Question

我已经初始化了1d和2d数组，现在我基本上只是希望能够对它们执行矩阵乘法。但是，我没有得到正确的答案。我想我已经混淆了for循环，我试图确保我只是乘以正确的值，但不能完全掌握它。

编辑：我已修复它，我误解了2D数组的长度方法返回的内容（认为它返回了列而不是行）。以下代码是我更正的代码。谢谢大家。

public static double[] getOutputArray(double[] array1D, double[][] array2D) {
    int oneDLength = array1D.length;
    int twoDLength = array2D[0].length;
    double[] newArray = new double[array2D[0].length]; // create the array that will contain the result of the array multiplication  
    for (int i = 0; i < twoDLength; i++) { // use nested loops to multiply the two arrays together
        double c = 0;
        for (int j = 0; j < oneDLength; j++) {
            double l = array1D[j];
            double m = array2D[j][i];
            c += l * m; // sum the products of each set of elements
        }
        newArray[i] = c;
    }
    return newArray; // pass newArray to the main method
} // end of getOutputArray method

Answer 1

存在一些问题，首先，你应该决定向量的表示方式，你是左右相乘。

对于数学：向量1xn次矩阵nxm将产生1xm，而矩阵mxn次nx1将产生mx1。

我认为以下内容适合您：

public static double[] getOutputArray(double[] array1D, double[][] array2D) {
  int oneDLength = array1D.length;
  int twoDLength = array2D.length;
  double[] newArray = new double[twoDLength]; // create the array that will contain the result of the array multiplication
  assert twoDLength >0 && array2D[0].length == oneDLength;
  for (int i = 0; i < twoDLength; i++) { // use nested loops to multiply the two arrays together
      double c = 0;
      for (int j = 0; j < oneDLength; j++) {
          double l = array1D[j];
          double m = array2D[i][j];
          c += l * m; // sum the products of each set of elements
      }
      newArray[i] = c;
   }
   return newArray; // pass newArray to the main method
} // end of getOutputArray method

我希望在尝试修复时我没有犯错。

将2d数组乘以1d数组

1 个答案: