
Welcome
=======

Theano is a Python library that allows you to define, optimize, and
evaluate mathematical expressions involving multi-dimensional
arrays efficiently. Theano features:

* **tight integration with NumPy** -- Use `numpy.ndarray` in Theano-compiled functions.
* **transparent use of a GPU** -- Perform data-intensive calculations up to 140x faster than with CPU.(float32 only)
* **efficient symbolic differentiation** -- Theano does your derivatives for functions with one or many inputs.
* **speed and stability optimizations** -- Get the right answer for ``log(1+x)`` even when ``x`` is really tiny.
* **dynamic C code generation** -- Evaluate expressions faster.
* **extensive unit-testing and self-verification** -- Detect and diagnose many types of errors.

Theano has been powering large-scale computationally intensive
scientific investigations since 2007.  But it is also approachable
enough to be used in the classroom (University of Montreal's `deep
learning/machine learning <https://mila.umontreal.ca/en/cours/>`_ classes).

News
====

* 2017/02/27: Release of Theano 0.9.0rc2, with crash fixes, bug fixes and improvements.

* 2017/02/20: Release of Theano 0.9.0rc1, many improvements and bugfixes, final release to coming.

* 2017/01/24: Release of Theano 0.9.0beta1, many improvements and bugfixes, release candidate to coming.

* 2016/05/09: New technical report on Theano:
  `Theano: A Python framework for fast computation of mathematical expressions <http://arxiv.org/abs/1605.02688>`_.
  This is the new preferred reference.

* 2016/04/21: Release of Theano 0.8.2, adding support for :ref:`CuDNN v5 <libdoc_cuda_dnn>`.

* 2016/03/29: Release of Theano 0.8.1, fixing a compilation issue on MacOS X with XCode 7.3.

* 2016/03/21: Release of Theano 0.8. Everybody is encouraged to update.

* Multi-GPU.

* We added support for :attr:`CNMeM <config.lib.cnmem>` to speed up
  the GPU memory allocation.

* Theano 0.7 was released 26th March 2015. Everybody is encouraged to update.

* We support `cuDNN <http://deeplearning.net/software/theano/library/sandbox/cuda/dnn.html>`_ if it is installed by the user.

* Open Machine Learning Workshop 2014 `presentation <omlw2014/omlw_presentation.pdf>`_.

* Colin Raffel `tutorial on Theano <http://nbviewer.ipython.org/github/craffel/theano-tutorial/blob/master/Theano%20Tutorial.ipynb>`_.

* Ian Goodfellow did a `12h class with exercises on Theano <https://github.com/goodfeli/theano_exercises>`_.

* New technical report on Theano: `Theano: new features and speed improvements <http://arxiv.org/abs/1211.5590>`_.

* `HPCS 2011 Tutorial <http://www.iro.umontreal.ca/~lisa/pointeurs/tutorial_hpcs2011_fixed.pdf>`_.
  We included a few fixes discovered while doing the Tutorial.

.. image:: images/talk2010.png
    :scale: 75%
    :align: left

You can watch a quick (20 minute) introduction to Theano given as a talk at `SciPy 2010 <http://conference.scipy.org/scipy2010/>`_ via streaming (or downloaded) video:

  `Transparent GPU Computing With Theano`_.
  James Bergstra, SciPy 2010, June 30, 2010.

.. _Transparent GPU Computing With Theano: http://www.archive.org/details/Scipy2010-JamesBergstra-TransparentGpuComputingWithTheano

Download
========

Theano is now `available on PyPI`_, and can be installed via ``easy_install
Theano``, ``pip install Theano`` or by downloading and unpacking the tarball
and typing ``python setup.py install``.

Those interested in bleeding-edge features should obtain the latest development
version, available via::

    git clone git://github.com/Theano/Theano.git

You can then place the checkout directory on your ``$PYTHONPATH`` or use
``python setup.py develop`` to install a ``.pth`` into your ``site-packages``
directory, so that when you pull updates via Git, they will be
automatically reflected the "installed" version. For more information about
installation and configuration, see :ref:`installing Theano <install>`.

.. only:: html

  Status
  ======

  .. raw:: html

     <a href="http://travis-ci.org/Theano/Theano/builds"><img src="https://secure.travis-ci.org/Theano/Theano.png?branch=master" /></a>&nbsp;

  .. raw:: html

     <a href="https://crate.io/packages/Theano/"><img src="https://img.shields.io/pypi/v/Theano.svg" alt="Latest PyPI version" /></a>&nbsp;

  .. raw:: html

     <a href="https://crate.io/packages/Theano/"><img src="https://img.shields.io/pypi/dm/Theano.svg" alt="Number of PyPI downloads" /></a>&nbsp;

.. _available on PyPI: http://pypi.python.org/pypi/Theano
.. _Related Projects: https://github.com/Theano/Theano/wiki/Related-projects

Citing Theano
==============

If you use Theano for academic research, you are highly encouraged (though not
required) to cite the following, most recent paper:

* Theano Development Team. `"Theano: A Python framework for fast computation of mathematical expressions"
  <http://arxiv.org/pdf/1605.02688.pdf>`_.
  (:download:`short BibTeX <theano-short.bib>`, :download:`full BibTeX <theano-full.bib>`)

Theano is primarily developed by academics, and so citations matter a lot to
us. As an added benefit, you increase Theano's exposure and potential user
(and developer) base, which is to the benefit of all users of Theano. Thanks
in advance!

See our :ref:`citation` for details.

Documentation
=============

Roughly in order of what you'll want to check out:

* :ref:`install` -- How to install Theano.
* :ref:`introduction` -- What is Theano?
* :ref:`tutorial` -- Learn the basics.
* :ref:`troubleshooting` -- Tips and tricks for common debugging.
* :ref:`libdoc` -- Theano's functionality, module by module.
* :ref:`faq` -- A set of commonly asked questions.
* :ref:`optimizations` -- Guide to Theano's graph optimizations.
* :ref:`extending` -- Learn to add a Type, Op, or graph optimization.
* :ref:`dev_start_guide` -- How to contribute code to Theano.
* :ref:`developer` -- Primarily of interest to developers of Theano
* :ref:`internal` -- How to maintain Theano and more...
* :ref:`release` -- How our release should work.
* :ref:`acknowledgement` -- What we took from other projects.
* `Related Projects`_ -- link to other projects that implement new functionalities on top of Theano

You can download the latest `PDF documentation <http://deeplearning.net/software/theano/theano.pdf>`_, rather than reading it online.

Check out how Theano can be used for Machine Learning: `Deep Learning Tutorials <http://www.deeplearning.net/tutorial>`_.

Theano was featured at `SciPy 2010 <http://www.iro.umontreal.ca/~lisa/publications2/index.php/publications/show/461>`__.


.. _theano_community:

Community
=========

    "Thank YOU for correcting it so quickly. I wish all packages I worked
    with would have such an active maintenance - this is as good as it
    gets :-)"

    (theano-users, Aug 2, 2010)


* Register to `theano-announce`_ if you want to be kept informed on important change on theano(low volume).

* Register and post to `theano-users`_ if you want to talk to all Theano users.

* Register and post to `theano-dev`_ if you want to talk to the developers.

* Register to `theano-github`_ if you want to receive an email for all changes to the GitHub repository.

* Register to `theano-buildbot`_ if you want to receive our daily buildbot email.

* Ask/view questions/answers at `StackOverflow`_

* We use `Github tickets <http://github.com/Theano/Theano/issues>`__ to keep track of issues
  (however, some old tickets can still be found on
  `Assembla <http://www.assembla.com/spaces/theano/tickets>`__).

* Come visit us in Montreal! Most developers are students in the LISA_ group at the `University of Montreal`_.


.. _support:

Help!
=====

How to Seek Help
----------------

The appropriate venue for seeking help depends on the kind of question you have.

* How do I? -- `theano-users`_ mailing list or `StackOverflow`_
* I got this error, why? -- `theano-users`_ mailing list or `StackOverflow`_ (please include the *full* error message, even if it's long)
* I got this error and I'm sure it's a bug -- `Github ticket <http://github.com/Theano/Theano/issues>`__
* I have an idea/request -- post the suggestion to `theano-dev`_ or, even better, implement the idea and submit a `GitHub <https://github.com/Theano/Theano/pulls>`__ pull request!
* Why do you? -- `theano-users`_ mailing list (not appropriate for StackOverflow)
* When will you? -- `theano-dev`_ mailing list (not appropriate for StackOverflow)

Please do take some time to search for similar questions that were asked and answered in the past. If you find something
similar that doesn't fully answer your question, it can be helpful to say something like "I found X but it doesn't
address facet Y" and link to the previous discussion.

When asking questions on StackOverflow, please use the *theano* tag, so your question can be found, and follow
StackOverflow's guidance on `asking questions <http://stackoverflow.com/help/asking>`__. Consider also using the
*python* and *numpy* tags, especially if you are unsure which library your problem relates to.

It's often helpful to include the following details with your question:

* If you have an error, the *full* error message, even if it's long
* Which versions of Python and Theano you're using
* Whether you're using a CPU or GPU device
* Details of your Theano configuration settings (you can print this in Python via `print theano.config <http://deeplearning.net/software/theano/library/config.html>`__)

Spending the time to create a minimal specific example of a problem is likely to get you to an answer quicker than
posting something quickly that has too much irrelevant detail or is too vague. A minimal example may take you a bit more
time to create but the first response is more likely to be the answer you need than, rather than a frustrated request
for clarification.


How to provide help
-------------------

If you see a question on the `theano-users`_ mailing list, or on `StackOverflow`_, that you
feel reasonably confident you know an answer to, please do support the community by helping others.

We were all newbies to Theano once and, as the community expands, there is a constant stream of new Theano users looking
for help. Perhaps you asked a question when you were first starting out? Now you can pay it forward by helping others.
It's also a good way to reinforce your own Theano knowledge.

Often it's easiest to answer a question directly but sometimes it may be better to refer people to a good answer that
was provided in the past. Pointing people to relevant sections in the documentation, or to a Theano tutorial, can also
be helpful.

When answering questions please `be nice <http://stackoverflow.com/help/be-nice>`__ (as always!) and, on
StackOverflow, follow their guidance for `answering questions <http://stackoverflow.com/help/answering>`__.



.. toctree::
   :maxdepth: 1
   :hidden:

   NEWS
   introduction
   requirements
   install
   updating
   tutorial/index
   extending/index
   dev_start_guide
   optimizations
   library/index
   troubleshooting
   glossary
   links
   internal/index
   acknowledgement
   LICENSE


.. _theano-dev: http://groups.google.com/group/theano-dev
.. _theano-users: http://groups.google.com/group/theano-users
.. _theano-announce: http://groups.google.com/group/theano-announce
.. _theano-github: http://groups.google.com/group/theano-github
.. _theano-buildbot: http://groups.google.com/group/theano-buildbot
.. _tickets: http://pylearn.org/theano/trac/query?status=accepted&status=assigned&status=new&status=reopened&group=milestone&max=200&col=id&col=summary&col=status&col=owner&col=type&col=priority&col=component&col=time&report=9&order=priority

.. _StackOverflow: http://stackoverflow.com/questions/tagged/theano

.. _LISA: http://www.iro.umontreal.ca/~lisa
.. _University of Montreal: http://www.umontreal.ca

