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xAct Tensor Computer Algebra
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Gwyne Druite
,
Jose
3
Jul 15
Mathematica tutorials of ideos of the xAct 20 Year Celebration
Yes, I want notebooks of these talks. I would be very grateful if you could provide these notebooks
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Mathematica tutorials of ideos of the xAct 20 Year Celebration
Yes, I want notebooks of these talks. I would be very grateful if you could provide these notebooks
Jul 15
Claire
Jul 12
Second order perturbations
Hello, I am expanding a Lagrangian to second order in perturbations, and I'm unsure about the
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Second order perturbations
Hello, I am expanding a Lagrangian to second order in perturbations, and I'm unsure about the
Jul 12
Haruhi Suzumiya (LaplaceSpell)
,
Leo Stein
3
Jul 7
Calculate Lie derivative in xCoba
OMG this is such a nice and clear answer! I have solved my problem ! Thanks Leo ! Sincerely, Haruhi
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Calculate Lie derivative in xCoba
OMG this is such a nice and clear answer! I have solved my problem ! Thanks Leo ! Sincerely, Haruhi
Jul 7
Jack Smithe
Jul 4
Hamiltonian Density from Lagrangian Density
Does anyone know if there is a function in xAct that can output the Hamiltonian density for a field
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Hamiltonian Density from Lagrangian Density
Does anyone know if there is a function in xAct that can output the Hamiltonian density for a field
Jul 4
Álvaro García Cendal
Jul 4
Perturbation EoM in a particular background using xCoba
Hi. I'm a new user of the xAct environment. I'm trying to compute the equations of motion of
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Perturbation EoM in a particular background using xCoba
Hi. I'm a new user of the xAct environment. I'm trying to compute the equations of motion of
Jul 4
Nail Khusnutdinov
,
Jose
3
Jul 3
From abstract tensor calculation to working with components
Hi Jose, Thank you for your help. Will try to use this file to learn. Best, Nail вторник, 2 июля 2024
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From abstract tensor calculation to working with components
Hi Jose, Thank you for your help. Will try to use this file to learn. Best, Nail вторник, 2 июля 2024
Jul 3
Asghar Muhammad
,
Jose
2
Jul 2
Equation of Motion for f(G) gravity
Hi, I'd recommend to start by having a look at what has been discussed in other threads about f(G
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Equation of Motion for f(G) gravity
Hi, I'd recommend to start by having a look at what has been discussed in other threads about f(G
Jul 2
Nail Khusnutdinov
,
Jose
3
Jul 1
PrintAs forbids ContractMetric
I tried to repeat it but without success. I remember that it happened, maybe I was wrong. At the
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PrintAs forbids ContractMetric
I tried to repeat it but without success. I remember that it happened, maybe I was wrong. At the
Jul 1
Miguel Yulo
,
Jose
3
Jul 1
Optimizing Calculation of the Squared Weyl Tensor on xCOba
Hi, Thank you for clarifying this. Also appreciate you rewriting the notebook for the computation. I
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Optimizing Calculation of the Squared Weyl Tensor on xCOba
Hi, Thank you for clarifying this. Also appreciate you rewriting the notebook for the computation. I
Jul 1
Ron Riegert
,
Jose
3
Jul 1
Contra- vs. Covariant Definition of Tensors?
Jose, thanks for your response and sorry for the version confusion: I am using xAct xTensor v.1.1.4.
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Contra- vs. Covariant Definition of Tensors?
Jose, thanks for your response and sorry for the version confusion: I am using xAct xTensor v.1.1.4.
Jul 1
Hudson Vinícius de Almeida Silva
,
Markus Fröb
2
Jul 1
spinor-tensor
Dear Hudson, yes, that's possible. Just add the corresponding indices when you define the spinor,
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spinor-tensor
Dear Hudson, yes, that's possible. Just add the corresponding indices when you define the spinor,
Jul 1
Ali Seraj
,
Jose
2
Jun 30
Chaning the primary metric of a manifold
Hi, This is a tricky operation. Once indices have been moved up and down with one metric, changing
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Chaning the primary metric of a manifold
Hi, This is a tricky operation. Once indices have been moved up and down with one metric, changing
Jun 30
Lucas Fernandez Sarmiento
,
Jose
2
Jun 30
Multiplying tensors with same dummies
Hi, The functions IndexSet and IndexSetDelayed help with this. For example with << xAct`xTensor
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Multiplying tensors with same dummies
Hi, The functions IndexSet and IndexSetDelayed help with this. For example with << xAct`xTensor
Jun 30
Sebastian Bahamonde
,
Jose
2
Jun 30
Computation is zero in one way but non zero in the other
Hi, You are working with partial derivatives of the metric, for which some operations of raising and
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Computation is zero in one way but non zero in the other
Hi, You are working with partial derivatives of the metric, for which some operations of raising and
Jun 30
Pawan Kumar Gupta
,
Jose
2
Jun 30
XPert+XCoba
Hi, No, I'm not aware of any recent progress on this front. Cheers, Jose. On Monday, June 17,
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XPert+XCoba
Hi, No, I'm not aware of any recent progress on this front. Cheers, Jose. On Monday, June 17,
Jun 30
Jack Smithe
,
Jose
2
Jun 30
Numerical SolveTensors?
Hi, No, there is no automatic support in xAct for solving PDEs numerically. The general case of this
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Numerical SolveTensors?
Hi, No, there is no automatic support in xAct for solving PDEs numerically. The general case of this
Jun 30
Geová Maciel de Alencar Filho
Jun 27
Expanding tensors in warped spaces
Hi, I am trying to expand tensors in warped spaces. I have taken the example of Leo Stein, but it
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Expanding tensors in warped spaces
Hi, I am trying to expand tensors in warped spaces. I have taken the example of Leo Stein, but it
Jun 27
Ali Seidabadi
, …
Gustavo Gutierrez-Cano
3
Jun 27
Calculatin Gauss Bonnet EOMs for FLRW Metric
Dear Ali, I have a file for a SSS metric in Gauss-Bonnet. I think you can review it and modify it for
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Calculatin Gauss Bonnet EOMs for FLRW Metric
Dear Ali, I have a file for a SSS metric in Gauss-Bonnet. I think you can review it and modify it for
Jun 27
Johannes Pirsch
,
Markus B. Fröb
2
Jun 25
ExpandPerturbation not working properly + some strange index behaviour
Dear Johannes, without a MWE it is difficult to see where the problem lies. What I can say is that
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ExpandPerturbation not working properly + some strange index behaviour
Dear Johannes, without a MWE it is difficult to see where the problem lies. What I can say is that
Jun 25
ehki...@gmail.com
,
Thomas Bäckdahl
2
Jun 24
Dummy and Free Indices
Hi! I think the problem here is that you are using $PrePrint=ScreenDollarIndices; This means that all
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Dummy and Free Indices
Hi! I think the problem here is that you are using $PrePrint=ScreenDollarIndices; This means that all
Jun 24
Nail Khusnutdinov
,
TB
3
Jun 24
TexAct gives wrong output
Thanks a lot, Thomas. It is useful info that I can not find in the documentation of TexAct.
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TexAct gives wrong output
Thanks a lot, Thomas. It is useful info that I can not find in the documentation of TexAct.
Jun 24
Nail Khusnutdinov
, …
Jose
5
Jun 20
epsilong with two identical indexes is not zero
Thanks a lot for the explanation. четверг, 20 июня 2024 г. в 17:26:35 UTC-3, Jose: Hi, Abstract
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epsilong with two identical indexes is not zero
Thanks a lot for the explanation. четверг, 20 июня 2024 г. в 17:26:35 UTC-3, Jose: Hi, Abstract
Jun 20
Daniel Volinski
, …
Sukruti
6
Jun 20
Strange messages on xperm
Hi, Thanks, Thomas! I did not get an error message mentioning ml64i3 anywhere. Since you mentioned
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Strange messages on xperm
Hi, Thanks, Thomas! I did not get an error message mentioning ml64i3 anywhere. Since you mentioned
Jun 20
Jitesh Kumar Singh 20136
Jun 20
3+1 decomposition of terms Involving Covariant derivative
Hi, I am tring to do 3+1 decomposition of the Einstein-Maxwell equations using Xtensor. In the
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3+1 decomposition of terms Involving Covariant derivative
Hi, I am tring to do 3+1 decomposition of the Einstein-Maxwell equations using Xtensor. In the
Jun 20
Jitesh Kumar Singh 20136
Jun 19
Assistance Required for 3+1 decomposition of Einstein Maxwell Equation using Xtensor
Hello Everyone, I hope this message finds you well. I am a new user of Xact, having started just a
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Assistance Required for 3+1 decomposition of Einstein Maxwell Equation using Xtensor
Hello Everyone, I hope this message finds you well. I am a new user of Xact, having started just a
Jun 19
Elias Leite Mendonça
,
Jose
2
May 28
Projection operators for propagators
Hi, First, the usual steps: <<xAct`xTensor` DefManifold[M, 4, {a, b, c, d, e, f}] DefMetric[-1,
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Projection operators for propagators
Hi, First, the usual steps: <<xAct`xTensor` DefManifold[M, 4, {a, b, c, d, e, f}] DefMetric[-1,
May 28
Dr. Subeom
, …
Jose
6
May 27
Inverse of perturbed product metric
Hi, It seems you have found this issue with Symmetry1D again: https://groups.google.com/g/xact/c/
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Inverse of perturbed product metric
Hi, It seems you have found this issue with Symmetry1D again: https://groups.google.com/g/xact/c/
May 27
Андрей Шушарин
,
Jose
2
May 24
A question about the form of the answers
Hi, Once you have performed a computation in a chart, it's generally difficult to re-express it
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A question about the form of the answers
Hi, Once you have performed a computation in a chart, it's generally difficult to re-express it
May 24
Tanush Reddy Vaka
,
Thomas Bäckdahl
2
May 24
How to define a scalar field dependent on R?
Hi! I didn't look into the details of your longer notebook, but I fixed the shorter one. Your
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How to define a scalar field dependent on R?
Hi! I didn't look into the details of your longer notebook, but I fixed the shorter one. Your
May 24
ehki...@gmail.com
,
Jose
3
May 18
Constant tensor
Thank you for your response! Actually, I am dealing with objects that are not tensors. Instead, they
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Constant tensor
Thank you for your response! Actually, I am dealing with objects that are not tensors. Instead, they
May 18