Sagemanifolds error in example notebook

[Dominic Steinitz]

I am in the examples folder trying to run 

• Electromagnetism in Minkowski spacetime [ipynb] (Electromagnetic field 2-form from E and B, Maxwell equations, conserved current, Lorentz force, Poynting vector)

but I get the error

AttributeError: 'DiffFormFreeModule_with_category.element_class' object has no attribute 'exterior_der'
Here's a MWE
M = Manifold(4, 'M', latex_name=r'\mathcal{M}', structure='Lorentzian') BL.<t,x,y,z> = M.chart(r"t x y z")
var('E_x E_y E_z')
dt, dx, dy, dz = BL.coframe()[:]
E = E_x * dx + E_y * dy + E_z * dzE.set_name('E')
(E.wedge(BL.coframe()[0])).exterior_der()

[Vincent Delecroix]

The error you get indicates that "exterior_der" is not a valid
operation. Maybe you want "exterior_derivative()"?

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[Dominic Steinitz]

Great thanks very much - I copied from the example - I guess I should have checked the manual - I wonder if there is some way of making sure the examples are always up to date.

[Eric Gourgoulhon]

Hi,

Le mercredi 7 février 2024 à 15:46:05 UTC+1, Dominic Steinitz a écrit :

Great thanks very much - I copied from the example - I guess I should have checked the manual - I wonder if there is some way of making sure the examples are always up to date.

Indeed, this notebook is 8 years old and is not at all up to date (there is even Python 2 print commands in it!).

Please open an issue at the Github repository hosting this notebook:

https://github.com/ernestyalumni/Gravite/blob/master/EMsage.ipynb

in order for the author to update it.  

I don't know about any automated way to check that the example notebooks are up to date. I am trying to maintain those hosted at

https://github.com/sagemanifolds/SageManifolds

up to date, but the one you are using is not part of them. 

 

By the way, note that since Sage 9.2 an alternative to 

F.exterior_derivative()

is 

diff(F)

Best wishes,

Eric.

[Eric Gourgoulhon]

Le mercredi 7 février 2024 à 16:00:07 UTC+1, Eric Gourgoulhon a écrit :

Indeed, this notebook is 8 years old and is not at all up to date (there is even Python 2 print commands in it!).

Please open an issue at the Github repository hosting this notebook:

https://github.com/ernestyalumni/Gravite/blob/master/EMsage.ipynb

in order for the author to update it.  

In order to avoid any further confusion, I've temporarily removed the link to this notebook from 

https://sagemanifolds.obspm.fr/examples.html

Any volunteer for providing a nice example notebook about electromagnetism is welcome!

To publish it on the above page, make it publicly accessible (i.e.  readable via nbviewer.org) and send a pull request to 

https://github.com/sagemanifolds/WebSite

(or simply send the ipynb file to me)

Eric.

[Matthias Koeppe]

On Wednesday, February 7, 2024 at 7:00:07 AM UTC-8 Eric Gourgoulhon wrote:

I don't know about any automated way to check that the example notebooks are up to date.

One can use "jupyter nbconvert --to notebook --execute" for this

https://nbconvert.readthedocs.io/en/latest/execute_api.html

 

[Dominic Steinitz]

I volunteer

[Eric Gourgoulhon]

Thank you for the tip!

Best wishes,

Eric. 

[Eric Gourgoulhon]

Le jeudi 8 février 2024 à 13:46:19 UTC+1, Dominic Steinitz a écrit :

I volunteer

Excellent!  Thank you!

Best wishes,

Eric.