“…According to the formula (27), the performance of the proposed approach on the mapping relationship between the input data x i and the output data y needs to be verified where the value range of the independent variable x i (i = 1, 2, 3, 4) is [0.17, 0.88], [2,4], [1,7], and [0, 2]. According to the range of x i , the range of y can be calculated as in References [3,35]. Randomly selecting 100 groups of data for the x i and the corresponding output y as the sample data set U = {x 1 , x 2 , x 3 , x 4 , y}.…”