too young 啊

l_stuCov.Omnivarance = pow(float(l_fEiVal1*l_fEiVal2*l_fEiVal3),float(1.0)/float(3.0));

1/3 = 0 !!!!!

这个代码 pow 类型的重载 以及类型转换

l_fEiVal1 = l_fEiVal1/l_stuCov.Sum; 
l_fEiVal2 = l_fEiVal2/l_stuCov.Sum;
l_fEiVal3 = l_fEiVal3/l_stuCov.Sum;