java - 矩阵列和java

Question

我最近才开始使用 Java。我仍然在 Java 方面遇到一些困难。任务是分别对列和行求和，示例如下所示。我设法获得了列的总和，但最终总是在我想要的输出中重复第一行，如何删除该错误。只需要所需的列总和即可。

它如何分别计算行的总和？

非常感谢您提前提供的帮助

代码如下所示:

public class MatrixColumnSums {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

    double [][] a = new double [2][3]; 
    a[0][0] = 1; 
    a[0][1] = 2; 
    a[0][2] = 3; 
    a[1][0] = 4; 
    a[1][1] = 5; 
    a[1][2] = 6;

    System.out.println( "A");
    for (int i = 0; i < a.length; i++) {
        String str = "";
        for (int j = 0; j < a[i].length; j++) {
            str += a[i][j] + "\t"; 
        }
        System.out.println(str);
        }
    // column sums 
    // creating another matrix to store the sum of columns matrices
                double c[] = new double  [a[0].length]; 

                // Adding and printing addition of 2 matrices
                System.out.println("C");

                for (int i = 0; i < a.length; i++) {
                    for (int j = 0; j < a[0].length; j++)
                    {   
                        c[j] += a[i][j]; 

                        System.out.print(c[j] + "\t");

                    }
                    System.out.println(); 
               }

             }
          } 

输出如下所示:

A

1.0 2.0 3.0

4.0 5.0 6.0

C

1.0 2.0 3.0 ( <= I want to get this row deleted)

5.0 7.0 9.0 ( I just want to have this as my output)

Answer 1

**矩阵列总和**

doOneColumnSum 方法对一列求和。

 private static double doOneColumnSum(double[][] arr, int col){

    double total = 0;
    for (int row = 0; row < arr.length; row += 1){
      total += arr[row][col];
    }
    return total;
  }

doColumnSums 方法使用 doOneColumnSum 方法对所有列求和

public static double[] doColumnSums(double[][] arr)
  {
    int numColumns = arr[0].length;
    double[] result = new double[numColumns];
    for (int col = 0; col < numColumns; col += 1)
    {
      result[col] = findOneColumnSum(arr, col);
    }
    return result;
  }