calculate the predefined AIMMS variable FlowCost .

  • PROPERTY : The PROPERTY attribute should be used to specify additional properties. Note that in order to retrieve sensitivity information from the solver, the ReducedCosts , ValueRange , or CoefficientRange property should be explicitly set. The img_def_Wizard_button_bmp wizard will let you specify the properties through a selection of radio buttons and check boxes.

Remark

Arcs are used to formulate network models and are considered to be variables when it comes to solving the network model.

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