extension of admissible indices conventions for tensors with indices

[LBrunswic]

Following a request from Jonathan Thornburg we include the following indices convention which is standard but up to now not implemented.

X_{ab} := R<sup>c{}_a{}</sup>d{}_b \bar{h}_{cd}

CC: @egourgoulhon @sagetrac-mbejger

Component: manifolds

Keywords: tensor, tensor_with_indices, contraction, symmetries

Author: Léo Brunswic

Branch/Commit: u/gh-LBrunswic/extension_of_admissible_indices_conventions_for_tensors_with_indices @ 93ec3e7

Issue created by migration from https://trac.sagemath.org/ticket/29099

[LBrunswic]

Description changed:

--- 
+++ 
@@ -1 +1,3 @@
+Following a request from Jonathan Thornburg we include the following indices convention which is standard but up to now not implemented.
 
+`X_{ab} := R<sup>c{}_a{}</sup>d{}_b \bar{h}_{cd}`    

[LBrunswic]

Branch: u/gh-LBrunswic/extension_of_admissible_indices_conventions_for_tensors_with_indices

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

93ec3e7

Bug correction and updated documentation and tests

[sagetrac-git]

Commit: 93ec3e7

[mkoeppe]

comment:5

Batch modifying tickets that will likely not be ready for 9.1, based on a review of the ticket title, branch/review status, and last modification date.

[egourgoulhon]

comment:6

See https://sympa.obspm.fr/wws/arc/sagemanifolds.list/2020-01/msg00003.html
and https://sympa.obspm.fr/wws/arc/sagemanifolds.list/2020-06/msg00000.html for discussions and issues relative to this ticket.