From the main menu bar, select .
In the Create Constraint dialog box that appears, do the following:
 Name the constraint. For more information about naming objects, see Using basic dialog box components.
 From the Type list, select Equation, and then click Continue.
The constraint editor appears.
In the table in the editor, enter a row of data for each term in the equation. The equation must have at least two terms. Click for a description of the relationship between the data in the table and the desired equation.
Each row should contain the following information:

The coefficient.

The name of an existing set. (For information on creating sets, see The Set and Surface toolsets.”) You can enter a set that contains one or more points in the first row of the table. Subsequent sets must contain only a single point.

The degree of freedom.

The ID of the coordinate system in which you will apply the constraint. You can either accept the default coordinate system or select an existing datum coordinate system. If the desired datum coordinate system does not exist, you can create it using the Datum toolset. (For more information, see Creating datum coordinate systems.)
To determine the ID of a coordinate system, select from the main menu bar. For more information, see Obtaining general information about the model.
Click OK to save your equation definition and to close the constraint editor.
