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/no...

which are actually used in the recording above.

Yours, Roland