First of all the construction of real data and representative of the system studied, then comes the stage of application of the notions of fuzzy logic and in this context it is recommended to test different fuzzy functions knowing that the triangular shape is the most used in the practice. Finally a work of completion makes it possible to obtain effective results would be necessary.
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The desired performance of designed system, in addition to your old experiences, as you may change the membership functions easily after you finish the design and start the testing phase. One of the most positve features of Fuzzy-based systems is their flexibility.