GitLocker: The Coding Marketplace

Description:

jaxcosmo 0.1.0

jax-cosmo

Finally a differentiable cosmology library, and it's in JAX!
Have a look at the GitHub issues to see what is needed or if you have any thoughts on the design, and don't hesitate to join the Gitter room for discussions.
TL;DR
This is what jax-cosmo aims to do:
...
def likelihood(cosmo):
# Compute mean and covariance of angular Cls, for specific probes
mu, cov = jax_cosmo.angular_cl.gaussian_cl_covariance_and_mean(cosmo, ell, probes)
# Return likelihood value
return jax_cosmo.likelihood.gaussian_log_likelihood(data, mu, cov)

# Compute derivatives of the likelihood with respect to cosmological parameters
g = jax.grad(likelihood)(cosmo)

# Compute Fisher matrix of cosmological parameters
F = - jax.hessian(likelihood)(cosmo)

This is how you can compute gradients and hessians of any functions in jax-cosmo,
all of this without any finite differences.
Check out a full example here:
Have a look at the design document to learn more about the structure of the code.
What is JAX?
JAX = NumPy + autodiff + GPU
JAX is a framework for automatic differentiation (like TensorFlow or PyTorch) but following the NumPy API, and using the GPU/TPU enable XLA backend.
What does that mean?

You write plain Python/NumPy code, no need to learn a different language
It runs on GPU, you don't need to do anything particular
You can take derivatives of any quantity with respect to any parameters by
automatic differentiation.

Checkout the JAX project page to learn more!
Install
jax-cosmo is pure Python, so installing is a breeze:
$ pip install jax-cosmo

Philosophy
Here are some of the design guidelines:

Implementation of equations should be human readable, and documentation should always live next to the implementation.
Should always be trivially installable: external dependencies should be kept
to a minimum, especially the ones that require compilation or with restrictive licenses.
Keep API and implementation simple and intuitive, minimize user and developer
surprise.
“Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.” -Brian Kernighan, quote stolen from
here.

Contributing
jax-cosmo aims to be a community effort, contributions are most welcome and
can come in several forms

Bug reports
API design suggestions
(Pull) requests for more features
Examples and notebooks of cool things that can be done with the code

You can chime-in on any aspects of the design by proposing a PR to the design document. The issue page is a good place to start, but don't hesitate to come chat in the Gitter room.
Please take a look at the Contributing Document for more information.
This project follows the All Contributors guidelines aiming at recognizing and valorizing
contributions at any levels.
Contributors ✨
Thanks goes to these wonderful people (emoji key):

Francois Lanusse💻
Santiago Casas🐛 💻
Austin Peel💻
Minas Karamanis💻
David Kirkby💻 🐛
Alexandre Boucaud💻
Denise Lanzieri💻

jecampagne🐛
Yin Li💻 🐛

This project follows the all-contributors specification. Contributions of any kind welcome!