code: public double getDouble(int index)
    {
      Object value = _values[index - 1];
  
      if (value instanceof Double) {
        return (Double) value;
      }
      else if (value instanceof Float) {
        return (Float) value;
      }
      else if (value instanceof Number) {
        return (Double) ((Number) value);
      }
      else {
        return Double.valueOf(value.toString());
      }
    }
docs: Returns the column as a double.
  
  @param index 1-based
  @return column as a double