# FAST-PT

FAST-PT is a code to calculate quantities in cosmological perturbation theory
at 1-loop (including, e.g., corrections to the matter power spectrum). The code
utilizes Fourier methods combined with analytic expressions to reduce the
computation time to scale as N log N, where N is the number of grid points in
the input linear power spectrum.

The FAST-PT way to get started:

* Make sure you have current version of numpy, scipy, and matplotlib
* download FAST-PT (or clone the repo)
* install the repo: `python setup.py install`
* run the example: `cd examples && python fastpt_example.py`
* hopefully you get a plot!

See the [user manual](docs/user_manual.pdf) for more details.

Our papers (JCAP 2016, 9, 15; arXiv:1603.04826) and (JCAP 2017, 2, 30; arXiv:1609.05978)
describe the FAST-PT algorithm and implementation. Please cite these papers
when using FAST-PT in your research. For the intrinsic alignment
implementation, cite arXiv:1708.09247.

FAST-PT is under continued development and should be considered research in
progress. FAST-PT is open source and distributed with the
[MIT license](https://opensource.org/licenses/mit). If you have comments,
questions, or feedback, please file an [issue](https://github.com/JoeMcEwen/FAST-PT/issues).