diff --git a/src/tensor.h b/src/tensor.h
index a32e9b04..a18aaa3f 100644
--- a/src/tensor.h
+++ b/src/tensor.h
@@ -1,4 +1,21 @@
 #pragma once
+/* Copyright (C) 
+ * 2016 - MLAMU & friends
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ * 
+ */
 
 #include <cublas_v2.h>
 #include <thrust/device_vector.h>
@@ -12,6 +29,13 @@
 
 namespace marian {
 
+/**
+ * @brief Debug shape by printing it. 
+ *
+ * @param shape Shape of Tensor.
+ *
+ * @return 
+ */
 inline std::string Debug(const Shape &shape)
 {
 	std::stringstream strm;
@@ -23,6 +47,13 @@ inline std::string Debug(const Shape &shape)
 	return strm.str();
 }
 
+/**
+ * @brief Calculate the vector size based on Tensor shape. 
+ *
+ * @param shape Shape of Tensor.
+ *
+ * @return 
+ */
 inline size_t GetTotalSize(const Shape &shape)
 {
 	size_t ret = std::accumulate(shape.begin(), shape.end(),
@@ -30,17 +61,28 @@ inline size_t GetTotalSize(const Shape &shape)
 	return ret;
 }
 
+/**
+ * @brief Class that manages the Tensor on the GPU. 
+ *
+ * @tparam Float Data type.
+ */
 template<class Float>
 class TensorImpl {
   private:
-    Shape shape_;
-    thrust::device_vector<Float> data_;
-    size_t tno_;
-    static size_t tensorCounter;
+    Shape shape_; /*!< Dimens of Tensor */
+    thrust::device_vector<Float> data_; /*< Vector of data that Tensor is managing on GPU. */
+    size_t tno_; /*< Tensor number */
+    static size_t tensorCounter; /*< Static counter of created Tensors */
 
   public:
-    typedef Float value_type;
+    typedef Float value_type; /*< Tensor value type */
 
+    /**
+     * @brief Constructor
+     *
+     * @param shape Shape of Tensor.
+     * @param value Value to fill Tensor's vector with.
+     */
     TensorImpl(const Shape& shape, value_type value = 0)
     : shape_(shape), tno_(tensorCounter++)
     {
@@ -59,54 +101,122 @@ class TensorImpl {
     TensorImpl(const TensorImpl&) = delete;
     TensorImpl(TensorImpl&&) = delete;
 
+    /**
+     * @brief Get value of vector specified with index.
+     *
+     * @param i Index.
+     *
+     * @return Value of Tensor vector indexed with i.
+     */
    value_type operator[](size_t i) const {
       return data_[i];
     }
 
+   /**
+    * @brief Get begin iterator of Tensor's vector.
+    *
+    * @return Vector begin iterator.
+    */
     auto begin() -> decltype( data_.begin() ) {
       return data_.begin();
     }
 
+   /**
+    * @brief Get begin iterator of Tensor's vector (const).
+    *
+    * @return Vector begin iterator (const)
+    */
     auto begin() const -> decltype( data_.begin() ) {
       return data_.begin();
     }
 
+   /**
+    * @brief Get end iterator of Tensor's vector.
+    *
+    * @return Vector end iterator
+    */
     auto end() -> decltype( data_.end() ) {
       return data_.end();
     }
 
+   /**
+    * @brief Get end iterator of Tensor's vector (const).
+    *
+    * @return Vector end iterator (const)
+    */
     auto end() const -> decltype( data_.end() ) {
       return data_.end();
     }
 
+    /**
+     * @brief Get Tensor's shape (const)
+     *
+     * @return Shape of Tensor
+     */
     const Shape& shape() const {
         return shape_;
     }
 
+    /**
+     * @brief Get size of Tensor's vector.
+     *
+     * @return Length of Tensor's vector.
+     */
     size_t size() const {
       return data_.size();
     }
 
+    /**
+     * @brief Cast data from Tensor's GPU to value_type.
+     *
+     * @return Pointer of value_type array.
+     */
     value_type* data() {
       return thrust::raw_pointer_cast(data_.data());
     }
 
+    /**
+     * @brief Get Tensor id (number).
+     *
+     * @return Tensor id.
+     */
     size_t id() const {
       return tno_;
     }
 
+    /**
+     * @brief Fill Tensor's vector with specified value on the GPU.
+     *
+     * @param value Value to fill vector with.
+     */
     void set(value_type value) {
       thrust::fill(data_.begin(), data_.end(), value);
     }
 
+    /**
+     * @brief Set Tensor's vector to values of specified vector by copying it to GPU.
+     *
+     * @param begin Begin iterator of a vector.
+     * @param end End iterator of a vector.
+     */
     void set(const std::vector<float>::const_iterator &begin, const std::vector<float>::const_iterator &end) {
 	  thrust::copy(begin, end, data_.begin());
     }
 
+    /**
+     * @brief Copy Tensor's vector from GPU to vector variable on CPU.
+     *
+     * @param out Vector to copy data to.
+     */
     void get(std::vector<float>::iterator out) {
 	  thrust::copy(data_.begin(), data_.end(), out);      
     }
     
+    /**
+     * @brief Debug function.
+     *
+     * @return Vector in string form.
+     */
     std::string Debug() const
     {
     	std::stringstream strm;
@@ -133,78 +243,170 @@ class TensorImpl {
 template <typename Type>
 size_t TensorImpl<Type>::tensorCounter = 0;
 
+/**
+ * @brief Class that communicates with GPU's Tensor.
+ */
 class Tensor {
   private:
-    std::shared_ptr<TensorImpl<Float>> pimpl_;
+    std::shared_ptr<TensorImpl<Float>> pimpl_; /*< Pointer to Tensor working on GPU */
 
   public:
-    typedef TensorImpl<Float>::value_type value_type;
+    typedef TensorImpl<Float>::value_type value_type; /*< Get value type of GPU's Tensor data */
 
+    /**
+     * @brief Default constructor
+     */
     Tensor() {}
+
+    /**
+     * @brief Constructor that allocates needed memory.
+     *
+     * @param shape Shape of Tensor. 
+     * @param value Value to fill Tensor's vector with.
+     */
     Tensor(const Shape& shape, value_type value = 0) {
       allocate(shape, value);
     }
 
+    /**
+     * @brief Default destructor
+     */
     ~Tensor() {}
 
+    /**
+     * @brief Allocate memory if Tensor doesn't exist on GPU.
+     *
+     * @param shape Shape of Tensor.
+     * @param value Value to fill Tensor's vector with.
+     */
     void allocate(const Shape& shape, value_type value = 0) {
       if(!pimpl_)
         pimpl_.reset(new TensorImpl<Float>(shape, value));
     }
 
+    /**
+     * @brief Get value of GPU Tensor in specified index (const).
+     *
+     * @param i Index.
+     *
+     * @return Value of specified element of Tensor.
+     */
     value_type operator[](size_t i) const {
       return (*pimpl_)[i];
     }
 
+    /**
+     * @brief Get size of GPU Tensor's vector.
+     *
+     * @return 
+     */
     size_t size() const {
       return pimpl_->size();
     }
 
+    /**
+     * @brief Return pointer to GPU Tensor's data.
+     *
+     * @return Pointer to GPU Tensor's data.
+     */
     value_type* data() {
       return pimpl_->data();
     }
 
+    /**
+     * @brief Return pointer to GPU Tensor's data (const).
+     *
+     * @return Pointer to GPU Tensor's data.
+     */
     const value_type* data() const {
       return pimpl_->data();
     }
 
+   /**
+    * @brief Get begin iterator of GPU Tensor's vector.
+    *
+    * @return Vector begin iterator.
+    */
     auto begin() -> decltype( pimpl_->begin() ) {
       return pimpl_->begin();
     }
 
+   /**
+    * @brief Get begin iterator of GPU Tensor's vector (const).
+    *
+    * @return Vector begin iterator (const)
+    */
     auto begin() const -> decltype( pimpl_->begin() ) {
       return pimpl_->begin();
     }
 
+   /**
+    * @brief Get end iterator of Tensor's vector.
+    *
+    * @return Vector end iterator
+    */
     auto end() -> decltype( pimpl_->end() ) {
       return pimpl_->end();
     }
 
+   /**
+    * @brief Get end iterator of Tensor's vector (const).
+    *
+    * @return Vector end iterator (const)
+    */
     auto end() const -> decltype( pimpl_->end() ) {
       return pimpl_->end();
     }
 
+    /**
+     * @brief Get GPU Tensor's shape.
+     *
+     * @return Tensor's shape.
+     */
     const Shape& shape() const {
       return pimpl_->shape();
     }
 
+    /**
+     * @brief Fill GPU Tensor's vector with specified value.
+     *
+     * @param value Value to fill Tensor with.
+     */
     void set(value_type value) {
       pimpl_->set(value);
     }
 
+    /**
+     * @brief Get GPU Tensor id (number).
+     *
+     * @return Tensor id.
+     */
     size_t id() const {
       return pimpl_->id();
     }
 
+    /**
+     * @brief Check if Tensor exists (is filled with data).
+     *
+     * @return True or False
+     */
     operator bool() {
       return pimpl_ != nullptr;
     }
 
+    /**
+     * @brief Run Debug on GPU Tensor.
+     *
+     * @return String of Tensor's data.
+     */
     std::string Debug() const
     {
     	return pimpl_->Debug();
     }
 
+    /**
+     * @brief Print Tensor data on CPU (?) (const). 
+     */
     void Print() const {
       for (int i = 0; i < size(); ++i) {
         std::cerr << (*this)[i] << " ";
@@ -213,21 +415,59 @@ class Tensor {
     }
 
     //void Load(const std::string &path);
+    
+    /**
+     * @brief Set GPU Tensor's vector to values of specified vector.
+     *
+     * @param data Vector copied to GPU.
+     */
     void set(const std::vector<float>& data);
+    /**
+     * @brief Set GPU Tensor's veector to values of specified vector.
+     *
+     * @param begin Begin iterator of vector being copied.
+     * @param end End iterator of vector being copied.
+     */
     void set(const std::vector<float>::const_iterator &begin, const std::vector<float>::const_iterator &end);
 
+    /**
+     * @brief Copy Tensor's vector from GPU to vector variable on CPU (const).
+     *
+     * @param out Vector iterator used in copying.
+     */
     void get(std::vector<float>::iterator out) const {
       pimpl_->get(out);
     }
     
+    /**
+     * @brief Copy Tensor's vector from GPU to vector variable on CPU.
+     *
+     * @param out Vector to copy data to.
+     */
     void get(std::vector<float> &vout) const {
       vout.resize(size());
       pimpl_->get(vout.begin());
     }
 };
 
+/**
+ * @brief Operator to set data on Tensor using vector.
+ *
+ * @param t Tensor.
+ * @param vec Vector used to set data in Tensor.
+ *
+ * @return Tensor with assigned data.
+ */
 Tensor& operator<<(Tensor& t, const std::vector<float> &vec);
 
+/**
+ * @brief Operator to get data from Tensor to vector.
+ *
+ * @param vec Vector to save copied data.
+ * @param t Tensor to copy data from.
+ *
+ * @return Vector with copied data.
+ */
 std::vector<float>& operator<<(std::vector<float> &vec, const Tensor& t);
 
 }