Mechanism Design and Mechanism Dynamics > Mechanism Design > Creating Mechanism Models > Measures, Graphs, and Evaluation Methods > Measures > Other Measures > About User-Defined Measures
About User-Defined Measures
You can create a customized measure by defining an expression including parameters, constants, and existing standard or user-defined measures. Create a user-defined measure to measure values that cannot be easily calculated using standard measures. Select the operators and functions you need to define your expression from the library of arithmetical operators and mathematical functions.
The expression may not be longer than 1023 characters.
The expression can be a function of one or more variables including time and measures, but you cannot include an analysis feature in a user-defined measure expression.
For example, to calculate the area of a circle whose diameter is defined by the separation between two points on your model:
1. Create the distance separation measure, sep_point.
2. Define an expression for the user-defined measure, for example pi*(0.5*sep_point)^2.
This expression uses the multiplication operator, *, the exponentiation operator, ^, and the constant pi, as well as the separation measure that you defined.