H represents the current historical turnover rate, H' represents the historical turnover rate of the previous day, H'' represents the historical turnover rate of the previous two days, and α represents the attenuation coefficient, usually between 0.5 and 0.9. Use the formula of historical turnover rate attenuation coefficient to adjust the value of historical turnover rate, so as to reduce the influence of past data on current data and better reflect the current market situation.