public double getDouble(int elementNum) {
    scratchTimestamp.setTime(time[elementNum]);
    scratchTimestamp.setNanos(nanos[elementNum]);
    return getDouble(scratchTimestamp);
  }
Return a double representation of a Timestamp.
@param elementNum
@return
storage-api/src/java/org/apache/hadoop/hive/ql/exec/vector/TimestampColumnVector.java