@Override
  public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations)
      throws Exception {
    value.clear();
    timestamp.clear();
    min = 0.0d;
    max = 0.0d;
    flag = true;
    configurations.setAccessStrategy(new RowByRowAccessStrategy()).setOutputDataType(Type.DOUBLE);
    compute = parameters.getStringOrDefault("compute", BATCH_COMPUTE);
    if (compute.equalsIgnoreCase(STREAM_COMPUTE)) {
      min = parameters.getDouble("min");
      max = parameters.getDouble("max");
    }
  }
This function is used to standardize the input series with min-max.
library-udf/src/main/java/org/apache/iotdb/library/dprofile/UDTFMinMax.java