Hello ! I don't know anything about mathematical or xAct, I just want to calculate the tidal

Hello there, I noticed a weird behaviour of xTensor Implode function with densities. Indeed, the

I installed a new binary -- that worked - Thanks On Sunday, April 19, 2026 at 7:54:24 PM UTC-4 James

Hi Héloïse, These calculations can quickly become very messy so it's good to simplify the

Hi, can you post the actual errors you get and describe what you did to compile it ? Best, Alfonso.

This is an issue related to the increased anti-malware protections that Apple has added to MacOS over

Dear Jose, sorry for bringing back this very old thread. I faced the same problem as Geoffrey and

Hello Nat, Welcome to the great land of Mathematica! I've actually just released an xAct package

Hello xAct community, I want to share a new package: xAlpha. This uses xPand to compute nonlinear

Hi there! I'm working with antisymmetric tensors. Let us call it F_ab for now. In the middle of

That worked thanks! On Thursday, April 30, 2026 at 5:21:14 PM UTC-4 Juan Margalef wrote: You have to

Hi all, I am having an issue when multiplying a CTensor object with a scalar that has defined label

Several comments: 1. Instead of CommutativityOfProduct -> None use CommutativityOfProduct ->

UseDimensionStart[] forces certain expressions to be zero when applying ToCanonical. It checks if

Dear Juan, I will have to take a closer look then. A huge thanks for your help! Cheers, Nils Le

Hi Alejandro, I suspect there is some inconsistency somewhere about the use of upper/lower components

Hi everyone, I am very new to xAct and was trying to reproduce the results in Eqs. C.23 to C.25 of

Hi AC, We would need a bit more information to help you. Provide a minimal working example of the

Hi, I think the derivative you are looking for is PDch[{0, -ch}][met[-b, -c]]. That's the

Hi Ehsan, If you want to perform assymptotic analysis using the coordinate r, you need to express

The red parentheses represent the Scalar head, which means that the indices inside are disconnected

Dear Juan, Thank you very much for your assistance! Best Petr On Thursday, February 12, 2026 at 12:45

It's working. Great thanks! Petr On Thursday, February 5, 2026 at 10:53:08 PM UTC+3 Juan Margalef

Thank you! On Tuesday, January 20, 2026 at 2:26:39 PM UTC+3 Yuqian Zhao wrote: In general, you should

Hi Thomas! Thank you for the quick response. I now see my elementary mistake. About the covariant

Dear Armando, Thanks for your reply! Can you please comment on the three points below? 1) You say

Hi everyone, Can you help me? I'm working with a metric: DefManifold[M, dd, IndexRange[a, s]]

Hello, I am trying to write a simple notebook to compute the Kubo formula in an isotropic background.

Dear Thomas, Now it works! Thank you so much for your help! It turns out that perhaps either I forgot

The last time I used xAct in Mathematica 14.3 was at the beginning of November. Now, I had to check