[xCoba] Inconsistency when multiplying CTensor object by scalar

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sam.d...@gmail.com

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Apr 14, 2026, 11:01:15 AM (8 days ago) Apr 14
to xAct Tensor Computer Algebra
Hi all,

I am having an issue when multiplying a CTensor object with a scalar that has defined label indices. When these two objects are multiplied together, the scalar stays sitting outside the CTensor object instead of being absorbed into it, that is:

scalar[LI[1]]*CTensor[...] -> scalar[LI[1]]*CTensor[...]

This is in contrast to a scalar without label indices which does get absorbed into the CTensor object:

scalar[]*CTensor[...] -> CTensor[scalar[]*...]

I have attached a notebook demonstrating this and am using xAct 1.3.0.

Is there a way to make it so that scalars with label indices have the second behaviour rather than the first? I am working with some long expressions featuring sums of products of labelled scalars with CTensor objects and would prefer not to re-expand everything using ToBasis and then re-collect everything again.

Many thanks,
Sam
xCoba CTensor Scalar Label Bug MWE.nb
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