#15916: Tensors on free modules of finite rank
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Reporter: egourgoulhon | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.4
Component: linear algebra | Resolution:
Keywords: free module, | Merged in:
tensor, tensor product | Reviewers:
Authors: Eric Gourgoulhon, | Work issues:
Michal Bejger | Commit:
Report Upstream: N/A | d8f518ff48c8be2ea73f2b51e067af9e6c87b4bf
Branch: | Stopgaps:
u/egourgoulhon/tensor_modules |
Dependencies: |
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Comment (by vbraun):
Doctest coverage: `sage -coverage src/sage/tensor/`
I don't think the string notation is very user friendly,
`A['^{ab}_{cd}']*B['^d_a']` looks more like line noise. How about
recognizing symbolic variables and the built-in function `any` as special:
sage: var('a, d')
sage: A[a, any, any, d] * B[d, a]
Or, perhaps better in the long run: Define your own index class that knows
about whether indices are upper or lower. Then we can also check that you
don't contract two upper indices, and/or automatically insert the metric
there:
sage: a, b, c, d = A.indices()
sage: a
Upper index
sage: A[a, b, c, d] * B[d, a]
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Ticket URL: <http://trac.sagemath.org/ticket/15916#comment:20>
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