Performing calculations with the Parametric Constraint Evaluator

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You can perform constraint-related calculations with the Parametric Constraint Evaluator.

Before you begin

Before using the Parametric Constraint Evaluator, you must do the following:

  • Install one of the supported computer algebra programs: Maxima or MATLAB.
  • Create a Rhapsody® model that uses the Systems Engineering profile.
  • Create at least one parametric diagram in your model.

Procedure

  1. Add the PCE.sbs profile to your model from <product installation folder>\Share\Profiles\PCE.
  2. Use the PCE Environment Settings window to specify the computer algebra software you are using. From the main menu, click Tools > PCE Environment Settings).
  3. Review the parametric diagrams to be analyzed, and verify that they contain all of the attributes and constraints that are required for the calculations you would like to perform.
    Note: To use the Parametric Constraint Evaluator, the syntax used to define the constraints for the constraint blocks must conform with the subset of the Modelica language (see http://www.modelica.org/) described in the Parametric Constraint Evaluator tutorial (see http://www.ibm.com/support/docview.wss?uid=swg27018723).
  4. In the model browser, create a ConstraintView element by selecting the relevant item from the popup menu for packages.
  5. Select the ConstraintView element that you created, and using Add New on the popup menu, create a reference to the parametric diagram that you would like to associate with the ConstraintView element.
  6. From the popup menu for the ConstraintView element that you created, select Open ConstraintView.
    A table is displayed listing all of the attributes and all of the constraints included in the associated parametric diagrams.
  7. In the Value column, you can modify attribute values and constraints.
  8. If you want to disable one or more constraints, select Disable in the Command column.
  9. If you want to calculate the maximum or minimum value of a certain attribute, based on the values entered for the other attributes, select the relevant option from the dropdown list for the attribute in the Command column.
    Note: Optimization is based on linear algorithms. Therefore, this feature can only be used if all of the constraints are linear.
  10. To perform calculations based on the values entered for the attributes in the parametric diagram:
    • Click Evaluate to calculate the value of equations.
    • Click Plot to have values calculated and displayed on a graph.