如何将2维数组相乘？矩阵乘法

Question

所以我有一个代码,将打印一个二维数组的表.我遇到的问题是我完全不知道如何繁殖并找到数组的乘积.任何帮助表示赞赏.谢谢

public class MultiplyingArrays {

    public static void main(String[] args) {
        int firstarray[][] = {{1, 2, -2, 0}, {-3, 4, 7, 2}, {6, 0, 3, 1}};
        int secondarray[][] = {{-1, 3}, {0, 9}, {1, -11}, {4, -5}};

        System.out.println("This is the first array");
        display(firstarray);

        System.out.println("This is the second array");
        display(secondarray);
    }

    public static void display(int x[][]) {
        for (int row = 0; row < x.length; row++) {
            for (int column = 0; column < x[row].length; column++) {
                System.out.print(x[row][column] + "\t");
            }
            System.out.println();
        }
    }
}

期望的结果是:

 -3   43
 18   60
  1  -20

Answer 1

int firstarray[][] = {{1, 2, -2, 0}, {-3, 4, 7, 2}, {6, 0, 3, 1}};
int secondarray[][] = {{-1, 3}, {0, 9}, {1, -11}, {4, -5}};

/* Create another 2d array to store the result using the original arrays' lengths on row and column respectively. */
int [][] result = new int[firstarray.length][secondarray[0].length];

/* Loop through each and get product, then sum up and store the value */
for (int i = 0; i < firstarray.length; i++) { 
    for (int j = 0; j < secondarray[0].length; j++) { 
        for (int k = 0; k < firstarray[0].length; k++) { 
            result[i][j] += firstarray[i][k] * secondarray[k][j];
        }
    }
}
/* Show the result */
display(result);

PS使用适当的命名约定.