public String toString(int radix)
public String toString()
  public String toString(int radix)  {    if (words == null)      return Integer.toString(ival, radix);    if (ival <= 2)      return Long.toString(longValue(), radix);    int buf_size = ival * (MPN.chars_per_word(radix) + 1);    StringBuffer buffer = new StringBuffer(buf_size);    format(radix, buffer);    return buffer.toString();  }