public int encodeDouble(PositionedByteRange dst, double val) {
    return OrderedBytes.encodeFloat64(dst, val, order);
  }
Write instance {@code val} into buffer {@code dst}.
@param dst the {@link PositionedByteRange} to write to
@param val the value to write to {@code dst}
@return the number of bytes written
hbase-common/src/main/java/org/apache/hadoop/hbase/types/OrderedFloat64.java