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xAct Tensor Computer Algebra
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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
Sebastian Bahamonde
Jun 18
Computation is zero in one way but non zero in the other
I am having a weird problem that I have been stuck for some hours: 1) I computed an expression given
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Computation is zero in one way but non zero in the other
I am having a weird problem that I have been stuck for some hours: 1) I computed an expression given
Jun 18
Ron Riegert
Jun 17
Contra- vs. Covariant Definition of Tensors?
(This question pertains to xAct v1.4.1 running under Mathematica 12.2.) As an exercise, I decided to
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Contra- vs. Covariant Definition of Tensors?
(This question pertains to xAct v1.4.1 running under Mathematica 12.2.) As an exercise, I decided to
Jun 17
Pawan Kumar Gupta
Jun 17
XPert+XCoba
Hi, Is the combination of XPert with XCoba available now? Best, pawan
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XPert+XCoba
Hi, Is the combination of XPert with XCoba available now? Best, pawan
Jun 17
Jack Smithe
Jun 10
Numerical SolveTensors?
Does anyone know if there is a numerical equivalent of the SolveTensors function in xAct? I have a
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Numerical SolveTensors?
Does anyone know if there is a numerical equivalent of the SolveTensors function in xAct? I have a
Jun 10
Ali Seidabadi
Jun 8
Calculatin Gauss Bonnet EOMs for FLRW Metric
Hi , im trying to calculate Gauss Bonnet EOMs for FLRW Metric when i vary lagrangian wrt to metric
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Calculatin Gauss Bonnet EOMs for FLRW Metric
Hi , im trying to calculate Gauss Bonnet EOMs for FLRW Metric when i vary lagrangian wrt to metric
Jun 8
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
Soham Acharya
,
Jose
3
May 18
Doubts regarding contraction of covariant derivatives in xCoba
Hi, There are two issues here. First, you are loading the packages in an incorrect way. You have this
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Doubts regarding contraction of covariant derivatives in xCoba
Hi, There are two issues here. First, you are loading the packages in an incorrect way. You have this
May 18
Sashwat Tanay
,
Jose
2
May 18
Weird problem: Simplify returns error; ToCanonical fixes the error
Hi, Thanks for reporting this. There is a confusion with indices during typesetting of the result,
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Weird problem: Simplify returns error; ToCanonical fixes the error
Hi, Thanks for reporting this. There is a confusion with indices during typesetting of the result,
May 18
Thomas M
, …
Alfonso García-Parrado Gómez-Lobo
9
May 18
xAct on Apple M2
Dear xAct users, in the following repo https://github.com/wtbgagoa/xpermLibraryLink you can find
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xAct on Apple M2
Dear xAct users, in the following repo https://github.com/wtbgagoa/xpermLibraryLink you can find
May 18
Elias Leite Mendonça
, …
Markus B. Fröb
4
May 15
General questions
Dear Thomas and Markus, Thank you very much for your kind responses. They were all very enlightening
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General questions
Dear Thomas and Markus, Thank you very much for your kind responses. They were all very enlightening
May 15
dario sauro
,
Jose
3
May 14
Compatible connections on VBundles
Hi, I'm sorry for not having written a piece of code right from the beginning. My problem is
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Compatible connections on VBundles
Hi, I'm sorry for not having written a piece of code right from the beginning. My problem is
May 14
Jose
2
May 10
Reminder: event tomorrow with six talks about xAct
Hi, Many thanks to all who attended the xAct 20 Years Celebration event, and special thanks to the
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Reminder: event tomorrow with six talks about xAct
Hi, Many thanks to all who attended the xAct 20 Years Celebration event, and special thanks to the
May 10
SHIVAM SINGH KUSHWAH
,
Jose
2
May 10
Levi Civita Symbol
Hi, If you define an 11-dimensional manifold M and add a metric G[-a, -b]: << xAct`xTensor`
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Levi Civita Symbol
Hi, If you define an 11-dimensional manifold M and add a metric G[-a, -b]: << xAct`xTensor`
May 10
Ilaria Brivio
,
Jose
2
May 10
Understanding RiemannToChristoffel and ExpandProductMetric for product spaces
Hi, ExpandProductMetric works in a rather restricted scenario. Following your notations it would be
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Understanding RiemannToChristoffel and ExpandProductMetric for product spaces
Hi, ExpandProductMetric works in a rather restricted scenario. Following your notations it would be
May 10
Vaggelis Koutsakis
,
Thomas Bäckdahl
3
May 3
Verifying solutions by replacing function in an ansatz
Hello, Many thanks for the fast and clear response. This is just what I was looking for! Best,
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Verifying solutions by replacing function in an ansatz
Hello, Many thanks for the fast and clear response. This is just what I was looking for! Best,
May 3
M
, …
Jose
5
Apr 22
Problems with Invar database
Thank you, Leo! In case it's not obvious to everyone, Leo's function makes use of the
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Problems with Invar database
Thank you, Leo! In case it's not obvious to everyone, Leo's function makes use of the
Apr 22
Zhibang Yao
,
Zhuhai Li
4
Apr 22
xCoba: Extract components of a CTensor
Dear Zhuhai, Thank you very much for your answer and it does help me a lot! I tried to apply your
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xCoba: Extract components of a CTensor
Dear Zhuhai, Thank you very much for your answer and it does help me a lot! I tried to apply your
Apr 22
Giulia Isabella
,
Armando Roque
4
Apr 3
Kerr-Schild metric
Hi Giulia, the idea is the same, only need to remove the option "MetricOn -> All" from
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Kerr-Schild metric
Hi Giulia, the idea is the same, only need to remove the option "MetricOn -> All" from
Apr 3
Zhibang Yao
,
Jose
3
Apr 3
From the algebraic calculations to the chart calculations
Dear Jose, Thank you so much for the link and this is exactly what I am looking for. It is certainly
unread,
From the algebraic calculations to the chart calculations
Dear Jose, Thank you so much for the link and this is exactly what I am looking for. It is certainly
Apr 3
C. Arias
,
Jose
3
Apr 2
xTerior: Rising/Lowering indices of forms in given coordinates
Hi again, My code is working fine thanks to your previous replies! The final step of my calculation
unread,
xTerior: Rising/Lowering indices of forms in given coordinates
Hi again, My code is working fine thanks to your previous replies! The final step of my calculation
Apr 2
Giuseppe Casale
Mar 29
Defining tensors with different sets of indices
Hi, I am quite new to xAct and xTensor, I hope I can find a solutions to my problems here. I have two
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Defining tensors with different sets of indices
Hi, I am quite new to xAct and xTensor, I hope I can find a solutions to my problems here. I have two
Mar 29
Diksha Jain
Mar 29
Writing expressions in product manifold in terms of base manifolds
Can someone help me with the following query: I have a manifold which is warped product of two base
unread,
Writing expressions in product manifold in terms of base manifolds
Can someone help me with the following query: I have a manifold which is warped product of two base
Mar 29
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