A fuzzy number is an extension of a regular number in the sense that it does not refer to a single value but to a set of possible values, which vary with a weight between 0 and 1, called member function. A diffuse number is thus a special case of a convex fuzzy set, just as fuzzy logic is an extension of Boolean logic (which only uses values 0 and 1, exclusively), fuzzy numbers are an extension of real numbers. The calculations with fuzzy numbers allow the incorporation of uncertainty in parameters, properties, geometry, initial conditions, etc.
Fuzzy logic tutorial (in English)
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