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.math2.ufuncs.expression;
  
  public class SigmoidWithDropout extends Unary {
  
    private double threshold = Math.log(Double.MAX_VALUE);
    private double proba;
  
    public SigmoidWithDropout(boolean inplace, double proba) {
      assert (proba >= 0 && proba <= 1);
      this.proba = proba;
      setInplace(inplace);
    }
  
    @Override
    public boolean isOrigin() {
      return false;
    }
  
    @Override
    public double apply(double elem) {
      if (proba == 1) {
        return 0;
      } else if (Math.random() < 1 - proba) {
        if (elem > threshold) {
          return 1 / (1 - proba);
        } else if (elem < -threshold) {
          return -1 / (1 - proba);
        } else {
          return (1.0 / (1.0 + Math.exp(-elem))) / (1 - proba);
        }
      } else {
        return 0;
      }
    }
  
    @Override
    public float apply(float elem) {
      if (proba == 1) {
        return 0;
      } else if (Math.random() < 1 - proba) {
        if (elem > threshold) {
          return (float) (1 / (1 - proba));
        } else if (elem < -threshold) {
          return (float) (-1 / (1 - proba));
        } else {
          return (float) ((1.0 / (1.0 + Math.exp(-elem))) / (1 - proba));
        }
      } else {
        return 0;
      }
    }
  
    @Override
    public long apply(long elem) {
      if (proba == 1) {
        return 0;
      } else if (Math.random() < 1 - proba) {
        if (elem > threshold) {
          return (long) (1 / (1 - proba));
        } else if (elem < -threshold) {
          return (long) (-1 / (1 - proba));
        } else {
          return (long) ((1.0 / (1.0 + Math.exp(-elem))) / (1 - proba));
        }
      } else {
        return 0;
      }
    }
  
    @Override
    public int apply(int elem) {
      if (proba == 1) {
        return 0;
      } else if (Math.random() < 1 - proba) {
        if (elem > threshold) {
          return (int) (1 / (1 - proba));
        } else if (elem < -threshold) {
          return (int) (-1 / (1 - proba));
        } else {
          return (int) ((1.0 / (1.0 + Math.exp(-elem))) / (1 - proba));
        }
      } else {
        return 0;
      }
    }
  }