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# boys

A Rust library for calculation of the Boys function

![equation](http://latex.codecogs.com/gif.latex?F_n%28x%29%3D%5Cint_0%5E1t%5E%7B2n%7De%5E%7B-xt%5E2%7Ddt)

via a number of methods:

- An "exact" algorithm originally from [Radovan Bast](https://github.com/bast/obara-saika/blob/52ff0fa4d470eeb7a41d932078b2e4d9a54d05e5/obara_saika.py#L371).
- A non-clean-room reimplementation of [Michael Böhme's algorithm](https://github.com/micb25/libboys).

## System dependencies

The [GNU Scientific Library](https://www.gnu.org/software/gsl/) (GSL) is used via the [`rgsl`](https://crates.io/crates/GSL) crate to provide the gamma and incomplete gamma functions for the exact implementation and the error function for Michael Böhme's algorithm.

| OS/distro              | install command                    |
|------------------------|------------------------------------|
| Debian/Ubuntu          | `sudo apt-get install libgsl0-dev` |
| Arch Linux             | `sudo pacman -S gsl`               |
| macOS (using Homebrew) | `brew install gsl`                 |

## Literature

[S. F. Boys, *Proc R. Soc. Am.* **1950**, *200*, 542.](https://doi.org/10.1098/rspa.1950.0036)