content: /*
   * Tencent is pleased to support the open source community by making Angel available.
   *
   * Copyright (C) 2017-2018 THL A29 Limited, a Tencent company. All rights reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in 
   * compliance with the License. You may obtain a copy of the License at
   *
   * https://opensource.org/licenses/Apache-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License
   * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
   * or implied. See the License for the specific language governing permissions and limitations under
   * the License.
   *
   */
  
  
  package com.tencent.angel.ml.GBDT.objective;
  
  /**
   * Description: interface of loss
   */
  public interface LossHelper {
  
    float transPred(float x);
  
    boolean checkLabel(float x);
  
    float firOrderGrad(float pred, float label);
  
    float secOrderGrad(float pred, float label);
  
    float prob2Margin(float baseScore);
  
    String labelErrorMsg();
  
    String defaultEvalMetric();
  
  }