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+# THNN
+
+THNN is a library that gathers nn's C implementations of neural network modules. It's entirely free of Lua dependency and therefore can be used in any application that has a C FFI. Please note that it only contains quite low level functions, and an object oriented C/C++ wrapper will be created soon as another library.
+
+There is also a CUDA counterpart of THNN (THCUNN) in the [cunn repository](https://github.com/torch/cunn/tree/master/lib/THCUNN).
+
+## Links
+
+* [API reference](doc/api_reference.md)
+* [Style guidelines](doc/style_guidelines.md)
+
+## Motivation
+
+Torch's neural network package (nn) provided many optimized C implementations of modules, but the source files contained Lua specific code and headers so they couldn't be easily compiled and included anywhere else.
+
+THNN is based on the same code, but is written in pure C, so it can be easily included in other code. **Future C implementations should be committed to THNN.**
+
+## API
+
+THNN is a purely functional library. It provides 2-3 functions for each module, that perform the most important operations:
+
+* **updateOutput** - applies the module to an input
+* **updateGradInput** - accepts gradient w.r.t. output and previous module input, and computes a gradient w.r.t. that input
+* **accGradParameters** - *(optional, only modules with parameters)* accepts gradient w.r.t. output and previous module input, and computes gradient w.r.t. the parameters
+
+For information on argument types please check the [API reference](doc/api_reference.md).
+
+## Developer docs
+
+* [Style guidelines](doc/style_guidelines.md)
+
+This section will be expanded when FFI refactoring will be finished.