Load the package and configure

Invar` requires the free package xTensor` to perform the underlying tensor and permutation manipulations. It can be downloaded from
    http://metric.iem.csic.es/Martin-Garcia/xAct/
For a single-user installation under Linux the file xAct_<version>.tar.gz must be unpacked in the directory $Home/.Mathematica/Applications giving a directory xAct. Then unpack the Invar.tar.gz file inside the xAct directory.  We assume that configuration in the following. See the Readme file for more information, including installation instructions for other operating systems.

We first load the Mathematica kernel, and the xTensor` package from the default directory

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Note: When loading xTensor` inside a Windows environment, a black DOS-like window may appear. This is caused by the C link used to speed computations and should not be closed.

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Then we read the Invar` package.

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<<xAct`Invar`

We see that, in Mathematica 5, the MathKernel takes only 2 Mbytes, xTensor` takes 9 Mbytes, and Invar` takes 41 Mbytes:

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Note the structure of the ContextPath. There are six contexts: xAct`Invar`, xAct`xTensor`, xAct`xPerm` and xAct`ExpressionManipulation` contain the respective reserved words. System` contains Mathematica's reserved words. The current context Global` will contain your definitions and right now it is empty.

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Created by Mathematica  (May 16, 2008)