Post-Newtonian theory results in some of the longest and most complex mathematical expressions ever derived by humanity.

These expressions form the core of most gravitational wave data analysis codes, but generally the expressions are written in a format that is either inaccessible by others (i.e., closed-source) or written directly in e.g., C code and thus incompatible with symbolic algebra packages like Wolfram Mathematica or the Python-based SymPy.

Once in a symbolic algebra package, these expressions could be manipulated, extended, and output as *more* optimized C codes (e.g., using SymPy/NRPy+, thus speeding up gravitational wave data analysis).

This repository aims to provide a trusted source for validated Post-Newtonian expressions useful for gravitational wave astronomy, using the open-source SymPy computer algebra system, so that expressions can be output into Wolfram Mathematica or highly optimized C codes using the SymPy-based NRPy+.

Available from: https://nbviewer.jupyter.org/github/zachetienne/nrpytutorial/blob/master/NRPyPN/NRPyPN.ipynb

The Black Hole Perturbation Toolkit has a similar repository within the context of pN expansions in the large mass ratio regime. The Post-Newtonian Self-force package is a Mathematica interface to the repository, but there is a desire within the community to have something which is tool-agnostic. There have also been discussions about extending the scope to cover more generic post-Newtonian series. It might make sense to coordinate those efforts with this one.