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xAct Tensor Computer Algebra
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xAct Tensor Computer Algebra
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K Inchov
Sep 29
Substitution of another tensor
Hello everyone! I want to perform calculations for an abstract metric, but in the specific form: g[-a
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Substitution of another tensor
Hello everyone! I want to perform calculations for an abstract metric, but in the specific form: g[-a
Sep 29
Nils Albin Nilsson
,
Thomas Bäckdahl
3
Sep 27
Define tensor symmetries in terms of Young tableaux
Hi Thomas, thanks for the detailed reply. I used TableauSymmetric for my three simplest tensors and
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Define tensor symmetries in terms of Young tableaux
Hi Thomas, thanks for the detailed reply. I used TableauSymmetric for my three simplest tensors and
Sep 27
Martín Pico
Sep 27
How to make rules to properly implement constraints on functions defined on a manifold.
Hi, I am a new xAct user who is finding some troubles with the following: I am working with a
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How to make rules to properly implement constraints on functions defined on a manifold.
Hi, I am a new xAct user who is finding some troubles with the following: I am working with a
Sep 27
Hengameh Bagherian
, …
Markus B. Fröb
5
Sep 26
Spin-connection on xPert and xAct
Dear all, in principle FieldsX should work well for these types of computations, section 4.5 in the
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Spin-connection on xPert and xAct
Dear all, in principle FieldsX should work well for these types of computations, section 4.5 in the
Sep 26
Naser Hawre
,
Jose
3
Sep 26
Tensor contraction
Thank you very much, Jose, that helped a lot. Regards, Hawre On Sun, Sep 3, 2023 at 10:53 PM Jose
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Tensor contraction
Thank you very much, Jose, that helped a lot. Regards, Hawre On Sun, Sep 3, 2023 at 10:53 PM Jose
Sep 26
G.Narasimha Reddy
,
Sergi Sirera-Lahoz
3
Sep 26
Working with components of metric perturbations
Hi Narasimha, Good to hear you found a solution! I have also been working on GWs in theories of
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Working with components of metric perturbations
Hi Narasimha, Good to hear you found a solution! I have also been working on GWs in theories of
Sep 26
Ashiqul Islam Dip
, …
Jose
4
Sep 19
Metric in a non-coordinate basis
Hi Ashiqul, I'd recommend that you look at the example 3.6.11 in the xCobaDoc file. There you see
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Metric in a non-coordinate basis
Hi Ashiqul, I'd recommend that you look at the example 3.6.11 in the xCobaDoc file. There you see
Sep 19
Aniket Khairnar
,
Thomas Bäckdahl
2
Sep 18
Put scalar not working on InertHead
Hi! I traced the problem to IsIndexOf[prime[X[i]], i] gives False. I think Jose should take a look at
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Put scalar not working on InertHead
Hi! I traced the problem to IsIndexOf[prime[X[i]], i] gives False. I think Jose should take a look at
Sep 18
Leo Stein
Sep 14
Re: [xAct] Wedge Product of a p-form with Itself
Hello, An odd form wedged with itself always vanishes; but while an even form *may* vanish when
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Re: [xAct] Wedge Product of a p-form with Itself
Hello, An odd form wedged with itself always vanishes; but while an even form *may* vanish when
Sep 14
G.Narasimha Reddy
Sep 11
How to represent Maxwell's Lagrangian in 1+3 formalism using xTensor??
Hi all, I am trying to represent Maxwell's Lagrangian in terms of gauge fields. I know how to
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How to represent Maxwell's Lagrangian in 1+3 formalism using xTensor??
Hi all, I am trying to represent Maxwell's Lagrangian in terms of gauge fields. I know how to
Sep 11
Bradji Okba
,
Jose
3
Sep 11
How to Define 3 rank tensor with CTensor
Thanks. On Sunday, September 3, 2023 at 2:28:27 PM UTC-7 Jose wrote: Hi, CTensor does not have any
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How to Define 3 rank tensor with CTensor
Thanks. On Sunday, September 3, 2023 at 2:28:27 PM UTC-7 Jose wrote: Hi, CTensor does not have any
Sep 11
William Barker
Sep 6
Pre-release of PSALTer (Particle Spectrum for Any Tensor Lagrangian)
Hi, A new package for xAct has been under development for some months and, following a talk at Tartu
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Pre-release of PSALTer (Particle Spectrum for Any Tensor Lagrangian)
Hi, A new package for xAct has been under development for some months and, following a talk at Tartu
Sep 6
Bradji Okba
,
Jose
2
Sep 3
How to define new tensor expression and uste its components
Hi, I attach a new version of your notebook with some suggested operations. I think the key operation
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How to define new tensor expression and uste its components
Hi, I attach a new version of your notebook with some suggested operations. I think the key operation
Sep 3
PUSHPARAJ CHAKRAVARTI
,
Jose
2
Sep 3
How to change the defined signature of a metric in Mathematica(xCoba)
Hi, I don't understand what you mean. Can you provide an example of a CTensor metric with actual
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How to change the defined signature of a metric in Mathematica(xCoba)
Hi, I don't understand what you mean. Can you provide an example of a CTensor metric with actual
Sep 3
G.Narasimha Reddy
,
Markus B. Fröb
2
Sep 1
Working with spacetime and lie group indices
Dear Narasimha, please find attached the changed notebook. What you were missing is: - if you work in
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Working with spacetime and lie group indices
Dear Narasimha, please find attached the changed notebook. What you were missing is: - if you work in
Sep 1
Ethan L
,
magma
3
Aug 31
Defining second order operators/expanding out Lie brackets
Excellent, thanks so much! One more thing: what would be the canonical way to expand out/simplify
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Defining second order operators/expanding out Lie brackets
Excellent, thanks so much! One more thing: what would be the canonical way to expand out/simplify
Aug 31
Ashim
,
Jose
3
Aug 11
Setting specific terms to 0 in perturbation expressions
Hi Jose, Thanks a lot for your reply. Embarrassingly, I don't appear to understand how to use
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Setting specific terms to 0 in perturbation expressions
Hi Jose, Thanks a lot for your reply. Embarrassingly, I don't appear to understand how to use
Aug 11
Debojyoti Mondal
Aug 11
Komar conserved quantity
Hi, can anyone tell me how can I calculate komar conserved quantities for kerr newman black hole?
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Komar conserved quantity
Hi, can anyone tell me how can I calculate komar conserved quantities for kerr newman black hole?
Aug 11
Shubham Kumar Sinha
,
Thomas Bäckdahl
2
Aug 4
constructing tensors with specific symmetries
Hi! You just need to specify a generating set for your symmetries. The cyclic symmetry is generated
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constructing tensors with specific symmetries
Hi! You just need to specify a generating set for your symmetries. The cyclic symmetry is generated
Aug 4
Brian Seymour
,
Jose
2
Aug 2
xPert with two perturbation parameters
Hi, xPert has no support for multiple perturbations. You can define different perturbations of the
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xPert with two perturbation parameters
Hi, xPert has no support for multiple perturbations. You can define different perturbations of the
Aug 2
Cristian Erices
,
Jose
2
Aug 2
Factorice by a tensor with dummy indexes
Hi, Try using IndexCollect: << xAct`xTensor` DefManifold[M, 4, {a, b, c, d, e, f}] DefTensor[{
unread,
Factorice by a tensor with dummy indexes
Hi, Try using IndexCollect: << xAct`xTensor` DefManifold[M, 4, {a, b, c, d, e, f}] DefTensor[{
Aug 2
Bulkilol
,
Jose
3
Jul 19
coordinate depending on another manifold
Hi, Sorry to necro, but I had to shelf that project, and just got to some time to work on it again
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coordinate depending on another manifold
Hi, Sorry to necro, but I had to shelf that project, and just got to some time to work on it again
Jul 19
Charles R. Hurley, KD2IHY
,
magma
2
Jul 14
xAct/xPrint: its link to homepage is broken. Why?
Hi Charles, Google Pages service which hosted xPrint website has been terminated by Google in mid
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xAct/xPrint: its link to homepage is broken. Why?
Hi Charles, Google Pages service which hosted xPrint website has been terminated by Google in mid
Jul 14
Nitol Attar
,
Jose
2
Jul 12
MakeRule use?
Hi, Please, please, always send full codes. It's impossible to know what you did before and that
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MakeRule use?
Hi, Please, please, always send full codes. It's impossible to know what you did before and that
Jul 12
Amelie Mierau
,
Jose
2
Jul 12
Problems with installing xAct (Windows 11, Mathematica 11.0)
Hi, It's difficult to help without more information. Can you send me (privately if you prefer) a
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Problems with installing xAct (Windows 11, Mathematica 11.0)
Hi, It's difficult to help without more information. Can you send me (privately if you prefer) a
Jul 12
David Kofroň
, …
Jose
4
Jul 12
posftix notation for valence 0 tensors
Hi, Yes, I'll fix this. Thanks all for the reports and suggested fix. Cheers, Jose. On Saturday,
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posftix notation for valence 0 tensors
Hi, Yes, I'll fix this. Thanks all for the reports and suggested fix. Cheers, Jose. On Saturday,
Jul 12
Jie Jiang
,
Jose
2
Jul 12
expand metric perturbation in parallel derivative
Hi, The computation you performed, and that was attached in your notebook, is the perturbation of the
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expand metric perturbation in parallel derivative
Hi, The computation you performed, and that was attached in your notebook, is the perturbation of the
Jul 12
Roxane Theriault
,
magma
2
Jul 1
Finding the equations of motion in a given coordinate chart
You can look at "Variation of Lagrangian with xPert and VarD" notebook in the xAct examples
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Finding the equations of motion in a given coordinate chart
You can look at "Variation of Lagrangian with xPert and VarD" notebook in the xAct examples
Jul 1
Thomas M
, …
Jie Jiang
4
Jun 24
xAct on Apple M2
Thanks for pointing out this. My M1 MacBook Air do not install rosetta and I meet the same problem.
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xAct on Apple M2
Thanks for pointing out this. My M1 MacBook Air do not install rosetta and I meet the same problem.
Jun 24
Nathan Agmon
, …
Jie Jiang
8
Jun 24
xAct broken on 12.3.1?
Hello, I download the xAct_1.2.0.tgz and run xattr -c xAct_1.2.0.tgz to clear all attributes, and
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xAct broken on 12.3.1?
Hello, I download the xAct_1.2.0.tgz and run xattr -c xAct_1.2.0.tgz to clear all attributes, and
Jun 24
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