Hi everyone, I am pretty new to xAct, so maybe this question is really simple. I'm doing a project for which I am using a perturbed Schwarzschild

How can this be done > while enforcing the correct rules, eg that the anisotropic stress is > traceless? > > Thank you for any help! > > Best wishes, > > Theo >

Hello, Identity (3.6) from the attached article 'Normal forms for tensor polynomials. I. The Riemann tensor', is not getting implemented by

For clarity purposes, I have formulated my problem/question into the attached PDF file. I'd appreciate any and all help!

transverse-traceless gauge on metric > perturbations and I can get it to work sometimes only if I have a specific > order of operations. > > If I first perturb the equations

transverse-traceless condition on perturbations to the equations of motion. Here is my setup: DefManifold[M, 4, IndexRange[a, q]] DefMetricPerturbation /. Options@DefMetric

Gamma-traceless condition (spinor > > tensor) on Xact, the program understands the condition, but in other > > expressions he don't implement this condition. Someone

, one traceless and one not. But that leaves me with the following puzzle: as you correctly observe, in 4D the Lagrangian-density L(U) for U^{ab} can be made conformally-invariant

Jose, thanks for your response and sorry for the version confusion: I am using xAct xTensor v.1.1.4. I've now attached a notebook with comments

is totally traceless. > > To do this I am using: > > DefTensor[ttensor[-\[Mu], -\[Nu], -\[Lambda]], M, > Antisymmetric[{-\[Nu], -\[Lambda]}]] > > AutomaticRules

the transverse traceless gauge condition while I am evaluating certain expressions in terms of metric perturbations while using xPert. How can I accomplish this. I want to impose

Hi, I am trying to use xPand to compute vector perturbations for a generalized action and have encountered a problem using ToxPand on a Projected

I used the commands from my previous post in the notebook you find attached. I hope this helps and explains a bit what they do and how you could use

I'd like to check some results I obtained by using the VarD command, but the results I obtain disagree. Under xCoba I define a Lagrangian *L* and

rules for traceless divergence-free:*) >>> (**************) >>> txyz=Sequence[t[],x[],y[],z[]]; >>> cTFRules = MyMakeRules[C11[txyz], -C22

Ct a traceless tensor, >>>>>> Cv a divergence-free vector, fa scalar, g_ij the 3D background metric, and >>>>>> y_|ij = cd[i][cd[j][y]]

an a traceless tensor). I create a matrix of the >>> form the metric shall have. Then, I set this matrix to be the metric by >>> using: >>> >>> metric

Dear B, I have a file about FG expansion. I found it last in the Internet but I forgot the website and the author of this file. Thus I could not give

Dear Daniel, I attach to this message a notebook implementing such a decomposition. Regards, Alfonso. On Tue, 2019-07-02 at 01:12 -0700, 'Daniel

(ie traceless, transverese and symmetric) and this I can do. After I do this I have to contract this tensor with the Riemann tensor and expand the expression just in the metric to first

Hi Leo, it works great, thanks for the help! On Monday, 6 November 2017 17:13:32 UTC+1, Albin Nilsson wrote: > > I am trying to define a new

I'm attaching a notebook showing how I did it a few years ago. The tricky part was working out the perturbations of quantities involving

any > traceless matrix A is such that Tr[AAA]=0. This is true only in dim=2 and > wrong in dim=3. > The first method is the fastest one, but it fails to use the fact that > there

symmetric transverse traceless rank-2 tensor H_{\mu \nu}. How can one tell Mathematica that H_{\mu \nu} is symmetric, transverse and traceless? I mean, I use bgRules=SymmetricSpaceRules

E_ij is traceless, this perturbation conserves the determinant of the metric, and you never have to care about the Lagrangian of matter. This is what has been done by Jonghee Kang. I

E_ij is traceless and transverse). The usual gauge choices in xPand do not consider this exponential form so I had to build the rule and not use SplitMetric, but this is very easy. You

Dear All, I'm currently dealing with a transverse traceless decomposition. What I'm doing is

Hi, I would like to define a symmetric second rank tensor which is also traceless. The usual syntax

Dear all, Is it possible to define traceless tensors in xAct? Ie specify that a tensor is traceless?

trace and traceless parts) to make it unique. Yes, this problem is difficult even to define. Unfortunately there are problems with the current code also without contractions in the