Groups
Sign in
Groups
xAct Tensor Computer Algebra
Conversations
About
Send feedback
Help
xAct Tensor Computer Algebra
Contact owners and managers
1–30 of 1317
Mark all as read
Report group
0 selected
Sukruti
,
Thomas Bäckdahl
5
Oct 26
FullSimplification not working inside MakeRule
Hi! The reason this worked for some cases, and not others is that SortCovDsStart[CD] sorts the
unread,
FullSimplification not working inside MakeRule
Hi! The reason this worked for some cases, and not others is that SortCovDsStart[CD] sorts the
Oct 26
Sukruti
,
Leo Stein
3
Oct 23
Pushing boxes to the right
Dear Leo, Thank you for your reply. I tried the command SortCovDsToBox /@ unsorted and it did not
unread,
Pushing boxes to the right
Dear Leo, Thank you for your reply. I tried the command SortCovDsToBox /@ unsorted and it did not
Oct 23
PUSHPARAJ CHAKRAVARTI
, …
Christian Pfeifer
6
Oct 23
xTensor compatiblity for Metric contraction
Hi together, I am currently setting up an xAct notebook to work with tetrads, and stumbled over a
unread,
xTensor compatiblity for Metric contraction
Hi together, I am currently setting up an xAct notebook to work with tetrads, and stumbled over a
Oct 23
John Session
Oct 20
Metric of a shell
Hi everyone, I have a question about submanifold. I have a surface in R^3 with the curvilinear
unread,
Metric of a shell
Hi everyone, I have a question about submanifold. I have a surface in R^3 with the curvilinear
Oct 20
Pushparaj Chakravarti
Oct 19
Incompatiblity of scalar functions in xPPN
Hey, I have been trying to work with xPPN package. Where I have got to face major problem. I hope you
unread,
Incompatiblity of scalar functions in xPPN
Hey, I have been trying to work with xPPN package. Where I have got to face major problem. I hope you
Oct 19
蒲实
,
Thomas Bäckdahl
2
Oct 18
Compatibility Issues When Introducing xTensor with xCoba
Hi! Can you please provide a small non-working notebook that shows the problem? If you are mixing
unread,
Compatibility Issues When Introducing xTensor with xCoba
Hi! Can you please provide a small non-working notebook that shows the problem? If you are mixing
Oct 18
Sukruti
,
Thomas Bäckdahl
3
Oct 8
Applying FullSimplification[] to a list
Hi, I see, thanks! Now whenever I use FullSimplification[], I apply ScreenDollarIndices right after
unread,
Applying FullSimplification[] to a list
Hi, I see, thanks! Now whenever I use FullSimplification[], I apply ScreenDollarIndices right after
Oct 8
Sukruti
,
Thomas Bäckdahl
5
Oct 8
Removing integer powers of a scalar
Hi, Thanks a lot for giving those two ways to achieve the goal! They both work fine. I too wondered
unread,
Removing integer powers of a scalar
Hi, Thanks a lot for giving those two ways to achieve the goal! They both work fine. I too wondered
Oct 8
Sukruti
,
Jose
3
Oct 7
Splitting Sums Inside a List
Hi, Thank you very much! Cheers Sukruti On Monday 23 September, 2024 at 4:52:23 am UTC+2 Jose wrote:
unread,
Splitting Sums Inside a List
Hi, Thank you very much! Cheers Sukruti On Monday 23 September, 2024 at 4:52:23 am UTC+2 Jose wrote:
Oct 7
clement Loup-forest
,
Thomas Bäckdahl
3
Oct 4
Tetrad Specification using xCoba
Hi! Higher order NP derivatives should work without extra care. If you use //. NPDerivativeRules
unread,
Tetrad Specification using xCoba
Hi! Higher order NP derivatives should work without extra care. If you use //. NPDerivativeRules
Oct 4
Di Zhang
Sep 28
Metric of a shell
Hi everyone, I have a question about submanifold. I have a surface in R^3 with the curvilinear
unread,
Metric of a shell
Hi everyone, I have a question about submanifold. I have a surface in R^3 with the curvilinear
Sep 28
M
,
Cyril Pitrou
3
Sep 28
Christoffel problems
Thank you very much for clarifying this Cyril! On Saturday, September 28, 2024 at 4:13:06 AM UTC-4
unread,
Christoffel problems
Thank you very much for clarifying this Cyril! On Saturday, September 28, 2024 at 4:13:06 AM UTC-4
Sep 28
Quim Llorens Giralt
, …
Geová Maciel de Alencar Filho
6
Sep 26
Evaluating xTensor expressions for a given metric using xCoba
Hi, can the same be done with a tensor? I have an abstract tensor, and now I wanna it in some
unread,
Evaluating xTensor expressions for a given metric using xCoba
Hi, can the same be done with a tensor? I have an abstract tensor, and now I wanna it in some
Sep 26
Geová Maciel de Alencar Filho
Sep 26
Varl for tensor fields
Hi, I am using the lagrangian of a symmetric tensor. I can find the correct equations of motion;
unread,
Varl for tensor fields
Hi, I am using the lagrangian of a symmetric tensor. I can find the correct equations of motion;
Sep 26
Pushparaj Chakravarti
,
Asghar Muhammad
2
Sep 19
VarL works differently for different actions
I will attach note book of EqM of F(r) in standard text book form On Thu, 19 Sept 2024, 11:50
unread,
VarL works differently for different actions
I will attach note book of EqM of F(r) in standard text book form On Thu, 19 Sept 2024, 11:50
Sep 19
Sukruti
,
Thomas Bäckdahl
3
Sep 16
Generalising rule to make it act on arbitrary scalar
Great, thanks! Cheers Sukruti On Sunday 15 September, 2024 at 6:56:22 pm UTC+2 Thomas Bäckdahl wrote:
unread,
Generalising rule to make it act on arbitrary scalar
Great, thanks! Cheers Sukruti On Sunday 15 September, 2024 at 6:56:22 pm UTC+2 Thomas Bäckdahl wrote:
Sep 16
Sukruti
,
Thomas Bäckdahl
3
Sep 15
Extracting explicit higher derivative terms from a list
Hi, This does the job. Thanks! Cheers Sukruti On Sunday 15 September, 2024 at 5:16:57 pm UTC+2 Thomas
unread,
Extracting explicit higher derivative terms from a list
Hi, This does the job. Thanks! Cheers Sukruti On Sunday 15 September, 2024 at 5:16:57 pm UTC+2 Thomas
Sep 15
Sukruti
,
Jose
3
Sep 15
AllContractions not working
Hello, I have deleted my last few emails in this thread because I was a bit too quick in posting them
unread,
AllContractions not working
Hello, I have deleted my last few emails in this thread because I was a bit too quick in posting them
Sep 15
Ayon Tarafdar (Joy)
,
Thomas Bäckdahl
4
Sep 13
Ignore tensors while canonicalizing
Hi! Could you send a small example notebook so we can see exactly what is going wrong? Regards Thomas
unread,
Ignore tensors while canonicalizing
Hi! Could you send a small example notebook so we can see exactly what is going wrong? Regards Thomas
Sep 13
Elias Leite Mendonça
,
Markus B. Fröb
2
Sep 11
gauge invariance on curved space
Dear Elias, since you were working with an Einstein space, you also must replace the Ricci tensor in
unread,
gauge invariance on curved space
Dear Elias, since you were working with an Einstein space, you also must replace the Ricci tensor in
Sep 11
Pavan Dharanipragada
,
Thomas Bäckdahl
3
Sep 11
Cancelling equal terms
Thank you Thomas! ToCanonical worked for me. Regards, Pavan On Tuesday 10 September 2024 at 17:47:39
unread,
Cancelling equal terms
Thank you Thomas! ToCanonical worked for me. Regards, Pavan On Tuesday 10 September 2024 at 17:47:39
Sep 11
Filomela Gerou
,
Juan Margalef
4
Sep 11
[xAct] Equations of Motion from Metric using VarD
Hi Filomela, I think you would benefit a lot from reading the documentation and the examples of the
unread,
[xAct] Equations of Motion from Metric using VarD
Hi Filomela, I think you would benefit a lot from reading the documentation and the examples of the
Sep 11
Sukruti
,
Jose
3
Sep 10
Defining rule with certain conditions on indices
Dear Jose, This works well. Thanks a lot! Cheers Sukruti On Sunday 8 September, 2024 at 4:35:18 am
unread,
Defining rule with certain conditions on indices
Dear Jose, This works well. Thanks a lot! Cheers Sukruti On Sunday 8 September, 2024 at 4:35:18 am
Sep 10
Sukruti
,
Jose
3
Sep 10
Replacement rule problem
Dear Jose, Thanks for explaining why the ReplaceAll command was not giving the desired output earlier
unread,
Replacement rule problem
Dear Jose, Thanks for explaining why the ReplaceAll command was not giving the desired output earlier
Sep 10
Sam Finn
, …
Leo Stein
5
Sep 9
Q: meaning \[EmptyUpTriangle]^-1?
Hi Jose & Leo - My apologies for an MWE that wasn't. I've attached an amended MWE, which
unread,
Q: meaning \[EmptyUpTriangle]^-1?
Hi Jose & Leo - My apologies for an MWE that wasn't. I've attached an amended MWE, which
Sep 9
S Josh
Sep 8
code??
sir how to type a code on XAct tensor ,Variation of mass with respect to the radius of compact stars
unread,
code??
sir how to type a code on XAct tensor ,Variation of mass with respect to the radius of compact stars
Sep 8
Juan Margalef
, …
Thomas Bäckdahl
3
Sep 8
$PrePrint = ScreenDollarIndices causes error in ?LieD
Hi! I agree that the interaction between ScreenDollarIndices and InformationData is too fragile. This
unread,
$PrePrint = ScreenDollarIndices causes error in ?LieD
Hi! I agree that the interaction between ScreenDollarIndices and InformationData is too fragile. This
Sep 8
Sam Finn
,
Jose
2
Sep 7
xPert Q: Lie Derivative of (covariant derivative) of -1 perturbation?
Hi again, As I said in the previous thread, we do not support negative perturbation orders in xPert.
unread,
xPert Q: Lie Derivative of (covariant derivative) of -1 perturbation?
Hi again, As I said in the previous thread, we do not support negative perturbation orders in xPert.
Sep 7
Jose
,
Leo Stein
3
Sep 7
The xAct web is down
Hi, The xAct web is back online. If there is any problem, please let me know. Cheers, Jose. On
unread,
The xAct web is down
Hi, The xAct web is back online. If there is any problem, please let me know. Cheers, Jose. On
Sep 7
Sashwat Tanay
,
Jose
2
Sep 7
Raise/lower indices with xPert
Hi, xAct assumes by default that the metric is not flat. There is an option of DefCovD and DefMetric
unread,
Raise/lower indices with xPert
Hi, xAct assumes by default that the metric is not flat. There is an option of DefCovD and DefMetric
Sep 7