我想用一个2D数组找到方差和标准差，我做了这个程序，但是输出的comming是不正确的

Question

我想用一个2D数组找到方差和标准差，我做了程序，但输出是不正确的。请帮助我，我应该做什么/修改它，以获得请求输出。

输入

3 4

1 0 1 1 1 1 1 1 1 1 1

解决方案输出

0.07513148009038192

0.27410122234383033

预期产出

0.0764

0.2764

我的程序：

import java.util.*;
import java.text.DecimalFormat;

public class Source {
   public static void main(String[] args) {
       Scanner s = new Scanner(System.in);
       int n = s.nextInt();
       int m = s.nextInt();
       int[][] arr = new int[n][m];
       for (int i = 0; i < n; i++)
           for (int j = 0; j < m; j++)
               arr[i][j] = s.nextInt();
       varianceAndStandardDeviation(arr, n, m);
   }

   // Method for calculating variance
   static void varianceAndStandardDeviation(int arr[][], int n, int m) {
       // Write your code here
       double[][] diff = new double[n][m];
       double avg = 0f;
       double var = 0f;
       double std_dev = 0f;
       for (int i = 0; i < n; i++)
           for (int j = 0; j < m; j++)
           {
               avg = (avg + arr[i][j]);
               avg = avg/(nm);
               diff[i][j] = (avg - arr[i][j]);
               var = ((diff[i][j] * diff[i][j])/((n*m)-1));
               std_dev = Math.pow(var, 0.5);
           }
           System.out.println(var);
           System.out.println(std_dev);
   }
}

Answer 1

https://www.geeksforgeeks.org/variane-standard-deviation-matrix/在这里您有完整的教程。