说明：  自适应中的牛顿法。结论，当u靠近0.5时，wk 迅速增加到最佳权， 当u小于0.5时，wk 沿着一个方向单向靠近最佳权；u大于0.5时wk沿着起始点指向最佳权的方向左右振荡并向最佳权收敛 ！
(The Newton method adaptive. Conclusion, when u close to 0.5, wk quickly right to the best, when u is less than 0.5, wk along the a direction close to the best the right way u greater than 0.5 wk point along the starting point about the best direction for the right to the right of oscillation and convergence of the best!)