private void transformDouble(Row row) throws IOException {
    double v = row.getDouble(0);
    if (Double.isFinite(v)) {
      doubleMin = Math.min(doubleMin, v);
      doubleMax = Math.max(doubleMax, v);
    }
  }
This function is used to calculate the spread of time series, that is, the maximum value minus
the minimum value.
library-udf/src/main/java/org/apache/iotdb/library/dprofile/UDAFSpread.java