我的公式由于不能在这写出来，我放在附件里了，请大家帮忙解决一下，下面是我原来的代码；我原来的代码中忘了说明Wij是矩阵，所以出了点错，Xi、Xj分别是已知的值，X上面一缸的是X的平均数，n是个数，请大家帮帮，谢谢了

  private double summation()
        {
            double[] x = { 1, 2, 3 };
            double [,] w ={{1,2,3},{4,5,6},{7,8,9}};
            double wxx = 0, wij = 0, x1 = 0, x2 = 0;
            int n = 3, i, j;
            for (i=0; i<n; i++)
            {
                x1 += x[i];
            }
            for (i = 0; i < n; i++)
            {
                for (j = 0; j < n; j++)
                {
                    wxx += w[i, j] * (x[i] - x1) * (x[j] - x1);
                    wij += w[i, j];
                    x2 += Math.Pow((x[i] - x1), 2);
                }
            }
            return n/x2*wxx/wij;
        }
或者带参数：

        private double summation(double[]x,double[,]w,int n)
        {
            double wxx = 0, wij = 0, x1 = 0, x2 = 0;
            int i, j;
            for (i = 0; i < n; i++)
            {
                x1 += x[i];
            }
            for (i = 0; i < n; i++)
            {
                for (j = 0; j < n; j++)
                {
                    wxx += w[i, j] * (x[i] - x1) * (x[j] - x1);
                    wij += w[i, j];
                    x2 += Math.Pow((x[i] - x1), 2);
                }
            }
            return n / x2 * wxx / wij;
        }

#include<stdio.h>
#include<conio.h>
#include<math.h>
 
 
double summation(void)
        {
            double x[] = { 1, 2, 3 };
            double w[][3] ={{1,2,3},{4,5,6},{7,8,9}};
            double wxx = 0, wij = 0, x1 = 0, x2 = 0;
            int n = 3, i, j;
            for (i=0; i<n; i++)
            {
                x1 += x[i];
            }
            for (i = 0; i < n; i++)
            {
                for (j = 0; j < n; j++)
                {
                    wxx+= w[i][j]*(x[i]-x1)*(x[j]-x1);
                    wij+= w[i][j];
                    x2+=pow((x[i] - x1), 2);
                }
            }
            return n/x2*wxx/wij;
        }  
int main()
{  
    double a=summation();
    printf("%f",a);
    getch();
    return 0;
}

看看这个，你自创数组啊