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Hello! One of the simplest (if not the simplest) examples of classical field theory is the complex scalar Klein-Gordon field, the relativistic version of the classical Schrodinger field. Now, Cadabra seems great for General Relativity, the DIrac field, the elecgtromagnetic field... but I see no clear treatment of complex scalars. It would be amazing if the tutorial would include a simple example with the Klein-Gordon field (i.e. how to find the Klein-Gordon equation given the action). This is done in the tutorial for the free classical Maxwell field, having another example would be great.

in Feature requests by (150 points)

Hi Mark.

I agree with you. Do you have a specific problem in mind? Have you tried to prepare a tutorial yourself?

If you have a specific idea I could help you to develop it (as long as it fits my capabilities).

Regards, Dox.

Dear @doxdrum, thank you for your reply. I was thinking about somethign like this:


(this is the first tutorial on the official website: finding the equations of motion for the Faraday field $F_{\mu \nu}$ by varying the action).

How about adding a complementary turorial where one derived the equations of motion for the complex scalar Klein-Gordon field? In this way, one can learn how to deal with complex fields and (at the same time) scalars: in fact, I see quite good references for vectors (i.e. $A^\mu$), spinors and, of course, the metric and higher rank tensors (since Cadabra seems to be very General Relativity oriented).

To be specific, it would be amazing to have a tutorial on these lines:


Since the compelx Klein-Gordon has a conserved U(1) charge, this tutorial would be extremely useful, a fort of first step for everyone interested in checking the conserved quantities of an action with the Noether theorem. Thank you again!

Hi Mark.

We could try to write a notebook ourselves. If you're interested, send me an email d o x d r u m (at) p m . m e to schedule a meeting.

Cheers, Dox.

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