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Fuzzy Inference System Modeling

Build fuzzy inference systems and fuzzy trees

Fuzzy inference is the process of formulating input/output mappings using fuzzy logic. Fuzzy Logic Toolbox™ software provides tools for creating:

  • Type-1 or interval type-2 Mamdani fuzzy inference systems

  • Type-1 or interval type-2 Sugeno fuzzy inference systems

  • Trees of interconnected fuzzy inference systems

For more information on fuzzy logic, see What Is Fuzzy Logic? For more information on fuzzy inference, see Fuzzy Inference Process.


Fuzzy Logic DesignerDesign, test, and tune fuzzy inference systems


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Type-1 Systems

mamfisMamdani fuzzy inference system
sugfisSugeno fuzzy inference system
genfisGenerate fuzzy inference system object from data
genfisOptionsOption set for genfis function

Type-2 Systems

mamfistype2Interval type-2 Mamdani fuzzy inference system (Since R2019b)
sugfistype2Interval type-2 Sugeno fuzzy inference system (Since R2019b)

FIS Trees

fistreeNetwork of connected fuzzy inference systems

FIS Conversion

convertToSugenoConvert Mamdani fuzzy inference system into Sugeno fuzzy inference system
convertToType1Convert type-2 fuzzy inference system into type-1 fuzzy inference system (Since R2019b)
convertToType2Convert type-1 fuzzy inference system into type-2 fuzzy inference system (Since R2019b)
convertToStructConvert fuzzy inference system object into a structure
convertfisConvert previous versions of fuzzy inference data in current format
addInputAdd input variable to fuzzy inference system
addOutputAdd output variable to fuzzy inference system
removeInputRemove input variable from fuzzy inference system
removeOutputRemove output variable from fuzzy inference system
fisvarFuzzy variable
addMFAdd membership function to fuzzy variable
removeMFRemove membership function from fuzzy variable
fismfFuzzy membership function
fismftype2Interval type-2 fuzzy membership function (Since R2019b)
addRuleAdd rule to fuzzy inference system
showruleDisplay fuzzy inference system rules
fisruleFuzzy rule
updateUpdate fuzzy rule using fuzzy inference system
evalfisEvaluate fuzzy inference system
evalfisOptionsOption set for evalfis function
plotfisDisplay fuzzy inference system
plotmfPlot membership functions for input or output variable
gensurfGenerate fuzzy inference system output surface
gensurfOptionsOption set for gensurf function
readfisLoad fuzzy inference system from file
writeFISSave fuzzy inference system to file
evalmfEvaluate fuzzy membership function
gaussmfGaussian membership function
gbellmfGeneralized bell-shaped membership function
trimfTriangular membership function
dsigmfDifference between two sigmoidal membership functions
gauss2mfGaussian combination membership function
linsmfLinear s-shaped saturation membership function (Since R2022a)
linzmfLinear z-shaped saturation membership function (Since R2022a)
pimfPi-shaped membership function
psigmfProduct of two sigmoidal membership functions
sigmfSigmoidal membership function
smfS-shaped membership function
trapmfTrapezoidal membership function
zmfZ-shaped membership function
defuzzDefuzzify membership function
proborProbabilistic OR
fuzarithPerform fuzzy arithmetic


Fuzzy Logic Basics

  • What Is Fuzzy Logic?
    Fuzzy logic uses linguistic variables, defined as fuzzy sets, to approximate human reasoning.
  • Foundations of Fuzzy Logic
    A fuzzy logic system is a collection of fuzzy if-then rules that perform logical operations on fuzzy sets.
  • Fuzzy Inference Process
    Fuzzy inference maps an input space to an output space using a series of fuzzy if-then rules.

Fuzzy Inference Systems

  • Mamdani and Sugeno Fuzzy Inference Systems
    You can implement either Mamdani or Sugeno fuzzy inference systems using Fuzzy Logic Toolbox software.
  • Type-2 Fuzzy Inference Systems
    You can create and evaluate interval type-2 fuzzy inference systems with additional membership function uncertainty. (Since R2019b)
  • FIS Trees
    You can implement a complex fuzzy system as a collection of smaller interconnected fuzzy inference systems.

Build Fuzzy Inference Systems