text: //
  //  LogTransform.cpp
  //  MNNConverter
  //
  //  Created by MNN on 2019/12/12.
  //  Copyright © 2018, Alibaba Group Holding Limited
  //
  
  #include <cmath>
  #include "CaffeExtraManager.hpp"
  #include "MNN_generated.h"
  
  namespace MNN {
  namespace Express {
  
  class LogTransform : public CaffeExtraManager::Transform {
  public:
      virtual EXPRP onExecute(EXPRP expr) const override {
          auto op     = expr->get();
          auto inputs = expr->inputs();
          auto base   = op->main_as_Extra()->attr()->GetAs<Attribute>(0)->f();
          auto scale  = op->main_as_Extra()->attr()->GetAs<Attribute>(1)->f();
          auto shift  = op->main_as_Extra()->attr()->GetAs<Attribute>(2)->f();
  
          auto exponent = _Add(_Multiply(inputs[0], _Const(scale)), _Const(shift));
          if (fabs(base - (-1)) < 1e-6) { // base == -1, which means natural base
              return exponent->expr().first;
          }
          auto newVar = _Divide(_Log(exponent), _Log(_Const(base)));
          return newVar->expr().first;
      }
  };
  
  static auto gRegister = []() {
      CaffeExtraManager::get()->insert("Log", std::shared_ptr<CaffeExtraManager::Transform>(new LogTransform));
      return true;
  }();
  
  } // namespace Express
  } // namespace MNN
  