Click the Add Input Variable, Add Output Variable, Edit Input Variable, or Edit Output Variable button on the Variables page of the Fuzzy System Designer to display this dialog box.

Use this dialog box to modify the linguistic variables in a fuzzy system.

This dialog box includes the following components:

Option Description
Name

name specifies the name of the membership function, or linguistic term, you want to modify.
Range

range specifies the minimum and maximum values of the linguistic variable.

  • minimum—

    Specifies the minimum value of the linguistic variable.

  • maximum—

    Specifies the maximum value of the linguistic variable.
Membership functions

Specifies the linguistic terms for the linguistic variable and the degree of membership of the linguistic variable within those linguistic terms. Each element of the Membership functions array corresponds to a linguistic term.

  • Name—

    name specifies the name of the membership function, or linguistic term, you want to modify.

  • Shape—

    shape specifies the shape of the function that determines the degrees of membership for the linguistic variable.

    You can select the following functions:
    • Triangle—Specifies that a triangle function determines the degrees of membership for the linguistic variable.
    • Trapezoid—Specifies that a trapezoid function determines the degrees of membership for the linguistic variable.
    • Singleton—Specifies that a singleton function determines the degrees of membership for the linguistic variable. A singleton function has only one value. Therefore, no value of the linguistic variable has partial membership within the corresponding linguistic term.
    • Sigmoid—Specifies that a sigmoid function determines the degrees of membership for the linguistic variable.
    • Gaussian—Specifies that a Gaussian function determines the degrees of membership for the linguistic variable.
    • User-Defined—Specifies that a user-defined shape determines the degrees of membership for the linguistic variable. Use the Fuzzy Logic VIs to create or modify user-defined membership functions. Do not create or modify user-defined membership functions in the Edit Variable dialog box.
  • Color—

    color specifies the color of the membership function when you view the membership function in the Fuzzy System Designer. You can wire a color box constant to this input.

  • Points—

    points specifies the values of the linguistic variable corresponding to the base and top points, in order from left to right and base to top, of the membership function. The degree of membership of the linguistic variable within the linguistic term name is 0 at the base points and 1 at the top points. Specify one point for a singleton function, three points for a triangle function, and four points for trapezoid, sigmoid, Gaussian, or user-defined functions.
Add Membership Function

Creates a new membership function for the linguistic variable.
Delete Membership Function

Deletes the membership function currently visible in the Membership functions array.
Previous Membership Function

Displays the previous membership function in the Membership functions array.
Next Membership Function

Displays the next membership function in the Membership functions array.
Membership functions graph

Plots the membership functions for the linguistic variable.