code: public static void printResult(Number[][] m1, Number[][] m2, Number[][] m3, char op, PrintStream out)
      {
          for (int i = 0; i < m1.length; i++)
          {
              for (int j = 0; j < m1[0].length; j++)
              {
                  out.print(" " + m1[i][j]);
              }
  
              if (i == m1.length / 2)
              {
                  out.print("  " + op + "  ");
              }
              else
              {
                  out.print("     ");
              }
  
              for (int j = 0; j < m2.length; j++)
              {
                  out.print(" " + m2[i][j]);
              }
  
              if (i == m1.length / 2)
              {
                  out.print("  =  ");
              }
              else
              {
                  out.print("     ");
              }
  
              for (int j = 0; j < m3.length; j++)
              {
                  out.print(m3[i][j] + " ");
              }
  
              out.println();
          }
      }
docs: Print matrices, the operator, and their operation result.
  @param m1 array-array
  @param m2 array-array
  @param m3 array-array
  @param op operator
  @param out printstream