I wrote to the corresponding author of Interval Type2 Fuzzy Logic Toolbox (IT2FLS), Engineering Letters volume 15 issue 1; unfortunately I received no reply.
However, there is another toolbox called MFLS described in Toolbox for Interval Type-2 Fuzzy Logic Systems. I was able to reach the corresponding author, who cleared the code for public use. Visit his page and go down to almost the bottom, to item 15, and click on the link there that says "[Software]" in order to obtain the toolbox. I am advised that the code was written for SciLab originally and so might need some tuning to work with MATLAB.
