docs: public static double[][] getImaginary(ComplexNumber[][] cn) {
          double[][] n = new double[cn.length][cn[0].length];
          for (int i = 0; i < n.length; i++) {
              for (int j = 0; j < n[0].length; j++) {
                  n[i][j] = cn[i][j].imaginary;
              }
          }
          return n;
      }