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bimetric 3+1 Exact Computations

bimEX is a Mathematica package making use of xAct. It provides a ready-to-use working framework in which one can manipulate the abstract bimetric equations in the 3+1 formalism, and compute them for arbitrary metric ansätze.

Getting started

To use bimEX, download the file bimEX.m and load it into a Mathematica notebook as,


This repository also includes

  • The source file bimEX.nb
  • The working example bimEX_Working_Example.nb
  • Two notebooks bimEX_Decomposition_Lists_Loader.nb and bimEX_Decomposition_xAct_Loader, which are complementary to the working example
  • Two packages Decomposition_Lists.m and Decomposition_xAct.m, generated by bimEX_Working_Example.nb.
  • The file
  • The file

The notebook bimEX_Decomposition_Lists_Loader.nb loads the file Decomposition_Lists.m, whereas the notebook bimEX_Decomposition_xAct_Loader loads the file Decomposition_xAct.m.


To run bimEX, you need to install Mathematica 11.0 (or later) and the xAct bundle.


The documentation is provided in the form of Usage messages in Mathematica. They are accessible by typing


in the Mathematica notebook. We also refer to the associated paper for additional information.

Testing the package

To test the package, do the following:

  • Put the files bimEX.m and the notebooks bimEX_Working_Example.nb, bimEX_Decomposition_Lists_Loader.nb and bimEX_Decomposition_xAct_Loader in the same folder
  • Open bimEX_Working_Example.nb and evaluate the notebook. This generates the two .m files Decomposition_Lists.m and Decomposition_xAct.m
  • Open bimEX_Decomposition_Lists_Loader.nb and bimEX_Decomposition_xAct_Loader in separate Mathematica's kernels, and evaluate them.


Please see the file


  • Francesco Torsello



A copy of this license is included in the file


It is a pleasure to thank Mikica Kocic for all the support and help he gave me during the development of bimEX.