Hi Dawid,
In MATLAB R2022b, the 'tunefis' function does not provide a direct option to save or store the validation error in function of the iteration during the training process. However, you can implement a custom solution to achieve this. You can define a custom callback function that is executed at each iteration during the 'tunefis' training process. Inside the callback function, you can calculate the validation error using the current FIS model and store it in some array. This array will contain the validation error at each iteration.
Hope it helps!
