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diff --git a/src/CuTNetLib/cuActivation.h b/src/CuTNetLib/cuActivation.h
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+
+#ifndef _CUACT_FUN_I_
+#define _CUACT_FUN_I_
+
+
+#include "cuComponent.h"
+#include "cumatrix.h"
+
+
+namespace TNet
+{
+
+  /**
+   * \brief Common interface for activation functions
+   */
+  class CuActivation : public CuComponent 
+  {
+    public:
+      CuActivation(size_t nInputs, size_t nOutputs, CuComponent *pPred);
+
+    protected:
+  };
+
+
+  /**
+   * \brief CuSigmoid activation function
+   *
+   * \ingroup CuNNActivation
+   * Implements forward pass: \f[ Y_i=\frac{1}{1+e^{-X_i}} \f]
+   * Error propagation: \f[ E_i=Y_i(1-Y_i)e_i \f]
+   */
+  class CuSigmoid : public CuActivation
+  {
+    public:
+      CuSigmoid(size_t nInputs, size_t nOutputs, CuComponent *pPred);
+
+      ComponentType GetType() const;
+      const char* GetName() const;
+
+    protected:
+      void PropagateFnc(const CuMatrix<BaseFloat>& X, CuMatrix<BaseFloat>& Y);
+      void BackpropagateFnc(const CuMatrix<BaseFloat>& X, CuMatrix<BaseFloat>& Y);
+  };
+    
+
+  /**
+   * \brief CuSoftmax activation function
+   *
+   * \ingroup CuNNActivation
+   * Implements forward pass: \f[ Y_i=\frac{1}{Z} e^{X_i} \f]
+   * where \f$ Z=\Sigma_{i=0}^{i=N-1} e^{X_i} \f$
+   * Error Propagation: \f[ E_i=Y_i - \Sigma_{j=0}^{j=N-1} Y_i Y_j e_j \f]
+   */
+  class CuSoftmax : public CuActivation
+  {
+    public:
+      CuSoftmax(size_t nInputs, size_t nOutputs, CuComponent *pPred);
+
+      ComponentType GetType() const;
+      const char* GetName() const;
+
+    protected:
+      void PropagateFnc(const CuMatrix<BaseFloat>& X, CuMatrix<BaseFloat>& Y);
+      void BackpropagateFnc(const CuMatrix<BaseFloat>& X, CuMatrix<BaseFloat>& Y);
+  };
+
+
+  //////////////////////////////////////////////////////////////////////////
+  // Inline functions
+  // Activation::
+  inline
+  CuActivation::
+  CuActivation(size_t nInputs, size_t nOutputs, CuComponent *pPred)
+    : CuComponent(nInputs,nOutputs, pPred)
+  { 
+    assert(nInputs == nOutputs);
+  } 
+
+
+  //////////////////////////////////////////////////////////////////////////
+  // Inline functions
+  // Sigmoid::
+  inline
+  CuSigmoid::
+  CuSigmoid(size_t nInputs, size_t nOutputs, CuComponent *pPred)
+    : CuActivation(nInputs,nOutputs, pPred) 
+  { } 
+
+  inline CuComponent::ComponentType
+  CuSigmoid::
+  GetType() const
+  {
+    return CuComponent::SIGMOID;
+  }
+
+  inline const char*
+  CuSigmoid::
+  GetName() const
+  {
+    return "<sigmoid>";
+  }
+
+
+
+  //////////////////////////////////////////////////////////////////////////
+  // Inline functions
+  // Softmax::
+  inline
+  CuSoftmax::
+  CuSoftmax(size_t nInputs, size_t nOutputs, CuComponent *pPred)
+    : CuActivation(nInputs,nOutputs, pPred) 
+  { } 
+
+  inline CuComponent::ComponentType
+  CuSoftmax::
+  GetType() const
+  {
+    return CuComponent::SOFTMAX;
+  }
+
+  inline const char*
+  CuSoftmax::
+  GetName() const
+  {
+    return "<softmax>";
+  }
+
+
+} //namespace
+
+
+#endif