Does anybody know about a specific package for handling tensors? Consider, for example, a contraction of the type
$g^{\alpha\beta}g^{\gamma\delta}R_{\alpha\mu\gamma\nu}=R^{\beta\;delta}_{\;\mu\;\nu}$
Handling the indices in the mixed tensor in the r.h.s. appears particularly annoying and the result is not aesthetically satisfying. Any suggestion?