Sigmoid

public static double MysigMoid(double value) {
        //Math.E=e;Math.Pow(a,b)=a^b
        double ey = Math.pow(Math.E, -value);
        double result = 1 / (1 + ey);
        return result;
    }

sigmoid求导：

public static double MysigMoidDerivative(double value) {
        double A = MysigMoid(value);
        double B = 1-MysigMoid(value);      
        double result = A*B;
        return result;
    }