功能: 计算神经网络SqrtNorm激活函数

格式: netFunBySqrtNorm(x)

x : 为矩阵变量或者数值

说明:
1. 函数执行成功返回和x同纬度的矩阵变量

2. 本函数主要计算的原理如下
SqrtNorm : 范围[-1, 1], 
$$
\mathbf{netFunBySqrtNorm}(x_i) = \dfrac{x_i}{\sqrt{\sum_{j=1}x_j}}
$$

例子:
x =
[-0.73290256607947   -1.95092696112158    0.21744714338213    2.19789781453921
 -4.72275318588258    1.99957438581603    2.94959032789319   -4.31942455462153
 -6.10488919615973   -1.19050327068684   -6.38943656901337    2.98098757280083
 -2.76742173278119   -4.81647247463300   -3.72662812435377   -4.00467786914887 ]
y = netFunBySqrtNorm(x)//回车得到如下结果
y =
[-0.05032860839759   -0.13397065801507    0.01493215146591    0.15093021027011
 -0.32431268036386    0.13731128922625    0.20254912919731   -0.29661599914352
 -0.41922431696184   -0.08175216690394   -0.43876425850621    0.20470518610973
 -0.19003956474760   -0.33074840811421   -0.25590851525786   -0.27500226300621 ]