code: public static Basic2DMatrix constant(int rows, int columns, double constant) {
          double[][] array = new double[rows][columns];
  
          for (int i = 0; i < rows; i++) {
              Arrays.fill(array[i], constant);
          }
  
          return new Basic2DMatrix(array);
      }
docs: Creates a constant {@link Basic2DMatrix} of the given shape and {@code value}.