From cccccbf6cca94a3eaf813b4468453160e91c332b Mon Sep 17 00:00:00 2001
From: Joe Zhao <ztuowen@gmail.com>
Date: Mon, 14 Apr 2014 08:14:45 +0800
Subject: First commit

---
 src/TNetLib/Activation.h | 104 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 src/TNetLib/Activation.h

(limited to 'src/TNetLib/Activation.h')

diff --git a/src/TNetLib/Activation.h b/src/TNetLib/Activation.h
new file mode 100644
index 0000000..90263d0
--- /dev/null
+++ b/src/TNetLib/Activation.h
@@ -0,0 +1,104 @@
+
+#ifndef _ACT_FUN_I_
+#define _ACT_FUN_I_
+
+
+#include "Component.h"
+
+
+namespace TNet
+{
+
+  /**
+   * Sigmoid activation function
+   */
+  class Sigmoid : public Component
+  {
+    public:
+      Sigmoid(size_t nInputs, size_t nOutputs, Component *pPred)
+       : Component(nInputs,nOutputs,pPred)
+      { }
+
+      ComponentType GetType() const
+      { return SIGMOID; }
+
+      const char* GetName() const
+      { return "<sigmoid>"; }
+
+      Component* Clone() const
+      { return new Sigmoid(GetNInputs(),GetNOutputs(),NULL); }
+
+    protected:
+      void PropagateFnc(const BfMatrix& X, BfMatrix& Y);
+      void BackpropagateFnc(const BfMatrix& X, BfMatrix& Y);
+  };
+    
+
+  /**
+   * Softmax activation function
+   */
+  class Softmax : public Component
+  {
+    public:
+      Softmax(size_t nInputs, size_t nOutputs, Component *pPred)
+       : Component(nInputs,nOutputs,pPred)
+      { }
+
+      ComponentType GetType() const
+      { return SOFTMAX; }
+
+      const char* GetName() const
+      { return "<softmax>"; }
+
+      Component* Clone() const
+      { return new Softmax(GetNInputs(),GetNOutputs(),NULL); }
+
+    protected:
+      void PropagateFnc(const BfMatrix& X, BfMatrix& Y);
+      void BackpropagateFnc(const BfMatrix& X, BfMatrix& Y);
+  };
+
+
+  /**
+   * BlockSoftmax activation function.
+   * It is several softmaxes in one.
+   * The dimensions of softmaxes are given by integer vector.
+   * During backpropagation: 
+   *  If the derivatives sum up to 0, they are backpropagated. 
+   *  If the derivatives sup up to 1, they are discarded
+   *  (like this we know that the softmax was 'inactive').
+   */
+  class BlockSoftmax : public Component
+  {
+    public:
+      BlockSoftmax(size_t nInputs, size_t nOutputs, Component *pPred)
+       : Component(nInputs,nOutputs,pPred)
+      { }
+
+      ComponentType GetType() const
+      { return BLOCK_SOFTMAX; }
+
+      const char* GetName() const
+      { return "<blocksoftmax>"; }
+
+      Component* Clone() const
+      { return new BlockSoftmax(*this); }
+
+      void ReadFromStream(std::istream& rIn);
+      void WriteToStream(std::ostream& rOut);
+
+    protected:
+      void PropagateFnc(const BfMatrix& X, BfMatrix& Y);
+      void BackpropagateFnc(const BfMatrix& X, BfMatrix& Y);
+
+    private:
+      Vector<int> mDim;
+      Vector<int> mDimOffset;
+  };
+
+
+  
+} //namespace
+
+
+#endif
-- 
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