activations.h

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/***************************************************************************/
#ifndef AURESERVOIR_ACTIVATIONS_H__
#define AURESERVOIR_ACTIVATIONS_H__

#include "utilities.h"
#include <math.h>

namespace aureservoir
{

enum ActivationFunction
{
  ACT_LINEAR,      
  ACT_TANH,        
  ACT_TANH2,       
  ACT_SIGMOID      
};




template <typename T>
inline void act_linear(T *data, int size)
{ }

template <typename T>
inline void act_invlinear(T *data, int size)
{ }





template <typename T>
inline void act_tanh(T *data, int size)
{
  for(int i=0; i<size; ++i)
    data[i] = tanh( data[i] );
}

template <typename T>
inline void act_invtanh(T *data, int size)
{
  for(int i=0; i<size; ++i)
    data[i] = atanh( data[i] );
}




DEVector<double>::Type tanh2_a_;
DEVector<double>::Type tanh2_b_;

template <typename T>
inline void act_tanh2(T *data, int size)
{
  assert( tanh2_a_.length() == size );
  assert( tanh2_b_.length() == size );

  for(int i=0; i<size; ++i)
    data[i] = tanh( data[i]*tanh2_a_(i+1) + tanh2_b_(i+1) );
}

template <typename T>
inline void act_invtanh2(T *data, int size)
{
  assert( tanh2_a_.length() == size );
  assert( tanh2_b_.length() == size );

  for(int i=0; i<size; ++i)
    data[i] = ( atanh(data[i]) - tanh2_b_(i+1) ) / tanh2_a_(i+1);
}




template <typename T>
inline void act_sigmoid(T *data, int size)
{
  for(int i=0; i<size; ++i)
    data[i] = 1.0 / (1.0 + exp(data[i]) );
}

template <typename T>
inline void act_invsigmoid(T *data, int size)
{
  for(int i=0; i<size; ++i)
    data[i] = log( 1.0/data[i] - 1.0 );
}


} // end of namespace aureservoir

#endif // AURESERVOIR_ACTIVATIONS_H__

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