hurst parameter: 給入一序列的資類，程式會畫出husrt 參數的figure和估計值 例 hurst_expo(sin(0:0.01:5*pi)) -hurst parameter: the sequence into a category of funding, the program will draw the figure and husrt parameter estimates were hurst_expo (sin (0:0.01:5* pi))

RATS 时间序列GARCH,EGARCH,IGARCH,GARCH-M模型-time series GARCH model