Use Formulas for Numerical Parameters

Formulas allow you to create parameters that depend on other parameters for their values.

A simple example would be a width parameter set to equal twice the height of an object. In practice, formulas can be used in many ways, both simple and sophisticated. Typical uses include embedding design relationships, relating a number of instances to a variable length, and setting up angular relationships. For example, formulas can be used to

• Calculate area or volume of geometry
• Create a clearance dimension parameter controlled by element size
• Convert continuously variable values into integer values
• Add shelves as the height of casework increases
• Add diagonals in an open web joist as the length increases

Note: When a formula is used to calculate the value of a parameter and contains only one variable, the value of the parameter can be changed in two ways:

• indirectly, by changing the value of the variable used in the formula.
• directly, and the value of the variable is derived from the formula calculation for the parameter.

If a formula contains 2 or more variables, then the parameter value is grayed out and cannot be changed directly. The value of the parameter must be derived by changing the input variables of the formula.

To see how formulas are used to control family geometry see: Formula Examples