for (double value : dataset) {
      if (Double.isNaN(value)) {
        return true;
      }
    }
    return false;
  }

  /**
   * Returns a value a fraction {@code (remainder / scale)} of the way between {@code lower} and
   * {@code upper}. Assumes that {@code lower <= upper}. Correctly handles infinities (but not
   * {@code NaN}).
   */