- 27 January 2013: Version 1.0.5 of xAct released:
(Thanks to Teake Nutma and Cyril Pitrou for much help with this release!)
- xAct is now compatible with Mathematica 9.
- New package xPand, by C. Pitrou, X. Roy and O. Umeh, for cosmological perturbation theory around homogeneous spacetimes.
- The xTras package is now included in the xAct distribution.
- Functions Permute and PowerPermute respectively renamed PermProduct and PermPower in xPerm.
- Improved some basic functionality in the area of induced metrics in xTensor.
- Started new notation for tensors by components in xCoba.
- 5 May 2012: Version 1.0.4 of xAct released:
(Thanks to Thomas Bäckdahl for much help with this release!)
- Yet another bug-fix version.
- Package TexAct excised from xTensor and SymManipulator to handle conversion to Tex output.
- Package AVF now included in the xAct distribution.
- Added command xTension to provide hooks to modify the action of the Def/Undef commands.
- The SymManipulator package can now do irreducible decompositions of spinor expressions.
- Added partial support for SeriesData expressions (everything but ToCanonical).
- 25 October 2011: Version 1.0.3 of xAct released:
- This is another bug-fix version.
- Updated Spinors for publication.
- Added messages reporting non-standard configuration in some packages.
- 15 July 2011: Version 1.0.2 of xAct released:
- This is mainly a bug-fix version.
- Release of the first public version of SymManipulator, a package
contributed by T. Bäckdahl to handle symmetrized tensors.
- Option FormatBasis for DefBasis and DefChart in
xCoba to help in the formatting of all vectors/covectors of a basis.
- 17 April 2011: Version 1.0.1 of xAct released:
- xAct is now compatible with Mathematica 8.
- Various bug fixes and extensions. See the respective .History files.
- Added support for conformal transformation using the option ConformalTo of
- Improved commands TexPrint and TexBreak using code provided by
T. Bäckdahl and B. Wardell.
- 30 September 2010: Versions 1.0.0 of xTensor and Spinors released:
- Added new commands TensorD/TensorDerivative for alternative treatment of
derivatives. See the example notebook
- Added new form of delta, the "superdelta", with groups of indices of arbitrary
symmetry. Added a symmetrizer Sym head.
- Tensors with non-atomic heads are now allowed.
- Improved treatment of "frozen" (non-first) metrics.
- Many small improvements and fixes. See
xTensor.History for full details.
- The main xAct webpage is now
- 10 January 2010: Version 0.9.9 of xAct rereleased with more bug fixes.
- 24 November 2009: Version 0.9.9 of xAct rereleased with some bug fixes.
- 9 September 2009: Version 0.9.9 of xAct released, on the same day of the celebration honoring the 65th birthday of Prof. Jesús Martín. This version of xAct will be nicknamed "Chus" after him.
- Note that now the xAct.tar.gz bundle contains all packages.
- Documentation of Spinors enlarged and rearranged.
- xCoba has a command MetricCompute to construct sequentially components of curvature tensors. See file KerrNewmanExamples.nb.
- Added Leibnitz operator, following Jan's suggestion.
- Support for LaTeX printing of tensor expressions, with commands Tex, TexPrint and TexBreak.
- Safer code for NoScalar.
- Fixed some problems with VarD.
- 1 December 2008: Version 0.9.1 of Spinors released.
- Added command IrreducibleDecomposition decomposing
spinors in their symmetric-tracefree parts.
- The package now handles spacetimes with torsion.
- 23 November 2008: Version 0.9.8 of xAct released.
- Transition version with many small improvements in xTensor:
- Better treatment of 1-dimensional spaces.
- New functions for ADM-like decompositions: commands
GaussCodazzi, ToInducedDerivative and
- Fixed a number of problems with variational derivatives.
- New command Cyclize, similar to Symmetrize, etc.
- Faster manipulations of products of delta's.
- Added option Method in ToCanonical, to choose
how to deal with metric-incompatible derivatives.
- 11 August 2008: Spinors released.
- Requires updating xAct to 0.9.7.
- There is a full new package, Spinors, developed
in collaboration with Alfonso García-Parrado, for
computations with spinors on four-dimensional Lorentzian
manifolds, including spinor-tensor translations. The
doc file SpinorsDoc includes as examples the full
Newman-Penrose and Geroch-Held-Penrose formalisms, developed
from scratch there. Package released with version number
0.9.0. Please send us feedback.
- Motivated by the use of an antisymmetric metric in
Spinors, the treatment of symmetries of the
delta and Basis tensors has been modified.
Now they have the symmetries of the corresponding metric,
or no symmetry if there is no metric available. This does
not affect the standard case with a symmetric metric.
- 30 June 2008: Version 0.9.6 of xAct released
- Version required by update of xPert.
- xPert rewritten and much improved. Version 1.0.0
- xTensor updated to version 0.9.6. Introduced
commands Implode and Explode to transform between
derivatives of tensors and tensors, and viceversa.
- xCoba updated to version 0.6.4. Treatment of
determinants fully reorganized, now without absolute values,
to handle complex changes of bases, like in Newman-Penrose
calculus. New commands RuleToSet and SetToRule.
- xCore has now a documentation file.
- 16 May 2008: Version 0.9.5 of xAct released
- xTensor has lots of small improvements.
Now there are variational derivatives and more powerful
versions of IndexCoefficient and IndexCollect.
Metric-compatible connections with torsion.
Much internal cleaning.
Unique ultraindices have been removed.
- Created Google group for discussion on the xAct
packages. Please register (see left panel in this page)
and report bugs and comments using it.
- I have been invited to spend 6 weeks this summer at
Wolfram Research Inc. as "visiting scholar". Please, help
to improve xAct before I get there on July 22nd.
- 5 March 2008: Version 1.0 of xPerm released
- Version for publication!
- The option MathLink has been transferred from
xTensor to xPerm. In particular,
it is now an option of CanonicalPerm instead
of an option of ToCanonical.
xTensor updated to 0.9.4 and Invar
updated to 2.0.2 for compatibility.
- 8 February 2008: Version 2.0 of Invar released
- Major update of the system:
- Now Invar also handles differential invariants
up to 12 derivatives of the metric and dual invariants
up to 8 derivatives of the metric.
- The new database contains more than 600 000 equations
- 6 November 2007: Version 0.9.3 of xAct released
- Transition version:
- The executable xperm has been finally compiled
under Windows using cygwin. Only for
- Reference Guide for xTensor
completed, as well as the individual help pages for its
332 reserved words.
- Function TraceDummy
introduced. Highly efficient, but still under testing.
- Further analyses and checks of compatibility between
xAct and Mathematica 6. See the
- 15 August 2007: Version 0.9.2 of xAct released
- This is a major update of the system:
- Package xCore created.
- xPerm now efficiently handles component indices
and several vbundles simultaneously.
- xTensor has several new functions: IndicesOf,
SeparateMetric, SplitIndex and others. Extended concept
of InertHead. Cut and paste now possible!
- xCoba has many new capabilities, including full
implementation of symmetries in the manipulation of
components, new algorithms for efficient storage, new
representation of component indices (allowing any integer),
- More than 300 pages of documentation.
- Full compatibility with Mathematica 6.0, and still with
all 5.* versions.
- There is a new webpage!