xTras: a field theory inspired xAct package for Mathematica
|Author:||Teake Nutma © 2012-2013 under GPL.|
Online documentation ▪ Release history ▪ Source code
xTras is a field-theory inspired add-on package for xAct. Some of the extra functionality it brings is:
- Generating a list of all contractions of a given tensorial expression. >>
- Generating lists of dimensional dependent identities, e.g. the vanishing of the Weyl tensor in D=3. >>
- Making any tensorial expression traceless. >>
- Computing equations of motion of monomials of Riemann tensors. >>
- Symmetrizing covariant derivatives. >>
- Perturbations around AdS spaces. >>
- Killing vectors. >>
- Young symmetrizers and projectors. >>
- Solving linear systems of tensorial equations. >>
Latest release: xTras version 1.4.2 (2014-10-30)
- Added RicciToRiemann.
- Added KretschmannToRiemann.
- ToRiemann also converts rank-2 curature tensors if the curvature relations are not enabled.
- ToRicci also converts contractions of Riemann tensors to Ricci tensors even if the curvature relations are not enabled.
The full release history can be found here.
xTras is not a stand-alone package. It depends on various packages contained in the main xAct bundle. In order to install xTras, do the following:
- Download and install the latest main xAct bundle, which contains xTras, from here.
- Download the Invar database and install it (instructions).
- Download the latest xTras zip file.
- Follow the installation instructions.
Q: FullSimplification doesn't work and returns the RInv::nodatabase message. What's wrong?
A: FullSimplification needs the Invar database to work. Install it from http://xact.es/Invar/ and the message should go away.
Q: I don't see any built-in documentation in Mathematica, nor does the xTrasHelp command work.
A: xTras only got built-in documentation from version 1.2 onwards. Installing the latest version should fix this.