############################################################################
#
# Readme file of the Invar (version 2) package - Installation Instructions
#
# Language: Mathematica 5.0 or later. (There is a version for Maple)
#
# Description: The Invar tensor package is a fast manipulator of generic
#   scalar polynomial expressions formed from the Riemann tensor
#   and its covariant derivatives. The package can maximally simplify
#   any polynomial containing tensor products of up to 7 Riemann
#   tensors or objects with up to 12 derivatives of the metric.
#   It has been implemented both in Mathematica and Maple algebraic systems.
#
# Developers: Jose M. Martin-Garcia and David Yllanes
#             Instituto de Estructura de la Materia (IEM), CSIC, Madrid.
#                   and
#             Renato Portugal
#             Laboratorio Nacional de Computacao Cientifica (LNCC)
#
# Contact and bug report: garcia@iap.fr
#
############################################################################

The authors kindly ask that researchers who have used the package cite
references describing it.

INSTALLATION INSTRUCTIONS

In order to run the Mathematica version of the package Invar you
need to have first:

1) Mathematica, at least version 5.0.

2) The xAct software, including Invar and other packages it needs.
   They can all be downloaded as a single file
   (the current version is 0.9.9):
 
   Linux/Unix/Mac users:
      http://metric.iem.csic.es/Martin-Garcia/xAct/xAct_0.9.9.tgz
   Windows users:
      http://metric.iem.csic.es/Martin-Garcia/xAct/xAct_0.9.9.zip

3) The Invar database of identities:

      http://metric.iem.csic.es/Martin-Garcia/xAct/Invar/Riemann.tar.gz

The file xAct_0.9.9.tgz (or .zip) must be unpacked in one of the
directories prepared for Mathematica addons. We recommend,
for single-user installations:

  Linux/Unix:
      $HOME/.Mathematica/Applications/
  Windows:
      C:\Document and Settings\<user>\Application Data\Mathematica\Applications\
  Mac:
      /Users/<user>/Library/Mathematica/Applications/

or for system-wide installations:

  Linux/Unix:
      /usr/share/Mathematica/Applications/
  Windows:
      C:\Documents and settings\All Users\Application data\Mathematica\Applications\
  Mac:
      /Library/Mathematica/Applications/

Everything will be placed in a directory xAct under Applications/.
For further installation hints see the "Installation Notes" at the
xAct webpage.

Finally untar the database Riemann.tar.gz inside the xAct/Invar/ directory.
There are additional files for the database in the file
Riemann_expand4order12.tar.gz. This must be untarred in the directory
xAct/Invar/Riemann/ .

That means that the structure should be something like

.../Applications/xAct/xTensor.m
                     /xPerm.m
                     ...
                     /Invar/Invar.m
                           /init.m
                           /InvarDoc.nb
                           /Riemann/1
                                   /2
                                   ...
                                   /6_4
                           ...

At this point, it should be possible to execute everything in the
InvarDoc.nb file. An example in section 7 (In[230]) requires the use
of the extended database Riemann_expand4order12.tar.gz.

SPECIAL NOTES FOR WINDOWS USERS:

1) The external executable of the xPerm package is required to speed up
   the computations. It works for all Mathematica versions under Linux and
   Mac, but only for Mathematica 6.0 under Windows.

2) A DOS-like window may appear when loading this executable. Do not
   close it; it can be minimized at the task bar.

3) Some Windows users have reported the file .../xAct/Invar/init.m being
   empty. This file must be identical to .../xAct/Invar/Invar.m. If your
   init.m file is empty copy Invar.m onto init.m