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Asked by Somesh Singh
on 30 Aug 2011

I am working in the Fuzzy Interface System. I have fuzzified the inputs and outputs and I have also framed fuzzy rules. I wish to know how defuzzification can be done in the Fuzzy logic Toolbox....

thanks...

Answer by Lucas García
on 30 Aug 2011

If you are using the Fuzzy Inference System editor, you can choose in the main GUI one of the defuzzication methods. The input for the defuzzification process is a fuzzy set. Actually, its the aggregate output fuzzy set which must be defuzzified in order to resolve a single value from the set.

The Fuzzy Logic Toolbox includes 5 defuzzification methods, from which the `centroid` calculation (which returns the center of area under the curve) is the most popular. The other methods are `bisector`, `mom` (mean value of maximum -the average of the maximum value of the output set-), `som` (smallest of maximum) and `lom` (largest of maximum).

I recommend you take a look at the following videos to see how the complete process is made:

Getting Started with Fuzzy Logic Toolbox (Part 1)

Getting Started with Fuzzy Logic Toolbox (Part 2)

Getting Started with Fuzzy Logic Toolbox (Part 3)

This demo shows the differences between defuzzification methods.

If you want to do defuzzification without using the FIS interface, you can use the defuzz function.

Somesh Singh
on 31 Aug 2011

I tried it out but how do I view the output, ie, the defuzzified values....what I am able to see presently is a surface corresponding to the defuzzified values...pl clarify further

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