xAct Tensor Computer Algebra

Hello everyone! I want to perform calculations for an abstract metric, but in the specific form: g[-a

Hi Thomas, thanks for the detailed reply. I used TableauSymmetric for my three simplest tensors and

Hi, I am a new xAct user who is finding some troubles with the following: I am working with a

Dear all, in principle FieldsX should work well for these types of computations, section 4.5 in the

Thank you very much, Jose, that helped a lot. Regards, Hawre On Sun, Sep 3, 2023 at 10:53 PM Jose

Hi Narasimha, Good to hear you found a solution! I have also been working on GWs in theories of

Hi Ashiqul, I'd recommend that you look at the example 3.6.11 in the xCobaDoc file. There you see

Hi! I traced the problem to IsIndexOf[prime[X[i]], i] gives False. I think Jose should take a look at

Hello, An odd form wedged with itself always vanishes; but while an even form *may* vanish when

Hi all, I am trying to represent Maxwell's Lagrangian in terms of gauge fields. I know how to

Thanks. On Sunday, September 3, 2023 at 2:28:27 PM UTC-7 Jose wrote: Hi, CTensor does not have any

Hi, A new package for xAct has been under development for some months and, following a talk at Tartu

Hi, I attach a new version of your notebook with some suggested operations. I think the key operation

Hi, I don't understand what you mean. Can you provide an example of a CTensor metric with actual

Dear Narasimha, please find attached the changed notebook. What you were missing is: - if you work in

Excellent, thanks so much! One more thing: what would be the canonical way to expand out/simplify

Hi Jose, Thanks a lot for your reply. Embarrassingly, I don't appear to understand how to use

Hi, can anyone tell me how can I calculate komar conserved quantities for kerr newman black hole?

Hi! You just need to specify a generating set for your symmetries. The cyclic symmetry is generated

Hi, xPert has no support for multiple perturbations. You can define different perturbations of the

Hi, Try using IndexCollect: << xAct`xTensor` DefManifold[M, 4, {a, b, c, d, e, f}] DefTensor[{

Hi, Sorry to necro, but I had to shelf that project, and just got to some time to work on it again

Hi Charles, Google Pages service which hosted xPrint website has been terminated by Google in mid

Hi, Please, please, always send full codes. It's impossible to know what you did before and that

Hi, It's difficult to help without more information. Can you send me (privately if you prefer) a

Hi, Yes, I'll fix this. Thanks all for the reports and suggested fix. Cheers, Jose. On Saturday,

Hi, The computation you performed, and that was attached in your notebook, is the perturbation of the

You can look at "Variation of Lagrangian with xPert and VarD" notebook in the xAct examples

Thanks for pointing out this. My M1 MacBook Air do not install rosetta and I meet the same problem.

Hello, I download the xAct_1.2.0.tgz and run xattr -c xAct_1.2.0.tgz to clear all attributes, and