Question

我尝试使用双数组进行矩阵乘法，但是数组＆＃39;使用+或* =等运算符既不能添加也不能乘以值。我做错了什么？

import java.util.Arrays;

public class MatrixMultiplication {

    public static void main(String[] args) {

        //Initializing all required arrays
        double[][] matrix1 = new double[][] { { 3.0, 2.0, 1.0 },
                { 1.0, 0.0, 2.0 } };
        double[][] matrix2 = new double[][] { { 1.0, 2.0 },
                { 0.0, 1.0 },
                { 4.0, 0.0 }};

        double[][] intermediate = new double[][] { { 0.0, 0.0, 0.0 },
                { 0.0, 0.0, 0.0 },
                {0.0, 0.0, 0.0}};
        double[][] result = new double[][] { { 0.0, 0.0 },
                { 0.0, 0.0 }};

        //check arrays' lengths and heights
        if ( matrix1.length == matrix2[0].length) {

            //multiply first line and first column
            for (int i = 0; i == matrix1.length; i++) {
                intermediate[i] = matrix1[i] * matrix2[0][i];
                result[0] += intermediate[i];
            }

            //multiply first line and second column
            for (int i = 0; i == matrix1.length; i++) {
                intermediate[i] = matrix1[i] * matrix2[1][i];
                result[1] += intermediate[i];
            }

            //multiply second line and first column
            for (int i = 0; i == matrix1.length; i++) {
                intermediate[i] = matrix1[i][1] * matrix2[0][i];
                result[0][1] += intermediate[i];
            }

            //multiply second line and second column
            for (int i = 0; i == matrix1.length; i++) {
                intermediate[i] = matrix1[i][1] * matrix2[1][i];
                result[1][1] += intermediate[i];
            }

            System.out.println(Arrays.deepToString(result).replace("], ", "]\n"));

    } else {

        System.out.println("Matrices can not be multiplied"); }

    }
}

Answer 1

问题在于：

   //multiply first line and first column
    for (int i = 0; i == matrix1.length; i++) {
        intermediate[i] = matrix1[i] * matrix2[0][i];
        result[0] += intermediate[i];
    }

您需要指定一个进行数组乘法的方法。您不能直接将数组的列与标量相乘。您可以手动模仿乘法（将每个元素相乘并添加它们，然后将其放入正确的索引中）。

矩阵乘法 - java中的双数组计算

1 个答案: