[Users] My problems with Thorn

[Roland Haas]

Hello Abderrahim El Khou,

You do not really have to run the tutorial notebooks through jupyter,
you can just use jupyter as a viewer for the information and follow
along using the video recording.

If you do not have Jupyter installed then github's online viewer also
works. e.g.:

https://github.com/EinsteinToolkit/jupyter-et/blob/master/tutorial-server/notebooks/CreatingANewThorn-HeatEqn.ipynb

you can see the content that goes into the individual files in the
cells that start with %writefile and the remainder of that cell is the
content written to the file.

SimpleWave.m is an example on how to use Kranc to generate a thorn. If
you intent to use Kranc then it is a good first example to start with.

Many more complex thorns are generated using Kranc eg the WeylScal4
thorn, the mclachlan thorns and the EinsteinExact thorns.

If you would rather write a thorn using C/C++ or Fortran then Yosef's
lecture on how to create a heat equation / wave equation may be your
best starting point.

Or you can use one of the very old examples of how to implement a wave
equation, like the attached one. There's not video recording of it
though.

Yours,
Roland

> [CAUTION: Non-UBC Email]
> 
> I found one problem here, i don't work with Juypter so the language is
> confusing me a little bit so i start following the example that you give me
> at the first "the SimpleWave.m" my question here is it necessarily to take
> the same process for any create of other thorns or the is just for the
> simple wave, if no what is the solution please.
> Thank you a lot sir.
> 
> On Tue, Jan 27, 2026 at 8:36 PM Roland Haas <rhaas at mail.ubc.ca> wrote:
> 
> > Hello Abderrahim El Khou,
> >  
> > > if it possible i want a tutorial how to write my own thorn if it is
> > > thank you a lot  
> >
> > Kranc has an example (the SimpleWave.m one) in:
> >
> > http://kranccode.org/documentation.html
> >
> > though note that it uses the `Bin/kranc` wrapper so that all required
> > Mathematica packages are being found.
> >
> > There are a number of recorded tutorials on how to write a new thorn
> > that you can find in:
> >
> > https://www.youtube.com/playlist?list=PLRxi-yB7cTGc6_RtPA8g3qm2XOGfmvkoH
> >
> > for example:
> >
> > https://youtu.be/PcuPhODh34o?si=tAaM54bRT584N7Qo
> >
> > There's also the CreatingANewThorn-*.ipyb notebooks in:
> >
> >
> > https://github.com/EinsteinToolkit/jupyter-et/tree/master/tutorial-server/notebooks
> >
> > which are actually used in the recording above.
> >
> > Yours,
> > Roland
> >
> > --
> > My email is as private as my paper mail. I therefore support encrypting
> > and signing email messages. Get my PGP key from http://pgp.mit.edu .
> >  


Yours,
Roland

-- 
My email is as private as my paper mail. I therefore support encrypting
and signing email messages. Get my PGP key from http://pgp.mit.edu .
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