From abstract tensor calculation to working with components

[Nail Khusnutdinov]

Hi,

I have used just one month the xAct`xTensors package, many thanks for this package. I think that it is a single package that works with abstract tensors.

I have a simple question. After long calculations with abstract tensors, I'd like to use obtained expressions but now in components. How can I quickly define components of all abstract tensors and make calculations obtained expressions in components? There is package xCoba, but I'd like to start components calculus just after abstract calculations. Could you show me a simple way to do this?

Nail

[Jose]

Hi,

I think the simplest way to switch from abstract computations to component computations is to construct CTensor objects with component information and then replace the abstract tensors by these objects. To work with CTensor objects you do need to load xCoba. The xCoba package is an extension of xTensor, and not an independent package.

See for example the notebook xPert_and_xCoba.nb in

https://groups.google.com/g/xact/c/BFErfGuSjjg/m/eJD76eLoAwAJ

for some suggestions of how this type of replacement works, including replacement of the metric, which is the nontrivial part.

Cheers,

Jose.

[Nail Khusnutdinov]

Hi Jose,

Thank you for your help. Will try to use this file to learn.

Best,

Nail

вторник, 2 июля 2024 г. в 22:13:58 UTC-3, Jose: