@Override
  public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations)
      throws Exception {
    configurations.setAccessStrategy(new RowByRowAccessStrategy()).setOutputDataType(Type.DOUBLE);
    this.wpass = parameters.getDouble(WPASS_PARAM);
  }
This function filters high frequency components.
library-udf/src/main/java/org/apache/iotdb/library/frequency/UDTFHighPass.java