论文标题
XPPN：使用XACT进行Mathematica的参数化后牛顿后形式主义的实现
xPPN: An implementation of the parametrized post-Newtonian formalism using xAct for Mathematica
论文作者
论文摘要
我们为计算机代数系统Mathematica提供了一个软件包，该软件包实现了参数化后纽顿（PPN）形式主义。该软件包名为XPPN，是建立在广泛使用的张量代数套件XACT上的，尤其是其中的软件包Xtensor。 XPPN的主要特征是提供功能，以执行张量的适当$ 3+1 $分解，以及所谓的速度订单中的扰动扩展，这是PPN形式主义中的核心任务。此外，XPPN实施了PPN形式主义中出现的数量的各种规则，这些规则有助于扰动地求解任何重力度量理论的现场方程。除了riemannian的几何形状外，还实施了远程和对称的远程几何形状。
We present a package for the computer algebra system Mathematica, which implements the parametrized post-Newtonian (PPN) formalism. This package, named xPPN, is built upon the widely used tensor algebra package suite xAct, and in particular the package xTensor therein. The main feature of xPPN is to provide functions to perform a proper $3+1$ decomposition of tensors, as well as a perturbative expansion in so-called velocity orders, which are central tasks in the PPN formalism. Further, xPPN implements various rules for quantities appearing in the PPN formalism, which aid in perturbatively solving the field equations of any metric theory of gravity. Besides Riemannian geometry, also teleparallel and symmetric teleparallel geometry are implemented.
