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.
- Symmetrizing covariant derivatives.
- Computing equations of motion of monomials of Riemann tensors.
- Perturbations around AdS spaces.
- Killing vectors.
- Easy access to the database of the Invar package.
- Young symmetrizers and projectors.
- Solving linear systems of tensorial equations, both for constant variables (SolveConstants) and for tensors (SolveTensors).
Installing the package in Mathematica
If you just want to run the xTras package as a end user, download the compiled zip file from http://www.xact.es/xtras, unzip, and follow the instructions.
Configuring the project in Wolfram Workbench
If you want to set up xTras in Workbench to edit the code, you'll have to take a few extra steps. This assumes you already have a Workbench environment up and running.
- Download and install the complete xAct bundle where Mathematica can find it,
but remove or rename the
- Checkout or download the xTras source, and import it in Workbench.
- Edit the file
buildfiles/main.xmlsuch that properties in the section
Machine-specific config variablesmatch your setup.
Running notebooks for testing code is the same as usual, but deploying and building the documentation is not,
due to xTras' unusual structure (it's a sub-package for xAct, which isn't supported out-of-the-box in Workbench).
Deploying can be done by running the
deploy target in the
buildfiles/main.xml file, and building the
documentation by running the
documentation target. The complete project can by build by running the
all target. Be sure to set the
Runtime JRE to
Separate JRE in the
JRE tab of the Eclipse external
tools configuration of the Ant targets.
The unit tests can be run by running the
tests/TestSuite.mt as a Mathematica Test.
The Workbench project is structured into the following directories:
buildfiles/ Ant files for building the docs, changelog, and the distributable zip. notebooks/ Mathematica *.nb files to run and / or test code. tests/ Unit test files. xAct/ The actual code of the package. xTras/ Documentation source.