code: @Override
    public Double sqrt2(Double arg1) {
      if (arg1 == null) {
        return Double.NaN;
      } else {
        return Math.sqrt(arg1);
      }
    }
docs: /*
  (non-Javadoc)
  
  @see
  mtas.codec.util.DataCollector.MtasDataOperations#sqrt2(java.lang.Number)