@Override
  public void transform(Row row, PointCollector collector) throws Exception {
    double value = Util.getValueAsDouble(row);
    if (Double.isFinite(value)) {
      this.count++;
      this.sumX1 += value;
      this.sumX2 += value * value;
      this.sumX3 += value * value * value;
    }
  }
This function calculates skew of input series.
library-udf/src/main/java/org/apache/iotdb/library/dprofile/UDAFSkew.java