Vector Expression

[Davide Sandona']

A few days ago I opened an issue requesting information about vector expressions [1]. Thanks to covid lock-down I had enough free-time to develop something. In the issue it was suggested that I could open a pull-request, but before doing that I would like to solve a problem I'm having a hard time comprehending. This is the link to the repo I'm working on [2].

The problem is with the class VecAdd; ideally, I would like it to subclass the class Add, so that it would "simplify" the arguments. However, if I do that, the evaluation of n-derivatives would return instances of the class Add!

I checked the output of  _eval_derivative_n_times which is of type VecAdd, however it must be intercepted by some other function and finally it returns an instance of the class Add. I absolutely need it to return an instance of VecAdd.

Can someone help me understand what the problem is and suggest corrective actions?

Thanks!

[1] https://github.com/sympy/sympy/issues/18987

[2] https://github.com/Davide-sd/sympy_vector_expressions

[Aaron Meurer]

Take a look at how the class MatAdd is implemented. Note that is isn't
a trivial problem to solve, and there are still ongoing discussions on
the best way to do it (see for instance
https://github.com/sympy/sympy/pull/18769).

Aaron Meurer

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[Alan Bromborsky]

You might find the following link of interest -

https://github.com/pygae/galgebra