Has anybody used tensors in Mathematica? How to properly work with them? I find Mathematica not very friendly in this field, as I am defining my own functions for lowering & raising indices, multiplication and stuff like that. I was wondering if there is some good package or a secret way to use tensors more properly in Mathematica. For example, I need tensor analysis for general relativity kind of calculations.
Mathematica 9 contains some functionality for working with symbolic tensors.
Here's a list of packages in no particular order, that may have some functionality for working with symbolic tensors.
See also the Wikipedia page on Tensor Software.