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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 function 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 mistake.

Theano has been powering large-scale computationally intensive scientific investigations since 2007. But it is also approachable enough to be used in the classroom (IFT6266 at the University of Montreal).



You can watch a quick (20 minute) introduction to Theano given as a talk at SciPy 2010 via streaming (or downloaded) video:

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


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 install.

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

git clone git://

You can then place the checkout directory on your $PYTHONPATH or use python 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 installing Theano.


 Latest PyPI version Number of PyPI downloads 

Citing Theano

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

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 Theano Citation Policy for details.


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

You can download the latest PDF documentation, rather than reading it online.

Check out how Theano can be used for Machine Learning: Deep Learning Tutorials.

Theano was featured at SciPy 2010.


“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 metaoptimize/qa/tags/theano (it’s like stack overflow for machine learning)
  • We use Github tickets to keep track of issues (however, some old tickets can still be found on Assembla).
  • Come visit us in Montreal! Most developers are students in the LISA group at the University of Montreal.