Project details for Theano

Logo Theano 0.3

by jaberg - November 23, 2010, 21:42:14 CET [ Project Homepage BibTeX BibTeX for corresponding Paper Download ]

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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.
* symbolic differentiation – Let Theano do your derivatives.
* 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).

Theano has been used primarily to implement large-scale deep learning algorithms. To see how, see the Deep Learning Tutorials (

Changes to previous version:

This is the first major release of Theano since 0.1. Version 0.2 development started internally but it was never advertised as a release.

There have been so many changes since 0.1 that we have lost track of many of them. Below is a partial list of changes since 0.1.

  • GPU code using NVIDIA's CUDA framework is now generated for many Ops.
  • Some interface changes since 0.1:
    • A new "shared variable" system to allow reusing memory space between Theano functions.
      • A new memory contract has been formally written for Theano, for people who want to minimize memory copies.
    • The old module system has been deprecated.
    • By default, inputs to a Theano function will not be silently downcasted (e.g. from float64 to float32).
    • An error is now raised when using the result of logical operation on Theano variable in an 'if' (i.e. an implicit call to nonzeros).
    • An error is now raised when we receive a non-aligned ndarray as input to a function (this is not supported).
    • An error is raised when the list of dimensions passed to dimshuffle() contains duplicates or is otherwise not sensible.
    • Call NumPy BLAS bindings for gemv operations in addition to the already supported gemm.
    • If gcc is unavailable at import time, Theano now falls back to a Python-based emulation mode after raising a warning.
    • An error is now raised when tensor.grad is called on a non-scalar Theano variable (in the past we would implicitly do a sum on the tensor to make it a scalar).
    • Added support for "erf" and "erfc" functions.
  • The current default value of the parameter axis of theano.{max,min,argmax,argmin,max_and_argmax} is deprecated. We now use the default NumPy behavior of operating on the entire tensor.
  • Theano is now available from PyPI and installable through "easy_install" or "pip".
BibTeX Entry: Download
Corresponding Paper BibTeX Entry: Download
Supported Operating Systems: Linux, Macosx, Windows
Data Formats: Agnostic
Tags: Automatic Differentiation, Cuda, Gpu
Archive: download here


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