30个现货收益率数据如下,根据EWMA公式,算出现货收益率标准差预测值,求大神帮写个代码,谢谢
0.029330 |
-0.004328 |
-0.002004 |
0.007660 |
0.018409 |
-0.003263 |
0.008137 |
0.009998 |
0.020331 |
0.015601 |
-0.067225 |
0.021295 |
0.015120 |
-0.011561 |
-0.000646 |
-0.000323 |
0.015718 |
0.008872 |
0.005035 |
-0.009461 |
0.008519 |
-0.007252 |
0.003160 |
-0.025884 |
0.004844 |
0.003538 |
-0.027007 |
-0.024709 |
-0.012245 |
0.017976 |