code: public Predictor frequency(double... frel)
      {
          frequencies = frel;
          CommandLine<Double> line = new CommandLine<>(FREQUENCY, 5);
          for (double f : frel)
          {
              line.add(f);
          }
          input.add(line);
          return this;
      }
docs: The FREQUENCY complement command line contains up to 11 user-defined
  frequencies that are used in the calculation.
  
  @param frel FREL is the array of up to 11 user-defined frequencies in
  megahertz.
  @return