@Override
  public void transform(Row row, PointCollector collector) throws Exception {
    double v = Util.getValueAsDouble(row);
    if (Double.isFinite(v)) {
      value.add(v);
    } else {
      value.add(0d);
    }
    timestamp.add(row.getTime());
  }
This function solves Yule-Walker equation to calculate partial auto-correlation factor.
library-udf/src/main/java/org/apache/iotdb/library/dprofile/UDTFPACF.java