Timeline for answer to What's an efficient way to relabel multiple dummy indices in a large expression? by Ben Niehoff
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| Apr 9, 2017 at 14:19 | vote | accept | Jonathan Rayner | ||
| Feb 27, 2017 at 22:54 | comment | added | Ben Niehoff | I'm a little confused what you're asking. All I've done in this example is write out your expression in the syntax expected by xAct. I haven't told it which dummy indices to rename, it figures that out on its own. (The DefManifold statement is just saying that the indices listed belong to a manifold which I've called M; you need to define a manifold before you can define tensors on it). The code may make more sense if you read a bit of the xTensor manual. It does require you to be a bit more methodical, and define things like manifolds and tensors in advance. | |
| Feb 27, 2017 at 22:22 | comment | added | Jonathan Rayner | Is there are way to use this package to perform the calculation without specifying the variables that will be replaced a priori, simply to replace repeated variables? For example it seems like it would be unwieldy to specify the variables when used on the longer input I posted. Alternatively, I could just apply march's code commented under the OP to get a common set of variables and then use this package if what I'm asking isn't possible. | |
| Feb 27, 2017 at 15:41 | history | edited | Ben Niehoff | CC BY-SA 3.0 |
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| Feb 27, 2017 at 15:40 | history | edited | Jason B. | CC BY-SA 3.0 |
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| Feb 27, 2017 at 15:28 | history | edited | Ben Niehoff | CC BY-SA 3.0 |
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| Feb 27, 2017 at 12:19 | history | answered | Ben Niehoff | CC BY-SA 3.0 |