Question

程序应将2个矩阵4x1和1x4相乘，并将结果输出到控制台（矩阵4X4）。但是什么也没显示。有什么问题吗？

public class Matrix {

public static void main(String[] args) {

    int[][] matrixA = new int [4][1];
    int[][] matrixB = new int [1][4];
    int[][] matrixC = new int [4][4];

    matrixA[0][0] = 1;
    matrixA[1][0] = 2;
    matrixA[2][0] = 3;
    matrixA[3][0] = 4;

    matrixB[0][0] = 4;
    matrixB[0][1] = 3;
    matrixB[0][2] = 2;
    matrixB[0][3] = 1;


    for (int i = 0; i < 4; i++) { // A rows
        for (int j = 0; j < 4; j++) { // B columns
            for (int k = 0; k < 1; k++) { // A columns
                matrixC[i][j] += matrixA[i][k] * matrixB[k][j];
                    System.out.print(matrixC[i][j]+ "   ");
            }
        }
    } 
    int j = 0;
    for (int i = 0; i < 4; i++) {
        for (int k = 0; k < 1; k++) 
        System.out.print(matrixC[i][j]+ "   ");
        System.out.println();   
    }

} //end main

} //结束课程

Answer 1

您在第二组j循环之前引入了变量for。另外，即使它们是可选的，我也强烈建议始终包含大括号。还有k < 4。喜欢，

for (int i = 0; i < 4; i++) {
    for (int k = 0; k < 4; k++) {
        System.out.print(matrixC[i][k] + "   "); // not [i][j]
    }
    System.out.println();
}

或就像

一样使用Arrays.deepToString(Object[])

System.out.println(Arrays.deepToString(matrixC));

Answer 2

我解决了这个问题！现在显示4x4。感谢您的帮助！

public class Matrix {

public static void main(String[] args) {

    int[][] matrixA = new int [4][1];
    int[][] matrixB = new int [1][4];
    int[][] matrixC = new int [4][4];

    matrixA[0][0] = 1;
    matrixA[1][0] = 2;
    matrixA[2][0] = 3;
    matrixA[3][0] = 4;

    matrixB[0][0] = 4;
    matrixB[0][1] = 3;
    matrixB[0][2] = 2;
    matrixB[0][3] = 1;


    for (int i = 0; i < 4; i++) { // A rows
        for (int j = 0; j < 4; j++) { // B columns
            for (int k = 0; k < 1; k++) { // A columns
                matrixC[i][j] += matrixA[i][k] * matrixB[k][j];
                    System.out.print(matrixC[i][j]+ "   ");
                    //System.out.println();
            }
        }
        System.out.println();
    } 

} //end main
} //end class

Answer 3

希望这会有所帮助：

public class Matrix {
    public static void main(String[] args) {
        int[][] matrixA = {{1}, {2}, {3}, {4}};
        int[][] matrixB = {{4, 3, 2, 1}};

        int[][] matrixC = new int[4][4];

        for (int i = 0; i < 4; i++) { // A rows
            for (int j = 0; j < 4; j++) { // B columns
                for (int k = 0; k < 1; k++) { // A columns
                    matrixC[i][j] += matrixA[i][k] * matrixB[k][j];
                    System.out.print(matrixC[i][j] + "   ");
                }
            }
            System.out.println();
        }
    }
}

输出：

4   3   2   1   
8   6   4   2   
12   9   6   3   
16   12   8   4

将2个矩阵4x1和1x4相乘

3 个答案: