The calculation method is: first find the average value S of data, and then divide the sum of squares of the difference between each data and the average value by the number of data to get the variance.
Variance S=[(x 1-s) square +(x2-s) square +(x3-s) square +...]/n
N is the number of data.
? This function is called the cumulative introduction distribution function of x, or distribution function for short.