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xAct Tensor Computer Algebra
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xAct Tensor Computer Algebra
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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
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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
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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
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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
Claire
,
Jose
4
Mar 29
Plugging in an ansatz for a metric perturbation
Hi, Question 1.: I guess you mean computations of the form ctensor[{...}, {...}]. In principle this
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Plugging in an ansatz for a metric perturbation
Hi, Question 1.: I guess you mean computations of the form ctensor[{...}, {...}]. In principle this
Mar 29
Sashwat Tanay
,
Jose
2
Mar 26
I get "Validate: Found indices with the same name" error, and it goes away with ToCanonical
Hi, Sending an image is not enough. We can only be sure about the origin of a problem if we have full
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I get "Validate: Found indices with the same name" error, and it goes away with ToCanonical
Hi, Sending an image is not enough. We can only be sure about the origin of a problem if we have full
Mar 26
Nitol Attar
,
Jose
2
Mar 26
function definition validate error
Hi, It is impossible to debug a question like this without having full code. Please, always send full
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function definition validate error
Hi, It is impossible to debug a question like this without having full code. Please, always send full
Mar 26
C. Arias
,
Jose
2
Mar 25
Working with components
Hi, Your notebook is good up to the point where you define the vector field A. First, you don't
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Working with components
Hi, Your notebook is good up to the point where you define the vector field A. First, you don't
Mar 25
Sashwat Tanay
,
Jose
2
Mar 23
Minor bug in xCoba
Hi, No, this is not a bug. ToCanonical can move indices and produce equivalent expressions. In both
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Minor bug in xCoba
Hi, No, this is not a bug. ToCanonical can move indices and produce equivalent expressions. In both
Mar 23
Sashwat Tanay
,
Jose
5
Mar 23
Covariant derivative with tetrads
Hi again, I forgot to mention that xCoba has a command RicciRotation[cd, B] that returns precisely
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Covariant derivative with tetrads
Hi again, I forgot to mention that xCoba has a command RicciRotation[cd, B] that returns precisely
Mar 23
Jose
Mar 21
Reminder: event tomorrow with six talks about xAct
Hi all, Let me remind you of this online event tomorrow Friday (morning in the US, afternoon in
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Reminder: event tomorrow with six talks about xAct
Hi all, Let me remind you of this online event tomorrow Friday (morning in the US, afternoon in
Mar 21
Bhaskar Shukla
Mar 20
Simplifying the gauge field equation
I am trying to vary the Born-Infeld action. I get accurate results for the Einstein field and the
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Simplifying the gauge field equation
I am trying to vary the Born-Infeld action. I get accurate results for the Einstein field and the
Mar 20
Bhaskar Shukla
, …
Armando Roque
5
Mar 18
Varying Einstein-Hilbert action through xAct
Dear Armando, Thanks a lot for rectifying my mistake and providing an additional illustrative
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Varying Einstein-Hilbert action through xAct
Dear Armando, Thanks a lot for rectifying my mistake and providing an additional illustrative
Mar 18
Omar Z
,
Thomas Bäckdahl
3
Mar 18
Print an Inert Head with additional labels
Thank you very much, your help is very appreciated. Omar On Monday, March 18, 2024 at 12:52:38 PM UTC
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Print an Inert Head with additional labels
Thank you very much, your help is very appreciated. Omar On Monday, March 18, 2024 at 12:52:38 PM UTC
Mar 18
Claire
,
Jose
2
Mar 18
Equations of motion for a given chart
Hi, Your notebook is quite large and I haven't looked at all computations. I evaluated it and see
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Equations of motion for a given chart
Hi, Your notebook is quite large and I haven't looked at all computations. I evaluated it and see
Mar 18
Joaquín Itu
,
Jose
2
Mar 18
Memory usage ramps up until crash
Hi, Your expressions are very large, and I doubt they can be simplified. I reattach your notebook
unread,
Memory usage ramps up until crash
Hi, Your expressions are very large, and I doubt they can be simplified. I reattach your notebook
Mar 18
Biel Cardona Rotger
,
Jose
2
Mar 18
Proper way to deal with flat indices
Hi, A first important comment is that xTensor never contracts metrics automatically. If we have a
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Proper way to deal with flat indices
Hi, A first important comment is that xTensor never contracts metrics automatically. If we have a
Mar 18
alej...@gmail.com
,
Jose
2
Mar 18
Charts with common coordinates
Hi, When a chart is defined, an upvalue like this is attached to each scalar field of the chart,
unread,
Charts with common coordinates
Hi, When a chart is defined, an upvalue like this is attached to each scalar field of the chart,
Mar 18
Jose
2
Mar 14
xAct is 20 years old today!
Hi again! The event celebrating the 20 years of xAct will be next week, Friday March 22nd at 10am,
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xAct is 20 years old today!
Hi again! The event celebrating the 20 years of xAct will be next week, Friday March 22nd at 10am,
Mar 14
Prosenjit Paul
,
TB
3
Mar 12
xTensor
Thank You. On Tuesday 12 March 2024 at 13:14:19 UTC+5:30 TB wrote: Hi! You have probably set up
unread,
xTensor
Thank You. On Tuesday 12 March 2024 at 13:14:19 UTC+5:30 TB wrote: Hi! You have probably set up
Mar 12
Debojyoti Mondal
,
Jose
3
Mar 1
Black hole in f(Q,T) gravity
Thank you for the reply and the edits you made. Ptensor, Qtensor and SE are P[-a,-b,-c], Q[-a,-b,-c]
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Black hole in f(Q,T) gravity
Thank you for the reply and the edits you made. Ptensor, Qtensor and SE are P[-a,-b,-c], Q[-a,-b,-c]
Mar 1
John Conrad
,
Jose
2
Feb 28
Specifying components of metric tensor then getting inverse
Hi, There is currently no automated way in xAct to compute the inverse of an object like this. For
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Specifying components of metric tensor then getting inverse
Hi, There is currently no automated way in xAct to compute the inverse of an object like this. For
Feb 28
PUSHPARAJ CHAKRAVARTI
,
Jose
2
Feb 28
Can't find the Invar database.
Hi, First, note that you need <<xAct`Invar` but you use <<xAct`Invar' The final quote
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Can't find the Invar database.
Hi, First, note that you need <<xAct`Invar` but you use <<xAct`Invar' The final quote
Feb 28
PUSHPARAJ CHAKRAVARTI
, …
Thomas Bäckdahl
5
Feb 28
xTensor compatiblity for Metric contraction
Hi! If something gives errors please provide a small example notebook where this is visible. Without
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xTensor compatiblity for Metric contraction
Hi! If something gives errors please provide a small example notebook where this is visible. Without
Feb 28
William Emond
,
Jose
2
Feb 24
How do I avoid repeated dummy indices in recursive sum
Hi, Note that you have something like g[k, l] (J[-m, -k] // ReplaceDummies) The function
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How do I avoid repeated dummy indices in recursive sum
Hi, Note that you have something like g[k, l] (J[-m, -k] // ReplaceDummies) The function
Feb 24
Nitol Attar
Feb 20
xPert for metric parametrization
Hi all, Is it possible to use xPert for a Kaluza-Klein decomposition of the metric g[mu,nu]? Any
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xPert for metric parametrization
Hi all, Is it possible to use xPert for a Kaluza-Klein decomposition of the metric g[mu,nu]? Any
Feb 20
Kivanc İbrahim Ünlütürk
,
Jose
2
Feb 19
Covariant derivatives computed as partial derivatives when computed in a coordinate chart
Hi, This is a common confusion, due to the way the CD derivatives and the basis components are
unread,
Covariant derivatives computed as partial derivatives when computed in a coordinate chart
Hi, This is a common confusion, due to the way the CD derivatives and the basis components are
Feb 19
Debojyoti Mondal
Feb 16
f(Q,T) gravity
Hi, I am trying to define weyl cartan connection and non metricity tensor and trace of stress energy
unread,
f(Q,T) gravity
Hi, I am trying to define weyl cartan connection and non metricity tensor and trace of stress energy
Feb 16
Joel Feske
,
Jose
2
Feb 7
Helmholtz decomposition
Hi, No, there is no special support for this type of computation in xAct. I'd recommend to have a
unread,
Helmholtz decomposition
Hi, No, there is no special support for this type of computation in xAct. I'd recommend to have a
Feb 7
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