private void transformFloat(Row row) throws IOException {
    float v = row.getFloat(0);
    if (Float.isFinite(v)) {
      floatMin = Math.min(floatMin, v);
      floatMax = Math.max(floatMax, 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