FL Set Membership Function (Fuzzy System) VI
- Updated2025-07-30
- 4 minute(s) read
Modifies the shape, color, or points of a membership function for a linguistic variable. You can modify a membership function from a fuzzy system or from an array of membership functions. The data type you wire to the fuzzy system in input determines the polymorphic instance to use.

Inputs/Outputs
membership function index
—
membership function index specifies the index of the membership function you want to modify. membership function index corresponds to the order in which the membership function was created.
variable index
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variable index specifies the index of the linguistic variable you want to modify. variable index corresponds to the order in which the linguistic variable was created.
input/output
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input/output specifies whether the linguistic variable corresponding to variable index is an input or output variable.
fuzzy system in
—
fuzzy system in specifies the complete information for a fuzzy system. Wire the fuzzy system out output from another VI to the fuzzy system in input of this VI.
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.
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.
error in (no error)
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error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
color
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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.
user-defined shape index
—
user-defined shape index specifies the index of the user-defined shape that determines the degrees of membership for the linguistic variable. This parameter is applicable only if you set shape to User-Defined. Define the user-defined shapes in the user-defined membership function shapes array in both the FL New Fuzzy System VI and the User-Defined instance of the FL Create Membership Function VI.
fuzzy system out
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fuzzy system out returns the complete information for a fuzzy system. Wire the fuzzy system out output of this VI to the fuzzy system in input of another VI.
error out
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error out contains error information. This output provides standard error out functionality. |
membership function index
—
input/output
—
fuzzy system in
—
name
—
points
—
error in (no error)
—
color
—
fuzzy system out
—
error out
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